Author: Katherine    Trebilcock

Major: Wildlife Ecology

Graduation Year: 2022

Thesis Advisor: Erik Blomberg

Description of Publication: The American Woodcock (Scolopax minor) has experienced steady declines in abundance over the past fifty years, which has raised questions as to why (Sauer et al. 1991). Migration for many birds, woodcock included, is energetically intensive, and may be the cause for greater mortality compared to other times of the year (Newton 2007). Despite this, there remains uncertainty in how conditions encountered during migration affect their movements and survival. One obstacle that birds must face is extreme weather, which has been increasing in intensity and occurrence due to climate change. How these events impact a migrating woodcock has been speculated but remains unknown. In my study I uncover different movement behaviors that woodcock exhibit when faced with extreme weather during both migration and winter pre-migration and explore variability in movement behavioral expression. Woodcock were tagged by the Eastern Woodcock Migration Research Cooperative, using GPS transmitters that provided fine-scale location data during the winter and spring migration period throughout eastern North America. I used a subset of this data and focused on winter pre- migrations and spring migrations in 2019, 2020, and 2021. I also collected information on storm occurrence from the National Oceanic Atmospheric Administration’s extreme weather database in order to identify birds that encountered extreme weather. I classified woodcock movement behaviors as either short movements, which included sheltering in place or moving a short distance to a local refuge, and long movements which were classified as a continued migration or a reverse migration. I found that very few woodcocks experienced mortality as a result of extreme weather. I also found that reverse migrations were prompted by snow and wind storms, and that birds in better body condition at time of capture were more likely to exhibit this behavior. Although reverse migrations are a normal part of nocturnal migrant phenology, previous research suggested birds would exhibit this behavior more if they were in poor body condition, counter to my results. I also found that male woodcock were more likely to move to a local refuge following extreme weather, regardless of time of the year, whereas females were more likely to shelter in place. This correlates with previous research which indicated that sex is a primary driver for cue selection in woodcock migration initiation. These results indicate that woodcock react to, and are affected by extreme weather, and have a number of strategies following these events that may help them to survive.

Location of Publication:

URL to Thesis: https://digitalcommons.library.umaine.edu/honors/732