We’ve probably all had this experience. Before you can get your binoculars out of their case, an expert birder in your group has already identified by sound alone, a dozen birds around the parking lot. During the walk they add many more, some perching unseen in the canopy and others flying over, too quickly to get your glass on them. This almost unfair advantage that some birders possess is one of the distinguishing traits of an “expert” birder. How do they learn this and can I also acquire this skill? Before I try to answer this let me review some basics of birdsong.
How do birds sing? Birds have a trachea, similar to humans, that divides in the chest into a right and left mainstem bronchus. Whereas humans have their single vocalizing organ or larynx at the upper end of the trachea, a bird has its instrument or syrinx in the proximal part of each bronchus near the bifurcation, giving it the advantage of two independent vocalizing organs. A thin membrane or tympanum is adjusted by small muscles to control pitch. The amazingly complex repertoire of some birds is explained by this intricate dual syrinx, operable during both inspiration and expiration. But bird sounds vary greatly. Why do some seem to produce only a guttural squawk (Great Blue Heron), while others can entertain you with countless themes and variations (Northern Mockingbird)?
Which birds sing? In the classification of birds the order Passeriformes is made up of small, perching birds, all with three toes projecting forward and one backwards. This order is divided into two suborders, Passeri (oscine) and Tyranni (suboscine). The large oscine suborder is made up of 4561 species and contains the best singers. The suboscines have a simpler and more primitive syrinx, limiting their vocal skills. The tyrant flycatchers are the most notable example of suboscines who all struggle to carry a tune. There is evidence that the suboscines inherit their limited song repertoire, whereas the oscines must learn to sing their more complex repertoire. Male birds do most of the singing, however some females join in the choir. The female Red-winged Blackbird, for instance has one song to respond to her mate, and another to scare off other females from sneaking in the backdoor.
Why do birds sing? The common answer to this is to defend territory and attract a mate. Birdsong has the advantage of being a multidirectional communication tool with no dead zone. The “keep out” call of the breeding season becomes less frequently heard in the winter, while the female becomes a the talent scout in spring, preferring to mate with the most sonorous male. But there is a downside to being loud and conspicuous. Some birds have evolved and survived by developing camouflage coloration and by being secretive and quiet. Others have taken the opposite evolutionary path and become visually and audibly apparent and aggressive. This may give them an advantage in attracting mates and defending their territories, but also may attract predators. Birdsong has risks and rewards.
Birds also have other reasons to sing. They use brief contact calls to stay in touch with family or mates, or to alert others to a threat or new food source. The Florida Scrub Jay has one call that indicates a ground intruder and a different call for an aerial threat. Flight calls are used to keep a migrating flock in formation. I suspect the periodic nocturnal honk of the Canada Geese I hear all night long from our cove in the Chesapeake Bay is the “all is well” call of the flock’s sentry. We’ve also all heard the juvenile’s call from the nest, begging to “feed me first” as the parent flies in with the next meal. I also believe that some birds just sing for pure enjoyment. You would probably agree if you have ever heard the impressive theme and variations of the Northern Mockingbird extending well into the night. Mimus polyglottos, the scientific name of this bird is very appropriate.
What do birds sing? It’s interesting and puzzling to note that some birds have only one or two songs, (Indigo Bunting, Ovenbird), while others have dozens (European Robin, 70) and others have thousands (Brown Thrasher, 2000+). Despite the occasional curveball thrown our way by the mimics such as the Parrots and Mockingbirds, most species have repeated and consistent songs that allow field identification. One notes the almost monotonic but rhythmic call of the White-throated Sparrow versus the rising and complex song of the Warbling Vireo, each a unique identifier in the field. The flycatchers of the Empidonax genus present a difficult visual identification challenge. Noting their range and habits helps some, but the definitive ID is made from their unique songs. The woodpeckers have added a percussion section to their rather limited vocal ensemble. Their drumming is not just the sound of them hunting for food in the tree trunks, but also a unique signature of pitch, rhythm, and strength, protecting a territory and giving us another tool for identification.
Techniques for learning birdsong: So how can we join the elite and bird by ear? First you already know more bird songs than you think. Add them up: Robin, Chickadee, Cardinal, Blue Jay, Canada Goose, American Crow, etc. I’ll bet a new birder knows at least a dozen, and a more experienced birder has learned several dozen without even trying. There are several tools available that I have used with varying results. The Stokes Field Guide to the Birds of North America has CD’s of 150 birds which I have played while commuting to and from work. You may get a second look from the next car at a stoplight with the bird sounds coming from the truck, but so what–we all know that birders are different. I also have used two apps (IKnowBirdSongs and Master Birder, and there are others) which combine the songs with a picture of the bird, and cleverly use a repetitive tool and quiz to gradually build your skills. Many guides have bird spectrograms, a graphic but somewhat confusing representation of each bird song. One can also learn mnemonics (“Who cooks for you” for the Barred Owl, etc.) and these also can be helpful for a some species. But for me these methods have all been entertaining, but only marginally successful. I believe the best learning is done in the field. Perhaps the most useful aid is birding with others who know the songs and point out the source birds. But even when you bird alone, make it a habit to observe the bird and listen for its call. So often I have made the ID from field marks and moved on, but if you take the extra time to listen to each bird you will soon add to your growing song list.
This next technique is also helpful, but I recognize it is controversial in the birding world. I have the app iBird Pro on my cell phone and use it in the field. It is similar to the standard field guide with pictures, ranges, descriptions, etc. but is lighter than my old field guide, which I usually now leave home. The added feature is its ability to play the bird songs, including multiple variations of the common calls. I often hear a call and am not quite sure of the source; is it the Red or White-breasted Nuthatch? Play the songs and solve it right there. Which vireo is that in the canopy? Play the song of the likely bird and see if it matches or responds. Some previously unseen bird will fly close or poke its head up out of the underbrush to check you out, giving a confirming visual ID. Some say this is intrusive and needlessly agitates the bird. I say that if used in moderation, briefly, and infrequently, it can be a powerful tool. When I bird with a group I ask permission before playing a call, as some are adamantly opposed to this technique. Two birders were chasing a rarity in southern Arizona, one on each side of the ravine and invisible to each other. Each was playing the song on their device and hearing the reply from the other, thinking they had finally found their long sought-after life bird. You can imagine the frustration and disappointment when they tracked the sound to the other birder’s I-phone.
I often bird with a creative friend who has come up with a great idea for identifying bird sounds in the field. I hesitate to reveal it, for fear of patent violations, but will anyway. You may have heard of the app Shazam that can identify almost any tune by name and artist, even in a crowded restaurant with loud background noise. Shouldn’t it be possible to create a similar app that can pick up birdsong and identify the artist bird? Someday someone will figure this out and create such a tool that will help countless birders, and also become rich in the process. Remember, you heard it here first. Birdsong has inspired poets and composers throughout our history and brought joy to millions, even when we cannot identify the specific source. I hope this post helps you match the song with the bird during your next trip afield. Learning bird songs and calls is a slow stepwise process, but the avian symphony that greets us at dawn is one of the wonders of nature and greatest joys of birding.