Article Abstract:
Research was conducted to examine the hypothesis that male pied flycatchers, Ficedula hypoleuca, living in a deciduous forest have higher plasma levels of testosterone and protect their territories more fiercely than males found in coniferous forest. Hormonal differences were tested by exposing unmated territorial males to simulated territorial intrusions. Results indicate that males in a deciduous forest had higher plasma levels of corticosterone and testosterone compared to males in a coniferous forest. However, no difference was observed in their dihydrotestosterone levels.
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Article Abstract:
An investigation was carried out to test the hypothesis that plummage color is an accurate index of male status or fighting ability among birds. The results showed that there were no discrepancies in the aggressive responses between black and brown territorial owners to the black or the heterospecific intruders. In addition, there was no dissimilarity in the number of attacks made by the black and brown territory owners towards a black dummy. These findings failed to support the previously mentioned status signalling hypothesis.
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Article Abstract:
Female pied flycatchers, Ficedula hypoleuca, have a patch of white feathers on their foreheads which are characteristic of male pied flycatchers. The phenotype of the father pied flycatchers influenced the appearance of the white patch in their daughters. Fathers with large white patches on their foreheads generally had daughters in whom the white patch manifests earlier in life. The study provides an insight into the evolution of sexual dimorphism and into the expression of male trait in female pied flycatchers.
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