Pronghorn increasing in South Arizona

Arizona Docent

Arizona Docent

Well-Known Member
15+ year member
Good news from my part of the world. Here in southern Arizona, pronghorn are increasing. The herd is up from less than one hundred just four years ago to over three hundred now. The only disturbing part of the article is that one of the several recovery methods was "predator control" (a euphemism for killing carnivores).
Sonoita-Elgin pronghorn herd now exceeds 300, AZGFD says | News | nogalesinternational.com
I have only driven down that way (Patagonia and Sonoita area) a couple times and it has been a while. I have never seen pronghorn there, but a friend of mine said she saw them there very recently. I have seen them reliably up north in Prescott Valley, but due to rapid development that herd is sadly doomed.
 
Thanks for sharing. Encouraging news of species recovery program for Sonoran pronghorn in southern US.

I again state my claim that the preponderance of some predators (coyotes versus the absence of wolves) in large parts of Arizona and New Mexico may have had something to do with the earlier lack of recruitment and low fawn survivability.

A similar and surprising recovery occurred in Yellowstone and surrounding wilderness areas with the reintroduction of wolves (which had a positive correlation with a significant decrease in coyotes and 'wilding' of wapiti and bison to wolf predation. A greater diversity of other wildlife, including otters and beavers, have been cited as another welcome by-product of wolf reintroduction.

I wonder what effect their expansion into the Sonoran pronghorn ranges would do?
 
Kifaru Bwana said:
A similar and surprising recovery occurred in Yellowstone and surrounding wilderness areas with the reintroduction of wolves (which had a positive correlation with a significant decrease in coyotes and 'wilding' of wapiti and bison to wolf predation. A greater diversity of other wildlife, including otters and beavers, have been cited as another welcome by-product of wolf reintroduction.
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The evidence for this cascade is far "woollier" than often suggested.

Good news on the pronghorn front, though. As for predator control, it depends as always on which species are targeted, how extensively, and what control measures are used. Unfortunately, there will always be uncomfortable ethical issues surrounding the killing of healthy animals for conservation purposes, be they zoo surplus, invasives or high-abundance predators.
 
I am not sure these are the Sonoran subspecies (I do not think they are). I believe those are only found in Mexico. These may be Chihuahan subspecies???
 
A quick search led me to the Arizona Antelope Foundation page, which confirms my suspicion regarding subspecies. In Arizona there are three subspecies and the ones in question here are in fact Chihuahuan.

Southeast Arizona - Chihuahuan (A. a. mexicana)

Southwest Arizona - Sonoran (A. a. sonoriensis)

North Central Arizona - American (A. a. americana)

source page: About Pronghorn
 
AD, I believe you may be right. But what got me squared is that the Sonoran pronghorn recovery effort is centered around the Sonoita area.

Sonoran pronghorn captive: Cabeza Prieta and Kofa NWRs, Arizona. In Mexico on the El Pinacate and Quitovac.

A central for both North America states is Highway 8 (US) and Highway 2 (Mexico). All Sonoran populations are S. of Phoenix and W. of Tucson.

The principal causes for decline are habitat fragmentation, blockage of migration route (fences, roads), climate change and prolonged drought and lack of water resources for wildlife. At some time, hunting was also a reason for significant declines.

So, what did I get wrong geographically?
 
Arizona Docent said:
Sonoita is southeast of Tucson :) (on the way to Tombstone)
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Forgive my insolence ... mea maxima culpa! (LOL). Kofa and Cabeza Prieta are indeed west of Phoenix and Tucson. Sonoita is thus part of the Chihuahuan ssp. range ...!(??).

However, I was specifically wondering and asking you about the exact dilineations between the Sonoran and Mexican/Chihuahuan pronghorn populations as these seem to lie somewhere in the midst of good old Arizona and where they geographically are on the US/Mexico map.

Just suppositions of mine (correct me if am wrong ..): Is it roughly between Highway 10 and Highway 19 (towards Nogales) and marked by the mountain range along Green Valley and Oro Valley and the Kitt Peak? The Tonto O'odham Nation Reservation and the basin south to El Humo peak by any chance? Is the Sonoran ssp. restricted to this depression going west towards the Pacific coastline?

Note: As far as I know there remain questions as to how far west the Sonoran pronghorn ranged and if part of the northern Baja California was in fact part of their historical distribution.


So, for better and for worse I would love to know where exactly these dilineations are and what specifically defines the separation between both ssp. (is it habitat or something else or a combination of various factors)??? :confused:
 
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I am not an expert, but here is what I think (but do not know for certain).

The Sonoran population is quite a bit west. In Arizona, I think there would be a large mountain range (Kitt Peak) which they would all remain west of. Incidentally this is the same mountain range where jaguars Macho A and Macho B (both now deceased) were found. The current jaguar, El Jefe, is found in the Santa Rita mountains due south of Tucson (much closer) and just west of the Sonoita area where the Chihuahuan pronghorns are. But I am getting off topic.

In the valley on the east side of Kitt Peak, which is still west of Interstate 19, there is Buenos Aeries National Wildlife Refuge which also has Chihuahuan pronghorn, or at least it used to. I saw them there years ago but a friend told me they did not do well and may be gone or at least very low numbers.

To summarize, the Chihuahuan subspecies covers far south Arizona from the east all the way to the center (up to the Kitt Peak mountain range). The Sonoran subspecies covers the far south (and more in Mexico than on this side of the border) to the west of the Kitt Peak mountain range.

Incidentally I drove down to Sonoita this afternoon. After failing to see any in good afternoon light, I finally saw a pair on the far east end of the valley (Highway 82) which I photographed after the sun set. Picture attached.

Fun trivia fact: Interstate 19 (referenced above) is the only USA freeway where the mileage signs are in kilometers instead of miles.
 

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AD, thanks for your comments. It seems some of my suppositions at least were correct.

BTW: Nice that you did observe some pronghorn in late summer's eve near Sonoita. They are a great sight to behold.

I will try to do a bit of further digging on the status of the US and Mexican Chihuahuan population and how it has developed. Part and parcel of the Arizona GFD is a coyote removal program. This has been practiced in near Sonoita (medium effort), St. John and Douglas (small numbers) and S of Winslow and NE of Williams (big numbers).

Coyotes, bobcats and eagles prey on pronghorn calves and and at the exclusion of the larger main predator wolf in large parts of SW US states (the Mexican wolf recovery program only recently eclipsed 100 wolves in the wild) is a significant factor. This removal program seems to have had some significant impact.

Along with roads, cattle fences (there is a program now with changing the underline fencing so pronghorn can go underneath while keeping in cattle) and habitat fragmentation and deforestation and drought.

The Chihuahuan pronghorn herds at Sonoita (18) and San Rafael (8) had decreased to 26 individuals by 2012 (down from 122 in 2005). So, an increase to over 300 is a big achievement. When so low in 2012, the plan was to augment both afore-mentioned groups to around the 50 mark with new animals from elsewhere in the state.

This strategy along with the coyote removal seems to have worked and brought the animals above a critical threshold. Recruitment from 2016 over 2015 is good and bodes well for the next few years if the program is maintained at the same level.

An organization working in tandem with Arizona GFD is the Arizona Antelope Foundation, which is participating in the augmentation releases (it has been demonstrated several smaller and sustained releases over some years are more effective than one big release only).

NOTA BENE: Your likelihood of seeing pronghorn spatially and statistically could be extrapolated by calculating distance travelled and individuals seen and distance to you from animals observed. We might want to try it some time ... :D
 
Giant Panda said:
As for predator control, it depends as always on which species are targeted, how extensively, and what control measures are used. Unfortunately, there will always be uncomfortable ethical issues surrounding the killing of healthy animals for conservation purposes, be they zoo surplus, invasives or high-abundance predators.
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As a pertinent addition to my previous post, a new study in 'Frontiers in Ecology and the Environment' has found predator control is an ineffective means of protecting livestock.

Study Debunks Theory That Killing Predators Reduces Livestock Losses | Common Dreams | Breaking News & Views for the Progressive Community
 
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