Avian Point Count Surveys 2023
Avian Point Count Surveys are one of the most efficient and effective ways to gauge the success of restoration efforts at the Cache Creek Nature Preserve.
This year, eight point count stations, situated at least 200 meters apart, were established in the riparian habitats and corridors of the Nature Preserve.
These bird surveys are conducted during the nesting season at the preserve, from mid-April to the end of May.
At sunrise on four designated count days, the Conservancy Biologist and volunteer team approached each point with caution and silence. They measured bird sightings and sounds for 10 minutes, out to a circle of 50 meters, and logged their findings.
You can download the report at the bottom of this page. This article summarizes some of the highlights.
Riparian Habitats are the Best!
Riparian habitats are the zones of vegetation right next to bodies of water. They provide filtration and erosion control, and can shade the water to regulate the temperature. They also provide food and shelter to animals and insects that have an aquatic component in their life cycles.
The riparian trees at the Nature Preserve are a mix of cottonwood, willow, mule fat, elderberry and some oak. Cottonwood predominates.
Migratory bird species tend to favor riparian habitats over woodlands or grasslands. The high canopies of cottonwoods at the preserve provide an ideal roosting and nesting environment. And the abundance of aquatic insects are a good source of food for insectivorous birds.
Twelve species of birds are great indicators of the health of riparian habitats in California’s Central Valley. These twelve species are also of significant conservation interest to the Central Valley Habitat Exchange meaning they are important species to monitor because they are “staples” of healthy riparian habitats.
The survey teams recorded all the bird species they observed and took special notice of the presence, abundance, and breeding status of these twelve species since they showcase the quality of the Nature Preserve’s riparian habitats.
Eight of the twelve were observed in this 2023 nesting season; they are in bold in the list below.
- Ash-throated Flycatcher
- Black-headed Grosbeak
- Common Yellowthroat
- Nuttall’s Woodpecker
- Lazuli Bunting
- Least Bell’s Vireo
- Song Sparrow
- Spotted Towhee
- Yellow-breasted Chat
- Yellow-billed Cuckoo
- Yellow Warbler
- Swainson’s Hawk
Birdwatchers: Over the year, let us know if you see or hear any of the four species our survey teams didn’t.
Breeding Success at the Preserve
There were 22 confirmed breeding species in the 2023 nesting season, the largest confirmed number in the Conservancy’s records!
The 2023 nest box monitoring program data (unpublished) shows that more eggs were laid and more fledglings left the boxes in 2023. The birds that use those boxes are Wood Ducks and cavity-nesting songbirds like Tree Swallow, Western Bluebird, and Ash-throated Flycatcher. Tree Swallow, by far, was our most popular nest box occupant.
The wildlife game cameras allowed staff to record baby chicks from more skittish birds like California Quail and Wild Turkey.
All in all, 2023 was a good year for breeding at the Cache Creek Nature Preserve.
This may be due to the plentiful water in the creek and wetlands this year.
The new Yolo County ordinance prohibiting Off-Highway Vehicles (OHVs) in the creek bed probably also played a role. There was certainly a lot less trash seen this year at the Creek Cleanup.
Abundance and Diversity
The abundance of each species and ‘species richness’ or diversity were determined for each of the point count stations. Stations with higher values can be seen as ‘hotspots’ while stations with lower values could be considered for additional environmental enhancement.
There were no significant differences between stations, though, especially in diversity of species.
There were slightly lower counts of abundance in the southern stations. These stations are closer to the creek and are thriving with dense foliage, so no enhancements are needed.
The dense foliage means surveyors had to rely on bird sounds to make their counts; a more difficult way to confirm numbers. Also, many of the types of birds at those stations are more elusive and do not call if they sense danger. Examples are Wilson’s Warbler, Townsend’s Warbler, Swainson’s Thrush
One can begin to see the obstacles field biologists have to contend with!
Past Year Surveys
Biologists at the Conservancy have done a few bird count surveys over the years. The first survey was taken in 1999, the year the Nature Preserve was established. Since then, a survey was performed in 2011 and then last year in 2022.
As you can imagine, survey design, the configuration and activities and the training and philosophies of the Biologists at the Nature Preserve would vary quite a bit over 20-some years. Harnawaz Boparai did a good review of past surveys in his 2022 report. He also set the groundwork for annual surveys going forward.
Felicia Wang made some refinements and conducted this year’s surveys. You can download a copy of both reports below which detail the methods, reasoning, results and conclusions.
Whether you are an academic researcher, a birding or environmental enthusiast, or an aspiring field biologist, you’re sure to find something of interest in this report and other Bird Surveys on this site.