Bird behaviors are synchronized with seasonal patterns in nature such as temperature, ocean upwelling, rainfall, and flowering. Shifts in these patterns are already disrupting many species’ life cycles. Results include breeding failure and reduced survival. Understanding how birds respond to these changes requires data from long-term monitoring—a signature strength of PRBO. [back to main climate change page]
Altered Migration Timing
With almost four decades of data, PRBO and partners linked changes in bird migration timing to climate factors including temperature, wind and ocean currents. Of 21 migratory songbirds studied in California, more than half have experienced climate-related changes in arrival and departure dates.
For example, the graph below shows migrating Wilson's Warblers arriving earlier to their North American breeding grounds.
Source: Herzog et al. 2009. Indicators of Climate Change in California, Cal/EPA Report
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Increased Ocean Variability
PRBO biologists have documented reproductive failure of Cassin’s Auklets, when krill—their primary food source—were unavailable during the peak of the nesting season in 2005 and 2006. This lack of krill was due to delayed timing and low intensity of ocean upwelling. Climate models predict increased variability in ecosystems as a result of climate change. As the figure shows, over the last 30 years, productivity of Cassin’s Auklets at the Farallon Islands has become more variable over time, with extreme consequences for the auklets in 2005 and 2006.
Cassin's Auklet
Photo by Ron LeValley
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*(when you click on this link, note that the 2nd to last picture on the left hand side of the page is a Marbled Godwit, a migratory shorebird, not a seabird. Some things always get lost in translation.)
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Mismatch in Food and Nesting of Pacific Seabirds
In spring, ocean upwelling brings nutrient-rich waters to the surface, spurring food production for marine wildlife around the Farallon National Wildlife Refuge. PRBO found that upwelling is occurring 20 days earlier than in the 1970s when our research began. Common Murres have not been able to adjust their nesting cycle to match this altered timing.
Common Murres
PRBO Photo
“How changes in the timing of seasonal events will affect the future of seabird populations is one of the climate-related questions we are working to answer.” — Dr. Jaime Jahncke, PRBO Marine Ecology Director
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