Linking weather to bird populations
PRBO studies have shown that weather variables such as rainfall and temperature are important influences on bird populations. For example the graph below shows the relationship between annual rainfall and Song Sparrow nest survival in California coastal scrub habitat using data collected between 1980 and 2000, from Chase et.al. 2005.   

Increased rainfall is associated with increased song sparrow nest survival (above), as well as a longer Nuttall’s White-crowned Sparrow breeding season, and increased avian abundance based on mist-net captures. However, above a certain threshold, excess precipitation can also lead to a decline in nest survival or avian abundance.  With the onset of climate change, adapting to variable rainfall and temperature changes could pose a threat to many bird species.  PRBO biologists aim to understand these relationships, predict future changes, and inform land and resource management in order to conserve ecosystem integrity.  

Phenology- Migration Departure and Arrival Times
Our studies have also shown relationships between global climate cycles, such as Northern and Southern Oscillation Indices and Pacific Decadal Oscillation, and phenology.  PRBO biologists and partners have found that the arrival timing of 10 bird species were associated with both temperature and a large-scale climate oscillation index (El Niño Southern Oscillation, ENSO; North Atlantic Oscillation, NAO; and/or Pacific Decadal Oscillation, PDO). An additional study of fall phenology involving multiple sites in California found widespread evidence of earlier fall phenology – likely from earlier breeding – consistent with research detecting both earlier western North American spring and advanced spring migration on the Pacific coast (MacMynowski et al. in review). 

Current Research: Predicting impacts of climate change in the Central Valley
PRBO biogists studying terrestrial ecosystems are examining long term climate patterns and projecting the effects of climate change on bird populations in the Central Valley of California. Biologists are creating statistical models that show current distributions of birds in California and predicting how distributions might change in the future under different climate change scenarios.

Click [here] to view an annotated bibliography of PRBO related terrestrial ecosytem studies.