Thursday, May 31, 2012

The Hidden Complexity of Birdsong

Birdsong, and even calls, sometimes exhibits complexity that we humans cannot hear. Birds use these complex vocalizations to communicate a wide range of information, from breeding status to warnings.

One of the amazing examples that I recently came upon was a video (see below) by Lang Elliot, a bird photographer and videographer. The video is about the Henslow's Sparrow (Ammodramus henslowii), a small and reclusive species of grassland sparrow. The song of the Henslow's Sparrow, to us, sounds simple and boring, a "tsidlick", as its song is often described. Roger Tory Peterson, the inventor of the field guide, called it one of the poorest vocal efforts of any bird. But to the sparrows, their song is certainly not simple. At 0:57, Elliot slowed down the song to show its hidden complexity, turning it from "tsidlick" to what I paraphrase to a "deet-dew-dewdew-deet-dew!" The song turns out to be a series of well-defined notes pushed together into a short period of time; one has to wonder if the sparrows can hear and discern each note of the song jumble better than we can. One also has to wonder if the ancestors of the Henslow's Sparrow's had a song that wasn't so jumbled, so that a human really could hear each individual note. Once again, we find a behavior shrouded in mystery...

Red Crossbill. Photo Copyright Michael Woodruff
A second example is that of the Red Crossbill (Loxia curvirostra). The Red Crossbill is a distinctive finch species with a crossed bill for feeding strictly on conifer seeds, (See how a relative, the White-winged Crossbill, uses its bill here) and shows a great deal of geographic variation in bill size and voice, with at least eight different types identified north of the U.S/Mexico border. Each type has a differently sized bill according to cone size preference. This results in each type feeding and nesting (my own inference) in different tree species; obviously, there has been some divergent evolution here. Ultimately, each type could be its own species, subspecies or some other taxa; so far, scientists haven't come up with an answer, but each population is steadily getting more attention. Even more convincing that each type is really distinct, David Sibley reported that when he was studying crossbill types in Montana, each type of the two that were present stayed in their own flocks and never mixed (see his article here). This is convincing evidence, because if each type is behaviorally isolating themselves and recognizing their own type, they probably aren't breeding together, either. Regardless, what we do know is that each type is almost never safely identified visually in the field. The best way to do it is by callnote, but unfortunately, the callnotes can be quite similar as well, and the human ear is unreliable in identifying each type--granted there are some that are easier to identify. With the ones that aren't, we have to resort to using spectrographs. So not only is this a fascinating example of what birds can hear and discern but we can't, on a larger scale, it's an example of each type coevolving with their preferred conifer species, and diverging from others; speciation by coevolution, if you will.

A third example is the Veery (Catharus fuscescens), a bird with arguably the most beautiful song in North America. A relative of the American Robin and other thrushes, the Veery is an adept songster. Within its song, their are actually two voices harmonizing each other with their own complex series of notes, slurs, and trills, but it's hard to discern this by listening to it at normal speed. But when slowed down to about 1/4 the speed, you can hear the intertwined voices of each side of the bird's syrinx, and the harmonies that result in the amazing song of the Veery. Read more from where I got this information at Earbirding.com, where you can also hear the individual voices within the Veery's song, as well as slowed down versions of the individual and the full songs. It's pretty awesome.

The complexity of bird vocalizations is something that recent technologies have allowed us to understand to a greater extent than ever before, and I'm sure there will be more to come.

Sunday, May 27, 2012

Flycatchers: An Introduction

Species in the groups of birds called Flycatchers are among some of the most challenging birds to identify to the species level. Flycatchers are songbirds that, as their name implies, feed mostly on flies and other insects that are caught on the wing. The term flycatcher actually refers primarily to two large and relatively unrelated families of songbirds: New World or Tyrant Flycatchers (Tyrannidae), and Old World Flycatchers (Muscicapidae), but also refers to a string of smaller families listed here: Monarch Flycatchers (Monarchidae), Silky-flycatchers (Ptilogonatidae), and Fairy Flycatchers (Stenostiridae). These families demonstrate the inaccuracy that common names can have; none of these families are particularly closely related, and yet they are all called flycatchers. Flycatcher more denotes ecological niche than natural relationship. Nonetheless, these are a fascinating group of families containing some of nature's most beautiful organisms, both visually and aurally.

African Blue-Flycatcher, a species of Fairy Flycatcher
Image credit  Steve G from Birdforum.net
The Fairy Flycatchers, known as 'stenostirids', are a group of African and tropical Asian species that were previously in a series of different families according to their morphological variety. Surprisingly, recent molecular studies have revealed these classifictions to be false, and that these outwardly dissimilar birds are actually part of one lineage. The family is composed of Crested-flycatchers (previously in Monarchidae with Monarch Flycatchers), Canary-Flycatchers (previously placed with a group of Australasian Family of flycatchers that were misnamed Robins, Petroicidae) and few others including the Fairy-Flycatcher itself and a species of Fantail. Based on our current knowledge, there are nine species within this family, but there may be more. In the future, it would not be surprising if more flycatchers and fantails are added to this family. It's this mystery that got me interested in birds in the first place, and I can't wait to see what about this family is discovered next. Click here to read more.

A male Phainopepla. Image credit Wikipedia

The Silky-Flycatchers, or Ptilogonatidae, are a small, new world family of flycatchers that are related to Waxwings in Bombycillidae and the Hypocolius of the Old World. They are characterized by soft, silky plumage, sexual dimorphism, and an elongated shape. The one species that reaches into the United States is the elegant Phainopepla, which takes its crazy common name from its generic name. You can find them from Central America north into the American southwest.

African Paradise Flycatcher.
Image credit Rubydbn from Birdforum.net
Monarch Flycatchers, or Monarchidae, are a diverse group of birds of around 140 species that include boatbills, shrikebills, paradise flycatchers, and magpie-larks. Most are forest birds with a broad-based bill and a slender shape. They can be found in many places throughout the Old World, where most are resident, or non-migratory. This family contains some of the most spectacular flycatchers, such as the African Paradise Flycatcher and the Buff-bellied Monarch.

Bluethroat. Image Credit Bas Meelker
 The Old World Flycatchers, Muscicapidae, are yet another large, diverse group of Flycatchers that are among some of the most well known and aesthetically pleasing birds on the planet. Arguably, the most famous species of Muscicapid is the Common Nightingale, which is well known for its singing ability and the fact that it often sings at night--the reason that it was named "Nightingale" by Anglo-Saxons around 1,000 years ago. Nightingale means "Night Songstress". Hear the song here. The Nightingale, along with its kin the Chats, Redstarts, Wheatears, etc., all in the subfamily Saxicolinae, were previously considered to be thrushes, but were recently lumped into Muscicapidae as a result of molecular evidence, effectively doubling the number of species in the family, which now contains 276 species. Some of these species, like the Nightingale in the genus Luscinia, are accomplished songsters. Others are just plain beautiful, such as the Bluethroat, Siberian Rubythroat, and White-throated Redstart. Some species that were originally in the family are quite beautiful as well, such as the Narcissus Flycatcher, which occasionally strays to North America. Overall, Muscicapids are some of the most prevelent birds in the Old World, and I'm sure that if you ever go to Europe and keep and eye out for birds, you'll be sure to see, or at least hear, one of its members.

Can you tell which species this is? Alder or Willow?
Image credit George Jett
How about this one? Image Credit Terry Sohl
And finally, we make it to the Tyrant Flycatchers (Tyrannidae). If there ever was a group of birds to epitomize difficult identifications, it would definitely be this one. Tyrannids can be found throughout North and South America in great variety, and includes some incredible species such as the Scissor-tailed Flycatcher and Vermilion Flycatcher, both of which breed in the U.S. Unfortunately, these species are exceptions, and most tyrannids are dull olive, gray, or brown. Not only are they dull colored, but over all their structures are often quite unvaried, and multiple genera of flycatchers can never be identified to species during certain times of the year. The Elaenias of the neotropics, for example, can be quite difficult to identify. An individual of this genus showed up all the way in Douglas Park in Chicago this April, and local birders have still never agreed to which species it is, even though it was well photographed. Myiarchus Flycatchers, an elongate, crested group of tyrannids, can also be quite difficult to identify. The most difficult genus that breeds in the U.S., however, would have to be the Empidonax Flycatchers, which are abbreviated as Empids. Eleven species breed regularly here in America, and provide some of the greatest identification challenges you can find on this continent. They are so similar, that many of them were once considered one species, and only defined as different species as time went on. An example in the East would be the Willow and Alder Flycatchers, which were once considered to be one species: the Trail's Flycatcher. They can only safely be identified by voice in the field. The Cordilleran and Pacific-slope Flycatchers of the West present a similar situation; they used to be together considered the Western Flycatcher. Not only can these species be incredibly frustrating to identify, they can also be a ton of fun, giving you the opportunity to use all of your brain power while trying to identify them. I personally love challenges like these, and will jump to the plate when presented with and empid to identify. They also happen to be quite entertaining to watch as they flit from branch to branch, bob their tails, and sally out for their fly prey with seemingly endless energy.  Read more about Tyrant Flycatchers here and here.

Over all, I think flycatchers are fascinating. The great variety that this term denotes can demonstrate many of the things that make birds so enthralling as a class. They are enormously varied; they can display amazing songs; they can sport plumages that are visually dazzling; they display behaviors that make us wonder; their relationships are still somewhat ambiguous; and they can be some of the most difficult species to identify. In all, this makes flycatchers some of the most emblematic birds, and something that I thought could make a great blog post.

A male Vermilion Flycatcher. Image credit galapagosmap.com

Tuesday, May 15, 2012

May 5: Spring Bird Count

Every year a group of knowledgeable birders get together to count birds during one of the most exciting tomes of the birding year: Spring Migration. During spring migration, one can easily see 100 species on a good day. That's a lot of species. To me, it seems to be almost the same as a Big Day, or a day when one or a group of birders attempts to see as many species as possible and potentially break a record for the most species seen during that time of year. The fundamental difference between a Big Year and a Spring Bird Count, is that a Spring Bird Count is considered a survey; the data collected by the observers is submitted to the National Audubon Society, which analyzes it to discover population trends, or long-term changes in migratory pathways. When Spring Bird Counts are done around the country, it helps to paint a picture depicting which birds are where during this time of year, which can be crucial when tracking natural cycles. This is called "Citizen Science", and is great for proffesional scientists because they can use amateur enthusiasts to do what they can't do alone.

Anyway, my group of three people began birding at Wadsworth Wetlands at 4:00 AM to get a head start on nocturnal species. We hiked around for around forty minutes in an attempt to hear owls, rails, and anything else that was out that early. Unfortunately, we didn't find any of the secretive rail species, but we did hear a hooting Great Horned Owl, and some early singing Sedge Wrens and swallows.

Next, we went to Osprey Lake in Gurnee, and just as the amber of the sun spread into the cloudy eastern sky, we heard Common Yellowthroats, a million Marsh Wrens, a singing White-crowned Sparrow, Gray Catbirds, and finally one of the reclusive rail species, a Sora. Soras have an eyrie and awesome call which can be heard in this video at the Internet Bird Collection.

Black-billed Cuckoo
After briefly observing a Great Egret, Northern Waterthrush, Eastern Meadowlark, and Savannah Sparrow near the Abbot facilities on atkinson road, we headed to our most productive spot of the day: Captain Daniel Wright Woods Forest Preserve, where my group saw 63 species. We started in the parking lot near the pond, and were greeted by singing Tennessee Warblers, Nashville Warblers, Black-and-white Warblers, Bay-breasted Warblers, Rose-breasted Grosbeaks, Baltimore Oriole, and more. We continued our way around the pond while sifting through the many species, including gorgeous Northern Parulas, dazzling Scarlet Tanagers, immaculate Indigo Buntings, and my first ever Blue-winged Warbler. After talking briefly to another birding group, we learned of a nearby Black-billed Cuckoo, and at our first learning of the uncommon bird, we dashed over to where it was reported and got some fantastic views. We continued on and found such species as Great Crested Flycatcher, Wood Thrush (hear its incredible song here), Swainson's Thrush, Yellow-throated Vireo, Philadelphia Vireo, Ovenbird, Golden-winged Warbler, and Canada Warbler - all great migratory birds.
Scarlet Tanager Image Credit Wikipedia

We continued through the day, getting such species as the declining Common Tern and a late migrant Horned Grebe at Independence Grove, and the elusive Henslow's Sparrow at a natural area at the West end of Old Mill Road in Lake Forest, which we heard singing in full view for an unbelievable 25 minutes.

Overall, I can't describe the joy it brings me to share my passion with others during this exciting time of the year, and knowing that my interest is helping ornithologists to learn more about birds makes it that much more worth it to me. I look forward to the Spring Bird Count next year, when hopefully we'll have just as many good birds as this year.