During the breeding season, male pectoral sandpipers undergo sleepless days and nights, as they are busy courting females and competing with other males.
Researchers from the Max Planck Institute for Ornithology in Seewiesen have now found that during the three-week mating period male pectoral sandpipers (Calidris melanotos) are active for up to 95 per cent of the time.
Pectoral sandpipers have a polygynous mating system where one male mates with several females. Because males do not engage in parental care, a male's reproductive success is determined exclusively by his access to fertile females.
"Males have to constantly repel their rivals through male-male competition and simultaneously convince females with intensive courtship display", director Bart Kempenaers said.
Using a combination of tags that monitored movement, male-female interactions, and brain activity in conjunction with DNA paternity testing, the authors discovered that the most sleepless males were the most successful in producing young.
As the first evidence for adaptive sleep loss, these results challenge the commonly held view that reduced performance is an evolutionarily inescapable outcome of sleep loss.
"Long sleeping males may lack genetic traits that enable short sleeping individuals to maintain high performance despite a lack of sleep," Kempenaers said.
However, in case of humans and animals daily sleep is thought to be essential for regenerating the brain and maintaining performance.
Given that the Sun never sets during the Arctic summer in Alaska where the birds have migrated to, males that can engage in this extreme competition 24/7 should be at an advantage.
Paternity was determined by collecting DNA from all males, all females, and all offspring in the study area. To measure activity patterns, the researchers attached transmitters to the feathers of all males and most of the females.
"Males that slept the least had the deepest sleep", co-author Niels Rattenborg said adding that this did not compensate for the sleep loss.
