"Audubon's warbler is a moderately abundant winter resident in the higher mountains of Guatemala, yet like the closely related myrtle warbler, appears to be less regular in its time of arrival and departure and less uniformly distributed, than the majority of the more common winter visitants. These attractive warblers were abundant on the Sierra de Tecpán from January until April, 1933; but strangely enough they did not return in August or September with all the other warblers that winter there; and none had appeared by the end of the year, although I kept close watch for them. Yet in the middle of the following September, I found them numerous among the pine and alder trees on the Sierra Cuchumatanes, nearly 11,000 feet above sea-level. The males were then resplendent in their full nuptial dress of yellow, black, white and gray, and sang enchantingly. I believe it not impossible that they breed in this remote, little-known region--for here also I found a breeding representative of the savannah sparrow, hitherto known only as a migrant in the country--and it is to be hoped that some day an ornithologist will study the bird-life of this lofty plateau during the breeding season, from April to August. "During the winter months, the Audubon warblers are truly social, and are nearly always met in flocks, sometimes containing 25 or more individuals. They are versatile in their modes of finding food. Sometimes, from the tops of the tall cypress trees near the summit of the Sierra de Tecpán, they would launch themselves on long and skillfully executed sallies to snatch up insects on the wing. As they twisted about in the air, they would spread their tails to reveal the prettily contrasting areas of black and white. At other times they foraged on the ground, like the myrtle warblers; and this habit brought them into contact with the bluebirds (_Sialia sialis guatemalae_), which are likewise arboreal birds that frequently descend to hunt on the ground. At altitudes of 8,000 to 9,000 feet I almost always found the Audubon warblers and the bluebirds together in the bare, close-cropped pastures where there were scattered, low, oak trees; and this association was so constant that it could not have been accidental. Both kinds of birds were exceedingly wary as they hunted over the ground, and would fly up into the trees if they espied a man approaching them, even from a long way off. The Audubon warblers, probably because they more frequently enter open, exposed places, where they are conspicuous and far from shelter and must exercise great caution not to be surprised, were by far the shiest and most difficult to approach of all the warblers of the Sierra, whether resident or migratory. This was true whether they happened to be in the trees or on the ground.