Pronghorn Biology, Behavior, and Management

1. Pronghorn Biology, Behavior, and Management Ken Cearley Extension Wildlife Specialist- High Plains, Trans-Pecos Texas A & M University Canyon

2. Objectives • Overview of pronghorn basic life history • Reproduction • Behavior • Pronghorn habitat requirements • Management practices Emphasis on Panhandle

3. Recommended Resources • Pronghorn Ecology and Management. Bart W. O’Gara and Jim D. Yoakum. 2004. • Common Rangeland Plants of the Texas Panhandle. NRCS. 2005. • A Handbook for Pronghorn Antelope Management in Texas. Tommy Hailey, TPWD. 1986. • Pronghorn Management Guide. R. E. Autenrieth, et al. 2006.

4. Distribution of Pronghorns TPWD 1986

5. Trans-Pecos Pronghorns • <12” precipitation typically • Vegetation • Grama grasslands • Creosote-tarbush shrublands • Tobosagrass

6. Lower Plains Pronghorns • ~16” precipitation • Vegetation • Bluestem • Buffalograss • Tobosagrass • Mesquite • Lotebush • catclaw

7. Panhandle Pronghorns • High Plains • 15-21 “ annual precipitation • Mixed prairie • Short-grass prairie • Tall-grass prairie • Vegetation • Buffalograss • Blue grama • Mesquite • Sand sage • Shin oak • Yucca

8. Panhandle Pronghorns • Rolling Plains • 22-30” precipitation • Tallgrass prairie • Mid-grass prairie • Vegetation • Little bluestem • Sand bluestem • Sideoats grama • Mesquite • Sand sage • Shin oak

9. Description • 70-140 lbs. • Adult size by 2 years • Does typically breed year two • Both sexes horned • Males have forked horns • sheath shed annually • Males have cheek/neck patch • Abnormally large eyes • Placement on skull beneficial • Excellent eyesight • Long legs- 45 plus mph

10. Physiology • Thermal regulation by counter-current blood flow to brain • Cools blood supply • Maximized airflow- by design • Lungs • Diaphragm • Esophagus • High hemoglobin concentration in blood

11. Other design features • Concentrated urine • Water conserved by concurrent exchange of oxygen • Water intake reduced by decreasing food intake in stressful / critical times

12. Reproduction • Breeding begins late summer • Polygynous breeders • Few males breed all adult females • Resource-defense polygyny • Resources clumped and predictable • Female-defense polygyny • Resources are evenly distributed and unpredictable • Harems gathered

13. Reproduction • Breed as early as 16 months • Breed annually until 8-10 years of age • Rut onset varies with weather • Photo-period driven, basically • Length breeding season • South- ~3 months • North- ~ 3 weeks • Does cycle until bred

14. Reproduction • 250 day gestation • Nutrition during pregnancy and lactation critical • 112:110 males to females at birth • Twinning common on healthy rangeland

15. Food Habits • Nutritional requirements • Provision depends on availability • Rainfall • Competition • Crop depredation • Concentrate selectors • Forbs- rank first in consumption, typically • more nutrients, in small package • Forbs high in water content • Browse ranks second • ~8 % of diet is grasses • Water provided from free-standing, pre-formed, and metabolic processes

16. Behavior • Foraging affected by “build” • Small frame • Small organs • Small mouth, muzzle • Foraging affected by social behavior

17. Behavior • Herding • Tighter as move north • Selfish herds • Predator avoidance • Increases feeding efficiency • White rump patch makes each individual highly visible • TX- nomadic • Farther north- more migratory • Seasonal movements in response to habitat • Most move less than 10-20 miles

18. Restrictions to movement • Fences • ~18” clearance best; net wire restricts • Highways

19. Disease Implications • Carriers of abortive diseases? • Brucellosis? • Leptosirosis? • IBR? • 10 years of sampling by TPWD 1060-1970 • N=827 • No brucellosis • No lepto • N=75 IBR • 5 false positives, end result- no IBR

20. Management • Inventory • Aerial • Mid to late summer, usually • Strip flying • Some important parameters • Total count • Doe:Fawn ratio • Exceptional animals • Overall range and animal condition

21. Management • Harvest • Permit issuance determined by TPWD • Surplus taken if necessary to maintain carrying capacity • Parameters • Age • 4 1/3 years+ best horns • 1:2 buck:doe ratio conducive • 1:4 more conducive to larger number young animals • Habitat conditions • Carrying capacity • Objectives and goals

22. Aging Pronghorns • Fawns • Short jaw length • Molars not fully erupted • Yearling • 1 yr 4 mos TPWD

23. Aging Pronghorns • 2 yrs 4 mos TPWD

24. Aging Pronghorns • 3 yrs 4 mos TPWD

25. Aging Pronghorns • 4 yrs 4 mos TPWD

26. Aging Pronghorns • ~8 yrs 4 mos TPWD

27. Management • Keep watering facilities functional • Maintain range condition to provide adequate food supply • Fawning cover • Thwarts predation efforts • Adequate nutrition • Especially during spring and summer when peak demands from gestation, then lactation

28. Management • Provide unrestricted movement • Pronghorn friendly fencing

29. Management • Deter crop depredation

30. Management • Supplemental feeding • May be beneficial in nutritionally stressful periods • Feed not readily accepted

31. Summary • Inventory • Plan the harvest • TPWD determines permit issuance • Monitor range condition and pronghorn condition to determine carrying capacity • Maintain water even when livestock not present, including breaking ice • Fencing conducive to goals • Restriction or movement • Age determination of harvested animals • Utilize supplemental feeding as required • Manage predators when necessary (coyotes primarily) • Maintain good range condition to provide physical protection (thermal, predation) and food requirements.