Abstract
The Florida Scrub-Jay is a non-migratory resident species and the state of Florida’s only endemic bird. It establishes and defends territories year-round. As habitat specialists, these scrub-jays depend on frequently burned xeric oak scrub; they are federally and state listed as a Threatened species due to habitat loss, fragmentation, and degradation resulting from fire suppression and other aspects of land development. Although scrub-jays depend on periodic fire, which maintains their preferred vegetation height (1-2.5 m), fire can have short-term negative consequences. Scrub-jays from large natal territories have a fitness advantage, possibly because the habitat in large territories is less likely to burn completely, which leaves patches of post-fire habitat refugia. However, patchy burns may lead to heterogenous habitat structure that may affect how scrub-jays utilize their territory. My thesis examined how structural habitat variation within scrub-jay territories influenced their habitat preferences, behavior and prey abundance at Archbold Biological Station, located in Highlands County, Florida. I also evaluated the relationship among territory size, structural variation, and fire metrics, which include time-since-fire, fire-return-interval, total number of fires, and number of fires patches. I used LiDAR data collected with a GatorEye Unmanned Flying Laboratory to map and measure the mean canopy height of scrub vegetation within 29 scrub-jay territories. Grid cells at a 30m resolution were classified as low (< 1 m), medium (1 – 2.5 m), and tall (> 2.5 m) based on mean canopy height. I conducted focal watches on individual males to construct time budgets by recording the amount of time they spent performing primary behaviors (e.g., foraging) and recording the location of each behavior using the software ArcGIS Collector version 20.1.0. I also conducted prey abundance surveys to assess structure-specific resource abundance. Using the Hill numbers (converted from Shannon Diversity) as an index to represent structural diversity within each scrub-jay territory, I found no significant relationship between any fire metric and structural diversity. Larger territories did not contain more structural diversity, though they did contain more distinct fire patches and experience a greater number of fires. Scrub-jays used low and medium vegetation structures more often than tall, but showed a stronger preference for tall, especially when acting as sentinels. When foraging, they preferred medium and avoided tall and low vegetation. There was no difference in prey abundance among the three structural classes. These results show that scrub-jays select different structure heights for different behaviors, suggesting that they require heterogenous habitat structure within their territories. Land managers can use these results to make more informed decisions for prescribed burning. I recommend that plans should consider the average size of a scrub-jay territory and their structural preferences: the creation of homogenously low structure within a scrub-jay’s territory should be avoided, in favor of creating a patchy burn that retains areas of medium to tall structure that can support the sentinel and foraging behaviors that are integral aspects of Florida Scrub-Jay ecology.