Download The Avian Brood Parasites: Deception at the Nest by Paul A. Johnsgard PDF

By Paul A. Johnsgard

This booklet discusses the entire world's approximately a hundred species of compulsory brood parasites--those birds that reproduce basically by means of laying their eggs within the nests of alternative species--and the ecological and evolutionary elements of this awesome behavioral variation.

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Extra info for The Avian Brood Parasites: Deception at the Nest

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10). The white feathers at the bend of the wing in several Cuculus cuckoos may become more apparent during such wing dropping; this contrasting area perhaps functions in an analogous manner to the white "shoulder spot" that is exposed during display by various species of male grouse that also display under dim-light conditions (Johnsgard, 1973). The long tail is sometimes lifted and partially spread, revealing the white spotting present in many cuckoo species. Cuckoos often begin singing earlier in the morning and continue singing later in the evening than nearly all other diurnal birds.

Perhaps this results from the female parasite having carried a ready-to-lay egg in her cloaca for up to a day or possibly even longer, and thus some early embryonic development may have occurred at the time of egg deposition. In any case, host-intolerant brood parasites consistently exhibit shorter incubation periods than do nonparasitic cuckoos of roughly the same adult mass. Similarly, host-tolerant parasitic cuckoos, finches, and cowbirds tend to have incubation periods somewhat shorter than their hosts (table 9).

The black-headed duck has a somewhat smaller proportionate egg mass than do the other stifftails, but this group as a whole is no24 ECO-MORPHOLOGY AND INTERSPECIFIC MIMICRY table for the large eggs that they lay and for their highly precocial young, which are hatched with a large fat reserve, require little parental attention, and exhibit a well-developed ability to dive for food almost immediately after hatching (Lack, 1968; Johnsgard & Carbonell, 1996). The average proportionate egg-slope characteristic of the typical dabbling ducks (Anas), as determined by Lack, is shown as a dotted line; this illustrates the substantial difference between the dabbling ducks and stifftails in terms of parental energy investment in eggs.

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