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The Hudson Valley is a treasured landscape that has undergone tremendous change over the past century. This forum explores how science-based stewardship on private land can help protect and promote healthy forests and open spaces, now and for future generations. Presentations explore threats our forests and natural areas face – from invasive species and climate change to deer overabundance – and actions that can be taken on a site-by-site basis to optimize conditions. A special focus will be given to the overlap between sport hunting and conservation communities, with a roundtable discussion on advancing common ground. Hosted April 12, 2014 at Cary Institute of Ecosystem Studies Presentation Part IV by: Raymond Winchcombe, Wildlife Ecologist, Cary Institute of Ecosystem Studies
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Impacts to Forests by Deer and the Use of Annual Controlled Hunts to Mitigate those Impacts
www.pa.audubon.org/search/node/PA Deer Ecosystem Forum Report
Take Home Message
• Deer overabundance leads to serious negative impacts on forested ecosystems.
• These impacts affect the abundance, distribution and diversity of plant & animal species.
• Over-browsing by deer threatens the survival & perpetuation of our oak dominated forests.
• Loss of oaks & the mast they produce would be devastating for a host of animal species & an economic loss of timber resources.
• A hunting program focused on consistent female removal can address the impacts of over-browsing by deer.
Valley Forge, PA - 2006
Robust Forest Under story
Discussion Outline
• Life History of White-tailed Deer
•Impacts to Forest Ecosystems by Deer
•Cary Institute’s Deer Management Program
•Role of Hunters & Landowners in Managing Deer
Deer Facts You Should Know
• Most abundant large herbivore in the United States
• Can live a long time; 10+ years in the wild
• Exhibit a polygamous breeding system
• Potential for rapid population growth in the absence of predators
• Humans are the most significant contemporary predator in most areas
• Adult females usually have twins, triplets possible
• Yearlings usually have singles, twins possible
• Well nourished fawns can breed & produce a fawn their first year
• Single male will breed with several females
Reproduction
Population growth experiment results:*
1928-34 6 deer grew to 222 in seven years
1975-80 10 deer grew to 212 in six years
* - George Reserve in southern Michigan inside a 1,146 acre fenced site controlling for all sources of mortality.
Polygamous breeding system requires control efforts be focused on females if population control is desired.
Contrary to early deer management efforts where females were protected & herds allowed to expand.
Early Goals: restock ranges where deer were extirpated due to market & subsistence hunting & habitat destruction.
Deer Impacts to Forested Ecosystems
Ecological Impacts of Too Many Deer
• Over browsed habitats
• Reduced species diversity (Flora)
• Reduced species diversity (Fauna)
• Loss of forest structural diversity
• Loss of forested systems functionality
• Overall decline in deer health/disease transmission
Valley Forge, PA - 2006Valley Forge, PA - 2006
Deer are Selective Browsers
• Select foods that are nutritious and highly palatable
• Selections based on food availability (feeding progresses from most desirable to least desirable species)
• Food abundance & species diversity are dependent on contemporary deer #’s & historical deer densities
R Map
le
S Map
leOAK
Bk Birc
h
Hicko
ryAsh
Bk Cher
ry
Amel
anc.
..0
500
1000
1500
2000
2500
3000
3500
Mean Available Buds/Species - 1998-2013
# B
ud
s a
va
ilab
le
R Map
le
S Map
leOAK
Bk Birc
h
Hicko
ryAsh
Bk Cher
ry
Amel
anch
ier
0
2
4
6
8
10
12
14
16
Mean % Browsing on Index SpeciesCary Institute - 1998-2013
% B
ud
s B
row
se
d
Overbrowsing: Direct Effects
• Reduced species richness & abundance• Altered species composition (loss of desired species)
• Reduced advanced regeneration of desirable species (important timber & mast producing species)
Hunting focused on recreation
Regeneration progressing nicely Regeneration stalled
Hunting focused on habitat protection
Not all hunting is equally effective
Overbrowsing: Indirect Effects
• Proliferation of undesirable & browse resistant species (Hay scented & NY fern, beech, striped maple)
• Can lead to a shift in balance between native & introduced species (introduced species less palatable)
• Can change the direction of forest development (competitive exclusion of desirable by undesirable species)
• Reduced abundance of forest dwelling animals (direct competition for food [acorns], altered habitats)
Gun Club Fern Understory
Impacts of Structural Component Loss
Loss of shrub & mid-canopy layers & spatial distribution of these layers:
• Songbirds: reduced species richness & abundance (loss of feeding, nesting & escape cover).
• Reduced abundance & higher predation on small mammal community; eventual decline in predators.
• Insect diversity is dependent on vegetation diversity (feeding, egg deposition, larval development).
Valley Forge, PA - 2006Valley Forge, PA - 2006
Structural/Habitat Loss • Microclimate shift: increased light, wind,
temperature and lower humidity at the forest floor (impacts germination & survival of some tree species, snails, salamanders, frogs etc.)
• Higher survival of less desirable shade intolerant species due to increased ambient light conditions (Hay Scented Fern).
• Degraded or loss of habitat for deer (loss of wintering areas, escape cover, food resources).
Deer Population Management at the Cary Institute of Ecosystem Studies
Deer Population Management Options
1. Allow nature to take its course
2. Trap & transfer excess deer
3. Use fertility control agents to regulate herd size
4. Reintroduce predators to control deer numbers
5. Control deer numbers with sharpshooters
6. Use regulated hunting
Program Goals
Protect the structure & function of forested ecosystems.
Minimize conflicts with planned uses of the property.
Cary Deer Management Program
Program Elements
• Vegetation monitoring - via surveys
• Population index - hunter observations
• Population control - annual hunts
Cary Deer Management Program
Vegetation Monitoring
• 45 Deer browse survey areas (spring)
• 4 deer exclosures with paired unfenced plots
Cary Deer Management Program
97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 AVG0
2
4
6
8
10
12
14
16
18
Percent Buds Browsed for All Species Cary Institute 1997 - 2013
Year
% B
row
se
d Mean
Cary Browse Survey Results – 1997 - 2013
R Map
le
S Map
leOAK
Bk Birc
h
Hicko
ryAsh
Bk Cher
ry
Amel
anch
ier
0
2
4
6
8
10
12
14
16
Mean % Browsing on Index SpeciesCary Institute - 1998-2013
% B
ud
s B
row
se
d
Cary Browse Survey Results 1998 - 2013
IES Site 1
0
1020
30
40
5060
70
80
50-99 100-149 150-199 200+
Height Class (cm)
# o
f S
ap
lin
gs
Fenced Unfenced
IES Site 2
0
20
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50-99 100-149 150-199 200+
Height Class (cm)
# o
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Fenced Unfenced
IES Site 3
0
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50-99 100-149 150-199 200+
Height Class (cm)
# o
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gs
Fenced Unfenced
IES Site 4
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50-99 100-149 150-199 200+
Height Class (cm)
# o
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Fenced Unfenced
Cary Institute’s Deer Exclosure Sites
Gun Club Site 1
020
4060
80100
120140
160
50-99 100-149 150-199 200+
Height Class (cm)
# of
Sap
lings
Fenced Unfenced
Gun Club Site 2
0
10
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50-99 100-149 150-199 200+
Height Class (cm)
# o
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Fenced Unfenced
Gun Club Site 3
0
10
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50-99 100-149 150-199 200+
Height Class (cm)
# o
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Fenced Unfenced
Gun Club Site 4
0
20
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100
120
50-99 100-149 150-199 200+
Height Class (cm)
# o
f S
apli
ng
s
Fenced Unfenced
Gun Club Location
Hunter Observation Method
Bowhunter Data Collection Bucks
Does
Fawns
Unknowns
Days Hunted
Hrs. Hunted
Area Hunted
Summary Deer Observation Data
Population Control
Population Control - Annual Reductions
Specific Goals
• Stabilize or reduce local deer numbers
• Achieve younger female age distribution
• Efficient and safe control effort
Cary Deer Management Program
Population Control via Controlled Access Hunt
• Participation by invitation
• Firearms proficiency requirement
• Orientation meeting requirement
• Antlerless permit requirement
• Effort requirement
Cary Deer Management Program
Shooting Proficiency Test3 shots on a 12” X 12” target
Maximum of 5 shots allowed
Cary Deer Management Program
Population Control - Hunt Specifics
Daily sign in/out at check station
Required deer check
Blaze orange requirement
Designated parking areas
Avoid research & restricted areas
Cary Institute Hunter Check Station
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 260
5
10
15
20
25
30
35
40
45
50
Avg. # Different Hunters and Avg. # of Trips by Sector - 2005-12
Mean # different hunters Mean # trips
Hunt Sectors
# of
hun
ters
& t
rips
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 260
5
10
15
20
25
30
35
40
Deer Harvest by Hunt Sector 2005-13
2005 2006 2007 2008 2009 2010 2011 2012 2013
Hunt Sector #
To
tal #
De
er
Cary Deer Management Program
Population Control - Hunt Specifics
Daily sign in/out at check station
Required deer check
Blaze orange requirement
Designated parking areas
Avoid research & restricted areas
Cary Institute Deer Check Facility
Tick Collections from Harvested Deer
Hunter Evaluation
• Compliance with rules and policies
• Hunter effort
• Hunter success (adult females)
• Cooperation and attitude
Cary Deer Management Program
Population Control – Summary
Averages – 1976-2013 (#)= range
• 53 hunters (30-89)
• 2,124 hrs. of effort (1128-2799)
• 55 deer removed per year (22-89)
• Hunter success rate - 66% (range 38 – 82%)
Cary Deer Management Program
Males51%
Females49%
Proportion of Deer in the 1976-2013 Deer Harvests at the Cary Institute
Landowner’s Role in Deer Population Management
Landowner’s Role in Deer Management
1. Control access to the resource
2. Should take a pro-active stance in deer mgmt.
3. Can customize programs/access as needed
4. Require doe harvest for access privileges
5. Require sincere hunter effort for access privileges
6. Don’t tolerate irresponsible behavior
The Role of Hunters in Deer Population Management
Role of Hunters in Deer Management
The primary role of hunters in deer population management is the removal of deer.
Hunters are the tool deer managers use to control deer numbers.
To maximize their effectiveness, hunters must focus their efforts on adult females.
Hunters provide important ecosystem level services to the community when adequate female harvests are achieved.
Hunter Responsibilities
1. Safety, safety, safety
2. Respect- for property & all persons
3. Exhibit the highest of ethical standards
4. Zero tolerance for unsafe & unethical behavior
5. Never forget, access is a privilege
6. Embrace their role as deer managers when making decisions regarding which deer to harvest.
Challenges for Deer Managers
Challenges for Deer Managers
1. Adequate access at the landscape scale?
2. Sufficient numbers of antlerless permits?
3. Sufficient hunter effort ( #’s of hunters)
4. Focused hunter harvest (adult females)
5. Providing a quality hunting experience ?
Is There a Recreational Threshold?Is there a deer density at which many hunters do not see enough deer to justify continuing to hunt? (Moyer and Shissler).
Basis for a Recreational Threshold – expectations based on past experience
Problem: Oscillations in deer #’s based on hunter interest would not be good when the management objective is forest ecosystem /habitat protection .
Challenges for Deer Managers
Result When the Need to See more Deer Trumps Habitat Protection
Questions ?
Primary QuestionAre these oak dominated forests positioned to perpetuate themselves under these different deer management scenarios?
1976 – 2013 Summary Stats, Firearms
284 Different Hunters Participated
15,746 Hunter Visits
67,030 Hours of Hunting Effort
2,078 Deer Harvested (171 additional deer with archery)
2,249 Total Hunter Harvest (mean 58/yr.)
Linking hunters and landownersP.G.C. must attempt to match the general population, who are the owners of public and private land, with those who hunt in a way that is beneficial to both and mutually agreeable. This is likely to depend on the willingness of P.G.C. to:
• enforce trespass laws on private land• surrender the traditional value of equitable distribution (the concept that all hunters should harvest an equal number of animals)• adopt more liberal season and bag limits that would allow hunters to be effective in resolving landowners’ problems with deer overbrowsing
Cited from the PA Audubon Deer Ecosystem Forum Report
IES Deer Exclosure StudyRay Winchcombe & Charles Canham
• Central Dutchess County• 3 Locations• 4 sites/location• 2 plots/site (fenced & unfenced 10x10 M plots)
• 1992 - present
Deer Management Scenario's
• Unhunted property – 1,000 acres; primarily forested habitat (borders 900 acres of hunted forest lands).
• Gun club property – 1,500 acres; mix of forest, cultivated field & old field habitat. Several decades of deer hunting; inconsistent doe harvest policy. Focus is on recreation and hunter satisfaction
• Cary Institute – 2,000 acres; mix of forest, old field & open field habitats. Over three decades of deer population management via controlled access hunting; consistent doe harvests. Focus is on protecting the structure & function of the forested ecosystem.
High tensile, woven wire mesh fence 6.5’ tall (10x10 m)
Unhunted Site 1
0
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50-99 100-149 150-199 200+
Height Class (cm)
# o
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apli
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s
Fenced Unfenced
Unhunted Site 2
0
20
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50-99 100-149 150-199 200+
Height Class (cm)
# o
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ap
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s
Fenced Unfenced
Unhunted Site 3
0
20
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50-99 100-149 150-199 200+
Height Class (cm)
# o
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Fenced Unfenced
Unhunted Site 4
0
5
10
1520
25
30
35
50-99 100-149 150-199 200+
Height Class (cm)
# o
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apli
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s
Fenced Unfenced
Unhunted Location
Response to Primary QuestionUnhunted site: data suggests this oak forest will not be able to perpetuate itself. Complete lack of any advanced regeneration.
Response to Primary QuestionCary Inst.: data suggests this oak forest will perpetuate itself. Presence of seedlings in the various height classes bodes well for this forest. Focused deer management must continue.
Consequences of Deer Over Abundance
• Severe overbrowsing of forested habitats
•Altered plant species composition, distribution & abundance
• Reduction of understory structural diversity
• Reduced habitat quality (deer & other fauna)
When overly abundant, deer can have serious negative effects on forest communities
• Mechanism – consumption of vegetation
• These effects can be either direct (species loss) or indirect (shifts in species composition).
• Overbrowsing alters the physical structure of forests thus having a negative impact on a host of other animal species (vertebrate & invertebrate).
• High deer densities & overbrowsing combine to threaten the future existence of our forests as we know them today.
Consequences of Deer Overabundance
• Long-term reduction in BCC (deteriorated winter habitat)
• Decline in herd health (disease transmission, losses)
• Conflicts with CCC (acceptable limits that people will endure)
• Increased frequency of deer/vehicle encounters
• Excessive damage to agricultural, nursery & landscape plantings & timber production.
IES Archery Hunting Areas Map
Day of the Month - Nov./Dec.18 19 20 21 22 23 24 25 26 27 28 29 30 1 2 3 4 5 6 7 8 9 10
Day of SeasonM T W TH F Sa Su M T W Th F Sa Su M T W Th F Sa Su M T
Name 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 T. Hrs. T. Days # 5+ Hrs. Succ. Deer Harv.**
Acuti 8 7 7 7 2.5 6 37.5 6 5 Y DAlexander 9 7 6.5 5 2 8 3.5 5.5 3 4 3 2 3.5 3.5 3 5 2.5 3.5 5 2 2.5 89 21 8 Y BBeasley 1.5 1.5 6 1.5 6 7 2 3.5 1.7 2.5 3.5 4.5 2.5 4 47.7 14 3 Y B*,D*,DBeck 3 5 5.5 3 4 3 23.5 6 2 NCahill 6 6 5 6 23 4 4 Y BClarke S. 5.5 3.5 3.5 4.5 4 3 3 27 7 1 NClarke B. 9 5.5 3.5 3.5 4.5 4 3 33 7 2 Y BCorona 9 7.5 7 7.5 2.5 8 2 5.5 49 8 6 Y B,FCrandall 5 8 6.5 7.5 27 4 4 Y DCrooker J. 9 4 8.5 4 8.5 8.5 6.5 8.5 8 3 5 73.5 11 8 Y BCrooker Jy. 9 4 8.5 4 9.5 8.5 8 8.5 8 68 9 7 Y D,FDeBonis 3.5 3.5 2.5 9.5 3 0 NDiggelmann 3.5 3.5 7 2 0 NDodaro S. 5 4.5 5.5 6 2.5 6 2.5 2 4 5 2.5 5 1.5 52 13 6 Y B,D,D
Record of Hunter Effort & Success
