deer density and supplemental feed in deer management: … · 2018-03-06 · tim fulbright, charles...
TRANSCRIPT
Deer Density and Supplemental Feed in Deer Management: Conclusions from the Comanche-Faith
StudyVegetation responses
Tim Fulbright, Charles DeYoung, David Hewitt, David Wester, Don Draeger
Vegetation response to deer density
►Traditional ideas of vegetation change►Plant community degradation
§ Decrease in preferred plants§ Reduced forb species§ Increase in unpalatable plants
Increasing deer density
►Preferred forbs varied more with rainfall
Increasing deer density
►Preferred forbs varied more with rainfall
0
5
10
15
20
2004 2005 2006 2007 2008 2009 2010 2011 2012
Can
opy
cove
r (%
)
Drought
Increasing deer density
►No reduction of preferred forbs
0
5
10
15
20
2004 2007 2010 2012
Can
opy
cove
r (%
)
0
5
10
15
20
2004 2007 2010 2012
Can
opy
cove
r (%
)
Low densityNo feed
Increasing deer density
►No reduction of preferred forbs
0
5
10
15
20
2004 2007 2010 2012
Can
opy
cove
r (%
)
0
5
10
15
20
2004 2007 2010 2012
Can
opy
cove
r (%
)
Low densityNo feed
Increasing deer density
►Did not affect§ Canopy
cover of other forbs
§ Number of forb species
§ Canopy cover of woody plants
0
10
20
30
40
50
Other forbs Preferredshrubs
Othershrubs
Can
opy
cove
r (%
)
Low Medium High
Why no effects detected?
►Variation in rainfall § Wet years (2004, 2007, 2010)
►Food abundant►Swamping effect
§ Drought years (2006, 2008-09, 2011)►44% of forbs annuals►Perennials dormant during drought►Avoid being eaten
§ Weakens influence of deer density
Why no effects detected?
►Changing food availability§ Deer switch forage classes depending on
availability§ Allows recovery of forage class not being eaten
Autumn-Winter
Spring Summer
Why no effects detected?
►Anti-herbivore defenses§ Replacing leaves removed by deer§ Canopy architecture§ Thorns and spines§ Anti-nutrition
plant compounds
Why no effects detected?
►Legacy effects§ Woody plants increased in past 200-300 years§ Developed under intensive use
►2.4 million sheep and goats in 1882►1 sheep (or goat)/3 acres in Dimmit county
Vegetation response to feeding
►Increased foraging§ Preferred plants?§ Unpalatable plants?
►Vegetation degradation?
Supplemental feed
►Preferred forbs increased
0
5
10
15
20
2004 2007 2010 2012
Can
opy
cove
r (%
)
Supplemental feed, lowdensityNo feed, low density
0
5
10
15
20
2004 2007 2010 2012
Supplemental feed,high densityNo feed, high density
Supplemental feed
►Preferred forbs increased►Increase (%) similar in low and high
0
5
10
15
20
2004 2007 2010 2012
Can
opy
cove
r (%
)
Supplemental feed, lowdensityNo feed, low density
0
5
10
15
20
2004 2007 2010 2012
Supplemental feed,high densityNo feed, high density
05
10152025303540
Supplementalfeed
No feed
Spec
ies/
7.5
m2
Number of forb species
Supplemental feed
Supplemental feed
►Did not affect§ Canopy
cover of other forbs
§ Canopy cover of woody plants
0
10
20
30
4050
60
Other forbs Preferredshrubs
Other shrubs
Can
opy
cove
r (%
)
Supplemental feed No feed
Why did preferred forbs increase with supplemental feed?
►Protective effect§ >50% of deer diets was feed§ Exclosures
►No cattle or pigs, controlled deer densities►Recovery from pre-enclosure grazing and browsing
Why did preferred forbs increase with supplemental feed?
►Reduced perennial grasses during 2009-2012
010203040506070
2004 2005 2006 2007 2008 2009 2010 2011 2012
Can
opy
cove
r (%
)
Why did preferred forbs increase with supplemental feed?
►Reduced perennial grasses during 2009-2012
010203040506070
2004 2005 2006 2007 2008 2009 2010 2011 2012
Can
opy
cove
r (%
)
DD
Conclusions
►Vegetation responses to deer do not follow traditional ideas of vegetation change
►Reducing deer densities unlikely to alter vegetation§ Within range of densities tested
►Time lags§ Years required for effects to be expressed§ 6 years at high density
Acknowledgements
►T. D. Friedkin, S. Stedman, Stedman West Fndt., Comanche Ranch, Faith Ranch
►Meadows Professorship in Semiarid Ecology
►Rene Barrientos►Houston Safari Club►Current and former graduate students,
undergraduate assistants
Questions?