Data loggers in artificial eggs reveal that egg-turning behavior varies on multiple ecological scales in seabirds

ABSTRACT In most avian species, egg- turningbehavior during incubationis vital for proper embryonic development and hatching success. However, changes in turningbehaviors are rarely studied across different temporal scales(e.g., day–night or across incubationphases), though the timing of incubationbehaviors affects reproductive success. We used data loggersencapsulated in artificial eggs to measure turningrates and angle changes of eggs in Western Gull ( Larus occidentalis) and Laysan Albatross(Phoebastria immutabilis) nests. We examined diurnal and daily cycles in egg- turningbehaviors across early, middle, and late incubationphases. Our results indicate that (1) egg- turningbehaviors remain similar throughout incubation, resulting in a consistent environment for developing chicks; (2) egg- turningrates and angle changes vary according to diurnal cyclesand day lengthin each species; and (3) egg- turningrates, but not angle changes, were similar between species. Egg- turningbehaviors may vary am...