BIRDS OF THE TRES MARIAS ISLANDS. 59 



Melanotis caerulescens longirostris Nelson. Trea Marias Blue Mockingbird. 



Melanotis ccerulescens Grayson Proc. Boston Soc. Nat. Hist., XIV, p. 275,1871; 



Lawr., Mem. Boston Soc. Nat. Hist., II, p. 266, 1874 (part). 

 Melanoiis ca-rulescens longirostris Nelson, Proc. Biol. Soc. Washington, XII, p. 10 



These fine songsters are very common on the Tres Marias. They keep 

 in the thickets and low trees and bushes like a catbird and were 

 especially numerous and familiar about the settlement on Maria Madre. 

 In one yard, among a few fruit trees, a trough was kept full of water, 

 where scores of blue mockingbirds came daily to drink and would 

 almost allow themselves to be caught by hand. Their numbers and 

 general distribution make them among the most noticeable birds on the 

 islands, and they frequently follow one with much curiosity. Their song, 

 although rich and varied, was not so clear and musical as that of their 

 relatives on the mainland. The birds on Maria Madre show a marked 

 tendency to albinism, which usually appears in the form of grayish or 

 whitish bars on the wings and tail. In addition to the barring on the 

 primaries and secondaries, the alula is often similarly marked and some 

 specimens have lighter spots on the tips of the wing coverts, produc- 

 ing well-defined wing bands. The markings are usually symmetrical, 

 but vary in amount and intensity with the individual. In some they 

 are barely distinguishable and in others very conspicuous. More rarely 

 the albinism appears on other parts of the body, occasionally in asym- 

 metrical areas of pure white, but these spots also are sometimes regu- 

 lar. One specimen has the entire under surface white, except some 

 blue feathers along the flanks, and the rump is white mixed with blue. 

 This bird has a striking general resemblance to the Central American 

 Melanotis Jiypoleucus. At least 2 or 3 per cent of the birds on the 

 islands are albinistic, and the constant recurrence of the same light 

 barring on the wings and tail seems to indicate the possible evolution 

 of a form in which these markings will be constant. 



Myadestes obscurus insularis Stejneger. Tres Marias Solitaire. 



Myiadentes obscurus Grayson, Proc. Boston Soc. Nat. Hist., XIV, p. 277, 1871; 

 Lawr., Mem. Boston Soc. Nat. Hist., II, p. 273, 1874. 



Myadestes obscurus var. insularis Stejneger, Proc. U. S. Nat. Mus., IV, pp. 371, 373, 



1882. 



This is a common bird in the heavy forest about the heads of can- 

 yons on Maria Madre and Maria Magdalena. They vrere not found 

 anywhere in the scrubby growth of the lower slopes, and if they occur 

 there at all it must be only as stragglers. They are shy birds, remain- 

 ing silent when approached, but when undisturbed flitting through 

 the tree tops like wandering spirits of melody uttering their sweet 

 strains from the mysterious, depths of the forest. Their song was 

 heard from the tops of tall trees where the birds sat amid the heavy 

 foliage, rarely coming down to lower levels except in the morning or 

 evening, or to drink at midday. Many were seen about a spring near 

 the top of Maria Madre where they came to drink at noon. 



