News/Reports
PREDATION ON RHINOCEROS AUKLET EGGS BY A NATIVE POPULATION OF PEROMYSCUS’
LOUISE K. BLIGHT AND JOHN L. RYDER Department of Biological Sciences, Simon Fraser University, Burnaby, BC VjA I%, Canada, e-mail: lkbZight@sfu.ca The Cooper Ornithological Society, 1999 DOUGLAS E BERTRAM Department of Biological Sciences, Simon Fraser University, Burnaby, BC V5A lS6, and Canadian Wildlife Service, PaciJc Wildlife Research Centre, RR1 5421 Robertson Road, Delta, BC V4K 3N2, Canada
Abstract. Predation by Keen’s mice (Peromyscus keeni) was the single greatest cause of egg loss for Rhinoceros Auklets (Cerorhinca monocerata) at the seabirdcolony on Triangle Island, British Columbia in 1998. Despite studies suggesting that gape-limited rodents are unable to open large eggs,mouse depredation was likely for the loss of more eggs than all other causes combined,with mice commonly opening and eating eggs of nearly twice their mass. In one study plot, mice depredated up to 34% of eggs. This high predation rate is likely related to temporary egg neglect by foraging parents.We suggest that egg depredation may increase in years of low marine productivity, when adults increase foraging time. Key words: Cerorhinca monocerata,egg neglect, egg predation, Keens’ mouse, Peromyscus,Rhinoceros Auklet, Triangle Island. See the PDF: condor101-871