On the morn- ing of April 20, 1946, at Binghamton Pond, northeast of Tucson, Arizona, we saw a Beardless Fly- catcher (Camptostoma imberbe) carrying nest material. It flew to a tent caterpillar nest, about fifteen feet up, that had been woven around a slender upright fork of a willow tree. This tree grew conspicu- ously alone in a grassy field fifty feet from the dense mesquite hedge which covered the main dike. While we watched, in the shade of the hedge, the bird disappeared completely through a small hole near the top of the caterpillar web. From the inside it arranged the nest material with such vigor that the entire branch shook and, once, the head of the builder, with wide open bill, broke through the thin web. Immediately it pulled bac.k, closing the break in the wall. On each trip to the nest the bird suddenly appeared from a group of trees 200 feet away and then flew directly across the open field to the willow tree. A second bird, evidently its mate, usually stayed in the tree, following the other about, but took no part in the work at all, at least not while we were present. Now and then we heard a three- or four-syllable whistled call note. Subsequent visits to the area were of necessity brief like the first visit. As we approached on April 27 we heard the characteristic call notes from one or two birds in the mesquite growth. In our twenty-minute stay we recorded only one trip. to the nest. So far as we could see these birds behaved -,t all times like other flycatchers, not like kinglets or vireos, as has been reported in the literature. Perhaps the foliage-gleaning habit is pursued chiefly in colder weather when flying insects are not so abundant. Typical flycatching, with short quick flights within the rather thick msquite canopy and from the top of the willow tree, was the rule here. When they perched quietly, their posture was upright and the slightly raised feathers at the back of their heads suggested a crest. The peculiar call- note or song consisted of from three to five syllables, the notes clear and distinct and of equal length. At close range it had an explosive, consonantal, hard t or p at the beginning of each note: teeee teeee teeee teee. Once we heard an additional brief twitter. On May 4 the calls ceased as we came in sight of the tree. Probably our presence caused some uneasine. We watched the nest for half an hour before we saw one of the flycatchers enter. Evidently incubation ha begun, for the bird remained inside. Its mate perched in the tree top most of the time, darting out occasionally after passing insects. Sometimes it stationed itself upon the wires of the nearby fence from which it scanned the field for prey. Oddly, it seemed to pay no attention to its mate when it entered the nest. On May 18 we saw both adults carry food to their nest. We heard only one call. Perhaps because of the fact that there were no other Beardless Flycatchers in the vicinity there was no defense of any extended territory. They drove away an English Sparrow (Passer domesticus) that edged too close, but a Mourning Dove (Zenaidura macroura) which paused in the tree received no threating gestures. A female Vermilion Flycatcher (Pyrocephalus rubinus) had now almost completed her nest in the lower part of the willow, eight feet below and on the west side of the nest of the Beardless Flycatcher. Evidently she had not been seriously molestet. She perched repeatedly in her lower horizontal plane, her mate usually not far away, while the other two flycatchers confined their housekeeping activities to the upper half of the tree. On the following day we heard the calls of the Beardless Flycatchers more frequently as both of the adults continued their regular trips with food to their nest. Again one of them chased an English Sparrow. Quick sallies by the flycatchers within the tree crown itself pro- vided much of the food. On one of these erratic flights a Beardless Flycatcher approached as close as two feet to the nest on which the female Vermilion Flycatcher was sitting. At once the male Vermilion Flycatcher drove the trespasser back into the top of the tree. We saw no further interference on this day. On our next visit on May 25 we found the female Vermilion Flycatcher incubating undisturbed while the upper story birds still carried food to their nest. A week later as we approached we heard numerous calls from the adjacent mesquites. The adults made sevesal flights to the willow tree but they did not go near the nest. Presumably the nestlings, if they had left, were somewhere in the nearby trees but our careful search of the vicinity was unsuc- cessful. We saw another inadvertent intrusion which again produced a brief defensive chase by the Vermilion Flycatcher. Apparently the extension of the breeding range of the Beardless Flycatcher into the Binghamton Pond area is recent, for we saw no individuals there in the preceding twelve years. On.May 26, 1946, we were fortunate in finding a second nest. It was located eight miles south of Tucson near the dry bed of the Santa Cruz River. Like the first one at Binghamton Pond, it also was built in a tent caterpillar nest in a vertical fork of a willow tree, although somewhat higher, about twenty feet above the ground. However, the tree grew in a wide arroyo crowded with tall cotton- woods and willows so close that their branches interlaced. A tangle of second growth mesquites fringed and overhung the high dirt bank. Were it not for the unmistakable call notes, we would not have discovered the two adults carrying food to their nest. They showed no alarm as we watched them a short distance away. Ten or twelve feet below, on a horizontal branch, a Ground Dove (Columbigal- lina passerina) sat undisturbed in her nest on two eggs. On our final visit on June 2 we observed a young Beardless Flycatcher perching in the upper part of the tree close to its nest. In a few minutes the parents arrived and one of them fed the begging fiedgling.--Am)ERs H. ANOnSoN and ANE AzmgRsor, Tucson, Arizona, January 18, 148.