Date of this Version
Ellis-Felege, S.N., A. Miller, J.S. Burnam, W.E. Palmer, and J.P. Carroll. 2012. Partial depredations on northern bobwhite (Colinus virginianus) nests. Pp. 161-172 in C.A Ribic, F.R. Thompson III, and P.J Pietz (eds). Video Surveillance of nesting birds, Studies in Avian Biology (no. 43), University of California Press, Berkeley, CA 240pp.
Partial clutch loss following a predation event is rarely studied in ground-nesting birds despite predation often being the leading cause of nest failure. Partial nest depredation occurs when predators attack but leave some eggs intact. Using continuous video monitoring, we documented a total of 372 initial predation events at nests of Northern Bobwhites (Colinus virginianus). From these, we observed a sample of partial nest pre-dation events (n=47). Partial predation events resulted in three outcomes: (1) The nest failed due to parental abandonment; (2) adult stayed with the nest, but clutch failed to hatch, usually due to further predation events; or (3) adult stayed with nest and the remaining eggs hatched, add-ing to the reproductive fitness of the adult. Most common predators causing partial depredations were ratsnakes (Pantherophis alleghaniensis and P. guttatus), kingsnakes (Lampropeltis getula), and fire ants (Solenopsis spp.). We used logistic regres-sion and model selection methods to assess six cues that parents may use to determine the value of remaining offspring and resulting abandon-ment decision. Overall, nests with fewer eggs remaining after the predation event or those pre-dated early in the incubation period were more likely to be abandoned; juveniles appeared more likely to abandon than adults. Future studies will be needed to confirm our findings of the relation-ships between cues and abandonment decisions, and video surveillance systems will be a necessary component of these studies.