BIRDS OF THE TRES MARIAS ISLANDS. 43 



and then rty, with an uuilnhitiug motion, to another tree in the vicinity. 

 Their notes are limited to a short succession of unmusical sounds, 

 which are frequently heard. They were reported to nest in hollow 

 trees. Unlike most of the birds of these islands, the trogous were 

 nearly as shy as their representatives on the mainlaTid. In life they 

 have light yellow bills and bright red eyelids. 



Ceryle alcyon (Linn.). Belted Kingfisher. 



Colonel Grayson records that during each of his visits one or two 

 belted kingfishers were observed sitting on rocke along the seashore. 

 None were seen by us. 



Dryobates scalaris graysoni (Baird). Grayson's Woodpecker. 



Picus scalaris var. graysoni Baird, Hist. X. Am. Birds, II. pp. 515, 517, 1874; Lawr., 

 Mem. Boston Soc. Nat. Hist., II, p. 294, 1S7 L 



This is the only woodpecker found on the Tres Marias. It is com- 

 mon on all of the islands and generally distributed, except in the most 

 heavily wooded areas. It seems to prefer second growth thickets and 

 other places where shrubs and scrubby trees form low and rather thin 

 forests, and was usually seen hunting for food along the trunks of large 

 shrubs or small trees. It was a common practice for them to aliglit on 

 tree trunks near the ground and work slowly to the top, and after 

 remaining there quietly for a time to make a short flight to another 

 tree. Like its relative of the mainland, it is a very quic^t bird, rarely 

 uttering any call notes and making little noise while searching for food. 

 From its habit of peering into crevices of the bark and doing only a 

 small amount of pecking it is evident that it finds most of its food on 

 or near the surface. Old nesting sites were seen in the trunks of both 

 living and dead trees and in the flower stems of large magueys. The 

 holes were usually between .5 and 10 feet from the ground. Colonel 

 Grayson found a nest about 12 feet from the ground in the green flower 

 stem of a large maguey {Agave) near the seashore in April. 



A comparison of a series of these i.sland woodpeckers with other forms 

 shows that the dorsal surface, including the crest of the males, is most 

 like typical D. scalaris from the plains of Puebla. On the ventral 

 surface it may be distinguished from all the other races by its whiter 

 color and scantier and smaller black markings along the sides. These 

 markings are usually in the form of small rounded spots instead of 

 more or less elongated streaks, as in the other races, aud the white 

 markings on the greater and lesser wing coverts are decidedly larger 

 and more conspicuous. I), s. graysoni averages a little smaller than 

 D. s. scalaris. The darker dorsal surface and unmarked bases of outer 

 tail feathers distinguish it trom D. s. hairdii. It has a shorter, stouter 

 bill than D. s. lucasanus, with considerably more barring on the outer 

 tail feathers. From J), s. sinaloensis it is distinguished mainly by its 

 larger size, darker dorsal surface, and paler, less marked lower sur- 



