August 09, 2005

Bad News for the Sage Grouse

Guest post by Steve Bodio

As all news seems to be. The magnificent Sage grouse (now considered to be composed of two species, the Sage, Centrocercus urophasianus, and the Gunnison, Centrocercus minimus) is the biggest grouse in North America and perhaps one of the ultimate quarries for dedicated falconers because it is so good in the air as well as large and strong. It is one of the few grouse that can be seen passing high in the air, like some sort of lumbering waterfowl or flapping B- 17 rather than a ground bird.

It is, (or they are) probably a "recent" species as such things go, one that split off from common stock with more conventional grouse species like the Blue grouse (Dendrogapus obscurus) during the Pleistocene glaciations. The polygamous males perform for the inspection of prospective mates on "leks," communal display grounds, making an eerie hollow hooting sound and erecting plumes and tails until they look like dancing plains warriors.

I am not one for doom and gloom about species, but the Sage grouse is an unusually unlucky bird. It migrates over lage distances for a so-called sedentary species, neds riparian areas and insects for its chicks, and above all needs SAGE, a major part of its diet. The sage ecosystem has been broken up and turned into center-pivot agriculture throughout the Great Basin and the valleys of western Wyoming and Montana. Invasive cheatgrass, which has no value as a food plant, is spreading via fire throughout the sagbrush ecosystem.

Now comes more disturbing news from the Swarovski Birding e-bulletin:

"We again visit the beleaguered sage-grouse scene, now with warnings about West Nile Virus. Over the past few years, Greater Sage-Grouse have been found infected with West Nile Virus at a number of locations, including Wyoming, Montana, and Alberta. Ongoing studies have suggested that the species is highly susceptible to the disease. None has shown neutralizing antibodies, intimating that most sage-grouse do not survive WNV. Indeed, researchers have yet to find a Greater Sage-Grouse that has survived infection by WNV, a grave situation for a species already facing diminishing habitat. Even the smallest doses of the virus have killed sage-grouse during experimentation. There is also evidence that WNV, usually spread by mosquitoes, can spread directly between sage-grouse. A 2003 study found that sage-grouse survival had fallen by an average of 25 percent in two locations in the Wyoming portion of the Powder River Basin, as well as at another site in Wyoming and one in Alberta. Studies are ongoing".

Libby reminds me that irrigation can create better conditions for mosquitos as well. I am glad that I have had the privilege to see the males dance , courtesy of Matt Miller of the Nature Conservancy and Tom Cade and Kent Christopher of the North American Grouse Partnership. If anyone can turn the great bird around, these organizations are the ones--check them out.

And, for a future post perhaps: the habitat of Sage grouse lies mostly within the "impact area" of that slumbering but uneasy dragon, the Yellowstone Supervolcano...

Update: apparently the WNV situation may not be as dire as first reported. In a North American Falconers Assocation email which I cannot quote in detail it because it is confidential, a veterinarian doubts that there is any confirmed bird- to- bird transmission. Which doesn't mean that these two spectacular grouse species do not continue to face all of the other problems mentioned above.

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