Chickadees Whistling in the Wind

Another find from this last weekend:

Black-capped Chickadee (Poecile atricapilla), Starved Rock State Park,
La Salle Co, IL 1/26/2014

This little fellow is a Black-capped Chickadee, a favorite of mine. They're adaptable, fairly tame, very vocal,...

Very vocal indeed. They have a fairly wide repertoire of call types. (Not like mimics, these are different calls for different situations.)

The call that gave them their name includes several high see notes, a couple of quick lower notes and a series of low, burry dee notes. They don't always use all of them, and the number of see and dee notes varies. What they do use, they always use in order, though. This set of calls is used in quite a few contexts, and the variation in the number of each note appears to actually convey information(1).
One context that these notes may be used in (especially the dee notes) is mobbing of predators, owls and small hawks in particular. Vervet Monkeys (Chlorocebus pygerythrus) and Prairie Dogs (Cynomys spp.) have different calls for different predator types (2,3), and apparently chickadees do something similar, encoding information about the size and potential threat posed by a predator in their calls (4).

One of the remarkable things about this species' vocal behavior is the geographic variation that is seen. Their well-known 'fee-bee' song is remarkably uniform across the entire continent, although they vary the pitch to add some variety (5). But another vocalization, typically termed the 'gargle', changes across a few miles (6). There is some evidence that isolated populations diverge faster than other populations (7), as might be expected. This suggests that there is a considerable degree of contact across the entire continent, given the speeds at which other species appear to develop geographic dialects. But that doesn't explain how local geographic variation in the gargle call occurs, and is a rather odd thing to contemplate for a small bird that doesn't migrate.

Quite a bit of work has been done on these little guys, and their behavior can still mystify us. If you hear someone complaining about how science removes the mystery from life, just remember these little guys.

(1) Freeberg, T. M., & Lucas, J. R. (2002). Receivers respond differently to chick-a-dee calls varying in note composition in Carolina chickadees,< i> Poecile carolinensis</i>. Animal Behaviour, 63(5), 837-845.

 

(2) Seyfarth, R. M., Cheney, D. L., & Marler, P. (1980). Vervet monkey alarm calls: semantic communication in a free-ranging primate. Animal Behaviour, 28(4), 1070-1094.

 

(3) Slobodchikoff, C. N., Kiriazis, J., Fischer, C., & Creef, E. (1991). Semantic information distinguishing individual predators in the alarm calls of Gunnison's prairie dogs. Animal Behaviour, 42(5), 713-719.

 

(4) Templeton, C. N., Greene, E., & Davis, K. (2005). Allometry of alarm calls: black-capped chickadees encode information about predator size. Science, 308(5730), 1934-1937.

 

(5) Kroodsma, D. E., Byers, B. E., Halkin, S. L., Hill, C., Minis, D., Bolsinger, J. R., ... & Wilda, K. (1999). Geographic variation in black-capped chickadee songs and singing behavior. The Auk, 387-402.

 

(6) Miyasato, L. E., & Baker, M. C. (1999). Black-capped chickadee call dialects along a continuous habitat corridor. Animal behaviour, 57(6), 1311-1318.

 

(7) Gammon, D. E., Baker, M. C., & Tipton, J. R. (2005). Cultural divergence within novel song in the black-capped chickadee (Poecile atricapillus). The Auk, 122(3), 853-871.