BIRDS OF NANTUCKET
by Kenneth Turner Blackshaw

Tree Swallow

FLYING KILLER WHALES

Orcas - they remind me of Orcas. They are so black and shiny above and so snowy white below. These are Tree Swallows and they are just now settling in to raise their families here on Nantucket.

I first wrote about these feathered darts back in late 2004 and called the article "The Swallows of Autumn." But now in spring they seem so omnipresent in the sky it's time to write about them again.

These are our hardiest swallows, normally staying with us late into November. They can do this because they switch over from an insect diet at that time of year and eat a lot of waxy fruit from our bayberry bushes.

Tree Swallows are a bit smaller than sparrows and lack the long 'swallow' tails of the Barn Swallows we spoke of a few weeks ago. Before Europeans settled in North America they nested only in holes in hollow trees, hence their name. Their Latin name is a bit of a mouthful, Tachycineta bicolor - a two-colored fast flier.

Like most hole-nesters, they adapt well to living in birdhouses and Nantucket has hundreds of suitable houses put up, ostensibly for bluebirds. There are very few bluebirds around, though, and Tree Swallows do very well in a home of the same dimensions. The swallows are fortunate in that there is a gentleman here who tirelessly builds birdhouses, using scrap wood recovered from the landfill and puts them up about any place where one could be hung.

I referred to these swallows as black above and unless you get good light on them that's how they appear. However in sunlight, you see a satiny blue appearance that can knock your eye out. Agood place to enjoy this is where the nesting boxes have been put up on the fence along New South Road, just east of the airport. In the morning, with sunlight behind you, you can get great looks at them with binoculars right from your car without disturbing them.

This is also a good time to learn their call notes. The sound is written 'silip' or 'chi-veet' depending on what bird book you examine. Imagine this in a high, spirited call. You can hear them call back and forth to each other as they are bringing material into the nest boxes. You may hear these notes most anywhere on the island and when you do, look for swallows above you.

Inside the cavity Tree Swallows build a nest of grass and straw, typically lined with white feathers. It's not unusual to see a swallow pursue a white feather in the air much like the one at the beginning of the Forrest Gump movie, catch it in their bill, and then carry it inside the nest box.

There are five Tree Swallow specimens in the Edith F. Andrews collection at the Maria Mitchell Association. Several of them were apparently killed by House Sparrows that wanted to take over their nesting cavity. There is great competition for nest boxes and nature isn't always pretty.

With a specimen it is possible to determine whether these swallows are boys or girls, something impossible to figure out otherwise, since they appear identical. When ornithologists make a museum specimen they examine the bird's insides to determine how they died, what they'd eaten, and what sex they are. How much body fat a bird is carrying provides an indication of their overall health. Some birds literally starve to death. But we see another extreme in the fall when they fatten themselves up before heading south across the ocean.

After our Tree Swallows nest, they have a few weeks or months to prepare for fall migration. In October we see flocks that number in the hundreds of thousands over the ponds along the south shore, looking like swarms of gnats until you put your binoculars on them. Then, barring the disruption of an autumn hurricane, they move down the coast, most of them ending up in Florida.

But this doesn't always go according to plan. In late October 2005, Hurricane Wilma boiled through the Gulf of Mexico and then up the Atlantic coast, finally striking land in Nova Scotia. The eye of the hurricane stayed intact from the Yucatan all the way to Canada and birds were trapped in its circulation. One species greatly affected was the Tree Swallow. Many of them, perhaps making their first migration south, took a long time to get back on track. We had a flock of very unhappy-looking Tree Swallows in the dunes at the end of Miacomet Pond until early February 2006, an unprecedented winter record. It would be interesting to know if they died or eventually made their way south. Perhaps a few of them are now setting up

residence in a nesting box on Nantucket. I

George C. West creates illustrations for these articles. If you enjoy 'social' birding, join the Nantucket Bird Club at 8 a.m. Sundays in front of Nantucket High School for a two to three hour birding trip. Call 228-1693 for more information. To hear about rare birds, or to leave a bird report call the Massachusetts Audubon hot line at 1-781-259-8805.

Ask Ken a question at: kenandcindy1@comcast. net