Welcome to the homepage for the Caltech weekly birdwalks. These walks began in the Fall of 1986 when Ernie Franzgrote contacted Alan Cummings and suggested they do it. The first few walks were actually lunches in Tournament Park on campus, and an early one of those produced a new life bird for Alan and he was hooked. By 1987 a regular route for the walks had been chosen and regular once a week walks at noon were taking place. These have continued to the present day. On this website you will find the raw data collected (in the form of an Excel work book), various plots of the data collected, reports of the weekly walks, articles in various publications that have been written about the walks or walkers, information on the participants, and links to other bird websites.
Some of the plots show distinct trends. Click the link to “bird data“ at the top and then “probability plots“ to see some of these. Some birds appear to be on the decline and some have become extinct on campus. For example, the Spotted Dove was regularly seen up through 1991. Thereafter it declined, presumably due to the removal of the houses on Lura St. where we often saw it. It was last seen on campus in 1996. Similarly, the Brewer’s Blackbird was present on about 40% of the walks through 1991 but dropped off abruptly thereafter. It was last seen on campus in 2000. Other common birds are showing a slow decline as well, e.g., the Scrub Jay and the Mourning Dove. White-crowned Sparrows were pretty steady at ~30% in the early going but have dropped off in the last three years to about 10%.
Other birds have gained in numbers, however, e.g., the Yellow-chevroned Parakeet, the Red-tailed Hawk, the Black Phoebe, the Raven, and the Band-tailed Pigeon. The Crow and Acorn Woodpecker have always been around but they seemed to have risen together in numbers from about 75% in 1987 to 100% by 1992.
Of course, there is a strong seasonal dependence in the overall numbers of species sighted during the year as bird migrations are a reality. There appears to be just one peak and one valley to the year. Winter walks produce the most species sighted and Summer the fewest. The record number of species recorded on a walk is 31, which was reached in 2006. The lowest total was 6, also “reached” in 2006. Click the link to “bird data“ above and then on to “two time plots“ to see this information.
the webmaster for any questions or
suggestions. (Note: This website was designed and created by Kelly Jung in 2004.
Kelly also participated in the walks that year. When she started her MBA program, I took over
as care taker of the website. “Webmaster“ is too strong of a title for me; I can edit
the source pages, add plots, upload the weekly report, etc., but don't suggest I make major structural changes
to the site. I have no desire to do that anyway. -- AC.)