Wednesday, May 13, 2009

Vocal copying by Pine Siskins

[10 July 2009 - update added at end]

In July 1990 I spent several weeks birding in west-central British Columbia, where Pine Siskins were one of the most conspicuous birds, and I became convinced that Pine Siskins were copying the sounds of other species of birds and incorporating these sounds into their songs. I was able to identify American Robin (squeal call), Evening Grosbeak (“krrr” call), Warbling Vireo (scold call and a song phrase), White-winged Crossbill (flight call and trill), and even House Sparrow (calls).

Since then I’ve heard this in many other places, and come to expect it whenever I hear siskins singing. From late March to early April 2009 I had the opportunity to listen to several individuals repeatedly in my yard in Concord, Massachusetts, and I was able to identify the following 14 species in the siskins’ songs:

Evening Grosbeak “krrr” call

American Robin, flight squeal and single “pup” call

Eastern Bluebird, rattling flight call

Eastern Towhee, “chewink”

Black-capped Chickadee, a single “dee” note

Northern Flicker, “kew” call

Hairy or other woodpecker, “wika” call

Dark-eyed Junco, soft “tew-tew-tew” call

Eastern Phoebe, song phrase and chase call

Blue-headed Vireo, two syllables of scolding call

Red-eyed Vireo, scold call

Song Sparrow, “jimp” call

Ruby-crowned Kinglet, two-syllabled whistled song phrase

Common Redpoll, flight call

These sounds can be very challenging to pick out, since the song moves along so rapidly that the bird is already singing other sounds while your brain struggles to process and identify the previous sound. The Evening Grosbeak call is commonly used and distinctive enough to stand out each time, but other calls like the Eastern Bluebird rattle simply blend in with the staccato jumble of sounds.

In my yard the same sounds were used repeatedly day after day, so as I became familiar with them I was better able to pick them out, and started to notice other copied sounds. I could not distinguish individual siskins, so I don’t know how many sounds were shared among birds, but the fact that the Evening Grosbeak call and American Robin call were heard virtually every time I listened carefully (and were heard years earlier in BC as well) suggests that most or all siskins use these calls, and probably share a lot of other sounds as well.

If you’d like to hear some of this, check out the recording catalog number 133352 at Cornell's Macauley Library, July 2, 2007, recorded in Newfoundland by Geoffrey Keller. [You’ll have to Search audio for Pine Siskin, and then find this recording]

The bird starts singing at about the 40 second mark, and between 47 and 56 seconds imitates Common Redpoll, Evening Grosbeak, Hairy Woodpecker, Dark-eyed Junco, American Tree Sparrow and American Robin (and probably others). Notice the clear sing-song notes of American Tree Sparrow at about 55 seconds, with the abrupt “pup” of American Robin following immediately after.

Amazingly, this vocal copying seems to have been almost completely overlooked. In Bent’s life histories (online here) copying of Evening Grosbeak and (in a captive bird) Common Redpoll and Canary, are mentioned. A study of vocal copying by Lawrence’s and Lesser goldfinches (Remsen et al, 1982, pdf here) specifically says that the song of Pine Siskin does not include any copied sounds, and the Birds of North America account makes no mention of it.

Presumably the sounds that are learned are simply the ones that are common in the siskins’ environment, so siskins from the western mountains must learn some sounds that are not heard in the east, and vice versa. Another Macauley Library recording from California (catalog number 120288) includes copies of Lesser Goldfinch flight calls, among others. Given how much siskins wander, it would make a really interesting exercise to listen for copied sounds that are “out-of-range”. Hearing, for example, Eastern Towhee in British Columbia or Lesser Goldfinch in Massachusetts would give you some idea of how far that individual siskin has traveled.

Update - in early June 2009 I spent a week at The Nature Conservancy's Pine Butte Guest Ranch near Choteau Montana, and was able to hear several Pine Siskins singing. I was able to hear copies of the vocalizations of seven species there. In addition to the now-expected calls of American Robin, Dark-eyed Junco, Common Redpoll, and Evening Grosbeak, the Montana siskins copied Western Tanager call, Mountain Chickadee dee note, and a Cassin's Vireo song phrase. Clearly these birds had learned their calls in the west, and would stand out in the east. So the challenge remains – to find a siskin that has traveled cross the continent, and recognize it based on the sounds it has learned.


NickL said...

Absolutely fantastic. What a great recording that is. Thanks for your insights.

Dan Lane said...

Interesting musings, David. It seems to me that nearly all siskins (at least the American spp with which I have experience) are accomplished vocal mimics, as are many of their relatives: the euphonias. At this point, I'm actually interested in knowing why it is that American Goldfinch *doesn't* seem to do much mimicry, since nearly every other American Carduelis does!

Kirk Marshall said...

Another bird which sometimes mimics other birds is the tufted titmouse but Ive never seen any mention of this in any of the field guides Ive seen. I once heard a titmouse doing a whipoorwill call perfectly in Andover, MA near Ward Reservation!

Sarah said...

I too have heard titmice imitating other birds. A few years ago one titmouse in my Connecticut yard would mimic the bluejays. Of course the blue jays are master mimics. From my home office, I often SWEAR that I hear a Red-Tailed Hawk overhead. I rush to the window: It's a blue jay, who has scattered all the other birds with the hawk call and is helping himself to the sunflower seeds. Smart birds! And they fool me more often that I care to admit. :-) Love those blue jays.