NESTING HABITAT, FOOD RESOURCE AVAILABILITY, AND LONG-TERM OCCUPANCY DYNAMICS IN THE ENDANGERED FLORIDA GRASSHOPPER SPARROW (AMMODRAMUS SAVANNARUM FLORIDANUS)
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Date
2020-01-20
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Department
Biological Sciences
Program
Biological Sciences
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Distribution Rights granted to UMBC by the author.
This item may be protected under Title 17 of the U.S. Copyright Law. It is made available by UMBC for non-commercial research and education. For permission to publish or reproduce, please see http://aok.lib.umbc.edu/specoll/repro.php or contact Special Collections at speccoll(at)umbc.edu
This item may be protected under Title 17 of the U.S. Copyright Law. It is made available by UMBC for non-commercial research and education. For permission to publish or reproduce, please see http://aok.lib.umbc.edu/specoll/repro.php or contact Special Collections at speccoll(at)umbc.edu
Abstract
Determining the cues by which an organism selects habitat for nesting or territory occupancy is important for conservation of endangered or threatened species. Understanding the role of vegetation and resources in habitat selection enables land managers to maintain preferred habitat. The Florida Grasshopper Sparrow is an endangered non-migratory grassland bird that resides in fire adapted habitat in Florida. To understand the influence of vegetation on nest site selection and nest success I measured microhabitat around Florida Grasshopper Sparrow nests at two sites, dry prairie and a private cattle ranch (Ch. 1 and Ch. 4) for managing the habitat for this endangered bird. Territory occupancy is determined by multiple factors, but one of those is likely food availability. I sampled arthropods, the primary food resource for Florida Grasshopper Sparrows, in different fire treatments to examine the effect of fire on abundance and the influence arthropods have on occupancy use of Florida Grasshopper Sparrows (Ch. 2). Accurate population assessment is important for monitoring endangered organisms over time. I looked at the impact that time since the last fire using different fire metrics (maximum, minimum, and mean) has on Florida Grasshopper Sparrow occupancy at different spatial scales (Ch. 3). Using a misclassification occupancy model also allowed us to control for the presence of eastern Grasshopper Sparrows, which are difficult to differentiate in the field. I found that Florida Grasshopper Sparrows select certain microhabitat characteristics when nesting in the dry prairie, but not the cattle pasture. Nest success at both sites seem to be influenced by factors other than microhabitat. There is a difference in arthropod abundance between fire treatments with the most recent fires having the most arthropods, which may explain why Florida Grasshopper Sparrows prefer recently burned habitat. Recent fires (<1 year) do not influence the probability of Florida Grasshopper Sparrows colonizing a new area, but they do influence the probability of remaining in an area. All of these studies contribute and provide information for the ongoing monitoring of this critically endangered bird.