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9/28/2018 | 2:40 PM - 2:55 PM | Physiological Responses to Grazing Pressure: Investigating Feather Corticosterone as a Measure of Stress Response in Greater Sage-Grouse | Eccles Conference Center Auditorium

Physiological Responses to Grazing Pressure: Investigating Feather Corticosterone as a Measure of Stress Response in Greater Sage-Grouse

Glucocorticoid hormones are used to assess stress response to environmental changes is captive and wild animals. For birds, corticosterone is deposited in feathers during feather growth. We measured feather corticosterone (fCORT) levels in over 280 female Greater Sage-grouse from three study areas in Northern Nevada and Southern Oregon from 2013-2017. These sites allow for comparison of different grazing regimes of cattle and feral horses. We sampled feathers at spring captures, however, since these feathers were grown during the previous fall, we applied corticosterone as an index of stress during fall growth. We found evidence for an interaction between study area and year. Birds captured from the site with no grazing had relatively low values of fCORT in all years. Birds that were captured from the population with only feral horses had the highest fCORT levels in the year with the highest horse abundance. Birds captured from the area containing both horses and livestock had one year with higher fCORT than other years at any site. These results suggest there could be factors affecting fCORT levels that interact with grazing. We found some evidence for differences in fCORT levels between juvenile and adult birds. Increased fCORT in adults could result from stress of previous breeding attempts. This may be exacerbated by breeding in grazed vs non-grazed areas. To our knowledge, this is the first study to measure feather corticosterone in sage-grouse. These results can help fill in gaps about the physiological response of sage-grouse to grazing pressure and other environmental variables.

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Presenters/Authors

Tessa Behnke (), tbehnke@nevada.unr.edu;
Ecology, Evolution, and Conservation Biology