Deer Overabundance is Impacting Biodiversity in Parks Located in Fairfax

County, Virginia.

Sean Campbell, Tammy Henry, Megan Scott,

Craig Shafer, and Jessica Trice

Overabundance of Deer

Animals are Overabundant* when:a) threaten human life or livelihoodb) are too numerous for their “own good”c) depress the densities of economically

or aesthically important speciesd) cause ecosystem dysfunction

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5

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15

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1900 1990 2000

white taileddeerpopulation

100 Years of Deer in United States Deer are Reproductive Machines

*Caughley (1981)

Impacts of an Overabundance of Deer

• Automobile Damage>1100 deer collected ~ 20% deer collisions

Average collision cost = $2300

7th highest rate of deer collision in the country

• Change to Forest Structure - Regeneration Patterns

• Disease: Human & AnimalLyme Disease & Others

Hemorrhagic Disease & Chronic Wasting Disease

• Ornamental Plant Damage• Biodiversity:

– Animals– Plants

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Causal Links:

People

Predators Hunting

Development

Fragmentation

PlantsAnimalsBiodiversity

DeerOverabundance

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AutoCollision

Disease

Carrying Capacity Theory (Caughley)Ecological Carrying Capacity (K)

Maximum Sustainable Yield (MSY) Economic Carrying Capacity (I)

Sociological Carrying Capacity (Cultural)

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Deer Carrying Capacity & Vegetation

Factors:

1. Plant biomass Environment

2. Rate of Plant Intake/Animal Density

of Plants

3. Rate of Population ∆ of deer Density

of Plants

Impacts on Biodiversity

- Browse-line shows degree of deer impact

- Changes forest structure (impacts on birds and invertebrates)

- Reduced habitat for ground-nesting animals, decreased food sources, affects on plant reproduction

- Reduced tree regeneration & decreased diversity in regrowth

- Increased ability for invasive/exotic species to establish QuickTime™ and a

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Criteria

1. Socially and Ethically Acceptable2. Economically Feasible3. Sustainable4. Efficient5. Quantifiable/Accountable Results6. Ecologically Sound7. Proven Methodology

Potential Solutions:• Ignore the problem• Reduce human population - relocation or birth

control• Unpalatable plants - naturally or chemically treated• Visible or audible deterrents • Prevent future land use changes (ie. development)• Corridors/underpasses for deer• Reintroduce predators (wolf, black bear, puma &

bobcat)• Immunocontraception• Fence deer in/out - physical or shock/alarm collars• Relocate deer• Change Fairfax County hunting regulations• Managed reduction - snipers or recreational hunting

Evaluating the criteria…

Managed reduction - snipers or recreational hunting

Meets all 7 criteria: socially acceptable, economic, sustainable, efficient, accountable, ecologically sound, & proven

Plan: multifaceted hunting approach• Police Force• Consulting Firm• Recreational Hunters

Reducing the deer population will lead to an increase in biodiversity - both in plants & animals.

Positive Results of an Appropriately Managed Deer

Population• Larger healthier deerLarger healthier deer• Improving habitat Improving habitat • Conserving biodiversityConserving biodiversity• Increased Environmental/Educational Increased Environmental/Educational

OpportunitiesOpportunities• Economic benefitsEconomic benefits• Provides food/sustenance Provides food/sustenance • Decreased human/wildlife conflictDecreased human/wildlife conflict• Cultural Traditions/Recreational Cultural Traditions/Recreational

OpportunitiesOpportunities• Funds raised to contribute to other Funds raised to contribute to other

wildlife management effortswildlife management efforts

Fairfax County Parks:

Huntley Meadows

Pohick Bay

NEXT: Application of Deer Management Strategy in Fairfax

County, VA

• Fairfax County Deer Management Plan

• Comparison of Huntley Meadows & Pohick Bay

• Recommendation to Hemlock Overlook

Huntley Meadows - sharpshooting, managed hunts

(shotgun & archery)

Pohick Bay - no planned reductions

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Questions?