Spring is just around the corner, and we are anxious for outdoor activities to start as days get longer and warmer. Early spring amphibian mating calls can now be heard in the ponds and wet field and forest areas of our rural neighborhood.
I have always enjoyed this time of year when nature seems to slowly wake up in the coolness of March's breezy days. Things are not really green yet in East Central Illinois, but the promise of spring is evident in the resurgence of animal movements in our backyards and surrounding fields and wooded areas. I see plenty of bird activity that is different from that of the winter months, and my mind can't help but wonder just why they do the things they do.
Why do birds seem to eat constantly?
Birds have a very short time period in which to grow up. One reason they must eat nearly all the time is because a hatchling born in May typically has only until September to grow large enough to participate in migration, as some species require. To get to this flight stage, called fledging, young birds must eat lots of insects that are high in protein to provide the fuel needed. This is true even if the species is mainly a seed-eating type.
Birds have an extremely high metabolic rate which requires much food relative to their small size. The rapid wing beats of a hummingbird, for example, require that it eat one and a half to three times its own body weight per day. This is almost 100 times the metabolic rate of an elephant. It seems like they constantly eat because they do!
It is also true that birds must replace ragged and worn-out feathers with new ones at least once a year. To accomplish a molt (replacement of feathers), birds require a lot more energy than mammals do to regrow hair or fur. And flying is a great way to travel, but it takes a lot of fuel.
Why do some birds eat seeds, while others eat insects?
Because birds have such extremely high metabolism, they must eat large quantities to keep up with the requirements of their bodies. It makes sense, then, that they would focus on abundant foods like seeds and insects. Species of birds have evolved to fill a wide variety of nature's jobs. All birds eat insects at some point in their lives, particularly when young. These protein-rich foods help birds grow at a remarkable rate. As they become adults, some species become mainly seed (or fruit) eaters. Of course, there are also flesh-eating birds like eagles, hawks, and owls, as well as birds that graze, such as geese.
Why do birds look different in the spring than they do during the fall and winter?
Many bird species have a surplus of males because the females have the much more dangerous task of laying and incubating one or more clutches of eggs each breeding season. Because they must sit still for long periods in the face of predation and bad weather, the mortality rate for females tends to be high. Males are in great competition with each other to attract the available females and must find a way to get noticed and stand out from the crowd. One way to do that is to grow new plumage that is brighter and more colorful than at other times of the year so that they can attract a mate.
Since females select the male (and not the other way around), a male must use a variety of means to convince the female that he is the best and brightest. He shows her that he possesses good territory by vocalizing and through ritual display. But his most obvious feature (at least to us as observers) is his bright and colorful nuptial plumage.
Why do birds sing, and why do we hear them mostly in the morning?
There are a couple of reasons for this. Singing helps to attract stragglers back that have become separated from the flock during the night. And birds sing gloriously in the spring breeding season to establish territories and attract mates. The rising of the sun seems to trigger these responses. It is true that in many bird species, the greatest amount of mate calling and territorial defense occurs in the hour just before and the hour just after the sun appears in the morning. Also, many songbirds group in large flocks that have a type of social order. Singing helps to shape, or reinforce, the pecking order among individuals. Most singing is done in the spring by the males of the species, often from the top of a conspicuous perch to gain attention from females and ward off rivals. Bird song is serious business and can also warn others of approaching danger. Singing and calling is not only the language of birds, it is also the feathered version of the dinner bell, the burglar alarm, and the neighborhood PA system.
Why do birds that feed on the ground cock their heads to one side?
The range of hearing in birds is very similar to ours, but much superior. Pigeons can hear lower sounds than we can, and owls have a sort of "binocular" vision with one ear lower than the other that helps them to pinpoint prey. Why, then, do the ground-feeders like the American robin sometimes cock their heads? The internal mechanism of a bird's ear is very similar to ours, but it lacks the external fleshy part which helps direct sound waves into the auditory canal. Cocking the head helps to point the ear in the direction of the sound. In the case of the robin and other thrushes, it is believed that they are also visually hunting for worms in the soil. It is safe to assume that they might be doing a little of both.
The behaviors of birds in springtime can give us valuable insight into the daily habits and lives of these delightful social creatures. It is during the spring of the year that many are at the peaks of their existence. Voracious appetites keep them well-nourished and always on the move. Colorful plumage is a quick and flashy way to tell mates and rivals who and where they are. Bird calls and songs are the musical serenades of the avian world, used by lovesick males to woo their mates and keep in touch. Sitting outside on a favorite porch swing or garden bench is a great way to take a break from our over-scheduled, technology-laden lives. Enjoy the antics of the birds. Our souls will be richly nourished, as Mother Nature always finds a way to captivate us.