You snooze, you lose: Less sleep leads to more offspring in male pectoral sandpipers

Aug 09, 2012
This is an attentive male sandpiper on the lookout for potential competitors. Credit: Wolfgang Forstmeier

During the breeding season, polygynous male pectoral sandpipers that sleep the least sire the most young. A team of researchers headed by Bart Kempenaers from the Max Planck Institute for Ornithology in Seewiesen has now discovered this extraordinary relationship. During three weeks of intense competition under the constant daylight of the Arctic summer, males actively court females and compete with other males. Using an innovative 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.

Sometimes it would be nice to have 24 hours available to finish the workload of the day. However, the drive for sleep inevitably compromises our performance or even causes us to fall asleep under , such as driving a car. Daily sleep is therefore thought to be essential for regenerating the brain and maintaining performance. This holds true both for humans and other animals. Researchers led by Bart Kempenaers from the Institute for in Seewiesen have now found that during the three-week mating period male pectoral sandpipers (Calidris melanotos) are active for up to 95% of the time. This is even more remarkable considering the fact that the birds have just arrived in their breeding area in Alaska, after migrating from their overwintering grounds in the .

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 is determined exclusively by his access to fertile females. However, gaining this access is not that easy for pectoral sandpipers: "Males have to constantly repel their rivals through male-male competition and simultaneously convince females with intensive courtship display", says director Bart Kempenaers. Given that the sun never sets during the Arctic summer, males that can engage in this extreme competition 24/7 should be at an advantage.

Indeed, the researchers found that the most active males interacted most with females and sired the most offspring. 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. These radiotelemetry based senders allowed the team to monitor whether the animal was moving or resting. Finally, recordings of brain and muscle activity confirmed that active birds were awake and that inactive birds were in fact sleeping.

Courtship flight: This male is trying to impress any watching female sandpipers with its feats of flight and inflated chest. Credit: Wolfgang Forstmeier

The recordings also reveal variation in sleep intensity: "Males that slept the least had the deepest sleep", says co-author Niels Rattenborg who conducts sleep research at Seewiesen. Although this suggests that the birds might compensate for by sleeping deeper, the researchers found that even when this was taken into consideration, the birds were still experiencing a deficit in sleep.

Based on the team's data on birds that returned to the study area across breeding seasons, this reproductive sleep loss apparently has no long-term adverse impact on survival. On the contrary, successful males returned to the breeding area more often when compared to males siring less offspring and were more likely to sire offspring in their second year. Does the study question the dominant view that the function of sleep is to regenerate the brain? The researchers do not wish to go that far, although the findings clearly show that under certain circumstances animals may be able to evolve the ability to forgo, or postpone, large amounts of sleep while maintaining high neurobehavioral performance.

Importantly, the finding that not every male does this, even when there are fertile females around, suggests that "Long sleeping males may lack genetic traits that enable short sleeping individuals to maintain high performance despite a lack of sleep", argues Bart Kempenaers. The researchers believe that determining why only some engage in this adaptive sleeplessness may provide insight into the evolution of this extreme behaviour, as well as the ongoing debate over the functions of and its relationship to health and longevity in humans.

Explore further: Lost sea lion in California found mile from water

More information: John A. Lesku, Niels C Rattenborg, Mihai Valcu, Alexei L. Vyssotski, Sylvia Kuhn, Franz Kuemmeth, Wolfgang Heidrich, Bart Kempenaers Adaptive Sleep Loss in Polygynous Pectoral Sandpipers, Science Express, published online August 09, 2012.

Related Stories

Night lights affect songbirds' mating life

Sep 16, 2010

In today's increasingly urbanized world, the lights in many places are always on, and according to a report published online on September 16 in of Current Biology, a Cell Press publication, that's having a real ...

Birdsong independent of brain size

Jun 13, 2011

(PhysOrg.com) -- The brains of all vertebrates display gender-related differences. In songbirds, for example, the size of the brain areas that control their singing behaviour could be linked to the size of ...

Females avoid incest by causing male relatives to leave home

Aug 15, 2007

Researchers at the University of Sheffield in the UK and Leibniz Institute for Zoo and Wildlife Research (IZW) in Berlin, Germany, have found that female hyenas avoid inbreeding with their male relatives by giving them little ...

Recommended for you

In sex-reversed cave insects, females have the penises

2 hours ago

Researchers reporting in the Cell Press journal Current Biology on April 17 have discovered little-known cave insects with rather novel sex lives. The Brazilian insects, which represent four distinct but re ...

Fear of the cuckoo mafia

2 hours ago

If a restaurant owner fails to pay the protection money demanded of him, he can expect his premises to be trashed. Warnings like these are seldom required, however, as fear of the consequences is enough to ...

Biologists help solve fungi mysteries

6 hours ago

(Phys.org) —A new genetic analysis revealing the previously unknown biodiversity and distribution of thousands of fungi in North America might also reveal a previously underappreciated contributor to climate ...

User comments : 0

More news stories

Tiny power plants hold promise for nuclear energy

Small underground nuclear power plants that could be cheaper to build than their behemoth counterparts may herald the future for an energy industry under intense scrutiny since the Fukushima disaster, the ...