TRANSACTIONS of the

Forty-fifth North American Wildlife and Natural Resources

Conference

Conference Theme:

Balancing Natural Resources Allocations

March 22-26. 1980 Deauville Hotel

Miami Beach. Florida

Edited by Kenneth Sabol

Published by the

.Wi~·~~~ft'6LtF~ SMVlcf ~f ~RVATfON TRAINING CE~'TI=:R

CONSEAVA TlON LIBRARY ~ n,..,..1 __

Biogeography and. the Conservation of Birds .

is a complex science encompassing several disciplines­biology, ecology. taxonomy, among others. It also is an old science

descriptive geography of plants and animals. During the last decade, theory has assimilated .new concepts and has emerged as the con­

point in the design of preserves for wildlife (Wilson and Willis 1975). ource management is often more art than science (Goeden 1979),

theory may aid in the decision-making process; thus, the intent of paper is to review the concept as a management tool in the conserva­

The emphasis is on inland islands-prairie relicts, forests in­among agricultural lands, mountains rising above low lying areas, or parks isolated by urban development. Nearly all inland nongame

are insular in character, clearly distinguished from surrounding un­and recognized as distinct by the birds utilizing them.

Jilit.riUln .. model of MacArthur and Wilson (1967) proposes the number of by an island reflects a dynamic equilibrium between immigration

extinction rates influenced by isolation between islands and island area ). Perhaps no other ecological theory has generated as much recent for over 100 articles involving the theory are included in recent reviews

1974, Stenseth 1979). The crowning achievement nas been the exten­of island concepts to the design of refuges for tropical birds to

species will be maintained and for how long (Faaborg 1979). to the model, species turnover (immigrations and extinctions) should

n small islands while total number of insular species remains relatively (Figure 1). In Illinois, Whitcomb et al. (1976) reviewed Kendeigll's an­

bird censuses of a small isolated (22 ha) forest preserve and repOrted . In that study, only 9 of 62 total species were represented in each of

since 1927 and 6 others only bred sporadically. Three birds, normally of the interior of eastern deciduous forests, were not recorded. of breeding species, however, remained relatively constant, thus in

. . with the equilibrium model. for the impact of isolation comes from comparisons of species numbers

in eastern forest islands isolated by agriculture or urban development species) to those islands similar in size and vegetation but near exten­

(more bird species [Whitcomb et al. 19761). Declines of 35 to 87 neotropical migrants are evident in metropolitan parks in the District of or Maryland as urban growth has increased their isolation from similar

G>

ro a:

Near to mainland

Far from mainland

\ , , , , , , " ",

" " ....

Extinction rate Immigration rate

Number of species present

Figure 1. The equilibrium model of island biogeography explains of immigration rates, extinction rates, island isolation, and area. immigration rates and low extinction rates, as do islands near maid)IU and Wilson 1967).

habitat. In a study I conducted in Missouri in 1978 and 1979,~t prairie in the southwest where relicts are clustered held 15 12 (1977) or 13 (1978) on an isolated 31A-ha relict.

Thus, available evidence suggests land managers shouI<l communities as dynamic entities changing in species co by rates of immigration and extinction and extent of isolation frtm'l

Island Area

Extensive evidence indicates that the number of plant or particular habitat island is strongly influenced by size of that the area of Great Basin montane "islands" is significantly permanent boreal bird species (Brown 1978). In Montana, predicted the number of bird species breeding in forests, habitats more than habitat heterogeneity, topographY, or reli~ Hills (Thompson 1978). On a local scale, insular area heterogeneity of mixed oak patches of varying size in New factor in predicting number of breeding bird species (Galli et al Avian use of Illinois lowland hardwoods (Graber and Graber northern hardwoods (Tilghman 1977), Seattle urban parks Chicago cemeteries (Lussenhopp 1977), and South Dakota 1978) is influenced by insular area. In my study in Missouri, habitat heterogeneity or food, had a significant influence on species breeding on 12 tallgrass prairies. '

from local species-area studies is a relatively new concept, the deIJen<tellcy of many bird species (Table I). It is clear that extensive

habitats are important to the long-term survival of many populations of et al. 1977, Robbins 1979). Nearly 50 percent of the birds breed­

Jersey mixed oak patches were habitat size-dependent (Galli et at ere 50 percent in Appalachian forests (Robbins 1979). Nearly two-thirds

breeding on tallgrass prairies are habitat size-dependent (Table 1). for the habitat size-dependent concept comes primarily from two

the species-area studies (Figure 2) and the observed localized extirpa­species. Declines of 20 to 92 percent in numbers of size-dependent and vireos occurred during the last four decades as large eastern forests

fragmented (Lynch and Whitcomb 1978). Formerly widely distributed cies, the Henslow's sparrow, upland sandpiper, and greater prairie

DOW on state rare or endangered species lists as their habitat has been to other purposes. Most species on the Blue List regularly reported in Birds are either colonial nesters or habitat size-dependent species ..

, there are clear biological correlates to the habitat size-dependent Habitat size-dependent eastern forest species are primarily neotropical nest on or near the ground in forest interiors, and raise a single brood

mall clutch. Several size-dependent prairie species share these patterns. size-independent species-the starling (Stumus vulgaris), gray catbird

carolinensis), common grackle (Quiscalus quiscu/a), American robin migratorius). rufous-sided towhee (Pipilo erythrophthalmus), and

biologically and have not been negatively affected by habitat frag­They are permanent residents or short distance migrants, have two or

per year, nest in the edge or higher in the forest habitat, and generally eater chance for reproductive success (Robbins 1979). Unfortunately, habitat size requirements for nongame birds breeding in riparian forests

, western montane forests and meadows, deserts, short or mixed .f1"''''U.'''''' and other major ecotypes are not known.

intent of the present paper is to contribute toward a management policy for American nongame birds, specifically the preservation of all naturally oc-North American species. In recent North American Wildlife and Natural

Conferences, two major management thrusts for nongame birds have , habitat diversity and a species-centered approach.

diversity is a major consideration in managing north-central forests and Radtke 1977). Its objective, to establish the greatest diversity with a mixture of habitat components. results in a forest with different vegeta­s, age stands and habitat types,

than 60 species of nongame birds breed in north-central forests, 80 per­rate annually, and the most abundant are warblers. Few of these are species and the overall species richness is dependent on presence of

species (Temple et al. 1979). As noted before, there is increasing that many migrants (particularly warblers) nesting in the interior of

are habitat size-dependent, requiring a large contiguous habitat area for

Lowland Hardwoods

_----- Mixed Oak Forests

__ - ....... ....------ Tall Grass Prairies

8

ISLAND SIZE (HAl Examples of avian species-area relations in lowland hardwoods after Graber and

mixed oak forests, Galli et aI. (1976); and tallgrass prairie, Samson (unpub.

survival. If habitat diversity is achieved by subdividing large contigu.ous then a clear possibility exists for the local .or regi.onal l.oss .of habitat

species. If the management g.oalis t.o maintain all naturally occur­large tracts need t.o be maintained (Temple et aI. 1979). Lastly, there

Qther issues related to this appr.oach. Notelati.on between habitat diver-number of breeding bird species exists in s.ome habitats (Tomoff 1974),

of diversity differ, and extensive.data.on s.ongbird habitat use suggest habitat diversity is hardly a valid .objective f.or n.ongame bird manage­issues have been discussed elsewhere (Webb 1977).

management approach centers .on a species either featured, sensi­indicalt.or. Featured species management has been rec.ommended f.or s.outh­

(G.ould 1977). The species sensitivity approach (Webb 1977) is directed vOiding drastic c.onsequences f.or selected s.ongbirds. An indicator species used by land management agencies to m.onit.or the effect .of lana use

this species, I suggest the habitat size-dependent species requiring minimum area in the habitat under c.onsiderati.on be selected fr.om a

curve (Table 1). By d.oing s.o, the integrity .of an entire bird c.ommu­its habitat is maintained; the effect .of habitat perturbati.on, particularly

IlloJllit()reld;' and the emphasis is .on the l.ong"term survival.of all species, size-dependent and independent. T.o illustrate,a tallgrass prairie in

with a viable greater prairie chicken populati.on, the species with the linilmUlfJ1 area (Table 1), also held all .other species. An excepti.on may be if endangered species occurs .on an area. H.owever, manY .of these species

minimum area requirements; thus both minimum area and rarity may as useful in the species appr.oach.

species-area approach als.o has land use applicati.ons. On a species-area a minimum area point is reached where a 5-percent i,ricrease in number .of

Table 1. Examples of preliminary estimates of minimum size tain viable breeding populations (Galli et aI. 1976, Robbins 1979,

Minimum area (ha)

1-10

>10-100

>100

Eastern deciduous forest species

YeUow-billed cuckoo (Coccyzus americanus)

Blackcbilled cuckoo (c. erythropthalmus)

Red-bellied woodpecker (Melanerpes carolinus)

Hairy woodpecker (Picoides villosus)

Downy woodpecker (P. pubescens)

Eastern wood pewee (Contopus virensj

Black-capped chickadee (Parus atricapiilus)

Tufted titmouse (P. bicolor)

White-breasted nuthatch (Sitta carolinensis)

Blue jay (Cyanocitta cristata)

Red-shouldered hawk (Buteo-lineatus )

Wood thrush (Hylocichla mustelina)

Yellow-throated vireo (Vireo flavifrons)

Red-eyed vireo (V. olivaceus)

Prothonotary warbler (Protonotaria citrea)

Northern parula (Parula americana)

Louisiana water thrush (Seiurus nwtacilla)

Scarlet tanager (Piranga olivacea)

Summer tanager (P. rubra)

Black-and-white-warbler (Mniotilta varia)

Worm-eating warbler (Helmintheros verminovorus)

Ovenbird (S. aurocapillus)

species requires a doubling in habitat size. This point is Missouri oak~hickory forests (M. R. Mitchell, pers. .. Jersey mixed oak forests (Formanet aL 1976), at 98 ha prairies, but few estimates for other habitats are available. ..

Lastly, not all management units, parks or refuges .. species. Thus, the minimum area point may be useful for the majority of the species in a community and erations, whether they be size of timber harvest in manaj;ed acquisition, or the design of urban, suburban or rural

Summary

First. habitat for nongame birds is becoming inc:re~lSitlgl~rj tural or other human activities, thus more insular in species on these islands is influenced by area, distance of immigration and extinction. These factors should be vation of nongame birds .. The need is urgent because the mentation is. escalating and generaI1yirreversible.

Second, to date no study has shown that a nongame America is restricted to small habitat islands. while dependent, requiring large contiguous habitats. Thus, I other authors (Whitcomb et aL 1976, 1977, Robbins 1979) emphasized in the conservation of nongame birds. This vation of small, unique or diverse habitats needed for these areas.

Third, I concur with Webb (1977) that a spe~cjes-centere:d most useful for nongame bird management. In practice. may aid in the selection of the species. and the concept use planning. The challenge now is to implement a widely cal theory in the management of nongame birds. Its of game birds (Fritz 1978), big game (Picton 1979) and·iI taxa is already evident.

Acknowledgments Financial support was provided by the Missouri Cooperative

Fish and Wildlife Service; Missouri Department of . . Fisheries and Wildlife, University of Missouri; and Wildlife ing), 1 thank: T. S. Baskett, C. F. Rabeni, U;S. Fish and G. E. Probasco. U.S. Forest Service; R. L. Clawson, Miss tion; W. W. Taylor. and E. K. FritzelI, University of Missouri; anti University. who provided helpful criticisin on the· manuscript; and Morgan for typing and styling the manuscript.

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