Overlooked sexual segregation of habitats exposes female migratory landbirds to threats

Abstract Male and female animals often segregate spatially among habitats and landscapes outside of breeding seasons, but it is unclear to what extent conservation efforts account for sexual segregation. Overlooking this phenomenon may result in conservation plans that don’t meet the needs of both sexes, especially when resources or threats vary spatially. We assessed the prevalence of sexual segregation and degree to which current conservation efforts account for it with a review of nonbreeding ecology and conservation planning literature for 66 North American migratory landbirds of conservation concern. Sexual segregation was common in the group—reported for one-third of all species and two-thirds of those with published nonbreeding sex ratios—and did not differ with dimorphism or conservation status. Despite this, only 3% of species distribution models and 8% of conservation recommendations considered sexual segregation, indicating the pattern is widely overlooked. Next, we used the declining Golden-winged Warbler (Vermivora chrysoptera) as a case study to test for sex-bias in habitats prioritized by current conservation efforts. By modeling nonbreeding occupancy and forest cover loss for males and females, we show that females lost twice as much nonbreeding habitat as males from 2000 to 2016, yet existing conservation focal areas remain heavily biased towards male-dominated landscapes. Furthermore, female-dominated habitats face higher rates of conversion than male habitats for multiple species of Neotropical migrants, suggesting the failure to address sexual segregation may compromise the effectiveness of migratory landbird conservation. We recommend greater effort to report sex ratios and create sex-specific habitat assessments and distribution models.