Status of the Plains Hognose Snake(Heterodon nasicus nasicus) in Alberta

Jonathan WrightAndrew Didiuk

Alberta Wildlife Status Report No. 15

October 1998

Published By:

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Publication No. T/414

ISBN: 0-7785-0234-1ISSN: 1206-4912

Series Editor: Isabelle M. RichardsonSenior Editor: David R. C. Prescott

Illustrations: Brian Huffman

For copies of this report, contact:Information Centre - PublicationsAlberta Environmental Protection

Natural Resources ServiceMain Floor, Bramalea Building

9920 - 108 StreetEdmonton, Alberta, Canada T5K 2M4

Telephone: (403) 422-2079

OR

Information ServiceAlberta Environmental Protection

#100, 3115 - 12 Street NECalgary, Alberta, Canada T2E 7J2

Telephone: (403) 297-3362

This publication may be cited as:

Wright, J. 1998. Status of the Plains Hognose Snake (Heterodon nasicus nasicus) in Alberta.Alberta Environmental Protection, Fisheries & Wildlife Management Division, and Alberta

Conservation Association, Wildlife Status Report No. 15, Edmonton, AB. 26 pp.

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PREFACE

Every five years, the Fisheries and Wildlife Management Division of Alberta Natural ResourcesService reviews the status of wildlife species in Alberta. These overviews, which have beenconducted in 1991 and 1996, assign individual species to ‘colour’ lists that reflect the perceivedlevel of risk to populations that occur in the province. Such designations are determined fromextensive consultations with professional and amateur biologists, and from a variety of readilyavailable sources of population data. A primary objective of these reviews is to identify speciesthat may be considered for more detailed status determinations.

The Alberta Wildlife Status Report Series is an extension of the 1996 Status of Alberta Wildlifereview process, and provides comprehensive current summaries of the biological status ofselected wildlife species in Alberta. Priority is given to species that are potentially at risk in theprovince (Red or Blue Listed), that are of uncertain status (Status Undetermined), or which areconsidered to be at risk at a national level by the Committee on the Status of Endangered Wildlifein Canada (COSEWIC).

Reports in this series are published and distributed by the Alberta Conservation Association andthe Fisheries and Wildlife Management Division of Alberta Environmental Protection, and areintended to provide detailed and up-to-date information which will be useful to resourceprofessionals for managing populations of species and their habitats in the province. The reportsare also designed to provide current information which will assist the Alberta Endangered SpeciesConservation Committee to identify species that may be formally designated as endangered orthreatened under the Alberta Wildlife Act. To achieve these goals, the reports have been authoredand/or reviewed by individuals with unique local expertise in the biology and management of eachspecies.

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EXECUTIVE SUMMARY

The Western Hognose Snake is currently on Alberta’s ‘Blue List’ of species that may be risk ofdeclining to non-viable population levels in the province. The Plains Hognose Snake (Heterodonnasicus nasicus) is the subspecies of Western Hognose Snake that occurs in Alberta. This reportreviews information on the Plains Hognose Snake in Alberta, as a step in updating the status ofthe species in the province.

Recent findings suggest that the Plains Hognose Snake is relatively liberal in its choice of habitatswithin the Grassland Natural Region of Alberta. It is found on open plains, rangeland, sandhills,and gravelly glacial till plains, about sloughs, and in riparian habitat. It probably reaches itshighest densities in areas of sandy soil, but is not limited to this soil type. It likely avoids heavilycultivated regions within its range, but may occur in roadside right-of-ways in these regions.

The Western Hognose Snake has never been considered abundant throughout most of its range.In Alberta, the range of the Plains Hognose Snake is poorly understood and lack of data makes itdifficult to recognize changes in distribution or population levels. Factors that may be limiting toPlains Hognose Snake populations in Alberta include agricultural activities, roads, and theavailability of suitable habitat, however, there is little understanding of the exact impacts thesefactors may have. Recent findings have suggested that the Plains Hognose Snake population inAlberta may, in fact, be stable and perceptions of rarity may be the result of the species’ secretivenature and lack of search effort. Nevertheless, research and population monitoring are essentialbefore status can be assessed with any confidence.

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ACKNOWLEDGEMENTS

Thank you to Larry Powell (University of Calgary) for his suggestions, for supplying unpublishedlocality data, and for his generosity in providing reference materials; to Dr. Anthony Russell(University of Calgary) for providing access to his personal files on the herpetofauna of Alberta;to Steve Brechtel (Alberta Natural Resources Service) for the time he spent in providingunpublished data over the telephone; to Dave Prescott for his editorial assistance; to DorindaScott (Texas Biological and Conservation Data System) for status information; to the CanadianWildlife Service, it’s employees and contractors, especially those who were present at CFBSuffield during the 1995 field season and who provided specimens: Brenda Dale, Andy Bezener,Hal Reynolds, Paul Goossen, and Henk Kiliaan; to James Sifert and Marnie Cooper (University ofSaskatchewan) for their tremendous efforts in the field and their resulting contributions to theCFB Suffield records; to Rick Lauzon (Axys Environmental) for his comments and involvement incollecting specimens; to Danna Schock (University of Saskatchewan) for her locality record; andto Nancy O’Brien and Joann Skilnick (University of Calgary) for providing locality data; HarryArmbruster’s (Canadian Wildlife Service) contribution of the Rolling Hills record is of importanceand is appreciated. Thanks to independent herpetologist John Meltzer of Minnesota for spendingmuch time on the telephone discussing his unpublished data from that state, and to Bart Bruno,amateur herpetologist, of Connecticut for sharing his observations. Dennis Flath (Montana Fishand Wildlife) supplied information on the species in his state, and this is appreciated. We aregrateful for the generous cooperation of the Alberta Energy Company in providing access to theirfield facilities and for supplying specimens, as we are for Don Kraft’s provision of Prairie FarmRehabilitation Association lodging.

Preparation of this report was funded by the Wildlife Management Enhancement Program of theAlberta Conservation Association.

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TABLE OF CONTENTS

PREFACE ......................................................................................................................iii

EXECUTIVE SUMMARY.............................................................................................iv

ACKNOWLEDGEMENTS............................................................................................. v

INTRODUCTION .......................................................................................................... 1

HABITAT ...................................................................................................................... 1

CONSERVATION BIOLOGY ....................................................................................... 3

1. Description ............................................................................................................. 32. Daily and Seasonal Activity Periods ........................................................................ 33. Reproduction .......................................................................................................... 44. Movements ............................................................................................................. 45. Food ....................................................................................................................... 56. Choice of Hibernacula............................................................................................. 6

DISTRIBUTION ............................................................................................................ 7

1. Alberta.................................................................................................................... 72. Other Areas .......................................................................................................... 11

POPULATION SIZE AND TRENDS........................................................................... 12

1. Alberta.................................................................................................................. 122. Other Areas .......................................................................................................... 12

LIMITING FACTORS.................................................................................................. 12

1. Agricultural Activities ........................................................................................... 132. Roads ................................................................................................................... 133. Oil and Gas Activity.............................................................................................. 144. Intentional Persecution.......................................................................................... 14

STATUS DESIGNATIONS ......................................................................................... 14

1. Alberta.................................................................................................................. 142. Other Areas .......................................................................................................... 15

RECENT MANAGEMENT IN ALBERTA.................................................................. 15

SYNTHESIS ................................................................................................................ 16

LITERATURE CITED ................................................................................................. 18

APPENDIX 1. .............................................................................................................. 21

APPENDIX 2. .............................................................................................................. 23

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INTRODUCTION

Three subspecies of the WesternHognose Snake (Heterodon nasicus) arecurrently described (Conant and Collins1991). The nominate race, the PlainsHognose Snake (H. n. nasicus) is thesubspecies found in Alberta, where itsrange enters into the extremesoutheastern corner of the province. Itis also the subspecies found inSaskatchewan and Manitoba.

In 1996, the Western Hognose Snakewas placed on Alberta’s ‘Blue List*’ ofspecies thought to be at risk of decliningto non-viable population levels in theprovince (Alberta Wildlife ManagementDivision 1996). The species had beenranked as a ‘Red List’ species in 1991(Alberta Fish and Wildlife 1991) but wasupdated in 1996 due to recent increasesin new Alberta records (Alberta WildlifeManagement Division 1996).Nevertheless, the lack of information onPlains Hognose Snakes makes it difficultto assess current population trends.

This report has been prepared as areview of current information relevant todetermining the status of the PlainsHognose Snake in Alberta.

HABITAT

The habitat of the Plains Hognose Snakein Alberta and Saskatchewan falls withinthe Grassland Natural Region of theHigh Plains, the latter being the third tierof the Interior Plains of Canada. TheHigh Plains include Alberta’s entireprairie region, as well as that of

* See Appendix 1 for definitions of selectedstatus designations

Saskatchewan, west of the MissouriCoteau. This area has been described aseither short or mixed-grass prairie(Coupland 1961) or a combination ofthe two. This semi-arid region is subjectto moderately long, hot but variablesummers, and moderately long, and attimes extremely cold, winters. InManitoba, where the only Canadianpopulation of Plains Hognose Snakesoccurs outside of the High Plains, thehabitat has been described as mixed-savannah, mixed-prairie, and mixedforest (Leavesley 1987).

Outside of Canada, habitat of the PlainsHognose Snake is found in the short,mixed, and tallgrass prairie regions, butthe range appears to be most continuouson the higher, more arid shortgrassplains (Platt 1969). On the easterntallgrass, or ‘low’ prairie, this speciesprefers areas of sandy soils, whichresults in disjunct pockets of hognosesnake populations where the habitat issuitable. In Minnesota, for example, atthe northeastern edge of its range, thePlains Hognose Snake is foundexclusively in pockets of sand-prairie (J.Meltzer, pers. comm.).

Records from Alberta suggest thatPlains Hognose Snakes preferpredominantly or completely sandylocations within the grasslands region(Pendlebury 1976, Smith and Wershler1989), although Moore (1953) reportedthe species from both sandy locationsand damp lowlands, without furtherdefinition of the latter. Two records,the first from the Milk River south ofComrey (Lewin 1963), and the secondfrom the Comrey breaks (G. L. Powell,pers. comm.), place this snake on thecoulee rim, grassland/badlands ecotone,

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where clay soil and/or gravel, scatteredrocks, jumbled boulders and groundjuniper are the prominent features.

In Alberta, the apparent preference ofPlains Hognose Snakes for sandy soilsresults in these habitats being mostfrequently searched by biologists.Recent records, however, show that thePlains Hognose Snake occurs in morediverse habitat than was formerlybelieved. The records include captureson, and adjacent to, Canadian ForcesBase (CFB) Suffield (1994 to 1997;n=32), where the species was trappedwithout any habitat bias, and two recent(1997) road-kills from the areaimmediately northeast of Medicine Hat.Specimens from CFB Suffield werecollected on open prairie with sandysubstrate, on open prairie with heavysod, on open prairie near sloughs, ongravelly rolling glacial till plain, on opendune sandhill country, and on a ripariansageflat with densely packed soilconditions (J. Wright, unpubl. data). Ofthe two recent road-kills mentionedabove, one was on a gravel roadbordered for many kilometers byovergrazed rangeland with heavy sod,and the other was on a major highwaybordered on either side by canola fieldswith a grassy, 20 m right-of-way (J.Wright, unpubl. data).

At CFB Suffield, the area in Albertafrom which the greatest number ofrecent Plains Hognose Snake recordshave originated, the species was mostfrequently captured on or near sandyareas (A. Didiuk, unpubl. data).Another prime area was near a wetland,where several live specimens, includingan adult male and a gravid female in thespring of 1995, and two newly hatched

young in the fall of 1997, were capturedon or near a township road (J. Wright,pers. obs.). The recent findings fromCFB Suffield and the Medicine Hat areaare not unusual in the sense that theyconform to the trend in habitat recordsfrom the United States. These U.S.records report Plains Hognose Snakesfrom the various prairie habitat types,including short and mixed grass plains,as well as badlands and river drainages,but, again, with a heavy emphasis onsandy or gravelly locations (Platt 1969).The record from CFB Suffield of a livesnake caught in a drift fence on ariparian sage-flat is an exception as littleor no mention of the use of this specifichabitat type occurs in the literature.

A summary of captures of PlainsHognose Snakes at CFB Suffieldsuggests the following listing of habitats,in approximate order of decliningrelative densities of snakes found: i)open, sandy plains, where grazingpressure is light, resulting in a heavycover of mixed grasses; ii) open plainswith light to moderate grazing pressurenear wetlands; iii) sandhill country; iv)short or mixed-grass plains with a heavysod layer and moderate to heavy grazingpressure and gravelly, glacial till-plains;v) riparian areas (A. Didiuk, unpubl.data).

A live specimen from the Rolling Hillsarea south of Brooks is unusual amongAlberta records in that it was observedon the north bank of the Bow River inclose proximity to the water (H.Armbruster, pers. comm.). It isinteresting to note that considerableareas of sandy soil occur in the RollingHills area (Pendlebury 1976). One otherAlberta record was of a Plains Hognose

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Snake swimming across the SouthSaskatchewan River at CFB Suffield (S.Brechtel, pers. comm.).

Plains Hognose Snakes have beenfrequently captured in Alberta in sandyareas where Northern Pocket Gophers(Thomomys talpoides) are abundant (J.Wright, unpubl. data). It is possible thatthe winter burrows of this rodent, whichextend below the line of frost-penetration, provide suitable hibernaculafor the essentially non-migratory PlainsHognose Snake, allowing this reptile toremain year-round on its summer range.

CONSERVATION BIOLOGY

1. Description. - The Plains HognoseSnake is a small to medium sized,heavy-bodied snake. It derives its namefrom a sharply upturned rostral scale. Ithas no facial pits, the scales are keeled,and the body colour is brown to graywith three to five rows of darker brownblotches down its dorsal and lateralsurfaces (Russell and Bauer 1993). Thepattern and colouration resembles thatof some specimens of the PrairieRattlesnake (Crotalus viridis viridis).The underside is completely black, orblack checkered with yellow or white.At maturity, the females are larger thanthe males, and the males have relativelylonger tails in comparison to their bodies(Russell and Bauer 1993). The fangsare at the rear of the mouth and thevenom is not normally considereddangerous to humans (Russell andBauer 1993). Plains Hognose Snakesare not aggressive towards humans, andcan rarely be induced to bite (J. Wright,pers. obs.).

2. Daily and Seasonal ActivityPeriods. - In Alberta, the PlainsHognose Snake emerges fromhibernation in late April or early May.Pendlebury (1976) gives an early seasonrecord of 10 May and the earliest recordat Suffield is 22 April (A. Didiuk,unpubl. data). It enters hibernation inthe fall in late September, and likely intoearly October. Pendlebury (1976) givesa late record of 20 September, and thelatest record from CFB Suffield is 25September (R. Lauzon, pers. comm., J.Wright, unpubl. data). On this date, in1997, two hatchlings were captured, onewith the dried umbilicus still attached,indicating that the snake had hatchedduring the preceding few days.

In the U.S., Wright and Wright (1957)list an early record of 15 May and a laterecord of 10 October, but fail tomention from which state(s) theserecords originate. In Kansas, Platt(1969) lists an early record of late Apriland a late record for the end of October.Trapping of snakes at CFB Suffield didnot continue into October, although it islikely that some hognose snakes areactive in Alberta at least until the middleof this month, when conditions arefavourable.

Plains Hognose Snakes in Kansas arediurnal, with peak activity periodsoccurring in the mornings and evenings(Platt 1969). On the sand prairie ofMinnesota, at the northeast limit of thespecies’ range, this snake is diurnal andshows a dislike for hot temperatures.Observations from that area suggest thatthe snakes are above ground for anactivity period of approximately onehour per day, primarily on sunny daysbefore the air temperature climbs above

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20° C (J. Meltzer, pers. comm.).Limited information suggests that suchactivity patterns are true of Albertapopulations as well (A. Didiuk, unpubl.data).

In Alberta, Plains Hognose Snakes arediurnal, and appear to be most active onsunny days, when air temperatures arebetween 10 and 20° C, and are rarelyseen when temperatures exceed 20° C(J. Wright, pers. obs.). This period mayoccur earlier or later in the morning,depending on the conditions of the day.Such a shift in daily activity period as afunction of temperature was noted inKansas, although the snakes there seemto have a higher preferred temperaturerange (Platt 1969). In Alberta, aselsewhere, snakes may again be active inthe evenings when the temperature fallsto within the preferred range.

Captures at CFB Suffield of snakesactive on the surface took placeprimarily on sunny mornings on gravelroads between 0900 and 1100, althougha number of snakes were capturedbetween 1500 and 1900 (A. Didiuk,unpubl. data). Leavesley (1987) noted apreferred body temperature of PlainsHognose Snakes in Manitoba of 27.5 to33.0° C. Attainment of this temperaturewould likely not take long for a smallsnake such as the hognose, even atrelatively low air temperatures, in theharsh, direct sun conditions of theAlberta plains. This may account for theapparently narrow window of surfaceactivity in this species.

3. Reproduction. - The mating seasonof the Plains Hognose Snake is in thespring, although some mating may alsooccur in the fall (Platt 1969). For this

reason, increased activity in the form ofgreater surface distances covered insearch of a mate might be expectedduring these times of the year.However, no changes in seasonalactivity levels were noted at CFBSuffield, with the exception of a shortlull in captures in late July and earlyAugust (A. Didiuk, unpubl. data). Thisspecies may breed in alternate years(Platt 1969).

The Plains Hognose Snake lays between4 and 23 eggs (Russell and Bauer 1993).In Alberta, eggs are deposited from mid-June to the beginning of July, in sandysoils at a depth of approximately 90 mm(Russell and Bauer 1993). Theincubation period is approximately 60days (Russell and Bauer 1993). Little isknown of their survivorship. The eggsmay suffer heavy mortality to StripedSkunks (Mephitus mephitus), Badgers(Taxidea taxus), and Coyotes (Canislatrans), all of which occur within thePlains Hognose Snake’s Alberta rangeand are known predators of snake eggs.The young may occasionally die ofstarvation, or fall victim to predators,but, perhaps due to this snake’ssecretive nature, neither the young northe adults have figured prominently inthe stomach contents of predators thatshare their habitat in Kansas (Platt1969). Badgers, Coyotes, and Red-tailed Hawks (Buteo jamaicensis) haveall been observed preying upon, orattempting to prey upon, PrairieRattlesnakes at CFB Suffield (J. Wright,pers. obs.), so it seems likely that theywould also prey upon hognose snakes.

4. Movements. - In Kansas, Platt (1969)calculated mean distances traveled byPlains Hognose Snakes from point of

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capture as an indicator of home-rangesize. The longest mean distancetraveled was 200 m for snakesrecaptured after 31 to 50 days, and theshortest recorded mean distance traveledwas 89 m for snakes recaptured aftermore than 200 days. Although suchdata have not been collected for theAlberta populations, it appears thatPlains Hognose Snakes have smallerhome ranges than the PrairieRattlesnakes and Bullsnakes (Pituophismelanoleucus sayi) that share theirprovincial range (A. Didiuk, unpubl.data). Both of these species, in spite oftheir much larger apparent ranges, arestill moderately common to common insuitable habitat in Alberta. Therefore,given what appear to be similar habitatrequirements, it may be that more thansufficient habitat remains in Alberta tosupport healthy populations of PlainsHognose Snakes.

A Plains Hognose Snake may undergomovements in order to shift its homerange to better meet its requirements,or, if it is a male, to seek a mate (Platt1969). Some hognose snakes may alsobecome ‘wanderers’ at any given time,for unknown reasons. One such snake isknown to have traveled approximately250 m per day for two days, after whichits movements became more moderate(Platt 1969). Such numbers indicatethat even ‘wanderer’ snakes haverelatively moderate range requirementswhen compared to other snake species.

Evidence in Minnesota suggests thatPlains Hognose Snakes travel very littlein the course of the active season, as thesame tagged snakes were repeatedlyfound outside the same burrows (thosedug by either Northern Pocket Gophers

or Thirteen-Lined Ground Squirrels,Spermophilus tridecemlineatus; J.Meltzer, pers comm.). Snakes werefound persisting in this same study areaon a 12 m wide right-of-way, five yearsafter the original habitat was convertedto a housing subdivision (J. Meltzer,pers. comm).

5. Food. - Plains Hognose Snakes feedon many organisms in the wild. It isgenerally agreed upon, however, thatthey exhibit, like all the Heterodon, apreference for toads of all kinds (Wrightand Wright 1957, Platt 1969,Pendlebury 1976, CottonwoodConsultants 1986) and have evolved anumber of adaptations for bufophagy(Platt 1969). These adaptations includehighly mobile maxillae, and enlargedrear maxillary teeth for handling of largeprey, a large gape, a thick body, and aphysiological resistance to toad venomwhich can kill other creatures (Platt1969). Other prey items include frogs,salamanders, turtle eggs, lizards, smallbirds, rodents, and other snakes(especially garter snakes; Platt 1969,Pendlebury 1976, Russell and Bauer1993). Pendlebury (1976) observed acaptive Plains Hognose Snake fromAlberta attempt to subdue a WesternPlains Garter Snake (Thamnophis radixhaydeni) when both were placed in thesame cage. A captive specimen fromMontana, from an area adjacent to theAlberta border, was reported to exhibita taste for hatchling Bullsnakes, whereascaptives from South Dakota andMinnesota refused the same food (B.Bruno, pers. comm.).

At CFB Suffield, the shells of Junebeetles appeared in the feces of PlainsHognose Snakes (J. Wright, pers. obs.).

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It seems likely that these remains wereinside toads eaten by the snakes, assnakes in general do not show fondnessfor hard-shelled insects (Pendlebury1976, J. Wright, pers. obs.). HatchlingPlains Hognose Snakes, as well asBullsnakes, have been observed withgrasshoppers in their stomachs (J.Meltzer, pers. comm.).

The fact that hognose snakes frequentlyfeed on rodents, combined with thefrequency with which they are foundamong Pocket Gopher colonies,suggests that they may include newbornexamples of this rodent in their diets, aswell as, perhaps, the young of theThirteen-Lined Ground Squirrels.Short-term captives from CFB Suffieldfed readily on live and dead newbornmice, small nestling birds, several frogspecies, and newly metamorphosedGreat Plains Toads (Bufo cognatus; A.Didiuk, unpubl. data).

6. Choice of Hibernacula. - PlainsHognose Snakes either dig their ownburrows, or use existing rodent burrowsas hibernacula (Platt 1969, J. Meltzer,pers. comm.). Platt’s (1969) suggestionthat these snakes likely do not migrateto and from communal denning sites hasbeen substantiated by Alberta findings(A. Didiuk, unpubl. data). However,what appeared to be a denningcongregation of Plains Hognose Snakeswas observed in Minnesota (J. Meltzer,pers. comm.). Thirty specimens werefound together in the fall, congregatingin a sand-prairie ditch over an area of nomore than 6 m2. The site wascharacterized by an abundance of rodentburrows (J. Meltzer, pers. comm.).

The Plains Hognose Snake hasoccasionally been observed denning incommunal hibernacula of other snakespecies. For example, CottonwoodConsultants (1987) report hognosesnakes at a ‘handful’ of communaldenning sites in the province. Tworecords from the south side of the RedDeer River in the Buffalo area relate theoccurrence of Plains Hognose Snakes intwo separate, communal PrairieRattlesnake/ Bullsnake/ gartersnakehibernacula (S. Brechtel, pers. comm.).One source documents Plains HognoseSnakes as having occurred with thesame species at a den near DrowningFord, on CFB Suffield, at an estimateddensity of “300 rattlesnakes for everyhognose snake” (S. Brechtel, pers.comm.).

Plains Hognose Snakes are rarelyrecorded in communal hibernacula fromother areas. A newly hatched youngPlains Hognose Snake was noted “at ornear” a Prairie Rattlesnake hibernaculawithin the proposed boundaries ofGrasslands National Park in southernSaskatchewan, along with EasternYellow-bellied Racers (Coluberconstrictor flaviventris), Western PlainsGarter Snakes, and Bullsnakes (Kissneret al. 1996). Two Plains HognoseSnakes were observed at a PrairieRattlesnake den in Tripp County, SouthDakota, along with 6 Bullsnakes, 2Eastern Yellow-bellied Racers, and 1Red Milk Snake (Lampropeltistriangulum syspila; Wright and Wright1957).

Nevertheless, recent surveys at CFBSuffield, resulted in no Plains HognoseSnake reports from hibernacula sharedby Prairie Rattlesnakes, Bullsnakes and

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Plains (Thamnophis radix radix) andWandering (T. elegans vagrans) GarterSnakes (A. Didiuk, unpubl. data).These hibernacula were thoroughlysurveyed, and occurred near areas ofprime hognose snake habitat. This andother evidence (see ‘Movements’section, above) suggests that PlainsHognose Snakes are essentiallysedentary and likely den most oftenwithin their summer range (A. Didiuk,unpubl. data). They probably hibernateby burrowing down into sandy substrate,or in the burrows of fossorial mammals.At CFB Suffield, the majority of PlainsHognose Snakes were captured farenough (>5 km) from the SouthSaskatchewan River, where rattlesnakehibernacula are located, to suggest thatthe river valley does not play a role inthe overwintering of this fairly sedentarysnake. The fact that they were nevercaptured at any of the severalhibernacula surveyed at CFB Suffieldsupports this view (A. Didiuk, unpubl.data).

DISTRIBUTION

1. Alberta. - The Plains Hognose Snakereaches the northern limit of its range inAlberta (Figure 1). The species’occurrence in the province is looselyassociated with the major riverdrainages of the extreme south-eastcorner of the province, as these were nodoubt used as post-glacial dispersalcorridors into the north. Historically,most records have fallen east of a linedrawn connecting Orion and MedicineHat, and south of the Red Deer River(Russell and Bauer 1993). Currentrecords extend this known range to thewest, perhaps as far as Rolling Hills(Figure 2), according to a recently

discovered record from the early 1970s(H. Armbruster, pers. comm.). It isimportant to note that this record doesnot likely constitute a range expansionfor the Plains Hognose Snake, but ratherreflects the lack of comprehensivehistorical data on this species (a directresult of the difficulty in conductingwork on such an elusive creature).There are unconfirmed records of PlainsHognose Snakes from the DinosaurProvincial Park area and from the FortMacloed area which, if credible, extendthe known limits of this species range inAlberta even further west (Figure 2).The Fort Macloed record, however,given its distance from the known range,may represent a case of speciesmisidentification.

The range of the Plains Hognose Snakein Alberta appears to be discontinuouswest from the Cypress Hills area (Figure2), resulting in what has been historicallyportrayed as separate populations of thissnake in the province (Pendlebury1976). The ‘south population’ occurs inthe Milk River Canyon/ Wild Horse/Manyberries region and is likelycontiguous with a Montana population(Pendlebury 1976, Reichel and Flath1995). Meanwhile, the ‘northpopulation’ is centered along the SouthSaskatchewan River from the area ofMedicine Hat in the south to the area ofEmpress in the north (Pendlebury 1976).Evidence to support the hypothesis thatthese two populations have perhapsbeen isolated from each other for sometime is illustrated by Pendlebury (1976).He points out that specimens from the‘northern population’ tend to have theirblack venters broken up into acheckerboard pattern by yellowishsquares, while specimens from the

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Figure 1. Distribution of the Western Hognose Snake in North America (adapted fromStebbins 1985).

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‘south population’ have predominantlyblack venters. In 1995, however, aspecimen was captured at a drift fence atSuffield (in the ‘northern population’region) with a solid black venter (J.Wright, pers. obs.).

These two populations may be thedivided remnants of what was once (andmay still be) a continuous population inAlberta, following the snake’snorthward post-glacial dispersal routearound the west side of the CypressHills. If this is the case, it is notunreasonable to suggest, especially inlight of the record from Rolling Hillsand a record from the southwest borderof CFB Suffield, that undiscoveredpopulations of this snake may still existwest of the Cypress Hills in suitablehabitat along the species’ dispersalroutes. Conversely, the ‘northpopulation’ of this species in Albertamay be the result of a separate migrationof snakes northward throughSaskatchewan, and around the east endof the Cypress Hills. Whichever thecase, this snake should be looked for insuitable habitat along all of southeastAlberta’s post-glacial spillwaydrainages, especially the Etzikom, theChin, and the Forty-Mile Coulees.

At CFB Suffield, hognose snakes werecaptured with the greatest frequency inareas where Northern Pocket Gopheractivity was high (J. Wright, pers. obs.).The Northern Pocket Gopher is absentfrom a large portion of southern Alberta(Smith 1993). It is interesting to notethat the bulk of the records for thePlains Hognose Snake in this provincefall within the eastern boundary of therange of the Northern Pocket Gopher.The fact that the ranges of these two

species closely overlap in the southeastcorner of the province may suggest aclose association between these twoanimals in Alberta. The Richardson’sGround Squirrel (Spermophilusrichardsonii) in comparison, was largelyabsent on the study area at Suffield, so itwas not possible to determine whetherthe snakes also favour the colonies ofthis rodent where their populationsoverlap.

The paucity of records points out thatthe actual range of the Plains HognoseSnake in Alberta has yet to be accuratelydefined. It is therefore impossible, atpresent, to determine whether thisspecies has a stable, expanding(unlikely) or contracting (more likely)range in the province. The sympatricPrairie Rattlesnake, for instance, isbelieved to have experienced rangecontraction in some areas of Alberta inrecent years, probably as a result ofmodern land-use practices (Watson andRussell 1997). It seems reasonable tosuggest that the Plains Hognose Snakewould be affected similarly by thesesame pressures.

The Plains Hognose Snake may beexpected to occur over an area adjacentto and south of the Red Deer River, andat least as far west as the longitude ofBassano, as suitable habitat wouldappear to be available for this snake inpockets throughout this block. Inattempting to determine the true limitsof the hognose snake’s range in Alberta,initial priority should be placed onhabitat that supports healthy (notovergrazed) native grassland on sandysurficial deposits. The areas nearseasonal or permanent wetlands,especially where Northern Pocket

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Figure 2. Currently defined and hypothetical range of the Plains Hognose Snake inAlberta. See ‘Distribution’ section, above, for explanation of the hypotheticalrange. Detailed descriptions of records are found in Appendix 2.

11

Gophers occur, should be consideredhabitat on which to focus efforts. Anexample of a potential area to search,which has yet to yield any records of thissnake, lies northwest of the town ofBrooks, south of, and adjacent to, theRed Deer River. Highway 36 bisects anextensive region of low, shrubby dunecountry in this area, which has theoutward appearance of being primehognose snake habitat. The RollingHills area near Brooks is another regionin which efforts to find this snake mightbe concentrated, as is the Grassy Lakearea west of Taber. It remains to beseen whether the fact that these areas lieoutside of the known range limits for theNorthern Pocket Gopher (Smith 1993)is relevant.

Recent findings that place PlainsHognose Snakes in a broader variety ofprairie habitats than was formerlyexpected are heartening. Based on thesefindings, potentially suitable areas forthis snake exist in large tracts from thearea north of, but adjacent to, the RedDeer River, west to at least thelongitude of Bassano, and south to theU.S. border. In contrast, the amount ofwhat we consider ‘pristine’ prairieremaining in Alberta is relatively small.If it is shown that the Plains HognoseSnake requires such conditions, then alarge portion of the area outlined abovewould not be suitable habitat, and lightlyimpacted areas such as CFB Suffield andthe Pinhorn Grazing Reserve could becrucial to the survival of this species inAlberta.

2. Other Areas. - The Plains HognoseSnake is found from extreme southeastAlberta, through western Saskatchewan(Secoy and Vincent 1976) west of the

Missouri Coteau, and into the UnitedStates, through North Dakota, and asfar east as Minnesota (Stebbins 1985;Figure 1). From Minnesota it occurssouth to northern Texas, west to west-central New Mexico, and north toMontana (Platt 1969, Conant andCollins 1991). The Rocky Mountainsare a barrier at the western range limit ofthe Plains Hognose Snake in the UnitedStates (Platt 1969). There is a relictpopulation in the sandhills of southwestManitoba (Leavesley 1987). Populationsat the eastern edge of the PlainsHognose Snake’s range in the UnitedStates (Minnesota, Iowa, Illinois,Missouri) tend to be highly fragmenteddue to the highly fragmented nature ofpreferred habitat in this region (Platt1969, Conant and Collins 1991).

There are two subspecies of the PlainsHognose Snake. The Dusty HognoseSnake (H. n. gloydi) overlaps thesoutheastern edge of the nominatesnake’s range in extreme southernKansas, through central Oklahoma, andsouth through south central Texas, withdisjunct colonies in eastern Texas,Missouri, and Illinois. It integrates withthe Plains Hognose where their rangesoverlap. The Mexican Hognose Snake(H. n. kennerlyi) is found from extremesouthern Texas to southeast Arizona,and south into central Mexico (Conantand Collins 1991; Figure 1).

The limited data available on the PlainsHognose Snake suggests that thisspecies has not undergone any changesin range or distribution, except perhapson a local basis, where, like the PrairieRattlesnake, populations may havebecome extirpated due to alteration ofhabitat.

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POPULATION SIZE AND TRENDS

1. Alberta. - Little is known about thepopulation size of the Plains HognoseSnake in Alberta. Population sizes ofreptiles can be very difficult todetermine with any degree of reliabilityunder the best of conditions, such as forcommunally denning species. With aspecies like the Plains Hognose Snake,which rarely dens communally, anyreliable method of determining actualnumbers of individuals is difficult todevelop and implement. As ageneralization, based on currentinformation levels, experts propose thatthis snake, which was historicallybelieved to be very rare in Alberta,might exist in greater numbers than wasonce believed (A. Didiuk, unpubl. data).

Similarly, trends in population for thisspecies in Alberta are currentlyundetermined. The increasing numberof records over the past few yearsalmost certainly reflects the trendtowards more herpetological research inthe province, rather than any actualincrease in the number of these snakes.Although the species has been perceivedas being very rare and perhaps in declinesince it first began receiving scientificattention in the province, the increasedfrequency with which the snake is foundmay indicate that the population inAlberta is in fact stable. An attempt at apopulation estimate for Alberta suggestsnumbers in the thousands, but not tensof thousands (A. Didiuk, unpubl. data).

2. Other Areas. - No reliable populationestimates exist for Manitoba, wheresome work on this snake has been done.However, the species is perceived to berare in the province in localized areas of

sandy soils (Leavesley 1987). Even lessis known about the species inSaskatchewan, so no comments can bemade regarding population size or trendin that province.

High densities of Plains Hognose Snakeshave been indicated in Minnesota, whereup to 200 different marked individualshave been observed on a single 8 ha fieldof native sand-prairie (J. Meltzer, pers.comm.). Population estimatesestablished from data from two studysites in Kansas give densities of 2.81 and5.98 snakes/ha (Platt 1969). It isprobable that these densities are higherthan those that exist in Alberta (A.Didiuk, unpubl. data).

LIMITING FACTORS

There are a number of natural factorsthat limit the distribution of the PlainsHognose Snake in Alberta. Whereas thePlains Hognose Snake has demonstratedsome adaptability to lightly ormoderately impacted prairie habitattypes in southeastern Alberta (see‘Habitat’ section, above), it is known tobe limited on the eastern extremities ofits range to areas of sandy substrate. Ifthis snake is found further west on theprairie in Alberta than was formerlybelieved (a pattern that is beginning toemerge) then perhaps it will be found tobe limited to sandy substrates on theextremes of its range in this province aswell. This assumption might aidresearchers in identifying areas wherethe species has a high probability ofbeing detected outside of its knownrange.

The Plains Hognose Snake may also bedependent on the burrows of Northern

13

Pocket Gophers for hibernacula.Northern Pocket Gophers appear to beimportant determinants of thedistribution of Bullsnakes and PrairieRattlesnakes of southeastern Alberta fora number of reasons, as well (pers.obs.). The presence of availablehibernacula may then not be as strong ofa limiting factor for the Plains HognoseSnake, which does not rely on majordrainages, as it is for the PrairieRattlesnake which relies on such areasfor denning sites.

The availability of habitat may be only aminor limiting factor to Plains HognoseSnakes in Alberta at present, as theknown range falls within an area whichstill contains adequate tracts of near‘natural’ grassland to support healthypopulations of other prairie snakespecies. What may be more importantto the Plains Hognose Snake is thequality of available habitat. Thefollowing sections discuss the effects offactors that may effect breeding andsurvival of the Plains Hognose Snakewith emphasis on impacts resulting fromhuman activities.

1. Agricultural Activities. - The fulleffects of agricultural activities onhognose snakes are poorly understood.Cultivation of the prairie renders itlargely or completely unsuitable forsnake habitat (Russell and Bauer 1993).Today, 68% of Alberta’s prairie iscultivated (Willms and Dormaar 1995),although the percentage is likely lowerin the extreme southeast part of theprovince. Taking these factors intoaccount, it is likely that cultivation is thesingle greatest limiting factor for thePlains Hognose Snake in Alberta.Although there is evidence to suggest

that this species, being relativelysedentary, can persist on fairly smallparcels of suitable habitat, cultivationlikely represents a barrier to dispersal,ultimately affecting genetic integrity.Furthermore, the breaking of new sodby the plow may kill most individualsoutright, with further individuals beingclaimed by machinery at harvest time. Itis possible that ditches and right-of-waysare important as dispersal corridors, andmay even support populations ofhognose snakes if rodents are abundant(J. Meltzer, pers. comm.). However, nowork has been done in Alberta tosupport this theory.

Specimens of Plains Hognose Snakeshave been found adjacent to heavilygrazed pastures in Alberta. No workhas been done to implicate grazingpressure - light, moderate or otherwise -as a limiting factor on this snake,although it is known that grazing bycattle may render habitat unsuitable orsuboptimal for some species (Russelland Bauer 1993).

Insecticides may be of concern as alimiting factor for the Plains HognoseSnake. Grasshoppers have been foundin the stomachs of hatchlings, somortality may occur as a result ofingestion of insecticides. Insecticidesmay also act indirectly as a limitingfactor by reducing the available prey-base for hognose snakes. They may alsoinhibit or prevent successful breeding(Russell and Bauer 1993).

2. Roads. - Roads are likely second inimportance as a limiting factor on thePlains Hognose Snake in Alberta. Onthe otherwise protected SuffieldNational Wildlife Area, natural gas

14

exploration and extraction activitiescreate heavy vehicular traffic, andsnakes, including the Plains HognoseSnake, are probably the only wildlifespecies present which suffer appreciableroad-kills (pers. obs.). Five of therecent specimens from CFB Suffieldwere road-killed, and a sixth had beenhit by a vehicle and recovered. The tworecent specimens from northeast ofMedicine Hat, along with the recentspecimen from near Manyberries werealso road-kills. Plains Hognose Snakesappear especially vulnerable during themorning when they are regularlyencountered on heavily-traveled accessroutes. It is possible, however, that thehognose snake’s essentially non-migratory habits, (in contrast to those ofthe wide-ranging Prairie Rattlesnake),afford protection to populations thatoccur a suitable distance from anythoroughfare. Therefore, mortalitiesfrom vehicles are likely of mostsignificance to populations in close-proximity to roads.

3. Oil and Gas Activity. - The primaryimpact of oil and gas activity on PlainsHognose Snakes is likely from vehiculartraffic on existing roads and on roadscreated during well and pipelineconstruction services. However,trenching during pipeline constructioncan also cause mortality of snakes. Dueto the short duration in which pipelinetrenches remain open, and because thePlains Hognose Snake does not appearto be a highly migratory species,mortality from falling into trenches islikely of minor impact on this snake.However, Prairie Rattlesnakes andBullsnakes are regularly found trappedin trenches (J. Wright, pers. obs.),especially in the spring and fall, and

therefore it seems probable that hognosesnakes may also become trapped(especially in prime habitat). Thisoccurrence, however, has not beendocumented. Hatchling Plains HognoseSnakes have been found dead, in thesunken gas-well structures at CFBSuffield on several occasions in recentyears (pers. obs.).

4. Intentional Persecution. - PlainsHognose Snakes are of small size,cryptic colouration, reclusive behavior,remote habitat, and do not makethemselves especially vulnerable bydenning communally. For these reasons,they likely do not often fall victim tointentional persecution. Nevertheless,this species, like the Bullsnake, isprobably killed occasionally as a resultof being mistaken for the PrairieRattlesnake, which is often killed onsight due to its venomous nature(Watson and Russell 1997), or as aresult of the general prejudice whichexists against all snakes. Reports bylocal residents north of Medicine Hat of‘small, rattle-less rattlesnakes’ (J.Wright, pers. obs.), probably refer tothis species, and it is conceivable thatsuch specimens may fall victim becauseof prejudice.

STATUS DESIGNATIONS

1. Alberta. - In 1991, due to theperception of its extreme rarity in theprovince, the Western Hognose Snakewas included on Alberta’s ‘Red List’ ofspecies at risk of declining to non-viablepopulation levels (Alberta Fish andWildlife 1991). Although little is knownabout the Plains Hognose Snake inAlberta, where it has been historicallyconsidered rare, and even “endangered -

15

the rarest of all reptiles in Alberta”(Alberta Fish and Wildlife 1984), recentstudies have greatly increased ourlimited knowledge of this snake.Currently, the Plains Hognose Snake ison Alberta’s ‘Blue List’ of species thatmay be at risk in the province (AlbertaWildlife Management Division 1996).The emerging picture is one of anextremely secretive and elusive creature.The question now is whether the PlainsHognose Snake is truly ‘rare’ in Alberta,or whether it is just rarely seen.

2. Other Areas. - The NatureConservancy (1998) gives a global rankof ‘G5’ to the Plains Hognose Snakemeaning the species is widespread,abundant and demonstrably secure. InSaskatchewan, the Plains HognoseSnake is rated as ‘S3’ (‘rare’) under thesame ranking system (SaskatchewanConservation Data Centre 1997). Fewrecords exist in the province but littlework has been done (A. Didiuk, pers.obs.). The Plains Hognose Snake isconsidered threatened in Manitoba andis rated ‘S2’ (‘imperilled’; Duncan1996). The species may be designatedas ‘vulnerable’ in the upcoming reportfor the Committee on the Status ofEndangered Wildlife in Canada (A.Didiuk, in prep.).

This species receives no officialprotection in the United States. It isconsidered of ‘special interest’ inMontana (D. Flath, pers. comm) where,it is ranked as ‘S3’ (‘rare’) due to thepaucity of records for that state (Platt1969, Reichel and Flath 1995, MontanaNatural Heritage Program 1998). InMinnesota and Iowa the Plains HognoseSnake is listed as ‘endangered’, and inMissouri it is considered ‘rare’ (Iowa

Department of Natural Resources 1997,Minnesota Department of NaturalResources 1997, Missouri Departmentof Conservation 1998). Few recordsexist from the Dakotas or northernWyoming (Platt 1969). It is consideredrelatively common in prairie regions ofOklahoma and Texas (Platt 1969) whereit is ranked as ‘S5’ (‘demonstrablysecure’; D. Scott, pers. comm.), one ofthe more common snakes in the past inNew Mexico (Wright and Wright 1957),and relatively common in westernKansas and Nebraska south of the PlatteRiver (Platt 1969).

RECENT MANAGEMENT INALBERTA

Attempts to understand, andsubsequently manage, populations of thePlains Hognose Snake have been nearlynon-existent in Alberta, due to thedifficulty in collecting meaningful dataon this species. This situation ischanging, as a number of recentlyinitiated projects are providing newinsights into the natural history of thissnake. Such research is necessary formanagement of the species.

1. Suffield National Wildlife Area. -Approximately 458 km2 within CanadianForces Base Suffield has recently (1992)been designated as a National WildlifeArea in a joint agreement between theDepartment of National Defense and theCanadian Wildlife Service (CWS). Aninventory of the herpetofauna of thearea was conducted by CWS from 1994to 1997 as part of an overall wildlife andhabitat inventory. The inventoryrevealed that the area supports anapparently healthy population of PlainsHognose Snakes (A. Didiuk, unpubl.

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data; J. Wright, pers. obs.). Snakeswere captured regularly in drift-fencesand on the area’s system of roads.Sixteen Plains Hognose Snakes werecaptured in 1995 alone as a part of theoverall herpetological efforts, and thesesnakes have provided a comparativewealth of new data on this species inAlberta.

2. Medicine Hat Area. - A study ofPrairie Rattlesnakes, initiated by AlbertaFish and Wildlife in conjunction with theUniversity of Calgary in 1997 at a sitenear Medicine Hat, yielded two new(1997) Plains Hognose Snakespecimens.

3. Pilot Project on the Study of theWestern Hognose Snake in Alberta. -This project was conducted in 1989 bySweetgrass Consultants and was fundedby Alberta Forestry, Lands and Wildlifeand World Wildlife Fund (‘Prairies forTomorrow’). A major focus of thestudy was to test the effectiveness oflive trapping as a way of improving thechance of finding hognose snakes.Traps were set up for a total of 222.5trap days in the Lost River area south ofCypress Hills Provincial Park and theEmpress area (Smith and Wershler1989). One individual was captured. Itis possible that the relatively short length(3.4 m) of drift fencing used for thewings of the traps in this study limitedthe number of snakes caught (A. Didiuk,pers. obs.).

4. Alberta Fish and Wildlife / WWFPoster Campaign. - Beginning in 1989,and into the early 1990s, a joint postercampaign sponsored by Alberta Fish andWildlife and the World Wildlife Fundwas initiated. Posters featuring a photo

of the Plains Hognose Snake andbearing the inscription, “Have You SeenThis Snake?” were distributedthroughout the province, urging peopleto respond with their sightings. Whilethe campaign was intended primarily toincrease awareness of the species (S.Brechtel, pers. comm.), numerous newrecords for Alberta were collected,although many are considered‘unconfirmed’.

5. Alberta Snake HibernaculumInventory. - Initiated in 1996 by theStatus and Surveys Branch of AlbertaNatural Resources Service, this programmaintains a central database ofinformation on the location, features,and longevity of hibernacula occupiedby all snake species in Alberta. Theinformation, which is obtained fromlandowners and naturalists, has yet toyield new Plains Hognose Snakerecords. Given the scarcity of historicrecords placing this species at communalhibernacula, this is perhaps notsurprising. However, the possibilityexists that future records may emerge.

SYNTHESIS

In response to recent records suggestingthat the Plains Hognose Snake may notbe quite as rare and localized in Albertaas previously thought, a renewedinterest in accurately determining thestatus of this species has resulted. Itremains to be seen whether this interestleads to more research, but it wouldappear that enough preliminary data hasbeen collected to suggest substantialdata accumulation can be expected infuture projects. At present, we havelearned only enough to hypothesize thatour past assumptions of extreme rarity

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may be faulty. More research is neededbefore any accurate statements can bemade about the status of the species inAlberta.

Few in-depth studies have beenconducted on this snake to date inAlberta. Such studies are imperative ifwe wish to accurately determine thestatus of this species in this province. Astudy with at least three prime areas offocus is recommended:

1.) Radio-telemetry would enableresearchers to follow transmitter-implanted snakes throughout their activeseason. The recent availability oftechnology allowing this type study hasrevolutionized the field of herpetology,providing data on the previouslyundetermined aspects of snake biology.

2.) The effects of rural land-usepractices on this species need to bedetermined. Research should beconducted in an area that is alreadyknown to support a healthy populationof Plains Hognose Snakes, and whichoffers a variety of range conditions, i.e.light, moderate, and heavily-grazedpasture. Ideally, some of the areastudied should be adjacent to cultivated

areas. Drift fences could be erected onclosely adjacent parcels of landrepresentative of each of the abovelevels of usage, and the occurrence ofthe snakes along with relativepopulation densities could bedetermined. Care should be taken toinclude edge habitat such as ditches andright-of-ways next to cultivated areas.

3.) The extent of the Plains HognoseSnake’s range in Alberta needs to beaccurately determined. The erection ofdrift fences in pre-determined areas ofprime habitat may help in determiningoccurrences beyond the presently knownrange of the species in Alberta. Thefences should be in place by mid-April,and monitored regularly until the end ofSeptember. Effort should beconcentrated on areas with anecdotalrecords, and perhaps from areas west ofthe Cypress Hills along potential historicdispersal routes (see ‘Distribution’section, above). A survey oflandowners should be part of thiscomponent. Drift fence and trap designsdeveloped at CFB Suffield have provento be effective, and should be used.

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LITERATURE CITED

Alberta Fish and Wildlife. 1984. Statusof the fish and wildlife resourcein Alberta. Alberta Fish andWildlife, Edmonton, AB. 127pp.

Alberta Fish and Wildife. 1985. Apolicy for the management ofthreatened wildlife in Alberta.Alberta Fish and Wildlife,Edmonton, AB. 49 pp.

Alberta Fish and Wildlife. 1991. Thestatus of Alberta wildlife.Alberta Forestry, Lands andWildlife, Fish and WildlifeDivision, Edmonton, AB. 49 pp.

Alberta Wildlife Management Division.1996. The status of Albertawildlife. Alberta NaturalResources Service, Edmonton,AB. 44 pp.

Conant, R., and J. T. Collins. 1991. Afield guide to the reptiles andamphibians, eastern and centralNorth America. HoughtonMifflin, Boston, MS. 450 pp.

COSEWIC. 1998. Canadian species atrisk. Committee on the Status ofEndangered Wildlife in Canada.URL: http://www.cosewic.gc.ca[revision date: 24 Apr. 1998].

Cottonwood Consultants. 1986. AnOverview of reptiles andamphibians in Alberta’sGrassland and Parkland NaturalRegions. Unpubl. rept. forWorld Wildlife Fund Canada and

Wild West Program, Calgary,AB. 53 pp.

Cottonwood Consultants. 1987.Alberta Snake HibernaculaSurvey. World Wildlife FundCanada and Wild West Program,Calgary, AB. 50 pp.

Coupland, R. T. 1961. Areconsideration of grasslandclassification in the northernGreat Plains of North America.J. Ecol. 49: 135-167.

Duncan, J. R. 1996. Conservationstatus ranks of the reptiles ofManitoba. ManitobaConservation Data Centre MSReport Number 96-03.Winnipeg, MN. 4 pp.

Iowa Department of Natural Resources.1997. The Iowa Natural AreasInventory. URL: ftp://ftp.heritage.tnc.org/pub/nhp/us/ia/species.html [revision date: 24 Mar.1997].

Kissner, K. J., D. M. Secoy, and M. R.Forbes. 1996. Assessingpopulation size and den use ofPrairie Rattlesnakes Crotalusviridis viridis in southernSaskatchewan. GrasslandsNational Park Annual Reportvol. 1:27-34.

Leavesley, K. L. 1987. Natural historyand thermal relations of theWestern Hognose Snake,Heterodon nasicus nasicus, inSouthwestern Manitoba. M. Sc.thesis, University of Manitoba,Winnipeg, MN. 158pp.

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Lewin, V. 1963. The herpetofauna ofsoutheastern Alberta. Can. Field-Nat. 77: 203-215.

Minnesota Department of NaturalResources. 1997. MinnesotaNatural Heritage Program. URL:http://www.heritage.tnc.org/nhp/us/mn/ [revision date: 28 May1997].

Missouri Department of Conservation.1998. Rare and endangeredspecies checklist of Missouri.URL: http://www.conservation.state.mo.us/nathis/check/index.shtml [revision date: 14 Sept.1998].

Montana Natural Heritage Program.1998. Species of specialconcern. URL: http://orion2.nris.state.mt.us/mtnhp/animal/index.html [revision date: 1 Oct.1998].

Moore, J. E. 1953. The Hog-nosedSnake in Alberta. Herpetologica9(4):173.

National Research Council. 1995.Science and the EndangeredSpecies Act. National AcademyPress, Washington, DC. 271 pp.

Pendlebury, G. B. 1976. The WesternHognose Snake, Heterodonnasicus nasicus, in Alberta. Can.Field-Nat. 90: 416-422.

Platt, D. R. 1969. Natural history ofthe Hognose Snakes Heterodonplatyrhinos and Heterodonnasicus. University of KansasMuseum of Natural History

Publication Vol. 18 (4):253-420.

Reichel, J., and D. Flath. 1995.Identification of Montana’samphibians and reptiles.Montana Outdoors 26: 30.

Russell, A. P., and A. M Bauer. 1993.The amphibians and reptiles ofAlberta. University of CalgaryPress, Calgary, AB. 264 pp.

Saskatchewan Conservation DataCentre. 1997. TheSaskatchewan ConservationData Centre. URL:http://www.unibase.com/~biodiversity/ [revision date: 7 October1997].

Secoy, D., and T. Vincent. 1976.Distribution and populationstatus of Saskatchewan’samphibians and reptiles.Saskatchewan Dept. ofEnvironment, Regina, SK. 46pp.

Smith, H. C. 1993. Alberta mammals:an atlas and guide. TheProvincial Museum of Alberta,Edmonton, AB. 239 pp.

Smith, W., and C. Wershler. 1989.Pilot project on the study of theWestern Hognose Snake inAlberta. Paper for AlbertaForestry, Lands and Wildlife bySweetgrass Consultants Ltd.,Calgary, AB. 17pp.

Stebbins, R. C. 1985. A field guide towestern reptiles and amphibians-field marks of all species in

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western North America,including Baja California.Houghton Mifflin, Boston, MA.336 pp.

The Nature Conservancy. 1998. Globalelement ranks. The NatureConservancy. URL: http://www.consci.tnc.org/src/ranks.html [Accessed: 16 Oct. 1998].

Watson, S. M., and A. P. Russell. 1997.Status of the Prairie Rattlesnake(Crotalus viridis viridis) inAlberta. Alberta EnvironmentalProtection, Wildlife ManagementDivision, and AlbertaConservation

Association, Wildlife StatusReport No. 6, Edmonton, AB.26 pp.

Willms, W. D. and J. F. Dormaar. 1996.Paper #1 from Proceedings ofthe fourth prairie conservationand endangered speciesworkshop. Provincial Museumof Alberta Nat. Hist. Occ. Pap.No. 23, Edmonton, AB. 337 pp.

Wright, A. H. and A. A. Wright. 1957.Handbook of snakes of theUnited States and Canada, vol.1. Cornell University Press,Ithica, NY. 564 pp.

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APPENDIX 1. Definitions of selected legal and protective designations.

A. Status of Alberta Wildlife colour lists (after Alberta Wildlife Management Division 1996)

Red Current knowledge suggests that these species are at risk. These species have declined, or arein immediate danger of declining, to nonviable population size

Blue Current knowledge suggests that these species may be at risk. These species have undergonenon-cyclical declines in population or habitat, or reductions in provincial distribution

Yellow Species that are not currently at risk, but may require special management to address concernsrelated to naturally low populations, limited provincial distributions, or demographic/lifehistory features that make them vulnerable to human-related changes in the environment

Green Species not considered to be at risk. Populations are stable and key habitats are generallysecure

Undetermined Species not known to be at risk, but insufficient information is available to determine status

B. Alberta Wildlife Act

Species designated as ‘endangered’ under the Alberta Wildlife Act include those defined as‘endangered’ or ‘threatened’ by A Policy for the Management of Threatened Wildlife in Alberta (AlbertaFish and Wildlife 1985):

Endangered A species whose present existence in Alberta is in danger of extinction within the next decade

Threatened A species that is likely to become endangered if the factors causing its vulnerability are notreversed

C. Committee on the Status of Endangered Wildlife in Canada (after COSEWIC 1998)

Extirpated A species no longer existing in the wild in Canada, but occurring elsewhere

Endangered A species facing imminent extirpation or extinction

Threatened A species likely to become endangered if limiting factors are not reversed

Vulnerable A species of special concern because of characteristics that make it particularly sensitive tohuman activities or natural events

Not at Risk A species that has been evaluated and found to be not at risk

Indeterminate A species for which there is insufficient scientific information to support status designation

D. United States Endangered Species Act (after National Research Council 1995)

Endangered Any species which is in danger of extinction throughout all or a significant portion of itsrange

Threatened Any species which is likely to become an endangered species within the foreseeable futurethroughout all or a significant portion of its range

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E. Natural Heritage Element Rarity Ranks (after The Nature Conservancy 1998)

Global or G-rank: Based on the range-wide status of a species.Sub-national or S-rank: Based on the status of a species in an individual state or province. S-ranksmay differ between states or provinces based on the relative abundance of a species in each state orprovince.

Rank Definition

G1 S1 Critically imperilled globally because of extreme rarity (5 or fewer occurrences, or very fewremaining individuals), or because of some factor of its biology making it especially vulnerable toextinction.

G2 S2 Imperilled globally because of rarity (6 to 20 occurrences), or because of other factors demonstrablymaking it very vulnerable to extinction throughout its range.

G3 S3 Either very rare or local throughout its range, or found locally in a restricted range (21 to 100occurrences).

G4 S4 Apparently secure globally, though it might be quite rare in parts of its range, especially at theperiphery.

G5 S5 Demonstrably secure globally, though it may be quite rare in parts of its range, especially at theperiphery.

Appendix 2. Locations where Plains Hognose Snakes have been reported in Alberta. Records correspond to sites mapped onFigure 2.

Description (1) Year Location (2) Source (3)Manyberries * no date 49°23' 47" N, 110°41' 40" W UAMZDunmore 1927 49°59' 00" N, 110°34' 45" W NMC, H. SeamansComrey 1938 49°07' 00" N, 110°44' 20" W UAMZ, E. Logier and J. BrownNone given 1940 W30-Tp17-Rge4-W4 Cottonwood Consultants 1987Craigmyle (South and west 89, state locationprobably incorrect) *

1949 51°37' 00" N, 112°15' 00" W J. Moore

Empress 1951 50°57' 00"N, 110°00' 40' W UAMZ, R. Lister and J. Moore13 mi. W and 5.5 mi. N of Wildhorse 1961 49°04' 49" N, 110°30' 15" W UAMZ, E. Stribney20 mi. W and 2.5 mi. N of Wildhorse 1962 49°02' 00" N, 110°39' 30" W UAMZ, J. RyderS14-Tp19-Rge2 1969 50°36'00" N, 110°10'00" W PMATp 13, Rge 1, Many Island Lake (PrairieTrail 2.4 km west of lake)

1969 50°08'00" N, 110°04'16" W PMA, M. Hampson

Hilda 1971 50°37'07" N, 110°05'40" W UAMZ23 mi. S and 4 mi. W of Empress 1971 50°37' 07" N, 110°05' 40" W UAMZ, N. PanterS14-Tp19-Rge2 1971 50°37'00" N, 110°11'00" W PMATp19-Rge 2, Hilda 1972 50°28'39" N, 110°02'00" W B. Shantz in Cottonwood Consultants 1986None given 1973 50°11' 00" N, 110°42' 38" W G. Pendlebury in Cottonwood Consultants 1986Bindloss 1975 Tp21-Rge3-W4 J. Picotte in Cottonwood Consultants 1986Atlee 1976 50°50'31" N, 110°54'25" W C. Wallis, C. WershlerComrey Breaks 1979 49°04'30" N, 110°41'28" W L. PowellN22-Tp22-Rge3-W4, Bindloss 1980 50°53'24" N, 110°19'12" W C. Wallis, C. Wershler in Cottonwood Consultants 1986Pakowki Lake; 14 mi. S, 1 mi. W of Orion 1980 49°15'07" N, 110°49'30" W UAMZ, J. AcornSouth of Onefour, north of Lost RiverCanyon

1980 49°04'04" N, 110°30'18" W L. Powell

Cavendish 1987 50°46'26" N, 110°27'14" W B. PicotteCFB Suffield 1987 50°18'03" N, 110°41'09" W C. Wallis, R. WershlerSandy Point Bridge 1987 50°44'24" N, 110°03'07" W C. WershlerRemount Ranch 1987 50°45'36" N, 110°21'03" W J. PicotteCavendish 1989 50°45'36" N, 110°22'51" W B. Worfell per W. SmithRemount Ranch 1989 50°45'36" N, 110°20'24" W W. Smith, C. Wershler

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Manyberries * no date 49°23'47" N, 110°41'40" W USMZRemount Ranch, SE Quadrant T21 R3 W4 * no date T21-R3-W4 J. PicotteBindloss Area SW Quadrant T22 R2 W4 * no date 50°51'21" N, 110°14'13" W J. PicotteJunction of highways 562 and 899 1990 50°58'22" N, 110°02'45" W S. Brechtel to J. Wright1.5 mi. W of junction of highways 562 and899

1990 50°58'22" N, 110°04'01" W S. Brechtel to J. Wright

SE8-Tp22-Rge7-W4 * no date 50°51'21" N, 110°57'50" W Gina OfadczukSW26-Tp23-Rge1-W4 1990 50 58'58" N, 110 02'09" W Carol Vokeroth, J. OliverWMU 148, N of Hwy 1 S and E of Suffieldto TWP 18 *

1990 Cory Schmidt

North of Many Island Lake 1991 50°13'44" N, 110°48'32" W Fred WeisgerberEtzikom 1992 49°12'39" N, 110°51'39" W Norman FinsteadS. Sask River at Koomati 1985 50°23'49' N, 110°35'16" W L. Hildebrandt, R&L EnvironN. end of Remount Pasture (use middle ofTwp)

1991 50°51'21" N, 110°13'55" W H. Fieldberg

Due N. of Cowley Bridge, Oldman R., W ofPeigan Reserve

1990 49°41'38" N, 113°43'44" W Chantal Pattenden, R&L Environ

North bank of Bow River, 2 mi. W ofHighway 875 Bridge

1972 50°08'49" N, 110°45'03" W Harry Armbruster

0.5 km N of junction of Hwy 501 and 502,near Manyberries

1996 49°14'06" N, 110°43'55" W Danna Schock

None given 1990 50°30'25" N, 110°31'51" W AECN. of junction of 1st road W of Bindloss andHighway 555

1990 50°51'43" N, 110°16'44" W Michael O'Shea

N. of junction of 1st road W of Bindloss andHighway 555

1990 50°51'43" N, 110°16'44" W Michael O'Shea

N. of junction of 1st road W of Bindloss andHighway 555

1990 50°51'43" N, 110°16'44" W Michael O'Shea

CFB Suffield 1994 50°22'25" N, 110°40'36" W AECCFB Suffield 1994 50°13'16" N, 110°50'45" W H. ReynoldsEllice Ranch - yard of first ranch house 1994 50°13'14" N, 110°37'18" W G. EllisCFB Suffield 1994 50°13'47" N, 110°40'39" W G. EllisCFB Suffield 1995 50°13'16" N, 110°59'10" W B. DaleCFB Suffield 1995 50°27'48" N, 110°38'52" W A. Bezner

24

CFB Suffield 1995 50°16'29" N, 110°43'10" W B. DaleCFB Suffield 1995 50°19'11" N, 110°43'59 W A. DidiukCFB Suffield 1995 50°13'16" N, 110°50'45" W B. DaleCFB Suffield 1995 50°28'53" N, 110°38'52 W P. GoossenCFB Suffield 1995 50°19'11" N, 110°43'59" W A. DidiukCFB Suffield 1995 50°28'21" N, 110°38'52" W B. DaleCFB Suffield 1995 50°20'17" N, 110°49'02" W J. WrightCFB Suffield 1995 50°21'20" N, 110°42'17" W J. SifertCFB Suffield 1995 50°30'27" N, 110°27'00"W A. DidiukCFB Suffield 1995 50°37'27" N, 110°20'59" W A. DidiukCFB Suffield 1995 50°33'44" N, 110°35'26" W AECCFB Suffield 1995 50°14'52" N, 110°43'10" W B. DaleCFB Suffield 1995 50°33'10" N, 110°29'31" W H. KillianCFB Suffield 1995 50°19'10" N, 110°38'05" W A. DidiukCFB Suffield 1996 50°19'11" N, 110°43'59" W A. DidiukCFB Suffield 1996 50°19'11" N, 110°43'59" W A. DidiukCFB Suffield 1996 50°20'16" N, 110°42'18" W A. BeznerCFB Suffield 1996 50°28'52" N, 110°33'47" W B. DaleCFB Suffield 1996 50°30'27" N, 110°27'00" W A. DidiukCFB Suffield 1996 50°33'42" N, 110°29'30" W J. WrightCFB Suffield 1996 50°19'11" N, 110°43'59" W A. DidiukCFB Suffield 1996 50°36'56" N, 110°27'46" W H. ReynoldsCFB Suffield 1996 50°22'25" N, 110°41'26" W A. DidiukCFB Suffield 1996 50°13'16' N, 110°51'35" W H. ReynoldsCFB Suffield 1996 50°13'15" N, 110°42'20" W AECBowmanton Road 1997 50°10'30" N, 110°28'55" W L. PowellHighway 41 1997 50°02'25" N, 110°31'31" W J. WrightCFB Suffield 1997 50°13'16" N, 110°50'45" W R. Lauzon, J. WrightCFB Suffield 1997 50°13'48" N, 110°50'45" W R. Lauzon, J. WrightCFB Suffield * no date 50°34'55" N, 11030'00” W AECTinny's Homestead Den At Sherwood Forest*

no date 50°27'43" N, 110°32'09" W Norm Rubelki

Majestic Ranch, Red Deer River South FaceOn South Shore *

no date 50°51'36" N, 110°47'38" W M. Schornhofer

25

Cavendish, South Shore Of Red Deer River,South And West Slopes *

no date 50°53'02" N, 110°24'07" W Tony Minor

Burdett Region * no date 49°50'13" N, 110°34'12" W Larry NelsonN. Of Red Deer Lake * no date 50°24'39" N, 110°24, 07" W Bert HargraveWolfer Residence Near Sandy Point OnSouth Sask. River *

no date 50°43'33" N, 110°03'07" W Floyd Wolfer

In Region of Special Areas Grazing Lease,Dinosaur Prov. Park (Mapped As “DateUnknown” in Figure 1)

no date 50°45'07 N, 111°30'32" W John Flyberger

(1) Locations denoted by an asterisk (*) are not mapped because specific location or date is unknown(2) Given as latitude/longitude or Sec-Twp-Rge; location information should not be used for any purpose without the permission of the authors(3) UAMZ=Univ. of Alberta Museum of Zoology; NMC=National Museum of Canada; PMA=Prov. Museum of Alberta; USMZ=University of

Saskatchewan Museum

26

List of Titles in This Series(as of January 1999)

No. 1 Status of the Piping Plover (Charadrius melodus) in Alberta, by David R. C. Prescott. 19 pp.

No. 2 Status of the Wolverine (Gulo gulo) in Alberta, by Stephen Petersen. 17 pp.

No. 3 Status of the Northern Long-eared Bat (Myotis septentrionalis) in Alberta, by M. CarolinaCaceres and M. J. Pybus. 19 pp.

No. 4 Status of the Ord’s Kangaroo Rat (Dipodomys ordii) in Alberta, by David L. Gummer. 16 pp.

No. 5 Status of the Eastern Short-horned Lizard (Phrynosoma douglassii brevirostre) in Alberta, byJanice D. James, Anthony P. Russell and G. Lawrence Powell. 20 pp.

No. 6 Status of the Prairie Rattlesnake (Crotalus viridis viridis) in Alberta, by Sheri M. Watson andAnthony P. Russell. 26 pp.

No. 7 Status of the Swift Fox (Vulpes velox) in Alberta, by Susan E. Cotterill. 17 pp.

No. 8 Status of the Peregrine Falcon (Falco peregrinus anatum) in Alberta, by Petra Rowell and DavidP. Stepnisky. 23 pp.

No. 9 Status of the Northern Leopard Frog (Rana pipiens) in Alberta, by Greg Wagner. 46 pp.

No. 10 Status of the Sprague’s Pipit (Anthus spragueii) in Alberta, by David R. C. Prescott. 14 pp.

No. 11 Status of the Burrowing Owl (Speotyto cunicularia hypugaea) in Alberta, by Troy I. Wellicome.21 pp.

No. 12 Status of the Canadian Toad (Bufo hemiophrys) in Alberta, by Ian M. Hamilton, Joann L.Skilnick, Howard Troughton, Anthony P. Russell, and G. Lawrence Powell. 30 pp.

No. 13 Status of the Sage Grouse (Centrocercus urophasianus urophasianus) in Alberta, by Cameron L.Aldridge. 23 pp.

No. 14 Status of the Great Plains Toad (Bufo cognatus) in Alberta, by Janice D. James. 26 pp.

No. 15 Status of the Plains Hognose Snake (Heterodon nasicus nasicus) in Alberta, by Jonathan Wrightand Andrew Didiuk. 26 pp.

No. 16 Status of the Long-billed Curlew (Numenius americanus) in Alberta, by Dorothy P. Hill. 20 pp.

No. 17 Status of the Spotted Frog (Rana luteiventris) in Alberta, by Janice D. James. 21 pp.

NOTES