Deutschman Lab - San Diego State University

Breeding surveys of California Least Terns (Sternula antillarum browni) have been conducted since 1969, with the number of breeders and nesting success documented for each colony. Beginning in 1976, banding studies and management efforts to increase breeding success were implemented, including use of chick shelters and decoys and identifying key feeding areas. Wide variations in management and monitoring methodologies exist among sites and years despite numerous attempts to standardize data collection protocols and documentation. Challenges still remain in accurately estimating key population parameters (e.g., number of breeding pairs and fledgling success) and identifying key drivers of California Least Tern population dynamics. Furthermore, despite nearly 40 years of continuous data collection on California Least Terns, little to no comprehensive analyses have been conducted to gain a clearer picture of these dynamics.

The goal of this project is to promote California Least Tern recovery by a) adopting a meta-analytical approach and conducting comprehensive and quantitatively robust analyses of the existing long-term datasets and b) evaluating the utility and efficacy of current monitoring and management protocols and actions. These efforts will facilitate the development of a more robust monitoring and management protocol for California Least Tern that can be used across nesting colonies and management jurisdictions to maintain viable populations in perpetuity.

Utilizing data collected in all previous years the tern has been monitored, determine if the current monitoring strategy (including standardized protocols and methods) is adequate for assessing tern population status, threats and stressors (including introduced predators and plants and overharvest of fish by fishing fleets) on the species. Analysis should result in identification of future research needs, gaps in the draft recovery plan and provide information necessary to determine if current level of data collection is beneficial and critical for recovery of the species

Research Tasks

1. Analyze existing California Least Tern data to identify population drivers

a. Conduct trend analyses on existing colony data to identify patterns in population parameters over time, including number of breeding pairs, fledgling success, predation rates, and non-predation mortality rates.

b. Quantitative exploration of abiotic and biotic variables that influence reproductive output.

c. Map changes in statewide colony sizes over time.

d. Develop a conceptual model that builds on activity 1 analyses and current literature to inform adaptive management of California Least Terns.

2. Evaluating the current monitoring protocols and colony management

a. Quantitatively evaluate reliability/bias in the different colony metrics (# of fledglings, nesting pairs, etc.).

b. Develop recommendations for modification of monitoring and data collection protocols as well as potential changes to the California Least Tern recovery plan and identify critical needs for research going forward.

Lead Biologist: Douglas Deutschman

This project was funded by a grant from the California Department of Fish & Wildlife and United States Fish & Wildlife Service.