30 NORTH AMERICAN FAUNA. 



newly hatched young succumbed to the heat when the parents left them 

 exposed to the rays of the sun. The nests were spaced at intervals of 

 4 or 5 feet, so that the old birds were safely out of reach of one another. 

 Although so gregarious in their breeding habits, they appeared to 

 have but little regard for one another. It was amusing to see the sav- 

 age way in which the nest owners assisted intruders of their own kind 

 out of their territory. While we were walking among them some of 

 the birds would often waddle ofi' to one side, and iu so doing neces- 

 sarily trespassed on their neighbors. The latter at once raised a 

 hoarse shrieking and set upon the outsiders with wicked thrusts of 

 their beaks, which continued until the victims took wing and escaped. 



We were also subjects of this iiroprietary rage, and had our legs nipped 

 every now and then, despite all efforts to walk circumspectly. Onr 

 progress over the breeding ground was accompanied by a wave of 

 hoarse, nasal cries that sometimes became almost deafening. Many of 

 the birds were valiant upholders of their rights and sturdily refused 

 to leave their nests, which they defended vigorously, all the time utter- 

 ing loud cries of rage. 



These birds show very little individual variation in color. As the 

 species is not well known the following descriptions are apj)ended from 

 specimens taken on Isabel and Maria Cleofa. 



Adult male. — Nearly entire head white, shading gradually on poste- 

 rior portion into drab of neck and then insensibly into dark, sooty brown 

 of back. On lower side of neck the drab becomes darkest at poste- 

 rior border, where it ends abruptly against the pure white of lower 

 parts. Bill light horn color; gular pouch in life livid blue; feet green- 

 ish yellow — the latter varying in intensity. 



Male in immature plnmafie, — Dorsal surface uniform dark brown, 

 slightly paler than back of adult; entire lower surface still paler and 

 more dingy brown. Feathers over much of body, especially about 

 head, neck, and lower parts, narrowly edged with grayish brown, giving 

 a faint wavy barring. Bill bluish horn color, with darker shade of 

 same about base and on gular pouch ; feet and tarsi dull fleshy yellow ; 

 iris greenish gray. 



Adult female. — Head, neck all around, and back sooty brown; ven- 

 tral surface below neck white. Bill light horn color; a spot of leaden 

 bluish on lores; base of bill, gular pouch, feet, and tarsi grayish yel 

 low; iris pale grayish. 



Average measurements of these birds from Isabel Island are as fol- 

 lows: S (5 siiecimens), wing 384.4; tail 189.6; culmen 93.6; tarsus 45.4; 

 2 (5 specimens), wing 416.0; tail 193.8; culmen 96.6; tarsus 48.8. 



Nestlings a few days old are covered with fluffy white down. A male 

 bird of the previous year, which still retained the immature plumage, 

 was taken at Is.abel on April 23, and several others were seen. 



