Practicum Project | 2011

Crow Density and Anthropogenic Subsidies Near the Venice, California Least Tern Colony

Students: Margarita Armendariz, Allison Davison, Alessandro Maganuco, and Aaron Whitby

Client: Los Angeles Audubon

Advisor: Travis Longcore

Final Report

Crow predation on California Least Tern colonies is a well-documented activity and decreases tern breeding success. In an effort to learn more about these generalist predators and their increases in urban environments, we investigated their spatial distribution around the Least Tern colony in Venice, California. In order to accomplish this we surveyed crows and food subsidies within a semicircle area of 5.52 square kilometers around the colony in the 2 months leading up to the 2011 tern nesting season. We mapped these location data with ArcGIS and used land use data to determine correlations between food subsidies and crow density. An increase in food subsidies, especially around developed parks, correlated with an increase in crow sightings. We also observed more crows on weekends than weekdays. The data conclusively showed that crows are found within all land use types; because of this, landscape management will likely not have a significant impact on deterring crow distribution from the Venice Least Tern Colony. While this research is novel in that it is the first crow survey done around this colony, further research is needed to determine seasonal variation and larger scale patterns in crow density before any conclusive recommendations can be made to enhance Tern nest viability.