Tuesday, June 9, 2009

Barn Swallows Under the Beltway

Just beside Holy Cross Hospital on Forest Glen Road, the Capitol beltway crosses over the Sligo Creek trail. This forms a funny place to enjoy nature. You go under the bridge into a huge echo chamber. If I’m riding bikes with my kids we bellow in low long notes and cause funny sound waves to cascade over us as we speed through. The clicks of our gears become huge and rhythmic, and we can’t help but laugh as we come out again into the sunshine.

But if I’m walking, I slow down and listen to the thumpa thumpa thumpa of cars hitting the bridge joints on the road over head. Its like hearing the heart beat of the beltway. It is not beautiful, but at the same time it makes you kind of relax your pace and slow down. I believe that this is some kind of primordial response, like hearing your mother’s heartbeat before you are born.

Anyway, last week I was walking under this bridge, listening to the usual thumpa thumpa thumpa when I realized a new noise was in the mix. It was the squeak and twitter of barn swallows. I found at least a dozen nests over head, tucked into the corners of the concrete girders. Watching, I found myself spellbound by their spirals of flight. A couple of the swallows sat on what looked to be a transformer box on the other side of the bridge, eyeing me with suspicion. Then they, too, were off to make acrobatic circles, pausing every now and then to feed their babies.

Swallows were once some of the most common birds of fields and the new suburbs of the early twentieth century. In those days, old fashioned barns, garages and car ports were often left open during summer months, affording the birds easy access to beams and rafters. The 1950s gave way to buildings which were sealed tight against the elements and garages were increasingly built into the main structure of the house, denying swallows some their best habitat. Although these birds remain common and abundant in farm fields, we rarely see them in urban Silver Spring now.

When we do see them, barn swallows are easily recognized in flight because of their forked tails, and they like to make nests of mud, straw and horsehairs. They are careful masons, building the mud up pat by pat with their beaks. Some bird-watching guides say that these nests, which are built by both the male and female working together, can involve as many as 1000 trips to a muddy area. For this reason they often choose to nest near ponds and wetlands.

Near the Forest Glen bridge, just past the area where the soccer fields are always in use and below the much debated Sligo Creek golf course, there’s a funny stormwater pond where I think these birds get the mud the need for building under the beltway. This spot also hosts a pair of Kingfishers each summer, stays rectangular and unnatural looking all year. Although this is by no means a lovely place, it is full of wildlife the same way a farm pond might be.

The Maryland Cooperative Extension service calls barn swallows a “friend of the farm.” In Fact Sheet 798 the office states that 98% of this bird’s diet is made up of insects, including all kinds of flies. They will also eat crickets, wasps, leafhoppers, ants, and moths. “For this reason,” the sheet goes onto say, “attracting barn swallows to your property may be one more positive step towards an integrated pest management approach to managing agricultural and garden pests.” It seems to me this would make them a friend off the farm, as well

The biggest pest in our local suburban life, hands down, seems to be the Asian Tiger mosquito. I have often wondered if working to attract these swallows to my yard would help to keep these annoying daytime visitors to a minimum. Still, without a barn or highway overpass on my property, I haven’t had much opportunity to find out. My little shed is too small, always closed for security, and does not have the rafters that swallows desire.

This makes me all the more glad to see the swallows there under the beltway bridge, and reminds me of the city of Austin, Texas, where residents were at first disturbed by bats that took up residence in their new highway overpasses. Later, after some intense public education efforts, the city embraced their flying bug eaters for the helpful neighbors they had become, and celebrated their presence on postcards and t-shirts.

I don’t think anyone will be putting pictures of the Beltway’s barns swallows on postcards or t-shirts anytime soon. But I am glad to see those birds and I enjoy pointing them out to fellow walkers on the trail when we pass. Here’s hoping the swallows stick around all summer and find lots to eat.

(This article originally appeared in the June 2009 issue of the Voice newspapers in Silver Spring and Takoma Park, MD. )

1 comment:

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