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Individual, Temporal, And Seasonal Variation In Sperm Concentration In Tree Swallows, Michael P. Lombardo, Armetris N. Forman, Matthew R. Czarnowski, Patrick A. Thorpe

Peer Reviewed Publications

We determined sperm concentrations in Tree Swallows (Tachycineta bicolor) by manually expressing semen samples from males during prelaying, egg-laying, incubation, and nestling periods. Sperm concentrations varied by orders of magnitude (0-10⁹ sperm mL^-1) among males. Sperm concentrations were highest during the incubation period and lowest during the prelaying period. None of the samples collected during the prelaying, egg-laying, and incubation periods were devoid of sperm. In contrast, 45% of samples collected during the nestling period lacked sperm. Sperm concentrations (1) did not vary over the course of the morning during prelaying, egg-laying, and incubation periods …