If you have been in open country anywhere in Montana, you have heard, and probably seen, thunderchunks. These birds are everywhere, proclaiming territories and singing from fence posts, sage brush, and telephone poles.
Thunderchunks are mostly colored a drab brownish tan, with brilliant yellow chests like gaudy vests worn under brown tweed jackets. To complete the outfit, they wear a thick black bib necklace in the shape of a V. You may know these birds by their common name of western meadowlark.
However, to some ornithologists, these birds are thunderchunks. I learned this nickname while doing bird surveys one summer across eastern Montana. For each survey, we had to record every bird we heard during a six-minute period. This was much harder than it seems, mostly because the western meadowlarks sing so boisterously that it was challenging to hear anything else. A thunderchunk that was 300 feet away from me sounded just as loud, if not louder, than the savannah sparrow that was three feet from my toes.
The “thunder” in the name thunderchunk comes from their decibel level: western meadowlarks are loud. I remember driving down dirt roads, windows rolled up against the heat and dust, and almost jumping out of my seat because I heard a western meadowlark burst into song in my backseat — or that’s what it sounded like. It was really perched on the fence post along the road.
The “chunk” in thunderchunk comes from a western meadowlark’s size. In many ways, western meadowlarks are similar in appearance and size to the American robin: they have an upright posture, with long legs. However, meadowlarks are, as one field guide describes them, stout. Husky, if you will. Or, if you’re an uncouth, ill-mannered ornithologist like myself, chunky. A western meadowlark weighs about 97 grams, which is slightly less than a bar of soap. An American robin weighs about 77 grams, which, if we continue weighing things in the bathroom, is equal to the weight of a pair of tweezers, a pair of fingernail clippers and a pair of toenail clippers.
Meadowlarks are Icterids, which means they are closely related to blackbirds and orioles. One way to see this close relationship is by comparing the bills of a Bullock’s oriole and a western meadowlark. Both are slim and pointed. Their bills also identify these birds as being mostly insect-eaters, as they are thin and precise for grabbing insects.
Compare these thin bills to that of a bird who primarily eats seeds, such as a house finch. The house finch has a beak that is much thicker, with a wide base. A western meadowlark’s beak is more the shape of an ice-cream cone, while a house finch’s beak is more an equilateral triangle, or the shape of a piece of pizza.
Despite having a thinner bill, western meadowlarks eat both seeds and insects. They eat the seeds of grassland plants and grains, which are much easier to eat than the thick-shelled sunflower seeds house finches devour from bird feeders. To catch insects that are hidden in the ground, western meadowlarks will do what is called “gaping”: they’ll push their bill into the ground and then force it open, which makes a hole from which they can grab juicy insects they otherwise couldn’t access.
Though I never saw any western meadowlarks gaping and probing the soil for insects, I heard them almost every day for the entire summer while I was doing surveys. When I left the prairies of eastern Montana for some surveys down near Gardiner, it was strange to wake up and not be bombarded with the song of the western meadowlark every morning. I found I began to miss their loud song and the sight of their chunky bodies, which had come to represent for me the wide-open spaces of the prairies.