Correlated evolution between the avian visual system and nest architecture

Nest architecture is central to avian life history evolution, and the degree to which visual systems mediate nest construction, defense from invaders, and interactions with eggs and nestlings under variable lighting conditions remains poorly understood. Here, we use a comparative approach to reveal correlated evolution between eye size and nest architecture for 1662 species of terrestrial birds. First, we found that open cup nesters had the largest eyes relative to body mass, followed by dome and cavity nesters. Second, species nesting in dark conditions appeared to compensate for reduced visual acuity by producing eggs with relatively brighter shells and young with brighter achromatic contrasts in gape coloration. Third, eye size was positively correlated with the prevalence of intricate nest material stitching behaviors requiring enhanced visual acuity. Our results point towards a pervasive set of interactions between the visual system and avian reproductive dynamics as mediated by nest architecture.The attached folder contains all datasets used to complete analysis. Please see the Read Me file for details and the R script for analyses.