Pronghorn Biology, Behavior, and Management

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Pronghorn Biology, Behavior, and Management

• Ken Cearley
• Extension Wildlife Specialist- High Plains,
  Trans-Pecos
• Texas A M University
• Canyon

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Objectives

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

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Recommended Resources

• Pronghorn Ecology and Management. Bart W. OGara
  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.

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Distribution of Pronghorns
TPWD 1986
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Trans-Pecos Pronghorns

• lt12 precipitation typically
• Vegetation
• Grama grasslands
• Creosote-tarbush shrublands
• Tobosagrass

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Lower Plains Pronghorns

• 16 precipitation
• Vegetation
• Bluestem
• Buffalograss
• Tobosagrass
• Mesquite
• Lotebush
• catclaw

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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

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Panhandle Pronghorns

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

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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

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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

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Other design features

• Concentrated urine
• Water conserved by concurrent exchange of oxygen
• Water intake reduced by decreasing food intake in
  stressful / critical times

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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

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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

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Reproduction

• 250 day gestation
• Nutrition during pregnancy and lactation critical
• 112110 males to females at birth

• Twinning common on healthy rangeland

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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

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Behavior

• Foraging affected by build
• Small frame
• Small organs
• Small mouth, muzzle
• Foraging affected by social behavior

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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

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Restrictions to movement

• Fences
• 18 clearance best net wire restricts
• Highways

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Disease Implications

• Carriers of abortive diseases?
• Brucellosis?
• Leptosirosis?
• IBR?
• 10 years of sampling by TPWD 1060-1970
• N827
• No brucellosis
• No lepto
• N75 IBR
• 5 false positives, end result- no IBR

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Management

• Inventory
• Aerial
• Mid to late summer, usually
• Strip flying
• Some important parameters
• Total count
• DoeFawn ratio
• Exceptional animals
• Overall range and animal condition

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Management

• Harvest
• Permit issuance determined by TPWD
• Surplus taken if necessary to maintain carrying
  capacity
• Parameters
• Age
• 4 1/3 years best horns
• 12 buckdoe ratio conducive
• 14 more conducive to larger number young animals
• Habitat conditions
• Carrying capacity
• Objectives and goals

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Aging Pronghorns

• Fawns
• Short jaw length
• Molars not fully erupted
• Yearling
• 1 yr 4 mos

TPWD
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Aging Pronghorns

• 2 yrs 4 mos

TPWD
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Aging Pronghorns

• 3 yrs 4 mos

TPWD
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Aging Pronghorns

• 4 yrs 4 mos

TPWD
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Aging Pronghorns

• 8 yrs 4 mos

TPWD
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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

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Management

• Provide unrestricted movement
• Pronghorn friendly fencing

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Management

• Deter crop depredation

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Management

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

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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.