286 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I50 



of the duck hawk in tone. And males harass passing large birds, es- 

 pecially the larger hawks, darting at them angrily. 



The bat falcon nests in hollows in trees, where the eggs are placed 

 on whatever material has been deposited by chance — usually decayed 

 wood fragments, perhaps with a few wind drifted leaves or twigs. 

 At Barro Colorado Island on March 23, 1955, a falcon of this species 

 of good size that I supposed was a female rested beside a hole near 

 the top of a tall stub that stood in the water 50 meters from shore. 

 I assumed it to be a nest cavity, for the bird turned to peer into it at 

 intervals, and she spread wings and tail in threat when a pair of red- 

 fronted parrots circled to alight. A Wagler's woodpecker, marooned 

 in a hollow branch 10 meters above, protested his immolation from 

 time to time but did not dare move except to thrust out his head to 

 call for a few seconds. A nest, with two small young, found by 

 J. P. E. Morrison on Isla San Jose on May 12, 1944, was in a hollow 

 12 meters from the ground. The nest described by Beebe was at an 

 elevation of approximately 15 meters, perhaps a little more. The 

 eggs in a set of 3 in the U.S. National Museum, collected near Vic- 

 toria, Tamaulipas, Mexico, on April 11, 1908, by F. B. Armstrong, 

 are short-subelliptical, with a pinkish white ground color almost 

 completely covered by a blotchy wash of clay color that changes in 

 some areas around the larger end to deeper brown. They measure 

 39.0x31.3, 40.3x32, and 40.8 x 32.1 mm. They were taken from 

 a hole in a tree about 10 meters from the ground. 



A juvenile only a few days old, from the nest on Isla San Jose, 

 is completely covered with white down except for the loral area and 

 the space around the eyes. Beebe describes the three in the nest that 

 he had under study as creamy white when about a week old. 



Disagreement as to the recognition of a northern subspecies of 

 the bat falcon has resulted from misunderstanding of variation due to 

 age. Immature individuals are blacker than full adults, the difference 

 in the two age groups being most pronounced in the area from north- 

 ern Colombia north through Central America. When adult specimens 

 are compared it is found that birds from this northern region are 

 lighter, grayer above, in particular on the head than those from Vene- 

 zuela and northern Brazil, The northern population may be separated 

 from typical F. r. rufigularis as the race petoewis. The nominate race 

 is found from the base of the eastern Andes of Colombia east through 

 Venezuela to Trinidad, and south to northern Bolivia, and northern 

 Brazil. 



