Data loggers in artificial eggs reveal wild Scarlet Macaw ( <i>Ara macao macao</i> ) egg turning behavior

Incubation is a fundamental component of avian reproductive biology. One element of avian incubation, egg turning, is nearly universal among avian taxa and is vital for optimal embryonic development, hatch success, and chick quality. Despite its importance, egg turning behaviors are poorly understood. Egg turn parameters, such as rate and angle, are subject to wide variation among and within taxa and may vary over the incubation period. In this study, we used data loggers in artificial eggs to measure the rate and angle of egg turns from wild Scarlet Macaw ( Ara macao macao ) hens nesting within artificial cavities in southeast Peru. Our results from four of these hens indicate that egg turn rates averaged 11.5 turns h −1 , turn angles averaged 42.2° turn −1 , and these parameters varied significantly among hens. Egg turn rates were dynamic over the incubation period, peaking during the middle third of incubation, whereas egg turn angles increased linearly over the incubation period. Comparison with the literature suggests that the highly altricial Scarlet Macaws turned their eggs at a higher rate than the more precocial taxa studied with similar methods. Our study is the first to characterize the egg turn parameters of any wild parrot using data loggers and may prove useful for discerning larger taxonomic patterns in incubation. We found wild Scarlet Macaw egg turn rates to be much higher than published recommendations for the artificial incubation of parrot eggs, suggesting this work could be used to inform captive breeding and other conservation techniques.