Date of Award
2024
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Natural Resources
First Advisor
Brittany A. Mosher
Second Advisor
Laura J. May-Collado
Abstract
As the world continues to change due to climate change and human modification of landscapes, some species have become threatened or extinct while others thrive in these new conditions. The coyote (Canis latrans) expanded its range across North America since the early 1900s and arrived to Cape Cod, Massachusetts in the 1970s. The Cape Cod National Seashore, located on outer Cape Cod, is a protected area that contains important nesting habitat for two threatened shorebird species: the least tern (Sternula antillarum) and the piping plover (Charadrius melodus). Human landscape modification, predation, and other factors have contributed to the decline and decreased ranges of both shorebird species. The coyote is known to be an opportunistic omnivore that consumes what is most readily available in their environment, including, potentially, shorebirds. However, the extent of shorebird predation by coyotes in this ecosystem remains unknown. To understand the potential impact of the coyote on protected shorebirds, we analyzed coyote diet using DNA metabarcoding. The objectives of this study were to (i) evaluate the presence and contribution of threatened shorebirds to coyote diet, and (ii) examine seasonal and sex-based variation in coyote diet. We collected coyote scats from surveys during the fall of 2022 (when no shorebirds were present on the landscape) and summer of 2023 (when shorebirds were present on landscape) and used metabarcoding to estimate diet composition. We first species-typed the scat samples to confirm species and genotyped the scats to identify sex and individuals. We used metabarcoding of a subset of samples to identify the presence of shorebirds and other vertebrates. In total, we collected 215 scat samples in the fall and 213 in the summer, identifying 57 and 55 unique individuals, respectively (21 individuals detected in both seasons). We chose samples for metabarcoding by selecting from as many distinct individuals as possible, providing at least one sample from each uniquely identified coyote.
We found 27 distinct vertebrate diet items, but no DNA from piping plover or least tern in any samples, suggesting that these shorebirds do not constitute a meaningful component of coyote diet. However, we observed a high proportion of human food sources, such as chicken, cow, and pig in our samples (over 70% of scats containing human food in the summer and over 50% in the fall). We also detected white-tailed deer in high abundance (45% in the fall and 65% in the summer), as well as smaller mammals (over 50% in the fall and 65% in the summer). Additionally, we found two threatened species: the New England cottontail (Sylvilagus transitionalis), a species of greatest conservation need, and Eastern spadefoot (Scaphiopus holbrooki), a state threatened species, present in samples from both seasons. We also detected a variety of fish and larger marine mammals in our samples. Dietary diversity, measured as species richness and Shannon’s diversity, was higher during the summer than in the fall, and no significant differences were detected between male and female coyote diets. Our work suggests that currently, coyotes are not likely to exert predation pressure on shorebird populations of concern. Our findings also indicate that alternate threatened species could be at risk of coyote predation, and human food consumption by coyotes should be monitored to examine risks to ecosystem health and coyote wellbeing.
Language
en
Number of Pages
58 p.
Recommended Citation
Hanrahan, Carolyn Rose, "Estimating Coyote Diet And Predation On Threatened Shorebirds Using Dna Metabarcoding On The Cape Cod National Seashore" (2024). Graduate College Dissertations and Theses. 1911.
https://scholarworks.uvm.edu/graddis/1911
Included in
Natural Resources and Conservation Commons, Natural Resources Management and Policy Commons