﻿BIRDS OF THE TRES MARIAS ISLANDS. 



51 



cently inquiring eyes as if wondering at the strange creature newly 

 arrived in tlieir haunts, but evidently quite unconscious of any feeling 

 that the newcomer might be dangerous. Such confidence made it very 

 trying work to collect many of these birds. 



They came familiarly about the houses and yards at the settlement 

 on Maria Madre. A number of them made several visits each day to 

 the verandas and shrubbery about the custom-house, and added greatly 

 to the attractive surroundings by their bright colors and frank uncon- 

 cern. They searched for insects among the shrubs and small trees in 

 the patio or court, came to the veranda railing, down upon the floor, 

 and along the walls, where plump spiders furnished many choice morsels. 

 Several bags of corn piled against the wall on one side of the veranda 

 were infested with weevils, which could be found creeping about on the 

 outside of the bags. A i^air of orioles was in the habit of regularly 

 visiting the veranda and soon discovered these insects. They walked 

 all over the bags, sometimes upside down or on one side like a nuthatch, 

 and i)ried into every spot likely to contain a little beetle. They were 

 frequently seen also clinging to the stems of the giant cactus ( Gereus) 

 and feeding on the juicy fruit. 



As Colonel Grayson has recorded, the nests of these orioles are about 

 a foot in length and of the usual purse shape. They are made of fibers 

 of grass or maguey plants, lined with silk cotton and swung near the 

 end of some slender branch overhanging a clear space, usually from 18 

 to 35 feet above the ground. 



Grayson's oriole is evidently an offshoot from the wide ranging 

 Icterus pustulatus of the adjacent coast, but has become sufficiently 

 distinct to rank as a species. Like so many of the island birds, it is 

 larger than its mainland relative. The yellow is much lighter than 

 on /. pustulatus and lacks most of the intense orange that is so 

 conspicuous on many of the latter birds. Some adult males of graysoni 

 have the back entirely bright yellow, while the backs of others are 

 marked with a few narrow black shaft streaks. The females of gray- 

 soni are more greenish-yellow and have but faint traces of the orange 

 vshade present in typical pustulatus. 



The following averages show the relative dimensions of the two 

 species : 



Measurements of Icterus (jraijsoni and I. pustulatus. 



ISTame. 



Locality. 



Sex. 



Num- 

 ber of 

 speci- 

 mens. 



"Wing. 



Tail. 



Cul- 

 men. 



Tarsus. 





Maria Madre Island 



ad. (S 

 ad. $ 

 ad. cS 

 ad, 9 



4 

 4 

 4 

 4 



104 



96.7 

 100.2 



91.7 



89.7 

 84.2 

 91 



81.5 



25.4 

 25.1 

 21 



20.2 



26.7 

 26.2 

 25.6 

 24.5 



Icterus pustulatus 



"Western Mexico 



do 







