But How Fast Do the Wings Beat?

The smallest avian genomes are those of hummingbirds, report T. Ryan Gregory and his colleagues in Proceedings of the Royal Society B. According to the paper abstract, the genome sizes of birds are thought to be inhibited by flight's metabolic demands and by the relationship between nuclear DNA content and the size of red bloods cells. From that hypothesis, it was thought that hummingbirds, which can hover — a power-draining exercise — would have the smallest genomes of birds. Gregory and his colleagues measured the genomes of 37 hummingbird species, with the sizes ranging between 0.91 picograms for the black-chinned hummingbird to 1.29 pg for the wedge-billed hummingbird.