Birds: To See Them Is Not to Know Them
There is so much more to the lives of birds than we can see on the surface.
I have been a field biologist and ornithologist for 25 years, so you might think I have high standards when it comes to connecting with the wild and am satisfied only with sightings of hard-to-find birds. During the winter, at my farmhouse in rural Pennsylvania, I have a bird feeder on the porch only a few feet from the dining room window, and admire the nearly nonstop visits by ordinary birds such as hairy woodpeckers, downy woodpeckers, black-capped chickadees, tufted titmice, white-breasted nuthatches, slate-colored juncos, blue jays, and northern cardinals.
These are some of the common feeder birds that I have seen thousands of times before, but every sighting brings an important token of a renewed connection with nature and, occasionally, a surprising observation. The experience of quietly viewing nature through a window, from the warmth and safety of your home, is obviously enhanced enormously by luring colorful and interesting birds to the scene with a concentrated source of food. Here, I argue that a deep knowledge and understanding of the natural history and behavioral ecology of birds provides us with a more meaningful experience than simply seeing birds as beautiful, entertaining ornaments for our backyards.
Chickadee winter flocks are comprised of breeding pairs who, during the summer, defended nesting sites and territories from each other. In fall, the breeding territory boundaries break down, and chickadee pairs come to together and cooperate to defend a much larger winter territory from neighboring flocks. That year's young birds, facing their first cold winter, join the adults. A chickadee flock is a complex social network and has a clear-cut pecking order, with older and larger birds in the top positions, and socially dominant over younger newcomers. There is a parallel hierarchy, one for males and one for females, and the top-ranked birds of each sex usually pair up and breed together the following spring. Social rank determines access to winter food and hence winter survival. Low-ranked birds are subordinate and promptly leave the feeder when a more dominant bird arrives, so as to avoid physical aggression and possible injury. Those low-ranked birds that do survive the winter often cannot breed because the top-ranked birds claim all the available nesting territories and there is not enough forest to go around for subordinate pairs.
Most young birds live as the lowest-ranked birds and wait in line for a higher social position, gradually moving up in rank in the winter flock as older birds die. Nevertheless, about a quarter of young chickadees take a different tack, drifting between flocks on a daily basis rather than having a single home flock. If a top-ranked chickadee disappears, then a wanderer quickly appears and jumps the queue, claiming the vacant position.
During the breeding season, the stakes shift from food and social status to sexual competition. According to DNA testing, although chickadees are socially paired and seemingly monogamous, many offspring are the result of females mating outside the pair bond. Female chickadees eavesdrop on male-to-male interactions by listening to dawn song contests between neighboring males that duel using their fee-bay song. A female can discern which male is dominant during boundary disputes, and then the next day she visits that neighbor to sneak copulations.