Ornithological observation for many years meant to sit and watch a bird and describe its behavior anecdotally. Arthur Cleveland Bent, a businessman who became interested in birds as a child, eventually spent nearly 50 years compiling 21 volumes of the Life Histories of North American Birds, said: “When we think of the kingbird, even if it be winter here in the north, and he is for the time thousands of miles away in the Tropics, we picture him as we see him in summer, perched on the topmost limb of an apple tree, erect in his full-dress suit--white tie, shirt-front, and waistcoat-.” No criticism of Bent; his works contained enormous amounts of credible information, but we miss considerable information by studying just one small component of the avian community. It wasn’t until the middle of the 20th century that ornithologists began looking at assemblages of birds as organized and integrated.

How would you define the workings of the human community where you live? What reference points would you use? Perhaps you could use the occupation of the residents or the flow of automobile and pedestrian traffic. Or maybe interactions within social networks like Twitter or Facebook. Whatever scheme or definition you come up with will be incomplete. Imagine then, how difficult it is to ferret out the functioning of a natural community. Robert MacArthur mockingly defined a community as “any set of organisms living near each other about which it is interesting to talk.”

Studying bird communities is a difficult business partly because some bird species are more numerous than others and some are easier to spot. Bird community composition changes with the season, further complicating any analysis. So we need to satisfy ourselves with a snapshot that reflects the avian community at one particular time. As we discussed in Chapter One, since bird bills outline the niche of a bird species and given that birds spend so much of their time and energy foraging, the study of foraging habits is a major tool in the study of bird communities.