Testosterone increases activity but not daily energy expenditure in captive male dark-eyed juncos, 'Junco hyemalis'

Article Abstract:

An investigation is conducted into the testosterone levels in male dark-eyed juncos, which have been observed to peak at an early stage in the breeding season and then decline. The study extends the early peak level throughout the season and evaluates the related expenditure of energy.

Observations, Birds, Bird breeding, Finches, Darwin's finches

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Female ornamentation and male mate choice in dark-eyed juncos

Article Abstract:

An experiment concerning female ornamentation and male mate choice was performed in dark-eyed junco, Junco hyemalis. It was found that the sexes apparently prefer different trait values, which suggests that preferences are expressed independently in males and females.

Science & research, Research, Sexual behavior in animals, Animal sexual behavior, Animal sexual behaviour

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Testosterone and mate choice in the dark-eyed junco

Article Abstract:

Variation in testosterone can have an impact on the attractiveness of male dark-eyed juncos to females, and thus affect male copulatory success. It appears that testosterone has the potential to determine all aspects of reproductive behaviour in male dark-eyed juncos. It is possible that testosterone is used by males to adapt their breeding behaviours to align with their status at any one time. Testosterone seems to be particularly important in allowing males to fight with other males for territory.

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