Deer Overabundance is Impacting Biodiversity in Parks Located in Fairfax County, Virginia. Sean...

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

0

5

10

15

20

25

30

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?