FULVOUS TREE DUCK 137 



The number of eggs found in the nests is extremely variable. In California and 

 in the Argentine large numbers, up to twenty or thirty are not unusual; but in India 

 the ordinary set seems to be from six to eight. Even when breeding the birds are 

 sociably inclined, and many may be found nesting together "as in a gullery" (P. L. 

 Sclater and Hudson, 1889). The most recent writer on the Argentine, however, 

 speaks of thirteen as the largest clutch foimd (Gibson, 19 l 20), and very probably 

 the large colonies are a thing of the past. Although the usual clutch in California 

 is from twelve to seventeen, huge aggregations in one nest have been frequently 

 reported, the most remarkable being the record of sixty-two eggs found in Los Banos 

 County, and placed on a pile of dead grass, about four inches above the water, with- 

 out any attempt at nest-building or concealment (Barnhart, 1901). These great 

 accumulations of eggs occurred when the species first began to occupy an irrigated 

 district of California in large numbers, but they have not been found since that 

 time. Shields (1899) found a nest with thirty-two eggs and others containing from 

 seventeen to twenty-eight. These large clutches are deposited in several layers. 

 Doubtless the females are very prolific at times, and it is extremely difficult to de- 

 termine the exact limit of individual fertility. Several observers who found late 

 broods in tropical regions, have taken this to be an indication that the birds nest 

 more than once a season; but this is undoubtedly incorrect, for in warm regions the 

 reproductive period is long-drawn-out, extremely irregular, and may extend through 

 the entire year. 



An important and very interesting find was made by Shields (1899), when he took 

 three of these Tree Duck eggs from the nest of a Red-head, and one from a Ruddy 

 Duck's nest, and afterward found other cases of this incipient parasitism. 



The period of incubation is long, and is given by Heinroth (1908) as thirty-two 

 days. It is not known whether the male ever takes part in the incubation. The eggs 

 measure 50.3 to 55.8 by 34.3 to 41.8 mm., and are elliptical-ovate in shape, ivory 

 white in color, with surface texture rather rough (Grinnell, Bryant and Storer, 

 1918). 



Status. There is very little in the literature bearing on the present status of this 

 species. In California, where the bird is almost entirely migratory, recent irrigation 

 systems had actually produced a temporary increase. Gibson (1920), recalling the 

 incredible numbers seen during the floods of 1877 in the Buenos Aires region, says 

 that huge masses covered the grasslands immediately bordering the swamps for 

 hundreds of yards in length, with a depth of from five to twenty yards. He adds, 

 however, "But where are the birds of 1877, which lined the shores of the canadas in 

 serried brown phalanxes, and permeated the whole atmosphere with brown sun- 

 moats?" In that part of the world the birds are at least partly migratory, but very 

 irregular in their appearance. In Africa, as has already been remarked, they are 

 nowhere so plentiful as the White-face. This applies also to Madagascar. 



