﻿38 NORTH AMERICAN FAUNA. 



lielow are averages showing the relative size of the two ishiiid forms: 



Aleaaurements of Buteo horealis fumosus and Buteo b. socorroensis. 



Name. 



Locality. 



Sex . 



Num- 

 ber of 

 speci- 

 mens. 



Wing. 



Tail. 



Cul- 

 nien. 



Depth 

 of bill. 



Tarsus. 



Buteo borealis fumo 



Maria Madre Island . 



Ad. (f 



3 



:^73 3 



207, 3 







26 



18.5 



81.3 



SllS. 



Bnteo borealis fumo 



.... do 



Ad ? 



I 



412 



214 



30 



20 



84 



sus. 



















Buteo borealis socor- 



Socorro Island 



Ad. 





387.5 



207.5 



25 



17.5 



80 



roensis. 



















Buteo borealis socor 



do 



Ad. ? 





425 



221 



30 



20 



86 



roensis. 



















Falco peregrinus anatum (Bouap. ). Duck Hawk. 



Falco jjeregrinus x&t. nigriceps Grayson, Proc. Boston Soc. Nat. Hist.. XIV, ]). 268, 

 1871. 



A single duck hawk was taken by Colouel Grayson, who mentions 

 that it was shot while in close pursuit of a sparrow hawk. We did 

 uot see this species during our visit to the islands. 



Falco sparverius Liun. Sparrow Hawk. 



The sparrow hawk was recorded from the islands by Colonel Gray- 

 son, but we did not see a single individual, and it probabl}^ occurs 

 merely as a straggler. 



Falco columbarius Linn. Pigeon Hawk. 



Colonel Grayson records this species as very common upon the 

 islands. ISTot a single individual was seen by us, and it probably 

 occurs onl}^ as a winter visitant or stray migrant. 



Falco albigularis Daudm. White-tliroated Falcon. 



Hypotriorchis rnfigularis Grayson, Proc. Boston Soc. Nat. Hist., XIV, }>. 269. 1871; 

 Lawr., Mem. Boston Soc. Nat. Hist., II, p. 301, 1874. 



Colonel Grayson took a specimen of this fine little falcon on the 

 islands. IsTone were seen by us, and it must, no doubt, be classed as 

 one of the numerous accidental visitants from the mainland. 



Polyborus cheriway pallidus Nelson. Tres Marias Caracara. 



Polyhoi'us auduhonii Grayson, Proc. Boston Soc. Nat. Hist., XIV, ]>. 268, 1871, 

 (part). 



Pol\)l)oru8 tharus var. miduhoni Lawr., Mem. Boston Soc. Nat. Hist., II, p. 303, 

 1874, (part). 



PolijborKs clierm-ay paUidns Nelson, Proc. Biol. Soc. Washington, XII, p= 8, 1898. 



Very abundant about the settlement on Maria Madre and rather 

 commonly distributed elsewhere over the island. They were also 

 rather common on the other islands, including San Juanito. The old 

 log roads and dry bottoms of the canyons on Maria Madre were 

 favorite resorts. The birds were met in many unexpected places, and 

 were frequently seen i)erclied in tree tops in the midst of the unbroken 



