BIRDS OF LOWER CALIFORNIA. 261 



graceful birds when flying that I have ever seen. In picking 

 food from the water, they scarcely disturb the surface; 

 descending airily, the object is taken in passing in such a 

 manner that at the moment of seizure the bird's head is 

 bent under, then quickly throwing the head upwards, they 

 rise again, silent and graceful. I have seen flocks of fiftv 

 or more circling over the land a mile from water and con- 

 tinually descending to the ground, bushes or cacti from 

 which they were evidently picking food, possibly land snails, 

 although I could not approach near enough to see even with 

 a field glass that any sizeable objects were taken. The 

 stomaclis of the specimens examined were either empty or 

 contained slender parisitic worms about 40 mm. long. The 

 principal feeding ground was probably at sea. They were 

 not seen to light anywhere except upon their nests or the 

 mangroves. In order to study more closely the habits of 

 these birds, I camped for a few nights upon the sand ridge 

 between the bay and lagoon. 



The birds were more quiet after dark, but some sounds 

 could be heard throughout the entire night. At the first 

 faint appearance of dawn, a continuous exodus would com- 

 mence from the rookery, some of the birds flying high over 

 the island more than four miles to the sea. The mangroves 

 bordering upon the western side only of the lagoon were 

 used for nesting sites, a partial vacancy midway seemed to 

 separate two colonies. The mangroves being higher at the 

 edge of the water, the nests were placed at heights varying 

 from five to tv/elve feet. Procuring a small boat and the 

 services of a Mexican, I skirted the edge of the lagoon for 

 specimens of eggs and photographs of the rookery, showing 

 the birds in all attitudes. They were usually quite tame 

 but seemed more afraid of me when in the boat than when 

 climbing over and through the mangroves, probably because 

 in the first instance I was more exposed to view. Several 

 birds were caught by hand and some others struck down with 

 an oar as they pitched from the nest to fly past. Upon the 



