A possible relationship between reversed sexual size dimorphism and reduced male survivorship in the Ruby-throated Hummingbird

Article Abstract:

An analysis of sex ratios across seasons and between adult and immature classes, return records and male mass during the breeding season was done to determine if the pronounced reversed sexual dimorphism in Ruby-throated Hummingbirds (Archilochus colubris) causes lower survivorship of males. Results showed that the small males do suffer greater mortality from the increased metabolic demands of the breeding season, although the effects of a capture bias resulting from differences in use by the sexes of the sampled habitats was not completely ruled out.

Physiological aspects, Hummingbirds, Dimorphism (Animals), Dimorphism (Biology)

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Playback of crows and male Japanese quail elicits female phonotaxis

Article Abstract:

Most of the family Phasianidae are characterized by male crowing. The loud, broadband crowing of the Japanese quail (Coturnix japonica) is only heard during the breeding season. A new study examines the reactions of female quails to speaker broadcast crows played forwards and backwards. It is shown that female quails exhibit positive phonotaxis to normal crowing, but do not respond to reverse crowing. Male quails show no response to either type of broadcast. It is concluded that the temporal pattern of crow syllables is linked to female response.

Sexual behavior, Japanese quail

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Song organization of house finches at the edge of an expanding range

Article Abstract:

Colonization of new areas by song birds is thought to be one factor influencing the regional differences in their song. A new study of a colony of house finches that have expanded their range in Wisconsin examines the regional differences in songs and the influence of colonization histories. Results are compared with previous studies.

Finches, Darwin's finches

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