Josh Greenfield on first YAS Phenology Survey after LNU Complex fire

Text by Joe Zinkl, Phenology Survey Coordinator

Yolo Audubon members have been conducting a phenology survey at Audubon California’s Bobcat Ranch for over four years. The study is conducted in cooperation with the National Phenology Network. All data collected by our surveyors is sent to NPN.

What is phenology exactly? It is the study of periodic events in biological life cycles (in this case, birds) and how these are influenced by seasonal and multi-year variations in climate, as well as habitat changes.

The phenology survey route at Bobcat Ranch is a loop which begins near the ranch headquarters. It proceeds uphill to a permanent spring and then returns to the ranch headquarters via a gently sloping downhill trail. It is approximately two miles in total distance with an elevation gain of about 400 feet; it takes the surveyors about two and a half hours to cover.

The surveyors typically leave Davis near sunrise and return in about four hours. The route is divided into four sections; data is collected separately for each section. The numbers of each species and associated behaviors (feeding, calling/singing, courtship, nest building, and tending to young) are recorded.

Since the study was begun, the survey route has burned three times (Cold Fire – early August, 2016; Winter Fire – early July, 2017; LNU complex – mid August, 2020). Additionally, there was another fire (County Fire – late June, 2018) that burned much of the west side of the ranch. The three fires that burned along the survey route damaged, but did not destroy, the blue oak habitat that makes up the bulk of the route, but there was some blue oak, gray pine, manzanita and buckeye mortality. The small riparian habitat associated with Buckhorn Spring at the northwest terminus of the route was damaged as well.

In March, 2020 the surveys were suspended because of concerns regarding Covid-19, but in September of that year, California Audubon agreed to allow Yolo Audubon to restart biweekly bird surveys on the phenology route under a Covid-19 protocol, which is designed to limit person-to-person contact. Its major stipulations are 1) only four people can participate in each survey; 2) carpooling is not allowed; 3) masks must be worn during the survey; 4) 6-foot spacing between individuals should be maintained; and 5) equipment and snacks cannot be shared. On September 17, the first survey in slightly more than six months was undertaken and since then, surveys have been conducted every other Thursday.

Over the four-plus survey years, 112 species of birds have been recorded and nearly every survey reveals one or more interesting observations. For example, on the September 17th survey, which was the first one after the LNU Complex fire, record numbers of acorn woodpeckers, oak titmice, white breasted nuthatches and Nuttall’s woodpeckers were found. Two weeks later (October 1, 2020) that two-week old record for acorn woodpeckers was broken again. Were these records related to the fire?

In addition to the every-other week Thursday survey, once a quarter a survey is performed on a Saturday in order to attract volunteers who want to participate but can’t do so during the week. 

If you are interested in participating as a volunteer surveyor, or if you would like a summary of a previous survey, sign up for group emails here. You can also email co-coordinator Sonjia Shelly for more information.