Toro Creek Bird Banding
A Partnership for Birds: MAS, VWS, BLM
Bird banding can be an effective method for monitoring bird populations, and over time can provide information on population demographics and trends, particularly if a consistent level of effort is maintained at a site. In 2017, Monterey Audubon Society and Ventana Wildlife Society, with site access granted by Bureau of Land Management, established a bird banding station along Toro Creek, a riparian corridor on Fort Ord National Monument in Monterey County, California. Our objectives were to monitor local bird populations, contribute to a continent-wide data set to evaluate multi-scale bird population trends, and engage youth and the public in bird study. We conducted spring and summer bird banding each year from 2017 through 2019 but did not continue in 2020 due to precautions associated with COVID-19. We resumed banding in 2021 with added health and safety protocols.
We operated ten mist nets at Toro Creek in each of the nine designated sampling periods from May through early August. Placement of the nets, dubbed net lanes, were established on either side of the creek bed in 2017, and these same locations were used for each session all four years. On banding days, nets were opened at sunrise to begin sampling. Each net was checked for birds every 30 minutes, captured birds were extracted, and transported in small bags to the banding area near the middle of the site. Nets were operated for six hours or if the weather became too hot or windy, were closed early.
We banded passerines (songbirds) only and determined each birds’ age and sex. In some cases, we did not band captured birds because they escaped before processing or were over-stressed and needed immediate release. Bird welfare is of highest priority. If we captured a bird that had already been banded (i.e., a recapture), we recorded the band number and continued processing it. Birds were then released at the banding area or nearer to the capture site.
We captured 757 birds of 42 species at Toro Creek during the banding period (Table 1). Since capture rates and the range of total birds captured can be highly variable year to year, continuation of these standardized methods for at least five years is necessary for reliable productivity indices and survivorship estimates. Continuation of the study for 10 to 20 years is necessary to make reliable statements about local passerine population trends.
Certain species were the abundant throughout the years (Table 2.). Bewick’s Wren (Thryomanes bewickii) was by far the most numerous species we caught. They are habitat generalists with a wide range of nesting tolerances. Some species were notably absent in recent years. Wilson’s Warbler (Cardellina pusilla), which had decent capture numbers in 2017 (6) and 2018 (8), were detected only once on site in 2021 (one bird). Song Sparrow (Melospiza melodia) also had a notable drop in numbers, with none captured in 2021. This contrasts with the higher capture rates of the first three years, with 7 birds in 2017, 21 in 2018, and 12 in 2019. Following a relatively wet winter in 2017-2018, some residual pools of water in Toro Creek might have been associated with the modest peak in captures we experienced in 2018. The current drought, producing dry conditions on a regional scale and completely drying out Toro Creek at a local scale, is likely influencing population size and site selection for these species. It seems clear even from our small sample that there were fewer Wilson’s Warblers and Song Sparrows at Toro Creek in 2021 than in the previous three seasons. We will monitor these species closely, since their population sizes might serve as an indicator of riparian habitat quality and the success of restoration efforts by the BLM in this area.
We continued banding in summer 2022, with health and safety protocols implemented as needed, to continue to collect valuable data on local bird populations and engage with local volunteers, youth, and the public to foster appreciation for birds and the natural world.
Adult Acorn Woodpecker (L) and juvenile Acorn Woodpecker (R) banded at the Toro Creek Banding Station.