CHESTNUT-SIDED WARBLER
- Order—Passeres
- Genus—Dendroica
- Family—Mniotiltidæ
- Species—pennsylvanica
National Association of Audubon Societies
They are pretty, dainty little objects, as is the case with all Warblers’ eggs. In size, they are about two-thirds of an inch long, and half an inch in diameter at the largest place.
In the latitude of Boston, fresh eggs may usually be found late in May or in the first week of June.
The Chestnut-sided Warbler feeds almost exclusively on insects. John James Audubon wrote that once in Pennsylvania, during a snowstorm in early spring, he examined the dead bodies of several, and found that their stomachs contained only grass-seeds and a few spiders. The birds were very poor, and evidently were in a half-starved condition, which would probably account for the fact that they had been engaged in such an un-warbler-like act as eating seeds. Ordinarily this bird is highly insectivorous, and feeds very largely on leaf-eating caterpillars. It also collects plant-lice, ants, leaf-hoppers, small bark-beetles, and, in fact, is a perfect scourge to the small insect-life inhabiting the foliage of the bushes and trees where it makes its home. Sometimes the birds take short flights in the air after winged insects. It will thus be seen that the Chestnut-sided Warbler is of decided value as a guardian of trees, which is reason enough why the legislators of the various states where the bird is found were induced to enact the Audubon Law for its protection.
All birds that depend so much on insects for their livelihood as does the Chestnut-sided Warbler are necessarily highly migratory. By the middle of September nearly all have departed from their summer home, which, we may say roughly, covers the territory of the southern Canadian Provinces from Saskatchewan eastward, and extends southward as far as Ohio and New Jersey. They are also found in summer along the Alleghany Mountains in Tennessee and South Carolina. Most of the migrants go to Central America by way of the Gulf of Mexico, and only a comparatively small number travel to Florida and the Bahama Islands.