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Each fall, hunters enjoy their time afield. Experienceswith family and friends become lifetime memories and

the basis for many deer camp stories. If successful, they havethe added benefit of venison in the freezer. It may not bereadily apparent, but the deer killed by those successfulhunters also provide much of the information necessary tomanage New Hampshire’s deer population.

The New Hampshire Fish and Game Department collectsa variety of information from New Hampshire’s hunter-killed deer to assist in deer management and to help assessthe health of the deer and their habitat. Mandatory registra-tion of hunter-killed deer at one of about 90 stations aroundthe state allows the collection of complete harvest informa-tion on a Wildlife Management Unit-specific basis.

This registration data allows the harvest to be accuratelymonitored and the deer population to be assessed in relation-ship to the specific population management objectivesdeveloped for the long-range New Hampshire Big GamePlan. In the process, we get a good snapshot of the health anddistribution of our deer.

WEIGHTS AND MEASURESIn addition to analyzing registration data, Fish and Game

biologists work at biological check stations each fall. Atvarious deer registration stations across the state, they col-lect more detailed information on harvested deer, includingweight, antler beam diameter, number of antler points andwhether females still have residual milk in their udder. Thebiologists also age the deer to the nearest year by looking atthe deer’s teeth. Replacement of “milk teeth” and tooth wearprovide an efficient method of assessing a deer’s age out toat least five years.

The detailed biological data collected during the seasonallows biologists to assess the health of the deer in relation-ship to habitat quality. Decreases in average antler beamdiameters, weights or lactation rates can suggest that deerdensities are beginning to approach the “biological carryingcapacity” of the habitat. As deer numbers increase, thequality of their habitat gets worse, and the animals’ physicalcondition begins to decline. These measures of physicalcondition are most sensitive in yearling deer (those that are1.5 years old in the fall). Yearling male antler beam diam-eters have recently averaged 17.5mm and field-dressedweights averaged 115 pounds in New Hampshire. An aver-age of about 16% of New Hampshire’s yearling does stillshow evidence of milk in their udder in the fall. This tells usthat at least this proportion must have been bred the previous

The hunter harvest is a rich sourceof management information for

wildlife biologists.

BY KENT GUSTAFSON

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fall, when they were ap-proximately 6 months ofage, and gave birth to afawn in early summer atthe age of about one year.

All of these measuresshow that NewHampshire’s deer arecomfortably within thebiological carrying ca-pacity of the habitat.However, if, for example,average yearling buckantler beam diameterswere consistently below16mm, it could indicate adecline in physical con-dition because high deernumbers are reducinghabitat quality.

In many cases, how-ever, increased deer-human conflicts betweendeer and gardeners, farm-ers and forest landownersbecome a problem beforedeer numbers exceed thetrue biological carryingcapacity of the habitat.This type of situation cancurrently be seen inWMU M in southeasternNew Hampshire. Whilethe herd is healthy, theregion has more deer thandesired. To address thissituation, since 1997 Fishand Game has offeredhunters special permits totake an additional antler-less deer in Unit M. Thenumber of these Unit M

special permits increased this year to a total of5,500 (up from 3,250 in 2005), reflecting a long-term goal of reducing deer numbers in thisurbanized area of the state.

WEATHER AND HABITATDeer hunting is the primary management tool

used to regulate deer numbers in New Hampshire,but many other factors also influence deer popu-lations. In northern New England, severe winterscan have a big effect on deer. In northern climateslike New Hampshire’s, deer are dependent onspecialized forest habitats commonly referred to

as “deer yards” or deer winter-ing areas. These areas aretypically mature softwoodstands, but may be composedof spruce and fir in the north,or hemlock and pine in thesouth. At times when snowdepths exceed approximately18 inches or temperatures fallbelow zero, these mature soft-wood stands provide deer withareas of reduced snow depthsand slightly warmer tempera-tures under the closedsoftwood canopy.

In spite of the benefits pro-vided by deer wintering areas,prolonged periods of deepsnow and cold can result inhigh deer mortality rates fromstarvation or predation. Win-ter feeding of deer by peopleprovides limited benefits, andcan even hurt the herd because of increased crowd-ing, stress and vulnerability to predators anddangerous roadways. In addition, following a se-vere winter, fawn production and survival may belower because of the poor condition of does.

New Hampshire Fish and Game has monitoredthe potential effect of winter on deer populationssince the winter of 1964-65. This winter severityindex (WSI) is collected from December 1 throughApril 30 each winter and is based on the numberof days with 18 or more inches of snow on theground and the number of days when the tempera-ture falls below zero. Large differences exist acrossthe state, with the long-term average WSI in far

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Fields, forest edges,swamp borders andwoodland openings aregood places to look fordeer, which feed on avariety of plantsdepending on theseason.

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northern New Hampshire be-ing 119, compared to 20 insoutheastern New Hampshire.

In addition to monitoringWSI, wildlife biologists moni-tor deer wintering areas acrossthe state by assessing theirquality and use by deer. About45 deer yards are assessedeach winter, monitoring in-tensity of use, browseavailability and the impact ofdevelopment and winter mor-tality. Deer populationmanagement efforts take intoaccount the potential increasein deer mortality during un-usually severe winters, anddeer seasons may be adjustedfollowing these severe win-ters to mitigate their effects.

An example of this wasseen after the harsh winter of

2002-2003, one of the most severe in decades,especially in central and southern New Hamp-shire. Fish and Game responded by reducing thenumber of days for taking antlerless deer thefollowing fall. The 2003 deer season saw a 14%decrease in the total statewide deer kill, reflectingin part the impact of the previous severe winter,including above-average winter mortality and lowproductivity (fewer fawns) the following spring.Fish and Game’s efforts to reduce the impact ofthe severe winter by limiting antlerless harvestduring the 2003 season also contributed to areduction in total harvest. Weather was kinder thefollowing winter (2003-04), and reducing theantlerless harvest in 2003 had helped offset theeffects of the previous hard winter. As a result, theherd rebounded, and in 2004 hunters in NewHampshire registered a 7 percent increase in deerharvest.

Development is another factor affecting deerpopulations, one that could potentially have themost adverse effect on deer and other wildlifehabitat in New Hampshire. While deer are veryadaptable and can thrive in relatively suburbanareas, development decreases the amount of deerhabitat; decreases its quality; increases deer-hu-man conflicts; and makes control of deer numbersmore difficult by limiting hunter access.

KEEN SENSESDeer hunters and others who have watched or

studied deer know that their senses — includinghearing, smell and vision — are very good. Adeer’s ears can rotate like radar to track suspicioussounds that might pose a threat. Their sense of

smell is highly developed andhelps them detect predators, findfood and recognize other deer. Italso allows bucks to find andfollow females during the fallbreeding season or “rut,” whichtypically peaks about the thirdweek of November.

Vision is one of the deer’smost important senses. Theplacement of their eyes allowsfor a wide field of view, andtheir eye structure allows deer tohave good vision both in thedaytime and at night. They areparticularly adept at detectingeven subtle movement. It is hardto interpret the deer’s ability tosee what we call “color,” butresearch suggests that deer aremost sensitive to violet, blue andgreen. They are less sensitive toorange and red than other col-ors, which explains why blazeorange clothing doesn’t alarmthem. Typically, brightness andcontrast draw a deer’s attention.

Hunters and many others haveprobably witnessed deer “snort-ing” or “blowing,” frequentlyaccompanied by stamping of thefront feet when a deer is suspi-cious, but uncertain, of something it has seen,smelled or heard. This is most likely an attempt tostartle the potential threat into moving, making iteasier for the deer to identify. Once aroused to thislevel of suspicion, a deer is unlikely to calm downand will almost certainly leave the premises,sometimes in a big hurry and most probably withits “white flag” raised.

HOW ANTLERS GROWMale white-tailed deer and other members of

the deer family grow antlers each year. Antlersare composed of true bone and are shed eachwinter. Typically, antler growth begins from mid-March to early April. Growing antlers are filledwith blood vessels and nerves and are coveredwith hairy skin called “velvet.” By August orSeptember, the antlers stop growing, the bonehardens and the velvet is shed or rubbed off byOctober. Evidence of this can often be seen as“buck rubs” on young trees or shrubs.

While a buck’s antlers tend to get larger withage, nutrition and genetics play an important role,so antler size and number of points are not neces-sarily good indicators of a buck’s actual age.

Deer are red-greencolor blind. Theypossess less sensitivityto long wavelengthcolors, so red, orange,yellow, yellow-green,and green appearshifted in hue andpaler to a deer’s visionthan they do to thehuman eye. With agreater sensitivity toshort wavelengthcolors, deer see bluesand violets as brighterthan humans do. Thelower image is anapproximation of whata deer might seelooking at the orangeand blue-clad hunter attop.

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Antlers are shed from December though Feb-ruary, and re-growth begins again in the spring.Rarely, antlers occur in female deer with hormoneimbalances or other problems, but these antlersare typically small and never lose the velvet.Occurring only in about 1 of 1,000 does, theseantlered females are usually fertile and are normalin other respects.

MANAGING THE HARVESTAntlers, while they are important to deer, and

to deer hunters, also play a role in deer manage-ment. Deer population management isaccomplished through the strategy of regulatingthe “antlerless” deer harvest. Antlerless deer areconsidered those with antlers less than 3 inches inlength, while antlered bucks are those that have atleast one antler 3 or more inches long. While someantlerless deer are buck fawns, most are females.Since it is female deer that have fawns each year,and older does can have twin fawns each year,controlling the number of female deer in thepopulation can control the productivity of the deerherd, causing populations to increase, decreaseor stay the same.

In New Hampshire, antlerless harvests havebeen regulated for many years by adjusting thenumber of “either-sex” hunting days allowed on aunit-specific basis. During these either-sex days,both antlered and antlerless deer can legally betaken, while at other times during the season, onlyantlered deer can legally be harvested. Long expe-rience allows biologists to estimate the effect ofeither-sex days on the antlerless harvest and to setseasons that will result in population growth,decline or stability. The deer harvest is monitoredannually to assess the results of the season, and thephysical condition of the deer and the impacts ofwinter severity are also considered in establishingdeer seasons.

In addition to population objectives, the BigGame Plan seeks to maintain a diversity of ageclasses in the deer population, specifically amongadult males. When at least 50% of the adult malesare 2.5 years old or older, hunters have an in-creased chance of harvesting deer of an older ageclass; it also helps avoid potential concerns overbreeding ecology that may occur when a very highproportion of adult males are only yearlings (1.5years old). During the last three years in NewHampshire’s North Country (WMU A), for ex-ample, the yearling buck frequency has averagedalmost 60%. Fish and Game needed to reduceharvest pressure on bucks in that unit, so this fallthe regular firearms deer season will close a weekearly in WMU A. Based on previous years, thisshould reduce the buck kill enough to maintain olderage bucks in that WMU. Once the management goalis met, the season can be lengthened again.

Deer can live to be 15 years old or more, butthis is rare in wild populations. Each year duringbiological check station operation, a fair numberof female deer are seen that are ten years old orolder. This is much rarer among bucks, as harvestmortality rates tend to be higher than for females,and the natural mortality rate of males is alsohigher, largely because of the stresses associatedwith the rut that make it less likely that a buck willlive to a ripe old age.

Twenty-two years ago, in 1983, the total deerharvest in New Hampshire was only 3,280. Thesedays, it typically exceeds 10,000 per year. With apopulation of about 85,000 deer in New Hamp-shire, hunters and the public benefit from therecreation, enjoyment and venison these deer pro-vide. While there are many facets to deer biologyand management, the future of white-tailed deeras a valued part of New Hampshire’s wildlifeis secure.

Wildlife Biologist Kent Gustafson is the DeerProject Leader and biometrician for the NewHampshire Fish and Game Department.

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continued from previous pageThe “antler beamdiameter” of hunter-killed deer can bean importantmeasurement of deernutrition and herdhealth.