I've been asked to host today's dawn chorus, so in the spirit of the season, bearing in mind the title of the series I've chosen to talk about the chorus itself.
For most of North America's neotropical migrants (far more birds nest in Boreal Canada and Alaska than in the lower 48) this is the week the females make camp. So those birds that haven't already bred will now begin courtship, nest building, and raising young'uns. Join me below the fold for some hot-bird action!
As a birder, I must confess my greatest shortcoming; the one critical skill that a great birder needs more than anything else is the ability to distinguish "who is singing that song"? It isn't that easy, unless you have that immediate feedback of being able to see the bird that is singing. You can go deaf this time of year listening to the explosive sounds coming from both the ground and the canopy. It is something I really need to work on. I've got the Birding By Ear CDs, I've seen "Watching Warblers" on tape a dozen times, but the only way to real become proficient is to go out and practice these necessary skills. Sadly I can't help you do that here, you've got to listen to the Dawn Chorus on your own, to build those connections between sound and bird; but I can provide a little help.
Why do birds sing? From an evolutionary basis, the DNA and brain structure needed to learn your species song requires a great deal of hardwiring in the brain, combined with learned behaviors. The payoff must be great, with such a significant investment. There must be a genetic advantage for birds that have either acquired or have invented the right sort of song. For such an elaborate artifact to have been bred through so intensively, the right song sung at the right time has to lead to a rather productive breeding advantage. For the most part, only male birds sing. But if you hear an improvised melody coming from above and you look up to see a female cardinal singing, don't be surprised. The male's song is pretty, but boring. Her's is more delicate, and nicer song. It might be that female birds are attracted to males that sound like her father- the song she heard when she was in the nest was imprinted on her, and she is attracted to in in a way similar to the way some insects are attracted by miles away to a few molecules of their species pheromones. It might also be a sign of hardiness- in this rough and tumble world, any bird that can spend the time singing instead of eating has to be physically hardy, have good genetic stock, and can find food proficiently enough that he can waste time singing. In some species it might be a sign of the males intelligence- if he can improvise his music so fluently, he's got to have the brains to survive, and he's going to have good genes to pass on to my chicks. Whatever the mechanism, song often plays as much of a role in sexual selection as does appearance.
Just as a lark (please don't throw tomatoes at that bird pun) I've decided to include photographs of birds in the process of singing.
Here we have a prairie warbler about a thousand miles east of the Great Prairie. How did they come up with that name? Its a grassland bird, with obvious similarities to it's cousins the yellow warbler and the palm. But he's got a different voice than those two. The prairie has an aggressive call for a warbler, eight or nine short staccato, rising pulses. The yellow has one of the most commonly heard songs in North America, "sweet-sweet-sweeter-than-sweet!" It is composed of two very fast notes, a pause, and four or five fast notes. (Often confused with the chestnut-sided warbler's "pleased-pleased-pleased-to-meet-you!" which has the same first two notes. The palm is yet another one of the "squeaky-wheel" warblers, a two-pitch call one high, one low, repeated 5 or 6 times rapidly.
This hooded warbler is a bird of shrubs and lower forests. A common nesting bird in the lower two-thirds of the eastern US. This was photographed at the northern part of his range, in upstate NY. I'm lucky to have a very productive spot for them nearby. His call isn't too far different than the redstart's; a fast series of ten or so notes, starting low, rising after about 6 notes to its peak, then going back down nearly an octave and rising again to peak. The last notes are slurred, which isn't that common.
The Canada warbler has a sound I can't really describe other than playing an answering machine's outgoing message way too fast. A few clicks, followed by 8-10 very fast whistling notes. I've heard it many times, and I've never been able to identify it in the field.
That's just to show that there are birds other than warblers that sing.
Song serves many purposes, most of which deal with breeding and territory maintenance. In the early morning, birds will often sing simply to state their continued existence. "I'm still here!" they are telling the community, and while that is often met with "me too", it does serve a social purpose for the many species that while competitive during breeding are cooperative the other 10 months of the year. During this time of year, males will go from tree to tree, delineating their territory and telling other males to "stay out". Birds need to acquire and maintain territory if they are to successfully raise chicks. If you can imagine how much food it takes to keep a bird alive, increase that by almost ten to keep a feed a mating pair, and their 5-6 rapidly growing chicks. Mating success depends upon territorial integrity, as much as it does attracting a mate.
And that's the main point of song, pair-bonding. Most species do keep the same mate for life, which in the case of a neotropical migrant can often be a very short one. Most birds die before their first year of life, and many others fail to breed more than once or twice so their entire genetic legacy can often rest on the success of one breeding season.
And that leads us to the next general topic; how to attract women!
Now you'd think that just being as pretty as this little guy is enough. Sadly it isn't, as he can't just make it on looks alone as the guy in the next tree looks just as good. Now it is unquestionably true that female birds do weigh physical appearance greatly in the decision making process, but he's also got to charm. For most birds, they learn their song from their father while they are in the nest, or fledging. There was a fantastic story about 6 years ago from Central Park, where they had what sounded like a very-early season black-throated blue warbler. It seemed like whenever they heard the warbler (this was IIRC in March) calling, they'd also hear and see this sparrow. After a frustrating time it was determined that the sparrow was singing BOTH songs. It was quite a revelation, the first confirmed bilingual songbird with a fixed song.
Tests conducted on finches (domesticated zebra finches I believe) showed that if they damage certain portions of the young birds brain they can induce them to sing fractured versions of their songs. Other tests conducted decades earlier showed that birds hand-reared by humans in the absence of their fathers were also unable to generate coherent song. They did attempt to sing, and it was (at least to the scientists) recognizable as zebra finch, but to other finches it was terrible. It didn't have the complexity, the characteristic signature that makes a breed's song singularly distinguishable.
Birds learn their song from their fathers. But what happens when the song mutates through time? Suppose due to environmental background noise, or as in the case of the white-throat, other birds nesting nearby cause "confusion" within the song? Anyone who has traveled from region to region watching birds can tell you that birds have "dialects" that vary in subtle ways from one part of the country to another. My favorite examples are the common yellowthroat (a small wren-like warbler with a raccoon mask) and the red-winged blackbird. Yellowthroats have that distinctive "witchety, witchety, witchety" sound that you hear in marshes or even in suburban grasslands. But there are multiple accents, which seem to get more slurred the further south you go. And the blackbird seems to get higher pitched the further south you go.
Two for the price of one! One singing, another resting- the singer isn't my favorite photo, so I thought I'd do it justice with a better one.
That's dialect- but some species such as the Carolina Wren or the white-eyed vireo have simply amazing variation from bird to bird. For the most part you can always tell that the bird is distinctly of that species, but many individuals have their own song. I was recently at Cape May, spending most of my time fighting mosquitoes and allergies at Higbee's beach. The DEET seemed to act more like a bird repellent than an insect, but there was an abundance of singing wrens and vireos. In the parking lot I witnessed three wrens in a confrontation- think of it as the bird version of American Idol. No feathers were ruffled, no injuries done to anything but pride. The three positioned themselves about 5 feet apart, one on a branch, the other two straddling reeds, and sang at each other. Oh if only we could settle international disputes in such fashion! Now two of these birds sounded the usual "tea-kettle, tea-kettle, tea-kettle!" song, one of the most familiar in NA (heard all year round in good weather) but the other was a slurred series of rapid changes; not "textbook" wren but still distinguishable based on timbre and volume.
This is different than the "improvisational" songs of cardinals, or orioles, thrashers, robins or thrushes. These birds use the brilliance of composition as a mating tool, as opposed to the unvarying songs which a bird is literally born with, and sings for his whole life. We can clearly hear that it is a vireo (note, many vireo species such as the red-eyed and warbling vireo are improvisational songbirds! So you can have a mixture of improvisational songs as well as fixed songs within one genera.)
The brown thrasher is the easiest of all the North American mimics to identify. He's somewhat stuck on the number two! He'll sing a phrase, repeat it once, and go to the next. I was out in Jamaica Bay a bit more than a year ago, talking to a photographer when a thrasher blurted out a perfect house wren, followed by a song sparrow. They do great improvised short riffs, but they can also do almost perfect impersonations of virtually any bird in NA (except perhaps the higher pitched birds, and the veery/wood thrush/hermit thrush complex). They aren't terribly common, and they are very shy except when singing. They are among my favorite of all songsters in their remarkable variety and fidelity.
Birds do more than sing, they also "call". They can impart specific information to other birds in the area, including members of other species. One of the most important features of calls is to announce your presence to family members, so they don't get lost. In social species this is very important. Chickadees are non-stop chatterers. This helps keep the flock together, and if one bird finds a rich food source the others will soon congregate towards it simply by preponderance of song emanating from the area. But other birds use chickadees' propensity for verbosity to help them "keep in touch". There are some birds that have weak voices, who join with the chickadees to form "mixed-winter flocks". Commonly you've got white-breasted nuthatches, downy woodpeckers, tufted titmouse and golden-crowned kinglets (along with the rare yellow-rumped warbler.) Out west replace the golden-crowned with the ruby-crowned, and the yellow-rumped with the Townsend's warbler. The odd combination of birds is essential for survival, not only as a tool for finding food, but as a means of keeping warm in difficult weather. Kinglets are just barely bigger than hummingbirds, and will huddle close together to pool warmth. Without having your siblings to keep you warm, death can be one bad night away. It really is amazing how prolific golden-crowned kinglets can be, with one pair laying two-dozen eggs within two weeks, and each parent either sitting on or maintaining its own nest! You'd think with all that divided attention they'd have a low survival rate, but I've seen estimates of 85-90% of all chicks surviving to their first winter. But again all it takes is one bad storm, to wipe out a family of dozens of birds. Life in the winter isn't easy.
I'm going to break for a moment to ask you all a little favor- Help the American Bird Conservancy's campaign "Act for Songbirds" ensure that a key bill is passed in Congress. The bill, cosponsored by Reps. Kind (D-WI) and Gilchrest (R-MD) is to reauthorize the Neotropical Migratory Bird Conservation Act, which is the sole federal grants program targeted specifically for bird conservation in the Americas. The campaign is seeking support from other Representatives to pass the bill with a maximum authorized spending of $20 million each year. Currently the Act is only authorized at $6 million, and so many worthy programs go unfunded. Grants must be matched at a rate of three to one by other sources, so this program can leverage another $60 million for bird conservation each year!
Please take part in this campaign today by visiting http://www.abcbirds.org/... Tell them a little birdie sent you!
Okay, now that we've got the begathon complete, let me hit you with a little anecdote. This was told to me by one of the directors of NJ Audubon, and I can't vouch for its authenticity except for the fact that it sounds good, and they wouldn't lie to a paying member (I should take the opportunity to mention that this wasn't told to me by Peter Dunne, who I had the chance to bird with for 15 minutes this spring and who totally floored me with his insane ability to identify a bird from what seemed like two states away. I'm struggling to identify the bird that just landed on me, he's calling out gulls and terns, oystercatchers and dolphins. Not to mention the fact that he's also thoroughly entertaining, genuinely nice, and a very good author.)
Once upon a time, Roger Tory Peterson the great old birder was feeling a bit under the weather. Some of his friends invited him to bird and he politely declined, deciding to stay the day indoors. After their hunt was completed, he described to Peterson the day's bird list. All in all, "we got 43 birds." to which Peterson replied, "I got 46 from in here." The great legend was able to identify more birds from his home by sound alone, than a group of birders could do by sight and sound. There is a entire cottage industry dedicated to blind birders, with serious competitions and conventions. So bird sing to talk to each other, seek out mates, warn each other of impending dangers, keep in touch with their family, and to delight and entertain us all!