BIRDS OF THE TRES MARIAS ISLANDS. 



By E. W. NELSON. 



The present paper is based mainly upon the birds found on the Tres 

 Marias, but for the sake of completeness the results of our work on 

 Isabel Island have also been introduced. 1 The situation of Isabel 

 Island between the mainland and the Tres Marias renders its bird life 

 of peculiar interest in the present connection. Mr. Xantus sent speci- 

 mens of birds to the National Museum labeled 'Tres Marias, 1861,' 

 but only one of these can be an authentic island species, and it seems 

 almost certain that Xantus did not visit the islands. 



Colonel Grayson's notes on his three visits to the group and his 

 trip to Isabel Island were published by George N. Lawrence in the 

 'Proceedings' and 'Memoirs of the Boston Society of Natural History,' 

 while the descriptions of new birds in his collections appeared in various 

 publications and are mentioned in the bibliography (see pp. 93-94). 

 Gray sou constantly refers to the 'Tres Marias Islands,' but the internal 

 evidence of his writings, in addition to the information given me by the 

 inhabitants, indicates that all of his work was done on Maria Madre. 



Mr. A. Forrer visited Maria Madre in 1881, but the publication of 

 Vireo flavoviridis forreri by Von Madarasz and a few notes in the 

 'Biologia Centrali- Americana' and in some of the British Museum 

 Catalogues are all we know of his work there. 



As already stated in the general introduction, our work was done on 

 Isabel Island on April 22 and 23, on Maria Madrc from May 2 to 25, 

 and six days were spent working about Maria Magdalena and Maria 

 Cleofa. It is quite certain that the bird fauna of Maria Madre is 

 now fairly well known, and it will be advisable for anyone visiting this 

 group in the future to give attention chiefly to the two smaller islands. 

 It is certain that a large proportion of the birds found on Maria Madre 

 occur also on Maria Magdalena, but some of the species living in the 

 dense forest at higher altitudes on these islands probably do not occur 

 in the more scanty forest of Maria Cleofa. 



At present 83 species and subspecies of birds are known from the 

 Tres Marias, and further observations will, no doubt, add to the list 

 various stragglers from the mainland. The bird fauna may be grouped 

 under the following headings : Resident land birds, 3G species or sub- 



1 The notes iu the following pages refer to Isabel Island only when BO stated. 



