388 BULLETIN 170, UNITED STATES NATIONAL MUSEUM 



laid in the same burrow or in another close by, if the first eggs are 

 taken." 



Grinnell, Dixon, and Linsdale (1930) observed an interesting habit 

 of young burrowing owls, of which they say: 



When the burrow had been dug out two-thirds of the way to the end, a buzzing 

 screech was heard that seemed so nearly like a muffled rattle of a rattlesnake that 

 it was hard to feel sure that there was no snake in the burrow. As the digging 

 proceeded this noise was heard more and more clearly. Finally the terminal 

 cavity was opened up, disclosing only the six young owls. Their main defense 

 was the utterance of the rasping, penetrating, rattling hiss, nearly like the angry 

 buzz of a rattlesnake when disturbed on a warm day. The bill clicks which were 

 produced less frequently than the rattling notes were reather weak. The latter 

 utterance was deterrent in our case; might it not be so as regards carnivores that 

 dig out or enter burrows such as the burrowing owls inhabit? Badgers, coyotes, 

 weasels, and possibly such rodents as marmots and ground squirrels might thus be 

 deterred from molesting the owls. 



John McB. Robertson (1929) gives the following account of the 

 methods employed in feeding the young, after they were large enough 

 to come out of the nest: 



The young owls were usually in a compact group on the highest part of the 

 mound, while the adult, only one adult being observed, had several lookout sta- 

 tions, the nearest one being the top of a pile of baling wire and other junk on the 

 alkali flat, and the others were fence posts at various distances from the burrow. 



The usual program was as follows: The adult, frequently looking skyward, 

 sighted some flying insect passing over, launched out in pursuit, climbing rather 

 laboriously upward at a sharp angle and sometimes spirally, often to a height of 

 150 feet or more, and on overtaking the flying prey seized it with one foot. Then 

 came a pause during which the prey was transferred to the beak, then a long 

 glide, on set wings, directly to the nest. The young, on seeing the adult coming 

 with food, rushed down the slope toward it, and then turned and rushed back as 

 the adult passed over their heads to alight on the highest point of the mound. 

 Then came a scuffle that would have done credit to a football game. However, 

 actual possession of the coveted morsel seemed to be respected, and the lucky 

 youngster was allowed to devour it at leisure. After a brief pause the adult 

 returned to a vantage point to watch for more game. * * * 



As the young grew older and learned to fly they sometimes flew toward and inter- 

 cepted the adult before the burrow was reached; this was successful only in cases 

 where the adult flew close to the ground after making a low, or a ground, capture. 

 The adults sometimes ate the prey themselves, and in this case it was sometimes 

 held up to the beak with one foot while the bird stood on its perch. 



On one occasion a weasel appeared, crossing the pasture, and was immediately 

 assaulted by the owls. The young were flying quite well at this time and they 

 joined in the attack, hovering over the scurrying weasel and swooping at it from 

 behind with extended claws. The weasel paused and faced them at times and then 

 hurried on; I could not be sure that they actually struck him, but they came close 

 enough to do so. Birds from other families joined the fun, and at one time there 

 were ten owls in the air together. The weasel was escorted about one hundred 

 yards before the chase was abandoned. 



Plumages. — The newly hatched young burrowing owl is but scantily 

 covered, on the feather tracts only, with grayish-white down, basally 



