White-tailed deer • The most popular big game animal in North America – Abundance

White-tailed deer • Most abundant and wide-spread large mammal in NA (excluding humans)

– Distribution = widespread = accessible

– In 1990s 5.3 million WTD harvested

– Early successional species, highly adaptable

– Over 10 million hunters – Elusive and challenging

Baker (1984)

White-tailed deer

White-tailed deer • 38 subspecies

Mule and WT-D • Tail • Antlers • Metatarsal glands • Skull characters

Fig 10-1 Geist 1998 Deer of the World

– – – – –

Canada 100-135 kg Kansas 90-95 kg Texas 40-70 kg Venezuela 45 kg Key deer 35 kg

Adult (same-aged) whitetailed deer males

Venezuela

Michigan

Baker (1984)

White-tailed deer • 2 T&E populations of WT-D – Key deer in Florida (listed in 1967) – Columbia WT-D (listed in 1968)

White-tailed deer • 2 T&E populations of WT-D – Key deer in Florida (listed in 1967) • Populations are doing well • Habitat is severely restricted • Human development • Hurricanes could be problem.

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White-tailed deer • 2 T&E populations of WT-D – Columbia WT-D (listed in 1968) • Populations in NW Oregon along Columbia river doing poorly

White-tailed deer • R or K selected compared to all mammals in NA? – R-selected: extreme example = mice – K-selected: extreme example = whales

• Populations in W and SW Oregon doing well – Even causing problems in suburban areas – Recently delisted, limited hunting allowed.

White-tailed deer • More R-selected than most

• Compared to other large mammals we discuss in this class?

White-tailed deer • High densities cause problems – Affect forest, habitat composition

• Population trends during past 500 yrs – Early 1900s 500,000 – Currently 20 million

• Range expansion

– Human-wildlife conflicts • Ag damage • Road kills

– Competition with mule deer?

– Eastern CO, Northern UT

from The Science of over abundance by McShea, Underwood, and Rappole

• Figs 3-4; Journal Wildlife Manage 58:715

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White-tailed deer • High densities of WT-D causing ecological problems – In PA, WT-D browsing affected songbirds • intermediate canopy nesting species

White-tailed deer • High densities of WT-D causing ecological problems – In MA, deer browsing reduced forbs, increased grass Æ fewer voles and shrews, and more mice

• Recommended deer densities: < 8/km2 (1 deer/30 ac)

– Loss of rare or sensitive plant species

White-tailed deer • Damage by WT-D is a concern – Ag Damage • 51% Ag producers reported deer damage; Wildlife damage to crops $4.5 billion/yr

White-tailed deer • Damage by WT-D is a concern – Suburban-Urban damage • Vehicle collisions – 1.5 million annually, 1.6 billion annually, 29,000 people injured and 200 killed annually

• Deer damage to timber industry $1.6 billion • 2.4 million households reported deer damage, primarily landscape plants

White-tailed deer

White-tailed deer

• Controlling urban deer (WSB 29:1105-1113) • 4 control methods in MN urban parks – – – –

• Table 2, Doerr et al. 2001. WSB 29:1105-1113

Controlled hunts (archery) Shooting by conservation officers in parks (deer drives) Sharp shooting over bait by park rangers Sharp shooting over bait by police officers

• Net cost of each approach – $117/deer; $108/deer; $121/deer; $194/deer

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White-tailed deer

Northern White-tailed Deer White-tailed deer ecology, populations, and management change outside of Texas

• Table 1, Doerr et al. 2001. WSB 29:1105-1113

More public land, smaller land holdings, and few high fences Few old bucks, low buck:doe ratios Highly seasonal, relatively predictable environment

Effects of Snow In the north, conditions are good in the summer and bad in the winter. Because this is predictable, deer have adapted to surviving winter conditions.

Effects of Snow

• Reduce food availability • Deer must search for high quality food under snow • Increase energy expenditure during travel

Adaptations to Survive Winter • Accumulate body fat summer & fall • Lower metabolic rate and obligate loss of body mass overwinter • Habitat use Æ Deer yards • High density (1/4 ac)

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Adaptations to Survive Winter • Large body size – Lower surface area:volume ratio • Volume = ability to produce heat • Area = potential to lose heat

– Enables deer to carry more fat relative to metabolic rate – Longer legs Æ Less impact from deep snow

Severe Winter Impacts • Fawns most susceptible – Reduced growth and lower survival

• Does’ body condition will decline – Affects fawn development and lactation – Up to 70% of fawns may die soon after birth after severe winter

• Bad winters = high adult mortality – 76% mortality has been documented

Timing of Fawning

3 Populations: Case Studies

• Strong selective pressure – Born early = susceptible to late freezes – Born too late = can’t get large enough and store enough fat to survive the winter

• What is a possible effect of highly skewed sex ratios on timing of fawning?

• Illinois – Nixon et al. 1991 Wildl. Monogr. 118 • Minnesota – Fuller 1990 Wildl. Monogr. 110 • Montana – Dusek et al. 1989 Wildl. Monogr. 104

Illinois Farm Land

Illinois Farm Land

• 600 ha park, unhunted and forested in a sea of agriculture with small woodlots

• Upland woodland plots used as summer range by deer that disperse or migrate from larger forests or refuges in spring. Woodlots were usually vacated each fall.

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Population Highly Productive • < 5% yearling had spikes • 10 pts common – Fawns weighed 75-95 lbs during winter

• 76% of female fawns conceived – – – –

1.13 fawns/female fawn in October Adults recruited 2.1 fawns/doe in October 14% of does had triplets Fawn survival to Oct. was 90%

Deer Movements • 50% of fawns dispersed each spring – Moved 40-50 km from the refuge – 21% yearling females dispersed from refuge – 20% adult does migrated • average 13 km off the refuge in spring • returned in fall

• λ = 1.09 to 1.37 – (Population double in 9 years)

• Nixon et al. 1991 Wildl. Monogr. 118 • Tables 5 and 6

Dispersal and highly productive herds necessary to maintain deer in this fragmented landscape Need to protect corridors

Central Minnesota • Deer herd in boreal forest – Habitat conditions relatively constant – λ = 0.79 to 0.84 – 10 Æ 4 deer/km2 (1 deer/25 ac to 1/62 ac) – Concern because deer are prey for wolves

• Is the decline due to excessive mortality or low recruitment… Study to determine which

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• Fuller 1990 Wildl. Monogr. 110 • Tables 4, 5, and 7

Central Minnesota

Lower Yellowstone River

• Fawn annual survival was 0.22 – 80% mortality during the summer of birth

• Fawn survival overwinter – 0.89 when snow depth 13-16 cm – 0.60 when snow depth 36-44 cm

• Author modeled population – No single factor could result in increasing pop. – No doe harvest or 3 day hunting season λ = 0.95 – Several mild winter and no doe harvest λ > 1.0

• White-tailed deer associated with riparian forests along river • Most agriculture in riparian areas – Hay meadows (alfalfa) – Grain fields (small grains) – Sugar beets

• Left: Lower Yellowstone River valley. • Right: White-tailed deer feeding in stubble field adjacent to a mature cottonwood stand. Riparian forest and shrub communities interspersed by agricultural croplands provide high-quality habitat for white-tails throughout the northern plains.

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Population trends

Lower Yellowstone River

Recruitment

Pregnancy rates

Some evidence of density-dependence….

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Mortality

Harvest

Lower Yellowstone River • White-tailed deer info – Population increased for 3 years, then declined – Dispersal was not a big factor • Nearly all dispersing deer stayed in the riparian area

– Overwinter mortality was low – Ag crops > 40% of diet

Lower Yellowstone River • Harvest was greater than recruitment – Main reason for the population decline

• Harvest rates vs. sustainability – Doe harvest > 30% - declining population – 25% - stable population – < 20% - increasing population – Harvest of up to 60% of bucks had no effect on population trend

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