| Abstract: | Although sex ratios at conception are close to 1:1 in most species of birds, skewed adult sex ratios (ASRs) are not uncommon in populations of birds, and occur frequently at local and temporal scales. ASRs are a key variable influencing population demography, breeding systems, and many aspects of the behavior of birds. However, factors contributing to variation in ASRs, particularly for tropical species of birds, remain poorly understood. By compiling information from field sites and records from bird collections, we found that the ASRs of four species of Columbina ground doves from Venezuela deviated significantly from parity. Males of all species outnumbered females at all field sites and in all museum samples. ASR, expressed as the proportion of males, ranged from 0.59 for Common Ground Doves (Columbina passerina) to 0.65 for Plain‐breasted Ground Doves (Columbina minuta) in the overall samples. Males outnumbered females by ~ 44% in Common Ground Doves and by 85% in Plain‐breasted Ground Doves. Our samples included birds collected as specimens over many decades and across broad geographic areas, suggesting that skewed ASRs are characteristic of Venezuelan ground doves. Because these ground doves do not exhibit pronounced sexual size dimorphism and have socially monogamous breeding systems, selection would be expected to favor equal investment in males and females at hatching. As such, we argue that greater post‐hatching mortality of females, rather than deviations in the sex ratio of embryos, is the main cause of the biased ASRs of Venezuelan ground doves. |
