Featured Research

from universities, journals, and other organizations

The rhythm of the Arctic summer: Diverse activity patterns of birds during the Arctic breeding season

Date:
June 19, 2013
Source:
Max-Planck-Gesellschaft
Summary:
Our internal circadian clock regulates daily life processes and is synchronized by external cues, the so-called Zeitgebers. The main cue is the light-dark cycle, whose strength is largely reduced in extreme habitats such as in the Arctic during the polar summer. Using a radiotelemetry system biologists have now found, in four bird species in Alaska, different daily activity patterns ranging from strictly rhythmic to completely arrhythmic.

The red phalarope is polyandrous, i.e. one female simultaneously lives with several males. It tries to woo and dazzle potential partners with a display flight.
Credit: Wolfgang Forstmeier

Our internal circadian clock regulates daily life processes and is synchronized by external cues, the so-called Zeitgebers. The main cue is the light-dark cycle, whose strength is largely reduced in extreme habitats such as in the Arctic during the polar summer. Using a radiotelemetry system a team of researchers from the Max Planck Institute for Ornithology have now found, in four bird species in Alaska, different daily activity patterns ranging from strictly rhythmic to completely arrhythmic. These differences are attributed to the species' mating systems and behaviours. The study shows that activity patterns can change according to social and environmental factors, which suggests a remarkable plasticity in the avian circadian system.

Biological rhythms are essential for the regulation of many life processes. During the annual cycle, seasonal rhythms regulate the timing of reproductive activities. In our latitudes this a relatively easy task, as the marked annual changes in a day-night cycle (the photoperiod) entrains the seasonal clock. At the equator, where there is almost no change in day length over the year the animals have to rely on cues other than the photoperiod to time reproduction. However, in order to adjust its circadian clock an organism needs a certain light-dark cycle as a Zeitgeber. In the absence of a suitable Zeitgeber animals run free, which means they develop their own rhythm that can substantially deviate from a 24 hours day. Free-running cycles have been observed in animals and humans. Polar regions constitute extreme environments in this respect, as there is, around the summer and winter solstices, either constant light or constant darkness. Therefore, animals living in these harsh environments may have to depend on other cues in order to adjust their internal clock. These cues are relatively hard to determine.

An attempt to identify such cues has been made by a team of researchers from the Max Planck Institute for Ornithology in Seewiesen and Radolfzell. They investigated four bird species living in Alaska; three shorebird species, the semipalmated sandpiper, the pectoral sandpiper, the red phalarope, and one songbird species, the Lapland longspur. Remarkably, all four species have different mating systems. While the semipalmated sandpiper is strictly monogamous, the Lapland longspur, in addition to its monogamous lifestyle, shows occasional polygyny, where one male mates with several females. Polygyny is the rule in the mating system of the pectoral sandpiper, while the red phalarope is polyandrous, i.e. one female simultaneously mates with several males. Moreover, in the latter species the sex roles are reversed. The study site was a mere two square kilometre tundra area near Barrow in Northern Alaska. The researchers equipped in total 142 birds with radiotelemetry transmitters and determined their daily activity patterns using so-called actograms.

When analysing the activity data the researchers detected a whole array of biological rhythms. The Lapland longspur exhibited a robust 24 hour activity cycle throughout the breeding season and showed a regular but short resting period from about midnight to 4:00 am. However, in the shorebirds, depending on sex and breeding stage, there was either a robust 24 hour rhythm, or continuous activity and "free-running" circadian rhythms. But why are there such different activity patterns within the same habitat? A closer look at the "lifestyles" of the investigated species provides an explanation. Although all these species are migratory and are entrained to a regular light-dark regime in their wintering and stopover sites, during the short breeding season of the Arctic summer, they have to cope with extreme environmental conditions. Food availability could be a major factor in entraining the 24 hour cycle found in the Lapland longspur and in the care-giving sexes of the two polygamous species during incubation. This reflects a higher nest attendance at night as there are marked daily fluctuations in ground temperature with "nights" being very cold.

Further, no insects are available at night and continuous incubation is necessary to prevent the eggs from cooling off. On the other hand, male pectoral sandpipers are almost continuously active. This intense wakefulness pays off as, in an earlier study, it has been shown that the most active males sired the most offspring. In the monogamous semipalmated sandpiper with biparental care, there is evidence of social synchronisation as both breeding partners exhibited the same "free running" activity pattern during the incubation period. Our comparative study revealed that the avian circadian system can be entrained by environmental as well as social factors within a short period in the Arctic summer, which suggests a remarkable plasticity, says Bart Kempenaers, head of the research team.


Story Source:

The above story is based on materials provided by Max-Planck-Gesellschaft. Note: Materials may be edited for content and length.


Journal Reference:

  1. S. S. Steiger, M. Valcu, K. Spoelstra, B. Helm, M. Wikelski, B. Kempenaers. When the sun never sets: diverse activity rhythms under continuous daylight in free-living arctic-breeding birds. Proceedings of the Royal Society B: Biological Sciences, 2013; 280 (1764): 20131016 DOI: 10.1098/rspb.2013.1016

Cite This Page:

Max-Planck-Gesellschaft. "The rhythm of the Arctic summer: Diverse activity patterns of birds during the Arctic breeding season." ScienceDaily. ScienceDaily, 19 June 2013. <www.sciencedaily.com/releases/2013/06/130619122127.htm>.
Max-Planck-Gesellschaft. (2013, June 19). The rhythm of the Arctic summer: Diverse activity patterns of birds during the Arctic breeding season. ScienceDaily. Retrieved September 30, 2014 from www.sciencedaily.com/releases/2013/06/130619122127.htm
Max-Planck-Gesellschaft. "The rhythm of the Arctic summer: Diverse activity patterns of birds during the Arctic breeding season." ScienceDaily. www.sciencedaily.com/releases/2013/06/130619122127.htm (accessed September 30, 2014).

Share This



More Plants & Animals News

Tuesday, September 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

California University Designs Sustainable Winery

California University Designs Sustainable Winery

Reuters - US Online Video (Sep. 27, 2014) Amid California's worst drought in decades, scientists at UC Davis design a sustainable winery that includes a water recycling system. Vanessa Johnston reports. Video provided by Reuters
Powered by NewsLook.com
Argentina Worries Over Decline of Soybean Prices

Argentina Worries Over Decline of Soybean Prices

AFP (Sep. 27, 2014) The drop in price of soy on the international market is a cause for concern in Argentina, as soybean exports are a major source of income for Latin America's third largest economy. Duration: 01:10 Video provided by AFP
Powered by NewsLook.com
Mama Bear, Cubs Hang out in California Backyard

Mama Bear, Cubs Hang out in California Backyard

Reuters - US Online Video (Sep. 27, 2014) A mama bear and her two cubs climb trees, wrestle and take naps in the backyard of a Monrovia, California home. Vanessa Johnston reports. Video provided by Reuters
Powered by NewsLook.com
'Crazy' Climate Forces Colombian Farmers to Adapt

'Crazy' Climate Forces Colombian Farmers to Adapt

AFP (Sep. 26, 2014) Once upon a time, farming was a blissfully low-tech business on Colombia's northern plains. Duration: 02:05 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins