2017 Pronghorn antelope survey report

[jackelope]

I'm going to post parts of this. If there's anything you're curious to know more about, I'll do my best to share that info as well.
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Summary report
Pronghorn antelope abundance survey in south-central Washington
March 16-17, 2017
Yakama Nation Wildlife Washington Department of Fish and Wildlife
Jared Oyster - Wildlife Biologist, WDFW
David Blodgett III – Wildlife Biologist, YNWP
Gabe Swan – Wildlife Biologist, YNWP
Rich Harris – Section Manager, WDFW May 8, 2017
SUMMARY
By the start of the 20th century, pronghorn antelope had become extirpated from Washington. Ninety-nine pronghorns were reintroduced onto the Yakama Reservation, Washington in 2011; these pronghorns have since since dispersed from their release locations and increased in abundance. We conducted aerial surveys on March 16-17, 2017 in Benton, Klickitat, and Yakima Counties in south-central Washington, both on the Yakama Reservation and off the Reservation. The objective of the survey was to obtain a minimum population estimate for pronghorn. We counted a total of 116 pronghorns during our aerial survey and an additional 5 from ground surveys, for a total minimum population estimate of 121 pronghorns. The true abundance is likely to be underestimated because small group sizes made detecting pronghorns difficult and they may reside in locations outside of our survey area. Despite the harsh winter of 2016-2017, there is little evidence that the pronghorn population has declined since 2015. Human-induced mortality must be kept low to protect this small population. The Yakama Nation and Washington Department of Fish and Wildlife (WDFW) consider that the population will require a few more years of growth before recreational harvest should be considered.
STUDY AREA
Our survey was conducted in portions of Benton, Klickitat, and Yakima counties in southcentral Washington (Fig. 1). The dominant habitat types are a mix of croplands (primarily winter wheat and crops with center pivot irrigation), Conservation Reserve Program (CRP) land, grazed rangeland, and shrub-steppe communities. In the central Basin of Washington, the winter of 2016-2017 was the coldest in over 30 years, with above average snowfall (NOAA 2017).
METHODS
We used a strip transect method, flying parallel transects in a north-south direction (Fig. 2). Transects were established prior to the survey in ArcGIS 10.1 (Environmental Systems Research Institute, Inc., Redlands, CA). Transects were spaced at 1.6 km apart on the Yakama Reservation, 2 km apart in Klickitat/Yakima Counties, and 3 km apart in Benton County. Transects with shorter spacing were selected based on higher perceived pronghorn abundance in
that area, and because terrain and vegetation in Yakima County (uneven, characterized by shrubs) made it more difficult to detect pronghorn than the typically flat terrain with agricultural fields in Benton County.
We conducted aerial surveys in a Cessna 182 fixed-wing aircraft at an approximate speed of 80—90 knots and at 100—150 meters above ground level. A ground survey crew, conducted by the Safari Club International (SCI), was actively searching for pronghorn concurrently with the aerial survey. When the ground crew detected a pronghorn group, they relayed the location to the aerial crew. The aerial crew then obtained a second count of that group from the plane to ensure a full count. We had 3 observers positioned in the plane: the front right, back right, back left; the pilot was seated in the front left. The main duty of the pilot was flight safety and remaining near the transect line; however, we included any pronghorns he detected in our count as well.
We began our survey at the western-most transect in Klickitat County and continued
west through all the transects in Benton County. The transects over the Yakama Reservation were flown last. When we observed a pronghorn group we left the transect and recorded: (1) a waypoint, (2) the total number of pronghorns, (3) the number of distinguishable bucks, (4) any pronghorns with collars or ear tags, (5) the observer that detected the pronghorns, (6) pronghorn activity (e.g. standing, bedded etc.), and (7) habitat type (crop, Conservation Reserve Program lands, or range). Bucks, does, and fawns are not as easily distinguished during the winter as other times of year. Nevertheless, we documented the number of bucks we were confident in identifying within each group. We surveyed for about 6 hours in Klickitat/Yakima County, 4.5 hours in Benton County, and 3.5 hours over the Yakama Reservation. We also recorded the number of coyotes (Canis latrans) detected during the survey. Surveys were conducted March 16-17, 2017.
RESULTS
We detected 19 pronghorn groups, a total of116 animals, 44 of which were on the Yakama Reservation, 72 of which were south and/or south-east of the Reservation. One additional group of 5 pronghorns was observed from the ground, outside of the surveyed area (west of US Highway 97). Combining this ground observation with those from the aerial surveys results in a minimum count of 121 pronghorns. Twenty-two (20%) pronghorns were classified as bucks. Of the 12 aerial detections southeast of the Reservation, 7 were in non-irrigated cropland, and 5 were in rangelands. All detections on the Reservation were in rangelands.
Mean group size was 6.1; group sizes varied from of 1 to 16. We did not identify any pronghorn wearing collars or eartags. We counted a total of 37 coyotes during the survey: 18 in the Klickitat/Yakima County portion, 15 in Benton County, and 4 on the Yakama Reservation.
Thus, our overall count may be lower than what it could have been if the survey had been conducted earlier, in mid-winter, when pronghorn groups are typically larger. Ideally, future pronghorn surveys should be conducted in December or January. Pronghorns also may have been missed if located in areas outside our survey area. Despite these potential negative biases, we detected 10 more pronghorns (9% more) than we had during our 2015 aerial survey. Additionally, although we benefited from ground crews during survey reported here, ground-
from transect
based effort was lower than those that augmented our aerial survey in 2015 (in part, because the 2017 survey was scheduled in haste due to weather complications, when many from the ground crew were busy at other events). Lower levels of concurrent survey effort from ground crews and from public sightings may have contributed to a negative bias. Despite the harsh winter of 2016-2017, there is little evidence that the pronghorn population in this part of Washington State has decreased since the last survey in 2015.
Does and fawns are not easily distinguished during this time of year because fawns are nearly full-grown. Yearling bucks are also difficult to distinguish from does and fawns because their horns (~ 7 inches) are only about as long as their ears (5-6 inches), and their dark cheek patches are only about 50% the size they attain during the pre-rut and rut (O’Gara and Yoakum 2004). Therefore, buck:doe ratios from our survey are likely underestimated and should be considered cautiously.
Coyotes can be effective predators of pronghorn adults (Bright and Hervert 2005) and fawns (Gregg et al. 2001). High coyote densities have been shown to have a direct impact on fawn survival (Berger et al. 2008). If there is a high coyote density relative to pronghorn density, they could effectively limit population growth by consuming a large proportion of pronghorn fawns every year (Holling 1965, Berger et al. 2008, Gregg et al. 2001)). For example, coyotes killed 72% (75 of 104) of collared fawns in south-central Oregon (Gregg et al. 2001) Although we saw more coyotes in 2017 than we did in 2015, this should not be interpreted that coyote densities were definitively higher in 2017, because we did not make a concerted effort to record all coyote sightings in 2015. In 2015, we began to record coyote sightings as an afterthought after a few groups were seen. Furthermore, the pilot in 2017 was an avid and experienced coyote hunter and he detected many of the coyotes.
Contacts made by the SCI ground crew with local landowners indicated that the majority of landowners viewed pronghorn favorably. However, there are some landowners that are still intolerant of having pronghorns on the landscape. For pronghorns to become self-sustaining and secure, it will be important to assure that human-induced mortality (e.g., from poaching or poor fence construction) remains low, and that any conflicts with agricultural use are minimized so as to maintain landowner acceptance. Both the Yakama Nation and WDFW consider that the population will require at least a few more years of growth before recreational harvest should be considered. Although recent surveys from Yakama Nation biologists indicate that the feral horse (Equus caballus) population has declined during the last few years, there is still likely competition between horses and pronghorns. Although horses and pronghorn do not overlap substantially in diet, indirect impacts likely exist (Gooch et al. 2017). Potential conflicts between pronghorns and feral horses should be investigated and described. If possible, it would also be desirable to assess genetic diversity in this herd to help understand the usefulness of additional transplants (Stephen et al. 2005)
ACKNOWLEDGMENTS
We thank Baker Aircraft and Wayne Bailey for safe and effective flying. Jason Fidorra and Stefanie Bergh (WDFW) were effective observers during the aerial survey. Stefanie also helped coordinate available aircraft vendors. We are grateful to Paul Whelan (WDFW) for flight-following during the survey. We thank SCI for coordinating ground surveys to locate pronghorn and making connections with local landowners. We especially thank SCI members Deb Barrett and Joe Greenhaw for coordinating ground surveys. We also offer thanks to Jim Stephenson, former big game biologist of the Yakama Tribe, who in coordination with the Yakama Nation Wildlife Department, Department of Natural Recourses, SCI, and the Yakama Nation, as a
whole made the pronghorn antelope reintroduction project possible.

[shanevg]

That's good news. Is The tribe/SCI planning any further augmentation?

[ctwiggs1]

So with a lot of negative factors going against the spotters getting higher numbers, and a harsh winter this year.... The population is still up over a two year span.

That's GREAT news!

[Bob33]

So with a lot of negative factors going against the spotters getting higher numbers, and a harsh winter this year.... The population is still up over a two year span.

That's GREAT news!

That's not how I interpret it.
2017: "We counted a total of 116 pronghorns during our aerial survey and an additional 5 from ground surveys, for a total minimum population estimate of 121 pronghorns. "

2015: http://w4wc.org/news/2015-washington-state-pronghorn-antelope-survey
“Combining the ground observations with those from the aerial surveys, we obtained a minimum population estimate of 132 pronghorns.”

[ctwiggs1]

So is this statement incorrect?

Despite these potential negative biases, we detected 10 more pronghorns (9% more) than we had during our 2015 aerial survey.

[Bob33]

So is this statement incorrect?

Despite these potential negative biases, we detected 10 more pronghorns (9% more) than we had during our 2015 aerial survey.

Perhaps the difference is that more antelope were detected in the 2017 aerial survey, but combined with the ground counts the total was less? I don't know. It doesn't seem to jive with the total numbers reported.

[Oh Mah]

What would it take to bring another 100 in?Do we need to form a group like the R.M.E.F only for PRONGHORNS?

[Rainier10]

It is good that they did the survey.  It is unfortunate that they didn't have better conditions.  With all of the limiting factors I don't think you can draw any real conclusions.

I think there is potential that there are more antelope than what they counted this year.  At the worst we are only down 10 or so from 2 years ago.

I am a little concerned at the shift in numbers on the reservation and off from 2 years ago.  71 on and 61 off two years ago and 44 on and 72 off this year.

Again I think the survey results could easily be off because of limitations in viewing this year.  Hopefully they can do it again in a couple of years with better varibles and we will see a big increase in the antelope numbers.

[wheels]

im sure there are a few states could spare a few

[Gringo31]

I don't think this is good news for the pronghorn population.


Of the 99 original goats, (I'm guessing here but will try to make a point) lets say 80-85 were does and I think it would be logical to assume most were pregnant.  One could argue that 6 months later there should have been over 150 total.

My point is it seems the population is indeed falling.

[winshooter88]

if all the does were pregnant you still wouldn't get 100% fawn survival, a survival rate of 50% would be amazing and most likely overly optimistic, the reality is that in most ungulate populations a lot of fawns never make it through the winter either because of predation or weather factors. according to the survey the population has grown but not a lot but they also say that this is most likely a low estimate, there may be a lot more out there than they saw.

[jackelope]

Lots of coyote issues, some poaching, roadkill, winter kill, bad weather for visibility. The folks doing the surveys were not pleased with the results. They were hoping to find a bunch more.

[Oh Mah]

im sure there are a few states could spare a few

YEAH WYOMING.

THEY HAVE MORE ANTELOPE THAN PEOPLE.
I would certainly give a couple bills to bring say 1000 to WA.If only to offset the elk the wolves eat.

[jackelope]

These goats and the more recent Colville transplant speedgoats came from Nevada.

[Oh Mah]

yeah  but they only have around 26k head.