A Wrentit nest with three eggs

Point Blue staff and interns collect weather data several times each day at the Palomarin Field Station to understand how climate change (over the long-term) and weather fluctuations (over the short-term) affect birds. Weather plays a huge role in the daily lives of birds, from successfully raising young to surviving the winter, while climate change can affect the long-term stability of bird populations.

Decades of weather fluctuations

To examine long-term weather patterns, we calculated annual average temperatures and total rainfall at Palomarin since 1976. Average temperatures are calculated from the average of the daily high and low temperatures. Rainfall totals are calculated from July through June of the following calendar year, to capture an entire winter rainy season. Both measures have fluctuated over the last 48 years, but rainfall totals are particularly variable. The wettest year we recorded was in the winter of 1997-98 (during a strong El Niño). More recently, we had two very dry winters in a row in 2019-20 and 2020-21, the driest years since 1976-77.

Average temperatures and rainfall recorded at the Palomarin Field Station each year, 1976–2023. 

Why is tracking weather and climate important for bird conservation?

Understanding how birds are affected by weather and climate requires long-term monitoring over decades. Because of our long-term bird monitoring and weather data collection at Palomarin, Point Blue has been able to identify changes in both the bird populations and the local climate, and uncover the links between them. This information helps us understand how well birds are adapting to climate change, and which species may be more vulnerable to climate change and may require more conservation attention. Here are just a couple examples of how our research has identified how birds are responding to global climate change.

Inconsistent Changes in Migration Timing

A changing climate may influence the seasonal timing (“phenology”) of blooming plants, hatching insects, and bird migration or nesting. In some cases, birds may not be able to easily change the timing of their migration to keep up with changes in the timing of their plant and insect food supplies, while others are shifting to try to stay in sync.

Spring arrivals. We have examined the dates migratory species arrive at Palomarin in the spring, and found that some species are arriving earlier (Orange-crowned Warbler), some are arriving later (Wilson’s Warbler), while others haven’t changed at all (Swainson’s Thrush).

For all of these species, it’s not yet clear why some birds aren’t changing the timing of migration (yet), and whether birds that are shifting the timing of their migration are able to keep up with changes in their environment. Future research could examine whether individuals that arrive earlier or later are more successful in raising young or surviving the winter, whether the optimal arrival time has changed over the years, and whether it depends on how far the birds are migrating.

Changes in Body Size

Birds at Palomarin have been getting longer wings! We confirmed this surprising finding using banding data from both Palomarin and the San Francisco Bay Bird Observatory. Studies from other parts of the world have found that birds are getting smaller, thought to be related to increasing temperatures. Longer wings could indicate birds in California are getting larger, possibly in response to increasing variability in our climate or more favorable conditions than in other places.

To understand why birds have been getting longer wings, future research could examine whether birds with longer wings arrive at the Palomarin Field Station at different times than birds with shorter wings, or whether they are better at raising young or surviving the winter.

How did we collect these data?

The tools have changed over time, but we have been collecting weather data on site since 1968, including daily records of precipitation, fog, temperature, cloud cover, wind, and barometric pressure. The bird body size and arrival dates data come from our long-term mist netting and banding operation. All of these data are collected by staff, volunteers, and especially the hundreds of interns who have trained at Palomarin over the years.

Plan your visit!

We welcome visitors to the Palomarin Field Station! We are located at the south end of the Point Reyes National Seashore, a hotspot for avian biodiversity with nearly 490 bird species recorded — the greatest number of any national park! Visitors are welcome to explore our Nature Center, take a walk down to Fern Canyon along our Nature Trail, and join our scientists for a banding demonstration to learn how we collect this important data. Check here for more information about how to check our current banding schedule and schedule a group visit.

Related research

There is much more to learn from these data! You can read more about what we have found here, and please contact us if you are interested in collaborating on future research.

• Migratory bird arrivals. Pages 232–242 in Indicators of Climate Change in California. [View PDF]
• Avian body size changes and climate change: warming or increasing variability? Published in Global Change Biology. [View online]
• Evidence of the effects of climate change on landbirds in western North America: A review and recommendations for future research. Published in Western Field Ornithologists. [View PDF]
• Projecting demographic responses to climate change: adult and juvenile survival respond differently to direct and indirect effects of weather in a passerine population. Published in Global Change Biology. [View online] [Read summary]
• Full list of Palomarin publications