By Kenneth Turner Blackshaw
"Sweet-sweet-sweet, I am so sweet," the whistled sound rings out from the willows near Hatch’s. It is one of the first real sounds of spring – much more so than the "Cheerup—cheerily" of the robin, which after all, has been with us all winter. No, this is a true neotropical migrant – the Yellow Warbler -- that arrives on Nantucket the last week of April.
This is a tiny mite, a little over five inches long and one of the birds my grandmother always referred to as a ‘Wild Canary’. She would come back from a ride and report that she had seen one of these, and this built my appreciation for the mystery of wild things. I mean, we had a perfectly wonderful tame canary that would sing away from his cage. So, I could just wonder what a wild one would be like. Only after I really started to learn our birds did I understand that she applied this term to any yellow bird she saw in the wild, goldfinch, warbler or whatever.
But this week’s bird is a member of a completely different family – the wood warblers. Wood warblers are among the most delicate and colorful of America’s birds. Unfortunately they are little known to the general public since they spend so much of their lives high in trees or deep in swamp foliage.
Yellow Warblers are almost completely insectivorous and consequently, only join us on Nantucket when there are bugs and little worms to eat. They find most of these by gleaning from leaves and branches as they move restlessly around in trees. Occasionally they catch insects on the wing too – their bills making audible snapping noises as they do so.
. Warblers are rarely at rest and the best way to see them is stare high into a tree where the song is coming from and wait for them to move. Indeed birders speak of an ailment known as ‘warbler neck’ caused by craning the head backwards to gaze up into a tree. Actually the best way to see them in your yard is to have a birdbath with water dripping into it. This sound is something many birds just can’t resist, and it brings them in to drink and bathe.
Yellow Warblers are as close as we get to a pure yellow bird. From head to tail, They show different shades of yellow, from brilliant on the head and breast, to a more greeny yellow at the other end. The males have orange streaks down the breast and the females tend to be just a little duller in color. When seen flying away, they show lighter yellow tail spots on each side of the tail.
One of the Yellow Warbler’s major enemies is the Brown-headed Cowbird, which parasitizes their nests. The female cowbird builds no nest of her own, rather, she sneaks onto another nest, like our Yellow Warbler’s, and lays a single egg. That egg tends to hatch ahead of the regular tenant’s and the cowbird soon dominates the nest, getting most of the food and driving the true offspring out of the nest to die.
Some warblers have gotten wise to this practice and are able to spot the differences in the eggs. Their response is to just build another nest over the first one and lay a new clutch of eggs. They do this as many as six times, before just giving up and raising the cowbird. Photos taken of a tiny mother Yellow Warbler, reaching up to feed her enormous foster child are amazing, and quite disturbing. Granted, this is a way of nature, but it still seems wrong. Cowbirds have become much more common, due to man’s clearing of the forests for farming.
Our Yellow Warblers go through a crescendo of song as they pursue their nesting activity in from mid-May until early July. Then they begin their journey south to Central America. We continue to see them through September, but these are migrants from northern Canada.
It’s interesting that although we consider them ‘our’ birds, the people in Guatemala where so many of them winter, also consider them theirs. Indeed they spend eight or nine months down south and only three or four up here. That is why the dramatic clearing of habitat in Central America is having a very detrimental effect on the population of birds like this warbler. You can fight this trend by drinking only ‘shade grown’ coffee. Nantucket Coffee Roasters can provide you with this type of coffee which is quite delicious. It costs a little more, but if enough of us make this statement, perhaps we can reduce the threat to this colorful gem’s winter home.
George C. West creates illustrations for these articles.
The Maria Mitchell Association sponsors bird walks every Saturday, leaving at 8 a.m. from the Hinchman House on at the corner of Milk and Vestal St. There is a fee. Call 228-9198 for more information.
To hear about rare birds, or to leave a bird report call the Massachusetts Audubon hot line at 888-224-6444, option 4.