196 ALOPOCHEN &GYPTIACUS 



The normal nesting site is undoubtedly in trees, often in the old nests of other 

 species, and sometimes in holes or hollow places. Many other locations have been 

 described, however, and where suitable trees are not available it nests in rushes, on 

 cliffs, and even among the grass and rock of the open kopjes in South Africa (Haag- 

 ner and Ivy, 1908). When placed in a tree the nest is usually on an overhanging 

 stump, in a hollow, or among the tangled roots on the shore, but never more than 

 four meters above the ground. Acacia, Tamarix and Zizyphus are commonly chosen 

 (von Heuglin, 1873). A. E. Brehm (1879) says that they are especially partial to the 

 Mimosa. Von Heuglin (1873) was not certain that they appropriate the nests of 

 other species, but since his time they have been found using the nests of the Ham- 

 merhead Stork (Haagner and Ivy, 1908) and the Vulture's nest (Horsbrugh, 1912). 

 The nest itself is usually constructed of twigs, broken from trees, but sometimes of 

 cane carried into the tree by the bird. In any case it is lined with grass (A. E. Brehm, 

 1879; von Heuglin, 1873). In South Africa nests have been found on cliffs two hun- 

 dred feet above the water (Layard, 1875-84). Other nests have been found that 

 were only slight depressions in the sand lined with reeds and down (R. and V. 

 van Someren, 1911). In Lichtenstein's Travels (vol. 2, p. 559, 1812) a nest is men- 

 tioned which was floating on the water, fastened only by a few reeds. This must 

 have been the nest of some other bird, I think, or possibly a nest which had become 

 flooded. 



The usual clutch numbers from five to eight eggs, but there are very few refer- 

 ences to the contents of individual nests. The average number is probably six. They 

 are yellowish white in color, very round and, for such a large bird, very small. They 

 vary in length from 55 to 68.6 mm., and in breadth from 44 to 48.3 mm. Eggs laid 

 in captivity are said to be distinctly larger, measuring from 68 to 72 mm. in length 

 by 48 to 53 mm. in breadth (Kuschel, 1895). The female performs the duties of in- 

 cubation alone, but is constantly guarded by the male (A. E. Brehm, 1879), who 

 remains with the family during the entire breeding period (Layard, 1875-84). The 

 incubation period according to A. E. Brehm (1879) is twenty-seven to twenty-eight 

 days, but this is without doubt, an understatement. Heinroth (1908) hatched eggs 

 under a hen in twenty-eight days, while under a Muscovy the period was thirty days. 

 Judging from related species I should say that the period is at least twenty-nine and 

 probably thirty days. While incubating, the female leaves the nest once a day, in the 

 afternoon, carefully covering the nest with down before leaving (A. E. Brehm, 1879). 

 Von Heuglin (1873) says that at the approach of a human being the old bird (male?) 

 seeks to attract attention to itself by running about, chattering and stumbling, as 

 though unable to fly. 



After hatching, the parents lead the young to deep water, where they soon learn 

 to dive expertly, and are guarded very closely by both the parents. When the young 

 are on the wing several broods flock together, such parties occasionally numbering 



