July 2018 Big Game Survey
This past July staff from the Sheldon-Hart Complex and from ODF&W conducted an aerial survey of California Bighorn Sheep and Pronghorn on Sheldon National Wildlife Refuge and Hart National Antelope Refuge.
To survey the bighorn sheep, the team used a Bell helicopter to fly transects along elevational gradients, recording GPS coordinates for observed animals and classifying them by ewe, ram and lamb. Rams were further subdivided into four categories according to horn curl. (¼ curl, ¼-¾ curl, ¾ curl, and ¾-full curl) A total of 100 sheep were classified on Hart and 144 on Sheldon. On Hart, all categories were down from the previous year, with lambs marking biggest drop; nearly 29% of them were extremely small–about ⅓ the size expected for the time of year. On Sheldon, the total was up, although rams and lambs were down.
The numbers of observed pronghorn on both refuges were also down from last year, with Hart declining from 2691 to 2650 and Sheldon from 1821 to 1627. Still, each refuge recorded a twenty year trend of +10.4%. Interestingly, the numbers of fawns was up over 2017, while those for adult bucks, yearling bucks, and does were down.
The team also recorded observations of feral horses and burros. GPS positions were marked and individuals classified as either adult or foal. No horses or burros were seen on Hart, while Sheldon recorded 15 adult horses and one foal and 16 adult burros and one foal. A total of 16 burros were seen on McGee Mtn. and 53 horses on Beaty’s Butte (45 adults, 8 foals).
To survey the bighorn sheep, the team used a Bell helicopter to fly transects along elevational gradients, recording GPS coordinates for observed animals and classifying them by ewe, ram and lamb. Rams were further subdivided into four categories according to horn curl. (¼ curl, ¼-¾ curl, ¾ curl, and ¾-full curl) A total of 100 sheep were classified on Hart and 144 on Sheldon. On Hart, all categories were down from the previous year, with lambs marking biggest drop; nearly 29% of them were extremely small–about ⅓ the size expected for the time of year. On Sheldon, the total was up, although rams and lambs were down.
The numbers of observed pronghorn on both refuges were also down from last year, with Hart declining from 2691 to 2650 and Sheldon from 1821 to 1627. Still, each refuge recorded a twenty year trend of +10.4%. Interestingly, the numbers of fawns was up over 2017, while those for adult bucks, yearling bucks, and does were down.
The team also recorded observations of feral horses and burros. GPS positions were marked and individuals classified as either adult or foal. No horses or burros were seen on Hart, while Sheldon recorded 15 adult horses and one foal and 16 adult burros and one foal. A total of 16 burros were seen on McGee Mtn. and 53 horses on Beaty’s Butte (45 adults, 8 foals).