PALO DATA EXPLORER
How Are the Birds Doing?
This question is frequently asked by those who care about birds — whether they are a scientist, a birder, or simply a nature lover — and answering it is the key first step to effective bird conservation. Operating year-round since 1966, the Palomarin Field Station provides a unique long-term perspective on West Coast bird populations.
Fewer birds at Palomarin
One way to measure the abundance of the local bird community is the number of birds captured as part of our long-term mist-netting and banding study. The bird community changes with the seasons as migrants come and go, so we examine total capture rates of individual birds during each season and overall in each year. Capture rates have declined overall, especially during the fall season, but these declines may be stabilizing.
Select lines at top right to view capture rates by season.
Annual capture rates at the Palomarin Field Station, 1979–2025. Note: Annual totals are calculated March through February of the following calendar year, to keep an entire winter season together.
Why is tracking bird populations important for bird conservation?
Our declining capture rates mirror the continent-wide pattern of declining bird populations across North America, with an estimated 3 billion fewer birds since 1970. In particular, the decline in captures during the fall suggests a reduced number of migratory birds passing through Palomarin on fall migration. By examining long-term variation in capture rates, we can identify individual species that are declining rapidly and determine where and when conservation attention is needed. These declines likely reflect a combination of habitat loss and degradation along migration routes, the additional impacts of climate change on their ability to raise young and survive each year, and local habitat changes that might make Palomarin more or less suitable for individual species.
Although we study the entire community of birds at Palomarin, we pay particular attention to a suite of focal species to understand how they are doing and what is driving any changes over time. Select a species below to see how annual capture rates of our focal species are changing over time and what this means.
Year-Round Residents
Present at Palo all year, these bird species often maintain their territories even during the nonbreeding season. Changes in the capture rates of these species are most likely to reflect changes to the local habitat and climate. While most of these populations are relatively stable, we have seen declines in Nuttall’s White-crowned Sparrows and Song Sparrows, thought to be related to the local habitat changes.
Seasonal Migrants
Present at Palomarin only for part of the year, Neotropical migrants like Wilson’s Warbler and Swainson’s Thrush spend the spring and summer breeding season with us, then migrate to the tropics of Latin America to spend their winter. Changes in the capture rates of these species may reflect a combination of changes in habitat or climate in the tropics, along their migration routes, or local effects of changes at Palomarin. For both of these species, trends in capture rates (from our forested mist-netting area) tell a different story than the growing number of nesting territories throughout other parts of the Palomarin study area, which are undergoing rapid habitat change.
Neotemperate migrants like Fox Sparrow, Golden-crowned Sparrow, and Hermit Thrush spend the summer as far north as Alaska, and then migrate to spend the winter with us. Changes in the capture rates of these species may reflect changes in habitat or climate in Alaska or Canada, along their migration routes, or local effects of changes at Palomarin.
Further research into the specific migration routes of our local populations of these species would provide additional insights into what is producing the patterns we see at Palomarin and how vulnerable these populations are to changes in habitat and climate.
How did we collect these data?
Since 1966, we have been mist-netting and banding birds at the Palomarin Field Station year-round. All of the birds we capture are carefully recorded and given uniquely-numbered bands provided by the U.S. Bird Banding Laboratory. All of these data are collected by staff, volunteers, and especially the hundreds of interns who have trained at Palomarin over the years.
For more information on how we carefully capture and band birds to collect this valuable data, please watch our video: Bird-banding and Mist-netting with Point Blue
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