Sunday, November 9, 2008

Snow Buntings and seed dispersal

I've been spending a fair bit of time up at The Lake of late, and have been fortunate to have good opportunities to study Snow Buntings on each excursion. "The lake" is Lake Erie, of course, Ohio's north coast, where some of the best birding in the Midwest can be found.

Flock of Snow Buntings foraging in a weedy gravel parking lot, Conneaut Harbor, yesterday. In spite of bold white plumage markings, they quickly blend well with their surroundings upon alighting in a habitat like this. It'd be quite easy to pass by and not notice them. The buntings are foraging on various weed seeds here, rapidly stripping fruit from the plants and bolting it down. Right little gluttons, they are.

Closer view. Winter-plumaged Snow Buntings are quite handsome in an understated way. Rusty-brown mixes with creamy-white to create an effect unique among our birds.

John Pogacnik went me this photo, which he took in Lake County a few days back. This Snow Bunting is standing smack in the midst of one of Ohio's rarest plants, Least Spikerush, Eleocharis parvula. Not only that, but it is wolfing the plants down - stem, roots, seeds, and all! Very cool observation and photo by John, and documents something I've long been interested in, which is the role of birds in seed dispersal.

If you are a plant, you want to migrate just like a bird. By getting themselves to new sites and establishing new populations, plants help to ensure their survival and success. But they have no wings to get places, so all manner of strategies are used. Some seeds float and boat themselves to new sites. Others are windborn and drift to farfung locales. Sometimes roots and seeds stick to mammals and thus are spread.

Or they are eaten by birds, make the perilous journey through a digestive tract - not all survive - and are expelled in new sites. Over the long haul, which is how we should think about conservation, nature, and ecology, birds undoubtedly play a huge role in determining how many plants got to where they are.

In the case of the Least Spikerush, its seeds are hard bony achenes. They are probably able to weather the ride through a Snow Bunting's digestive tract well, and it is possible that the bunting that John saw will transport some plants to a new site, resulting in establishment of a new colony of this rare and local sedge.

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