Metroparks Deer Management: Initial Findings and Ecological Implications

Timothy A. Schetter, Ph.D. and Timothy D. Gallaher

White-tailed Deer Ecology

• A generalist herbivore: - Preferred habitat: forest edges

- Highly adaptable & selective

- Dietary preference varies by season & habitat

• Lack of predators

• High reproductive potential

Reproductive Potential: an example

• George Reserve, Michigan:

1,100-acre fenced natural area

1928: 6 deer introduced (2 bucks, 4 does)

1935: 222 total deer ---------------------------------------------------------------------------------------------------------------------------

1975: population reduced to 10 deer

1981: 212 total deer Data from McCullough (1984)

Ohio’s Deer Population

Data from Ohio Division of Wildlife

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

800,000

1920 1940 1960 1980 2000 2020

Ecological Impacts of Too Many Deer

• Negative impacts on forest regeneration

• Loss of plant diversity

• Habitat degradation for other wildlife species

Photo from www.nature.org Photo from cougarrewilding.org

Deer Damage in the Metroparks

• Wide-spread browse damage to tree seedlings

• Persistent damage to rare plant populations

• Long-term decline in spring ephemeral wildflowers

Metroparks Deer Management

• Monitor deer population levels

• Assess ecological damage

• Targeted population reductions – Controlled archery hunting – Culling performed by professional marksmen

Survey Methods: Helicopter Snow Count

Survey Methods: Aerial Infrared Count

Surveys conducted by Davis Aviation, Kent, Ohio

Deer Survey Results: Population Index

0

20

40

60

80

100

120

March2013

Dec2013

Jan2015

Num

ber o

f Dee

r

0

100

200

300

400

500

Jan2013

Dec2013

Jan2015

Wildwood Preserve Oak Openings Preserve

15 deer per mi2

25 deer per mi2

Population Density

50 deer per mi2

management target

2016 Population Reductions

0

20

40

60

80

100

Jan 2015 Jan 2016

Num

ber o

f Dee

r

0

100

200

300

400

Jan 2015 Feb 2016

15 deer per mi2

25 deer per mi2

Wildwood Preserve 30 deer removed by marksmen

Oak Openings Preserve 165 deer removed by marksmen 20 deer removed by archery hunters

management target

Population Density

Overwinter Browse Damage Assessment 1. Not Browsed: no visible browse damage 2. Light: 0 - 50% of stems browsed 3. Moderate: >50% of stems browsed, seedlings not hedged 4. Heavy: >50% of stems browsed, seedlings severely hedged but >0.5 ft. 5. Severe: no seedlings >0.5 ft., seedlings severely hedged

Heavy Browse Severe Browse

Adapted from Benner (2007)

Browse Damage Assessment: Results

0

2

4

6

8

10

12

14

16

18

No Regeneration

Perc

ent o

f Plo

ts

0

10

20

30

40

50

Oak Ash Maple Cherry Othertrees

Nativeshrubs

Invasiveshrubs

Plot

s w

ith R

egen

erat

ion

(%) 2015 (before)

2016 (after)

Wildwood Preserve: Regeneration of Woody Plants

Browse Damage Assessment: Results

Oak Openings Preserve: Regeneration of Woody Plants

0

10

20

30

40

50

Oak Ash Maple Cherry Othertrees

Nativeshrubs

Invasiveshrubs

Plot

s w

ith R

egen

erat

ion

(%) 2015 (before)

2016 (after)

0

2

4

6

8

10

12

14

16

18

No Regeneration

Perc

ent o

f Plo

ts

Browse Damage Assessment: Results

0

10

20

30

40

50

60

70

80

90

100

Oak Ash Maple Cherry Othertrees

Nativeshrubs

Invasiveshrubs

Hea

vy -

Seve

re B

row

se (%

)

2015 (before)2016 (after)

0

2

4

6

8

10

12

14

16

18

No Browse

Perc

ent o

f Plo

ts

Wildwood Preserve: Browse Damage to Woody Plants

Browse Damage Assessment: Results

Oak Openings Preserve: Browse Damage to Woody Plants

0

10

20

30

40

50

60

70

80

90

100

Oak Ash Maple Cherry Othertrees

Nativeshrubs

Invasiveshrubs

Hea

vy -

Seve

re B

row

se (%

) 2015 (before)2016 (after)

0

2

4

6

8

10

12

14

16

18

No Browse

Perc

ent o

f Plo

ts

Lupine Browse Study Plots

Woodland Edge

Savanna

Sand Barrens

Lupine Browse Study: Results

0

100

200

300

400

500

600

700

Sand Barrens Savanna Woodland Edge

Flow

erin

g St

ems

0

100

200

300

400

500

600

700

Sand Barrens Savanna Woodland Edge

Flow

erin

g St

ems

2014

2016

p=0.153

p=0.127

p=0.037

p=0.049 p=0.156

p=0.011

1-tailed t-test, equal variance

Conclusions • Deer population management is necessary to protect

park natural areas.

• We observed immediate benefits when population reduction goal was achieved.

• Park ecosystems will require many years to fully recover from deer impacts.

Acknowledgements We thank the following people for their help with browse surveys and data collection: Karen Menard Samantha Neuman Penny Niday LaRae Sprow Derrick Unverferth Alexa Vogel