A CLOSER LOOK—Variations in Southern California Birds

By Kimball Garrett

Originally published in The Western Tanager Vol. 46 No. 10 July/August 1980

In this issue [July-August 1980], we'll take a closing look at variation in southern California's birds, and zero in with a strigid analysis of one of the most unique creatures in the region—the birdwatcher.

A unique attribute of the science of ornithology—the study of birds—is the degree to which the amateur, untrained in the disciplines of biology, can contribute to empiricism and theory alike. Many landmark studies and guides have been authored by persons with little or no formal training in ornithology. Massive date collection efforts, such as Christmas Bird Counts, U.S. Fish and Wildlife Breeding Bird Surveys, Audubon Breeding Bird and Winter Bird Plot Censuses, the Cornell Nest Record Program, and the American Birds Regional Distributional Reports, depend almost completely on the efforts of volunteer amateurs. This heroic contribution is possible because proficiency at bird identification requires little academic training, and this proficiency is the cornerstone of bird data gathering.

While field marks and behavior patterns of individual birdwatchers vary to an astonishing degree, all are united by a common potential to contribute to an advancement of our knowledge of birds. Motivations and goals of birdwatchers are about as varied as the facial patterns of alternate plumaged Ruddy Turnstones or the songs of Bewick's Wrens. Some birders might be likened to a sallying Olive-sided Flycatcher, actively darting after a prey item (in the birder's case, an interesting bird) within easy reach of the home perch. Others recall a sandgrouse, with regular long-distance flights for a fix of a vital resource (for the sandgrouse, water; for the birder, some lost warbler in Death Valley on Memorial Day weekend). There are the birding jaegers who wait for another birder to locate an interesting species and then close in for their share. And, happily, there are the gleaning creepers who search every nook and cranny on their home territory to turn up whatever they can. Some birders, like waxwings, are highly social; others resemble the most solitary raptors. There are storm-petrels among birders who come ashore only when conditions or urges dictate; and in contrast, there are the birders who are as comfortable on the open ocean as a roadrunner.

This variation in birdwatchers is a simple consequence of human nature. But any birder, from loon to bunting, enjoys that potential position of contributing knowledge to further the state of the art and the science. Previous "Closer Look" articles have summarized our knowledge of some field challenges below the species level, while posing a few questions along the way. Let me conclude this series by suggesting a few additional challenges for the birder. No lone birder will master any of these challenges, but light can be shed on each of them. Birdwatchers particularly interested in any field problem should consult their local museum, university, ornithological club, or Audubon society for advice on investigating the problem and publishing the results. Here are a few hastily thought-up examples:

1. A certain proportion of adult Heerman's Gulls show conspicuous white patches formed by the primary coverts of the wing; what is the frequency of this trait?

2. The Fox Sparrow has several well-defined subspecies groups occurring in southern California: gray, swollen-billed local breeders; gray, small-billed northern montane breeders; brown north coastal breeders; and rusty boreal/eastern breeders. What is the relative seasonal abundance of these forms? Remember that only large series of museum specimens can answer some of these questions.

3. Phalaropes employ a foraging method which involves "spinning" on the surface of the water in order to stir up food particles. Do individuals spin clockwise, counter-clockwise, or both? Does this depend on whether the individual is "right-footed" or "left-footed?" Does the direction of spinning change when the migrating phalarope moves to the southern hemisphere? (Pardon the tongue-in-cheek questions). One might concoct a host of other such questions.

4. Barn Owls have recognizably different color morphs, one quite white below and buffy above, and the other buffy below and deep gray and cinnamon above. What is the frequency of the darker morph? Are there any noticeable geographical patterns in its occurrence?

5. The songs of Rufous-sided Towhees are simple, but quite variable geographically (a la Mountain Chickadee, see June 1980 Western Tanager). What are the salient geographical patterns of such dialects?

6. Many passerines, such as most orioles, grosbeaks, tanagers, goldfinches, and Carpodacus finches, have distinct male and female plumages, with year-old males either resembling females or at least being noticeably duller than fully adult males. How often do these "immature" males successfully breed, or at least attempt to breed?

7. Swainson's Hawks have easily distinguishable light and dark morphs (with many birds being intermediate). Do like birds tend to pair? What is the geographical pattern of occurrence of the two forms and their intermediates?

Clearly, the number of problems to be tackled is infinite. Try, as a personal exercise, picking a small, easily definable problem. Sorting out the facts, and the underlying evolutionary bases, will be rewarding, challenging, and very stimulating.