100 BULLETIX 17 9, UNITED STATES NATIONAL MUSEUM 



larger resident members of the family have long been mated and 

 in many cases have occupied their breeding territory for a consid- 

 erable period, the new arrivals must hurriedly pick their mates and 

 their nest sites, which they do with much noisy bickering and many 

 loud disputes among themselves. They must find suitable cavities 

 for their nests, ready made and unoccupied, and there may not 

 always be enough of these to go around." 



Nesting. — The sulphur-bellied flycatcher does not reach southern 

 Arizona until sometime during the latter half of May, or sometimes 

 not until the first week in June. My companion, F. C. Willard, told 

 me that we might look for it at any time after May 15, but we did 

 not actually see it until May 29; Mr. Swarth (1904) says that his 

 earliest date is May 19; O. W. Howard (1899), who has probably 

 collected more eggs of this species in Arizona than anyone else, thinks 

 that it generally does not arrive before the first of June. The birds 

 are probably paired when they arrive, and they are apparently in 

 no hurry to start nesting; consequently they are among the latest 

 of the birds to breed ; Mr. Howard says : "I do not know of any eggs 

 being taken before the first of July and I found a nest with young 

 just hatched on August 28, 1899." 



In the Huachuca Mountains the nest is invariably, so far as known, 

 built in a natural cavity in a large sycamore at heights varying from 

 20 to 50 feet above ground ; the cavity normally selected is a knothole, 

 where a large branch has broken off and the cavity rotted out to 

 varying depths. This flycatcher does not like to incubate its eggs 

 in darkness, but prefers to be able to see out while it is sitting on its 

 eggs ; so, if the cavity is a deep one, it is filled up to within an inch 

 or two of the opening with nesting material. The opening is gener- 

 ally large enough to give the bird free access, and, to the advantage of 

 the <^g'g collector, it is usually large enough to admit a man's hand. 

 If the cavity is a deep one, the lower part of it may be filled in to 

 the desired height with twigs, bits of bark, or other rubbish, on top 

 of which the peculiar and characteristic nest is built. This nest 

 proper is almost always entirely made of the petioles and midribs 

 from the dry leaves of the walnut tree, but sometimes there is an ad- 

 mixture of pine needles or fine, stiff weed stems. These petioles are 

 rather stiff and somewhat curved ; and they are so arranged that the 

 curve conforms to the somewhat circular shape of the nest or the 

 cavity. There is no soft lining, to make a comfortable bed for the 

 young, but the finer leaf stems are smoothly laid in the hollow of the 

 nest. The diameter of the inner cup of the nest is 3 or 4 inches, and 

 the outside measurements conform to the size of the cavity. The 

 same cavity seems to be used year after year, probably at least one 

 of the pair returning each year to the old abode. The female gathers 



