As is my habit, I strolled outside at seven this morning, followed our slate walk to the driveway, picked up the papers and headed back. As usual, I paused under the giant 24-year old mesquite that shades our walkway to look for birds. I saw nothing at first, but suddenly became aware of a change from yesterday. The tree was singing, or so it seemed. To be accurate, a Northern Mockingbird thirty feet above me was singing loudly and non-stop, a delightfully unending string of different melodic phrases, and mesmerized, I remained in place enjoying this beautiful song while worry evaporated. A Gila Woodpecker’s call added counterpoint, and then a female Cardinal flew to a branch just inches above me where she broke into a soft, barely audible version of her mate’s glorious song, her open bill fluttering with each chorus of trills. Later, during our usual outdoor breakfast the yard was rich with springtime song, from the mechanical chortling of Cactus Wrens to the mockingbird-like mimicry of Curve-billed Thrashers. Is anything lovelier, more calming than birdsong? I think not.
The singing of birds likely has fascinated humans for as long as they have coexisted, and for good reason; apart from humans, singing is exclusive to birds. Bioacoustics, the study of animal use of sound to communicate, has discovered widespread communication through sound among species ranging from elephants and whales to insects. But this array of trumpets, howls, buzzes and roars doesn’t captivate us like the caroling of birds. And while many birds are restricted to non-musical vocalizations as well (think parrots, ducks and hawks), singing is limited to a single suborder of just one of thirty taxonomic orders of birds. A small percentage of birds taxonomically speaking, but the suborder oscines in the order Passeriformes represents nearly half of the world’s 10,000 avian species. Appropriately, oscines are known as ‘songbirds.’
Birdsong is not inherited. Almost all birds other than songbirds, and, as far as we know, every other non-human animal are born with genetically encoded vocalizations. But young songbirds learn to sing the way humans learn to speak, by listening and practicing, which is why we find geographic variation in the songs of identical species. And why do birds sing? The answer is ‘it’s complicated.’ Birds seem to sing for the pure joy of it, and maybe that’s true sometimes, but it’s mostly about holding territory and finding a mate. Both males and females use brief vocalizations (calls) such as chips and other simple sounds to communicate location or influence behavior, but singing is almost exclusively the role of males, and heard most often during mating season. It’s known that lengthening spring days trigger hormone release, leading males to establish territories and announce this to both rivals and potential mates by singing. But why don’t all birds sing? And why do some birds sing a single song while others sing dozens? And why do some birds sing one song in the morning and another in the evening? Why do mockingbirds mimic other birds, and why do some females sing? And so on. As I said, it’s complicated. A lot of ornithologists spend a lot of time trying to find answers, aided in part by the incredible Macaulay Library of Natural Sounds at Cornell University’s Laboratory of Ornithology, a repository of more than 130,000 recordings of animal sounds from gorillas to triggerfish, and consisting predominantly of most of the world’s bird species, including some now extinct. This invaluable resource is not exclusively maintained for scientific research. For 13 bucks, you can download their ‘Essential set of bird sounds for North America’, the most common 1,376 vocalizations of 727 regularly occurring U.S. and Canadian species. Or you can join more than 2 million birders and download the free Audubon Bird Guide app, which gives you the full resources of a hardcover field guide as well as the songs of more than 800 North American species. If you do use an app to learn the songs of birds, please be discrete in its outdoor use—playback can be confusing and irritating to both birds and other birders, and is prohibited in some areas.
Fortunately, we don’t have to know all the answers in order to appreciate the music of birds. Hearing and learning the songs of birds is truly enjoyable, and it’s a thrill to recognize the song of an unseen bird and then see him present himself to erase all doubt. As you enjoy the melodious spring, remember what a tiny fraction of the world’s life is responsible for your joy. Snakes rattle, frogs croak, lions roar and coyotes howl, but only birds sing.
(This article was first published in the April, 2018 Saddlebag Notes newspaper)