Abstract
Wading birds occupy a variety of coastal and wetland ecosystems that provide resources to support their survival and breeding requirements. Along the coasts of Southwest Florida, wading bird communities are a conspicuous part of mangrove ecosystems. As the coastal avifauna of subtropical regions has evolved within an active storm regime, this study aimed to assess the suitability of damaged mangroves as a habitat for wading birds following the hit of Hurricane Irma in September 2017. Field observations were conducted in a two-month period from June 10 to August 10, 2018 at Rookery Bay National Estuarine Research Reserve and at the Ten Thousands Islands Wildlife Refuge in Collier County, Florida. Wading birds were counted along boat routes within both study sites. Wading bird presence, behavior, and position within vertical strata of mangrove vegetation were documented, along with the approximate extent of defoliation in the used habitat. Additionally, canopy density measurements were evaluated from directly under the mangroves. Data analysis evaluated wading bird presence, foraging behavior, and strata selection with respect to mangrove defoliation from a 10m vantage point; the same measures of wading bird presence, foraging behavior, and strata selection were also compared in relation to canopy cover measurements. For all objectives, Chi-Square and G-Test Goodness-of-Fit tests were used to compare ratios of observations among categorical variables. Shared patterns emerged between both sites, whereby wading birds demonstrated a distinct occupancy of mangrove prop roots, as well as a presence in mangroves with 51-75% mangrove defoliation and 51-100% canopy cover. Interestingly, wading birds in the Ten Thousand Islands indicated an aversion to 76-100% defoliated areas, suggesting that while wading birds have undoubtedly adapted to hurricane impacts throughout time, too much defoliation could make the area unsuitable for supporting their ecological needs. With anthropogenic climate change and global sea level rise posing major threats to wading birds due to alterations in hydrology and water depth, studies of wading birds within mangroves and other impacted habitats are critical to understanding the implications of global change for these coastal ecosystems. My findings that wading birds occupy moderately defoliated mangroves while avoiding severe defoliation enhances our understanding of how storms impact coastal ecosystems, knowledge that will become more and more relevant in an area of increasing hurricane frequency and intensity.
