Birds sing at a higher pitch in urban noise: great tits hit the high notes to ensure that their mating calls are heard above the city's din

Article Abstract:

Investigation in an urban population of great tits in the Dutch city of Leiden shows that the spectral composition of ambient noise was generally characterized by loud, low frequency sounds. It is noticed that urban great tits at noisy locations sing with a higher minimum frequency.

Bird songs

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Why do birds engage in extra-pair copulation?

Article Abstract:

Extra-pair fertilizations are more likely when social mates are genetically closely related in case of birds. However, there is still no convincing evidence that extra pair copulation in birds is influenced by the relatedness between partners.

Genetic aspects

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Delta-wing function of webbed feet gives hydrodynamic lift for swimming propulsion in birds

Article Abstract:

Results indicate that in foot-propelled swimming birds, delta shape of their webbed feet can propel them continuously through two successive modes, from the drag at the beginning of the stroke through hydrodynamic lift later in the stroke.

United States, Sweden, Analysis, Influence, Underwater propulsion, Hydrodynamics, Animal swimming

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