What male pectoral sandpipers lack in looks when breeding in northern Alaska during the summer, they make up for in stamina.
After flying thousands of miles from the southern hemisphere to their breeding grounds in Alaska, these chunky shorebirds go without sleep for three weeks while they mate with as many females as possible.
And they get results.
Researchers from Germany and Switzerland have found male pectoral sandpipers that sleep less sire more offspring, according to a report published in Science magazine.
"Male pectoral sandpipers (calidris melanotos)… are able to maintain high neurobehavioral performance despite greatly reducing their time spent sleeping during a three-week period of intense male-male competition for access to fertile females," the researchers wrote in a report titled: "You snooze, you lose."
"Our results challenge the view that decreased performance is an inescapable outcome of sleep loss."
Transmitter devices fitted to 29 male birds to record brain activity showed individuals were "active" for up to 95 percent of the time.
Birds that had the least shut-eye during the almost continuous daylight of Alaska summers had the most reproductive success, the researchers found, according to the BBC.
But it's not easy for the males, either, the Daily Mail reported.
"Males have to constantly repel their rivals through male-male competition and simultaneously convince females with intensive courtship display," said study leader Dr. Bart Kempenaers, from the Max Planck Institute for Ornithology at Seewiesen in Germany.
Males competed in "aerial chases" of females and engaged in physical fights.