No one knew if they would come. If a few slabs of wood nailed together and hung in trees could replace the natural tree cavities that these birds had relied upon for millennia. But big trees and natural cavities were scarce—lost to the axe, the plow, and invasion by introduced species—and cavity-nesting birds were declining in the California. Artificial nest box programs had been successful in bringing back birds in other parts of the country so we decided to give it a go at UC Davis. The Putah Creek Nestbox Highway was founded by Dr. Melanie Truan in 2000 as part of her doctoral research with the Wildlife, Fish, and Conservation Biology Department at UC Davis. After Dr. Truan received her Ph.D., she continued the project with support from the Museum of Wildlife and Fish Biology, Lower Putah Creek Coordinating Committee, and Solano County Water Agency.  The program supports conservation as well as research and education, and is established, as a series of nest box trails arrayed along 20 miles of lower Putah Creek, Yolo and Solano counties California.  Next season will mark our 22nd year. It is the longest-running, scientifically monitored nest box program west of the Rocky Mountains. In addition to our core Museum staff, we have an active and enthusiastic group of undergraduate interns that help us maintain and monitor the nest boxes. To learn more about our nestbox internships, click here.

Members of the community stepped in with donations of labor and materials and soon we had a batch of brand-new nest boxes (cedar!) and private landowners provided safe locations for boxes.  To keep things simple, we designed what we hoped would be a one-size-fits-many box, able to accommodate a variety of species. We set the hole size large enough to admit Ash-throated Flycatchers, our largest target species, but too small to admit European Starlings, a major non-native competitor.  Our initial concerns about whether birds would use the nest boxes turned out to be unfounded. Over 95% of boxes are occupied each year. Since the project began, over 13,000 fledglings have been produced, from seven different species:  Ash-throated Flycatcher, Bewick’s Wren, House Wren, Oak Titmouse, Tree Swallow, Western Bluebird, and White-breasted Nuthatch. Western Bluebirds, once nearly extirpated as breeders on the creek, are recovering in good numbers. In 2020, over fifty pairs nested, producing 170 fledglings. Bluebirds are becoming increasingly common throughout the region, now recolonizing woodlots, parks, and gardens in nearby cities.

Each species has a different life history strategy. Resident birds are often tied to a permanent territory centered on a particular nest box.  For example, Western Bluebird super-dad Tufty and his mate(s) have produced at least five clutches, for a total of 22 fledglings, all from a single nest box on west campus. Migratory species—like the Ash-throated Flycatcher—head south in the winter but return again in the spring to breed. Band re-sightings confirm that some of our venerable old Ash-throats have made that journey at least fourteen times! We band our chicks, naming them as we go. We have had Cleopatra, Poppy, Espresso, and Maggie, to name just a few. Sometimes birds name themselves. One bird drew a band whose last three digits were 007, so we named him . . . James Bond!

Managing 200 nest boxes each year begins in February when all the boxes are inventoried, damaged ones repaired, missing ones replaced.  New boxes are made by volunteers each year. By Mid-March nesting seasons in full swing and staff and students begin tracking each nest box for the duration of the breeding season which ends in July each year.  Funds have been secured from the Solano County Water Agency to help pay salaries and travel.  It is about half of what we need to carry out the work. The good news is that the SCWA commitment is annual through at least the year 2027.  This allows us to chart a new and exciting course for the effort.  This includes long-term data analysis, expanding the highway along the creek and implementing a new highway in another region of the Sacramento Valley.  All of this would be undertaken by researchers and students of the Museum of Wildlife and Fish Biology.  Additional funding can aid us in engaging more undergraduate interns and analysis of long-term data sets by museum researchers.  The analysis and publication of data will help us better understand the ecology and life histories of our birds.  All this work is geared towards the conservation and recovery of cavity-nesting songbirds in the region.

All banding, marking, and sampling is being conducted under a federally authorized Bird Banding Permit issued by the U.S. Geological Survey’s Bird Banding Laboratory.

Putah Creek Nestbox Highway Flyer

2020 PCNH Annual Report