The Effects of Adult Fecal Material on Egg Hatchability in Glaucous-Winged Gulls (Larus glaucescens)

Abstract

Abstract The effect of gull and cormorant feces applied to naturally incubated Glaucous-winged Gull eggs upon hatching success was studied on Mandarte Island, British Columbia. Gull feces, but not cormorant feces, significantly reduced the hatching success of treated eggs below that of control eggs. Eggs treated with gull feces lost significantly less water during incubation than either control eggs or eggs treated with cormorant feces. Eggs that were covered with gull feces but that nevertheless hatched had a significantly longer incubation period than did control eggs. The removal of the fat from the feces with ether before application to the eggs did not significantly improve hatching success.