Finch sperm go long to fertilize more eggs

Guest post by Bethany Brookshire

Size matters for bird sperm. Zebra finch males with longer sperm fertilize more eggs, and father more chicks, than males with shorter sperm.

Scientists from the University of Sheffield in England bred male finches, one group with long and one with short sperm. They showed that long-sperm finches sired 64 percent of embryos, leaving short-sperm males a paltry 36 percent. The results, published December 9 in Proceedings of the Royal Society B, suggest longer sperm swim faster and end up in more of the female’s sperm storage spots for later use.