deer density and supplemental feed in deer management: … · 2018-03-06 · tim fulbright, charles...

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?