Term of Award

Spring 2021

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Biology

Committee Chair

Elizabeth Hunter

Committee Member 1

Ray Chandler

Committee Member 2

Michelle Cawthorn

Abstract

Predation, the leading cause of nest-failure in birds, not only exists as a direct threat to nesting success, but may exacerbate other sources of nest mortality. Birds inhabiting Atlantic coastal marshes, such as Seaside Sparrows (Ammospiza maritima; hereafter SESP), are experiencing significant and rapid changes to their habitat, particularly sea level rise (SLR) and encroaching urbanization, that may affect the relative influence of nest predation on overall productivity. For SESPs, SLR presents an inherent threat to nest success in its potential to increase the frequency of nest flooding. In addition to this direct threat, the ability of SESPs to adaptively respond to SLR can be constrained by predation pressure. As SESPs elevate their nests to avoid flooding, their nests become more vulnerable to predation. This research aimed to understand the predictability of SESP nest predation in Georgia’s saltmarshes along two major gradients: distance to roads and distance to tidal rivers (rivers ≥ 45m wide), both of which may be attractants for predators in the marsh. In coastal Georgia, USA, I assessed mammalian predator activity, an index for mammalian predator distribution, along the two gradients of interest, and hypothesized that predator activity would be higher close to roads and tidal rivers. Second, I recorded SESP nest predation events and hypothesized that nest predation events would increase with increasing probability of predator presence. Consistent with my hypothesis, predator activity increased close to roads and tidal rivers. However, mammalian predator distribution did not predict the spatial variation in SESP nest predation. Given my findings regarding predator distribution in the saltmarsh, I recommend that management efforts to decrease predator access to SESP habitat focus on road-marsh edges, particularly if they are connected with urban landscapes. Understanding the predictability of mammalian predator distribution equips us with valuable information for crafting conservation strategies for SESPs, such as predator management, that would relax the constraint of nest predation on their ability to respond to the ever-intensifying threat of SLR.

Research Data and Supplementary Material

Yes

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