Author: Demetrius Lafkas

Publisher:

Published: 2021

Total Pages: 244

ISBN-13:

The endangered population of Great Lakes piping plover (Charadrius melodus) has nested at Cat Island Restoration Site in lower Green Bay, Wisconsin since 2016. Daily monitoring and research at Cat Island during the 2016-2021 breeding seasons have provided a detailed description of nesting and fledgling success of individually marked birds in a 5 ha (12.36 acres) gridded area. I acquired more detailed information about social behavior and species interactions of nesting piping plovers during the 2019 and 2020 nesting seasons. The goal of this analysis is to better understand the ecology and demography of the population and to provide a foundation for future management and monitoring decisions at Cat Island. The number of nesting piping plover pairs has increased from a single nest in 2016 to 6 nests in 2021. A total of 40 young birds have fledged during this 6 year period, with significant variation among years due to management-relevant issues including predation, avian botulism (2020), and demographic stochasticity resulting in a shortage of breeding males (2021). Adult piping plovers with unique band combinations have revealed a high degree of site philopatry and site specificity at the level of individual territories within the nesting area. Vegetation sampling during August 2020 showed that the native American searocket, (Cakile edentula); colonized Cat Island naturally and is associated with sand/cobble substrates characteristic of the main piping plover nesting area. Non-native invasive species like Phragmites australis (common reed) and Lythrum salicaria (purple loosestrife) were negatively associated with the piping plover nest area. During the past 6 years vegetation has gradually encroached into the habitat used by piping plovers, although management efforts have been fairly successful in controlling the spread of unwanted vegetation into the core nesting area. Piping plovers at the Cat Island Restoration Site shared their nesting habitat with killdeer (Charadrius vociferous), spotted sandpiper (Actitis macularius), common tern (Sterna hirundo), and transient or migrant birds that used the site irregularly. Interactions with killdeer were generally antagonistic when piping plover chicks were present, whereas interactions with killdeer at other times and interactions with spotted sandpipers were more neutral. Presence of common terns benefitted nesting piping plovers because the terns provided an effective warning system for potential predators. At least 16 potential avian predators and 4 mammalian predators were observed in or near the piping plover nesting area. I provide a literature review of the impacts of these and other predators on piping plover populations, with recommendations for control or eradication in the core piping plover nest area. Brinno BCC100 time-lapse construction cameras in the plovers' nesting area at Cat Island provided hundreds of thousands of images showing seasonal vegetation change and presence of bird and mammal species during the 2019 and 2020 nesting seasons. Coupled with daily location information for individual piping plovers, this information helps document where the birds spent their time at the Cat Island Restoration Site and what types of substrate and microhabitat are most important for their survival.Based on observations at Cat Island and published literature I provide recommendations regarding vegetation and habitat management, predator control, avian botulism, and other factors that affect long term success of the Cat Island piping plover population. Like most endangered species populations, ongoing monitoring and habitat management will be needed to ensure long term survival of piping plovers at this site. The attractiveness of Cat Island to migrating piping plovers and the potential demographic success of this local population have been demonstrated during the 2016-2021 observation period. Even if overall nesting success is moderate or low, the relatively long life and site specificity of individual birds suggests that this local population may contribute valuable genetic diversity, culturally evolved behavioral traits, and perhaps even improved demographic stability of the overall Great Lakes piping plover metapopulation.