Now is the time of year when the woods are alive with chipmunks, busying themselves collecting beechnuts and acorns to cache in their burrows for the coming winter. Now is also a productive season for forest hawks, hoping to swoop down and snatch-up unwary chipmunks that are pre-occupied with gathering food. But what is most interesting for us nature-listeners is that chipmunks respond to hawk fly-bys with a special “aerial predator alarm call” … a hollow, resonant cluck … cluck … cluck … cluck … cluck … that is unmistakable. It sounds like this:
An Eastern Chipmunk giving cluck calls. 7:30am, 8 August, 2016, Land Between the Lakes, Kentucky. © Lang Elliott.
What’s even more interesting is that the clucking is contagious; if one chipmunk begins clucking, others will soon join-in. Before long, the whole forest comes alive with clucking, and the clucking may continue unabated for many minutes. Here’s a recording I made last weekend. Quite a chorus of “clucking munks”, don’t you agree?
A large group of Eastern Chipmunks clucking, with drip from the trees. 8am, 25 September, 2017, Shindagin Hollow near Brooktondale, New York. © Lang Elliott.
I studied this phenomenon while I was a graduate student at the University of Maryland, my thesis being The Social Behavior and Foraging Ecology of the Eastern Chipmunk (Tamias striatus) in the Adirondack Mountains, published as a Smithsonian Monograph in 1978). In my opinion. a chipmunk need not actually see a hawk to begin clucking — it only needs to hear other chipmunks sounding of and it will follow suit.
During my field study, I observed Broad-winged Hawks flying through understory on numerous occasions. In every instance, chipmunks responded with clucking, their calls erupting through the forest along the flight path of the hawk (usually there was a slight delay in response, a chipmunk perhaps not beginning to call until it was certain the hawk wasn’t coming directly for it).
The function of the clucking is probably twofold. First, the clucks alert other chipmunks that a hawk is in the vicinity, making them far less likely to be captured. A second function is that hawks are probably deterred by all the vocalizing. Clucking chipmunks usually perch motionless and alert on a log, making them almost impossible for a hawk to catch (they will instantly jump for cover if a hawk does indeed head for them). Thus, a lot of clucking probably discourages a hawk and causes it to move from the area.
I love to hear all the clucking during early autumn. It tells me that the chipmunks are doing well, that’s there’s lots of food for them to gather, and that the hawks are getting their share of the action. I may feel sad for the unlucky chippies that become hawk food, but I am nonetheless happy to hear them sounding off and have some notion of what the fuss is all about.
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