An important study released today concludes that the presence of cattle in important sage grouse habitats increases the number of ravens that prey on sage grouse and their nests by 45.8% in the Curlew Valley of southeast Idaho. The study found that anthropogenic subsidies were increased in areas where livestock grazing occurred and raven populations increased as a result. The increased numbers of ravens selected areas close to active sage grouse leks (breeding areas) which are correlated to areas where sage grouse choose their nests.

Anthropogenic subsidies from livestock grazing can include carcasses of cattle, feed grain, dung, insects in dung, water from livestock water troughs, perching structures that make it easier for ravens to see their prey, and nesting structures.

Previous studies have shown that, areas where grazing reduces grass and forb cover which are important for nesting and brood rearing cover, the ability of ravens and other predators to locate nests and chicks increases. Raven populations have also been implicated in the reduction of reproductive success of sage grouse. Cattle can also disturb sage grouse nests and flush the hens letting the ever observant ravens locate nests. Previous studies on sage grouse predation have documented ravens as one of the most frequent predators to sage grouse nests. These studies also documented that cattle actually eat sage grouse eggs right from the nest.

The paper suggests that limiting anthropogenic subsidies and segregating livestock from sage grouse breeding areas is likely to reduce raven predation of sage grouse eggs.

Here is the USGS press release: Cattle Increase Occurrence of Ravens That Prey on Sage Grouse (3/2/2016 10:00:00 AM)

References

Coates P. S., B. E. Brussee, K. B. Howe, K. B. Gustafson, M. L. Casazza, and D. J. Delehanty. 2016. Landscape characteristics and livestock presence influence common ravens: relevance to greater sage-grouse conservation. Ecosphere 7(2):e01203. 10.1002/ecs2.1203

Coates, Peter S., and David J. Delehanty. “Nest Predation of Greater Sage‐Grouse in Relation to Microhabitat Factors and Predators.” The Journal of Wildlife Management 74.2 (2010): 240-248.

Coates, Peter S., John W. Connelly, and David J. Delehanty. “Predators of Greater Sage‐Grouse nests identified by video monitoring.” Journal of Field Ornithology 79.4 (2008): 421-428.

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About The Author

Ken Cole

Ken Cole, Western Watershed Project’s Idaho Director, is a 5th generation Idahoan, an avid fly fisherman, wildlife enthusiast, and photographer. He is also serves as a member of the board of directors for Buffalo Field Campaign.

7 Responses to Cattle Grazing Increases Raven Populations that Prey on Sage grouse.

  1. avatar snaildarter says:

    I can say is duh!! Of course this just means a war on Ravens instead of removing the cows.

    • avatar Barb Rupers says:

      Similar to getting rid of cormorants at the mouth of the Columbia to save salmon, or sea lions at The Dalles Dam, or barred owls to help spotted owls, or – –

      • avatar rork says:

        We can get rid of cows pretty quickly, the giant damns not so much, and old-growth forest restoration is harder still.

    • avatar Ken Cole says:

      There is already a war on ravens. The Idaho Department of Fish and Game completed some raven killing in this same area last year and USDA Wildlife Services is analyzing raven killing in their Predator Damage and Conflict Management Environmental Assessment. I submitted this study to them today for consideration in their analysis.

      USDA Wildlife Services has also been killing ravens in Nevada.

      • avatar rork says:

        Pretty nice paper. It’s open access. I noticed that IDFG actually funded it. Thanks for all your work on this and many other things (like the sheep issues).

      • This is absolutely true. The very sad fact is that scientific information which should be used to limit cow grazing will instead be used as an excuse to kill ravens — beautiful native birds who should be protected, not killed.

  2. avatar Ida Lupines says:

    Our activities just have a terrible domino effect. 🙁

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