Mar., 1910 
A GLIMPSE OF BIRD LIFE ON THE WEST COAST OF MEXICO 
75 
parrots, parakeets and Mexican Caciques ( Cdssiculus melanicterus) . The birds are 
not hard to approach, tho the parrots and parakeets are somewhat wild. 
We stayed in San Bias two days this time, which was spent in getting 
acquainted with and skinning birds. On the ninth of April we embarkt for the 
Las Marietas Islands, some sixty miles south and four miles from the mainland, 
known for their considerable guano supply and immense numbers of Blue-footed 
and Brewster Boobies. The guano is found in large caves and is not the product of 
our present day birds or bats. The guano of the boobies is considered worthless 
and on this coast it is the cormorant guano that is sought. As we approacht 
the islands they seemed to be literally covered with boobies, the Brewster greatly 
exceeding the Blue-footed in numbers. This group of islands consists of two main 
islands, one of which is about a mile and a half in diameter, composed mostly of 
piled-up lava. The other, slightly smaller, has a large flat grassy plain and a small 
spring of fresh water, a few small trees and some patches of cactus. There are 
several small outlying rocks and it was on these rocks that we found Heerman 
Gulls ( Lams heemnanni ) nesting. 
On these islands the Brewster and Blue-footed Boobies have distinct nesting- 
habits. No Blue-faced Boobies were seen. At the time of our visit Brewster 
Boobies were all thru their nesting, the young being well able to fly about and fish for 
themselves. These Boobies make their nests on the high parts of the islands and 
on the hillsides among the rocks, while the Blue-footed seek the flat plains. Brew- 
ster Boobies construct a well-made nest of grass, while the Blue-footed simply 
scratches a hole in the bare earth and deposits her eggs without any lining to the 
nest. The captain of the ship told me that when he was there, about the 
6th of January, Brewster Boobies had young and eggs. We found Blue-footed 
Boobies with eggs and young in all stages of development. Their colonies never 
encroacht on those of Brewster’s and the two boobies did not seem to associate with 
each other. Sets of their eggs consist about equally of two or three eggs, and out 
of hundreds examined only three nests containing four eggs were noted. A singu- 
lar thing is the large number of runts, and the difference of size of the eggs in the 
same nest. The eggs when first laid are identical in appearance to those of the 
cormorants, but soon become badly nest stained. 
Altho there were hundreds of Frigate Birds about during our stay of five days 
I did not see any attempt to rob the boobies of their fish, tho when we moved 
around the colonies the brooding birds would vomit quantities of small fish before 
flying, which the Frigate Birds would be on the alert to pick up. The boobies do 
considerable fishing at night and, as the water gave off a phosphorescent light when 
disturbed, it gave the appearance of flashes of flame when the birds made their 
dives. The Frigate Birds had their nests in a large tract of wild pineapple plants, 
which, being exceedingly prickly, made their nests well protected, at least from us. 
After some very careful work and many stabs I managed to reach a few of the 
nests and there found young and eggs in all stages of development. The single 
egg is placed on a platform, flimsily made of twigs and it is a marvel to me how the 
bird can brood without destroying it. The white downy young often fall victim to 
their own indiscretion, by falling out of the nest, and once among that wild pine- 
apple death is inevitable, as testified by many mute witnesses. 
Tho we made careful search for that exceedingly dainty and graceful bird, the 
Red-billed Tropic Bird, the only evidence of one was a dried up dead one on the 
beach. Old friends such as Great Blue Fleron, ( Ardea herodias) . California 
Brown Pelican, (Pelecanus calif or nicies') and Heennann Gull were nesting. At 
this date eggs of the Great Blue Heron were fresh, California Brown Pelican were 
