Fig. 1
From: Comparative egg attendance patterns of incubating polar petrels
Photo by S.A. Shaffer
Photo of artificial egg, data logger, and microSD flash memory card used to measure egg turning behavior and incubation temperatures of snow and Cape petrels. Eggs were made of molded plastic (40 mm breadth × 57 mm length) and both halves were filled with barite powder to add mass to the approximate mass of petrel eggs.