Mangrove forest age as a predictor of overwintering habitat quality for migratory songbirds

Wetland ecosystems are critical habitats for a host of organisms including resident and migratory birds. Forested wetlands (i.e., mangroves) surrounding Panama City, Panama are currently being drained and cleared to allow for commercial development. Restoration or replacement of mangroves (i.e. younger stands) may not be a sufficient surrogate for existing mature stands. Our main objective was to determine if mature mangrove forests provided higher quality habitat to (wintering) birds compared with younger mangroves. To assess this, we compared the following in mature and young mangroves in Panama (1) Prothonotary warbler and Northern waterthrush body condition, our most abundant species, and (2) feather reflectance criteria (specifically, carotenoid content) in prothonotary warblers occupying both types of mangroves. Carotenoid pigments are an honest indicator of the overall health and condition of a bird. By comparing reflectance of the carotenoid-pigmented breast feathers of prothonotary warbler, we are using feather reflectance as a proxy for an individual bird’s condition. After accounting for sex and age differences in our model, breast feathers from prothonotary warblers in mature mangroves had higher carotenoid content than feathers from prothonotary warblers occupying younger mangrove stands. Site occupancy strongly predicted body condition of prothonotary warblers in our study, such that, mature mangroves supported birds in better body condition than younger mangrove sites. Together, these results suggest mature mangroves offer higher quality habitats for migratory songbirds during their overwintering period.https://scholarscompass.vcu.edu/uresposters/1036/thumbnail.jp