Bird Population Studies

Scientific Papers

We investigate past and present conditions influencing variation in the survival, reproduction, and behavior of birds. We analyze long-term data from focal studies and citizen-science data to understand changes in bird populations in response to weather, predation, competition, and disease, as well as human activities such as pollution and urbanization. To do this, we explore ways to expand public participation in science to gather data across wide geographic scales; we lead multidisciplinary, collaborative studies; and we develop new techniques to analyze millions of data records on birds and the environment.

Project Highlights

Birds and Climate Change

Climate has an enormous influence on where birds survive and reproduce. In the short term, weather can influence the timing of migration, territory establishment, breeding, and egg laying. Over the long term, species have adapted to seasonal weather trends. We combine data from citizen-science projects with long-term weather data to examine climate's role in the changes we are seeing in the ranges of some bird species, as well as the timing and outcomes of breeding.

Data Analysis Toolkits

Using new techniques to analyze millions of data records, we study how bird distribution and abundance change through time and geographical space. We start by identifying large-scale patterns. This seemingly basic task is challenging because bird observations are unevenly distributed across the continent and are influenced by observers’ ability to detect birds. In collaboration with statistical and computer scientists, our researchers are developing novel methods to analyze data collected by both ornithologists and citizen-science participants. 

House Finch Eye Disease

During the winter of 1993–94, people began reporting House Finches with red, swollen eyes. The cause was a mutated form of bacteria common in poultry. Within three years, roughly 60% of House Finches in eastern North America were dead. Our Bird Population Studies researchers launched a citizen-science program called the House Finch Disease Survey to document the spread of the disease and they continue to investigate why the bacteria has been so persistent and successful.

Evolution of Variation in Life Histories of Birds

Looking at temperature and day length, we investigate why the pace of life among birds varies so consistently with latitude. These patterns include slower metabolism and embryonic development, smaller clutches, and longer incubation periods in tropical birds than in their cousins at high latitudes. We analyze data from citizen-science programs, such as NestWatch, and the NSF-funded Golondrinas de las Americas network, consisting of study sites focused on Tachycineta swallows across the Western Hemisphere.

Cooperative Breeding: Acorn Woodpeckers

The Acorn Woodpecker is highly dependent on acorns from California oaks. We study the complex relationship between this species and the trees, as well as their fascinating breeding biology. Acorn Woodpeckers live in family groups of up to 15 individuals. Several related males compete to mate with several breeding females, all of whom lay their eggs in a single nest cavity. Offspring from these joint nests help raise the group's young for up to several years.

Population Synchrony: Acorn Production by California Oaks

Oaks are well known “masting” species—acorn production varies greatly from year to year, but is highly synchronized among trees. Acorns are a critical food for many kinds of wildlife, including Acorn Woodpeckers. Walter Koenig leads a team in surveying acorn production to understand variability in acorn production, including why productivity differs, how far synchrony in acorn production extends, and what effects the variability has on California’s wildlife.

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