FAMILY PROCELLARIIDAE 35 



Family PROCELLARIIDAE: Shearwaters and 

 Petrels ; Pardelas y Petreles 



Only one species of this family, a race of Audubon's shearwater 

 that nests on a rocky islet on the coast of Bocas del Toro, is a 

 permanent inhabitant of Panamanian waters. Others have been 

 recorded as ocean wanderers from the outer reaches of the Gulf of 

 Panama, or casually from nearer the Pacific coast. Most of the re- 

 ports have been sight records of uncertain status, since not many 

 naturalists have had sufficient experience with the shearwater and 

 petrel group to identify them in life. It is probable that several 

 species will be found regularly, and others casually, when more 

 information is available. 



The name fardela by which shearwaters are known along the 

 western coast of South America, appears to be a corruption of pardela, 

 the usual term in the Spanish language for birds of this group on 

 the coasts of Spain. 



KEY TO SPECIES OF PROCELLARIIDAE 



1. Tarsus heavier, much compressed; space between nostrils as wide or wider 



than the nasal openings (genus Puffinus) 2 



Tarsus heavier, not compressed; space between nostrils narrow, less in 

 width than the nasal openings (genus Pterodroma). 



Dark-rumped petrel, Pterodroma phaeopygia, p. 35 



2. Tail nearly half the length of the wing, definitely graduated, wedge-shaped. 



Wedge-tailed shearwater, Puffinus pacificus, p. 42 



Tail definitely less than half of the length of the wing, rounded, or only 



slightly graduated • 3 



3. Under surface white; smaller, wing less than 200 mm. 



Audubon's shearwater, Puffinus Iherminieri, p. Z7 

 Under surface gray, or dusky, wing more than 260 mm. 



Sooty shearwater, Puffinus griseus, p. 36 



PTERODROMA PHAEOPYGIA PHAEOPYGIA (Salvin) : Dark-rumped 

 Petrel; Petrel de Rabadilla Oscura 



Oestrelata phaeopygia Salvin, Trans. Zool. Soc. London, vol. 9, May 1876, p. 

 507, pi. 88, fig. 1. (Chatham Island, Galapagos Archipelago.) 



A large petrel with sides of the head black. 



Description. — Length 400 to 431 mm. Brownish black above; wings 

 and tail black with concealed white patches; forehead and under 

 surface white ; sides of head black. 



Iris brown; bill black; tarsus and base of toes bluish flesh color; 

 distal part of web and toes, with most of outer toes black. 



Measurements (from Murphy, Oceanic Birds S. Amer., vol. 2, 



