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Nature Notes

Henslow's Sparrow

Life is all about the details, isn’t it? When you want something, be it a new car, a new pair of jeans, or dinner, you usually know exactly what you want. Not just any pasta, but linguini with marinara sauce, lightly sprinkled with pepper and shavings of fresh mozzarella.  It’s the details that make things perfect. 

And even in large scale restoration work, like our 7,800 acre Efroymson Restoration at Kankakee Sands, the details are very important. One such detail that we anxiously await as the grassland birds return to Kankakee Sands this March, is the teensy, 5” tall, Henslow’s sparrow (Ammadramus henslowii). 

In 1829, John James Audubon named the Henslow’s sparrow after his friend, John Stevens Henslow. He was a naturalist, geologist and professor of Botany at Cambridge Univeristy and had helped Audubon to sell subscriptions to his Birds of North America during a trip to England. 

The Henslow’s sparrow looks like many of the other sparrows of our area, small and brown. But if you look closely, you will see that the Henslow’s sparrow has a large flat olive-tinged head, grey bill, and short tail. Its breast is buff, streaked with black; its wings and rump are chestnut colored, also boldly streaked with black. 

But you needn’t concern yourself too much with what the Henslow’s looks like. They are rarely seen. Henslow’s are secretive and solitary birds, preferring to stay on the ground and run mouse-like through the grass rather than flush and fly away. Males will make short flights from plant stalk to plant stalk to sing; their flight is low and jerky. Females rarely fly at all. 

But familiarize yourself with the male’s song, which on a calm day can carry 300 feet across the open prairie! The song is a somewhat insect like, a short, fast, sweet tsi-LICK. To hear an excellent recording of the Henslow’s song, go to Cornell Lab of Ornithology’s website, All About Birds at http://www.allaboutbirds.org/guide/Henslows_Sparrow/sounds.

The Henslow’s sparrow occurs only in North America, in the central and eastern U.S. It is common in our Kankakee Sands restorations in the summer, wintering in the Gulf Coast states. Henslow’s numbers are declining nationally due to the loss of grassland habitat. In fact, the Henslow’s sparrow is state endangered in Indiana.  However a recent survey of Henlsow’s at the Efroymson Restoration at Kankakee Sands found over 300 calling males!

The Henslow’s sparrow is a grassland species, found in wet meadows, grassy swamps and sometimes in dry upland prairies; all of which we have a lot at the Efroymson Restoration at Kankakee Sands. In fact, the Henslow’s sparrow is one of the target species for our restoration work. If we have a vibrant population of Henslow’s sparrows at Kankakee Sands, then we know we have created the right habitat for a whole range of grassland birds. Having the Henslow’s sparrow, that one little detail, allows us to rest assured that our restoration is on its way to being nearly perfect. -Alyssa Nyberg

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