GROOVE-BILLED ANI 29 



which covered the bottom two layers deep, and six birds were in- 

 terested in them. * * * Of ten nests which I found in Honduras 

 and Guatemala and was able to watch for an adequate period, four 

 were the property of single pairs, five of two pairs together, and one 

 belonged to three pairs in common." 



All the birds of both sexes took turns in incubating the eggs, but 

 their shifts on the nest had no regular order and no fixed duration. 

 "Just as the parents cooperate in incubating the eggs, they all join 

 in the care of the nestlings. I have watched three nests, each belong- 

 ing to two pairs, during the time they contained young. Two of 

 them, I made quite sure, were attended by four adults, but at the 

 other I could not convince myself that there were more than three 

 attendants. Possibly some calamity had befallen the fourth bird, or 

 possibly also I failed to recognize it, since the anis at this nest were 

 unmarked and indistinguishable." 



Eggs.—T\iQ groove-billed ani lays 4 to 13 eggs, the smaller num- 

 bers being apparently commoner. The eggs vary in shape from oval 

 to elliptical-oval, or rarely to elliptical-ovate or rounded-ovate. The 

 ground color, when visible, varies from "glaucous-blue" to "Nile blue" 

 or "pale Nile blue" ; when first laid, the ground color is completely 

 covered with a thin layer of dull white, chalky deposit, which even- 

 tually becomes somewhat discolored; as incubation progresses this 

 chalky covering becomes more or less scratched, by contact with the 

 twigs in the nest or by the action of the bird's feet in turning the 

 eggs, or m relining the nest, so that ultimately much or nearly all of 

 the blue ground color is visible; even then the shell is not glossy. 

 The measurements of 51 eggs average 30.93 by 24.06 millmieters; 

 the eggs showing the four extremes measure 35 by 25, 32 by 26, and 

 27.68 by 21.84 millimeters. 



Young. — Mr. Skutch determined, by close observation of marked 

 birds and by noting which individual of a marked pair laid the 

 eggs, that both sexes share in the duties of incubation. They were 

 very impatient sitters, constantly changing about; 30 minutes was 

 the longest time that he saw one incubate, during the early stages, 

 and they sometimes left the nest unguarded for 10 or 20 minutes, 

 while they enjoyed each other's company ; during the last two days of 

 incubation they lengthened their periods on the eggs to from 30 

 minutes to an hour. He describes the hatching process in detail: 



"Fourteen days after the last egg had been laid, I held one in my 

 hand while the birdling worked its way out of it. When I first took 

 it up there was a gap in the larger end, which extended about a 

 third of the way around the circumference. The little bird's short, 

 thick bill was in this gap, and so pressed out of position that the 

 lower mandible overshot the upper, only a temporary condition. 



