PURPLE MARTIN , 505 



would think it unbearable at times. Forbush (1929) states that the 

 "parents have a habit ,of collecting many green leaves and placing 

 them in the nest, a practice which may tend by evaporation to 

 reduce the heat." This is a very interesting observation and one 

 that has been made also by P. A. Taverner (1933). 



Apparently there is rather little specific data on migration casual- 

 ties, but there is little doubt that such occur. Wintering in South 

 America, the nortliAvard migration of the birds is very deliberate, 

 as has been pointed out, covering the time from late January until 

 into June. Thus, there are perhaps less mass movements over the 

 Gulf of Mexico than are true of other birds, and it follows that 

 casualties would be fewer, but bad weather over that body of water 

 must result in the loss of some. Lighthouse victims do not figure 

 largely. 



S. S. Dickey (MS.) writes that in his observation "screech owls are 

 the worst foe" of martins. He states that he "made it a practice to 

 frequent the vicinity of occupied boxes well into the night, and 

 every once in a while a screech owl would come shadowlike, alight 

 for a moment on the runway or porch of a bird-house, then begin a 

 scrambling kind of a noise. By the use of a strong flashlight I was 

 enabled to get some conception of how Asio performs his piUaging. 

 He peers intently into an occupied room, then leans sideways, lifts 

 his face skyward, and reaches as far as he possibly can with one 

 leg into the orifice. Shortly he creates consternation. The squeals 

 of the inmates resound. He brings forth squirming birds. With the 

 prey in his talons, he flits to the nearest tree or shed roof, there to 

 devour his bill-of-f are. I have known him to continue such ravages 

 for an hour at least, taking as many as a half dozen martins to 

 appease his ravenous appetite." 



Fall. — The martin is an early migrant. Sometimes the roosting 

 habit of late summer is noted on the part of certain birds before 

 young have left the nest boxes. Stone (1937) mentions this, and 

 again speaks of barren or nonbreeding birds "roosting" as early as 

 Jmie 25. After the young have flown the southward movement really 

 takes place. This seems to be very general over much of the martin's 

 range. Forbush (1929) gives September 30 as the latest date for 

 New England, F. M. Chapman (1912) gives departure dates from 

 Cambridge, Mass., as August 25; Ohio, September 5; Illinois, Sep- 

 tember 10; Minnesota (SE.), September 9. In Michigan, Barrows 

 (1912) states that "it is one of the first of our swallows to move 

 southward in autumn, usually disappearing about the middle of 

 August and rarely seen as late as September 1." The migration in 

 New Mexico is even earlier, Mrs. Bailey (1928) stating that "only 



