An evaluation of nest placement theory using artificial and Columbian sharp-tailed grouse Tympanuchus phasianellus columbianus nests
Apa, A.D., Reese, K.P. & Connelly, J.W., Jr. 1997: An evaluation of nest placement theory using artificial and Columbian sharp-tailed grouse Tympanuchus phasianellus columbianus nests. - Wildl. Biol. 3: 278.
Avian predation is a major factor affecting clutch success for ground nesting birds, especially during egg laying when the nest is unattended. Nest predation could influence nest placement by hens of lek-attending species by causing an over-dispersion of cryptic prey and/or it may also have an indirect or direct influence on lek evolution and development. This study tested two lek evolution hypotheses; the male-avoidance and sentinel/decoy models. In total, 551 artificial nests were constructed around seven active Columbian sharp-tailed grouse Tympanuchus phasianellus columbianus leks over two years. Nests were checked following 1, 3, 6 and 9 days of exposure during two egg-placement periods. Forty-eight Columbian sharp-tailed grouse nests were also evaluated. Distance from lek contributed significantly to the artificial nest logistic regression model for each day checked. Finite daily survival of artificial nests increased with increasing distance from the lek as nest density decreased. Vegetation structure was homogeneous across all distances for artificial and grouse nests. Similar survival patterns were not apparent with sharp-tailed grouse nests. The data obtained in this study lend credence to the male-avoidance model and suggests that female sharp-tailed grouse in Idaho may reduce predation on their nests by nesting farther from leks where they encounter lower nest densities. The sentinel/decoy model predictions and hypotheses may not be applicable to Columbian sharp-tailed grouse in southeastern Idaho. Distance from and density of nests from active leks are interrelated aspects of nest survival.
Key words: Columbian sharp-tailed grouse, Idaho, lek evolution, nest placement, Tympanuchus phasianellus
Anthony D. Apa & Kerry P. Reese, Department of Fish and Wildlife Resources, University of Idaho, Moscow, Idaho 83843, USA
John W. Connelly, Jr., Idaho Department of Fish and Game, 1345 Barton Road, Pocatello, Idaho 83204, USA