By Steve Senesac – Science Chair
[Editor’s note: This is the full article referred to on page 5 of El Tecolote March-May 2020.]
In 2004, Jan Wasserman presented the Tree Swallow Nest Box Program that she was doing in Ventura. This ignited the interest of some our members at that time, David Kissner, Dave Eldridge, and Don Schroeder. Dave Eldridge was instrumental in building many of the boxes and Don Schroeder developed a scientific methodology for monitoring the boxes, as well as the basic training materials that we still use. In time, the reins passed on to Andy Lanes and Richard Figueroa, who involved students from UCSB and evolved our basic training program. Elaine Tan, Peter Thompson, Betsy Moony, Jayne Wamsley, Diane and Leah Vasquez, and again, Don Schroeder have been the mainstay of the program these past several years, as well as a continued interest from UCSB. Recently Conor McMahon has started a UCSB chapter of Audubon and is injecting new vigor into our UCSB connection, and the program overall. David Kissner came back into the larger picture a couple of years ago, developing a parallel program at La Cumbre Country Club. Lots of activity!
Birds: Even though the original intent was to provide habitat for Tree Swallows, we also have a significant number of Western Bluebirds at Lake Los Carneros, as well, there is an occasional refugee of another stripe such as a Violet Green Swallow. Last year, our twenty-two boxes there had full occupancy. Over the past years, the fledging success has been:
In 2019, twenty boxes had Tree Swallows and only two boxes had Western Bluebirds. These numbers have been varying from year-to-year. While it is not clear how long these birds live in the wild and this could be decreasing each year, at least at Lake Los Carneros, about twice as many chicks fledge each year as adults arriving.
In 2017, Don Schroeder, Elaine Tan, and crew began banding the birds and some interesting tid-bits of information have arisen (subject to more data). The Western Bluebirds seem to come back to the same nest box each year and with the same mate. Not so, the Tree Swallows. One of the pair may come back to last year’s box, or one close by; but not generally with the same mate. And, while many of the Tree Swallows do two nests in one box per year, the second nest is often with a different mate – a lot of genetic diversity there!
The following table shows the box and mate history of the birds we have banded. Because one of the pair might have been too elusive to capture, not all of the boxes have both parents recorded. You might note box L02 in 2017 and wonder what was going on. We do.