Is foraging efficiency a key parameter in aging?

Mar 23, 2010

The male wandering albatross, which can live more than 50 years, modifies its foraging behavior with age.

CNRS researchers, working with the Université de Bourgogne (France), have for the first time shown such changes by studying aging in these birds under natural conditions.

The scientists have discovered that old males forage in different waters from younger males, and are less active at the sea surface. However, none of the classic markers of human aging are altered in old albatrosses, which underlines the importance of taking account of foraging efficiency in studies on aging.

The work has been published online on the website of the journal PNAS.

Aging in animals, the causes of which are increasingly well understood in laboratory conditions, is hardly ever studied in a natural environment. Researchers from the 'Marine Predator' group at CNRS's Chizé Center for Biological Studies studied wandering albatrosses, which stand out among other birds because they are exceptionally long-lived (over 50 years). With a life expectancy close to that of humans, they therefore make exceptional models for the study of aging in the natural environment. Wandering albatrosses travel huge distances. During their lifetime, they fly millions of kilometers across the Southern Ocean, only returning to dry land to breed once every two years. Their reproductive performance declines from the of thirty, but the reasons for this decline were unknown until now.

The scientists undertook the first multidisciplinary study ever carried out on the aging of these seabirds under natural conditions. They did this by observing around a hundred albatrosses aged 6-49 years breeding on Possession Island in the Crozet islands (French Southern and Antarctic Territories). By using miniature devices (Argos transmitters and activity loggers), they were able to analyze foraging trips by the birds during the egg incubation stage.

The researchers discovered that the older male albatrosses foraged in areas of ocean that were somewhat different from those favored by younger birds. For reasons that remain unclear, during the incubation period they undertake very long foraging trips to the cold waters of the Antarctic, at a distance of over 3000 km from their nest. They are less active at the sea surface and return to dry land with elevated levels of stress hormone, which suggests a fall in foraging efficiency (a parameter which is very hard to measure except under natural conditions). Only males appear to modify their foraging strategy with age. No difference was observed between females aged over 30 and younger birds.

At the same time, the researchers measured seven physiological parameters naturally associated with aging in humans, including stress hormone (corticosterone) levels, parental hormone (prolactin) levels, the amount of oxidative stress, the ability of plasma to respond to attack by free radicals, and humoral immunity levels. Quite unexpectedly, no variation in these parameters was detected for the older albatrosses (30-49 years old) within this population. The older birds therefore appear to maintain a 'normal' physiological level.

This study is the first to directly show that, under natural conditions, several aspects of foraging behavior decline with age, without this resulting from a deterioration in their physiological state. As a result, a fall in foraging efficiency may be one of the first signs of aging.

Explore further: Research helps steer mites from bees

More information: Patterns of aging in the long-lived wandering albatross. Vincent Julien Lecomte, Gabriele Sorci, Stéphane Cornet, Audrey Jaeger, Bruno Faivre, Emilie Arnoux, Maria Gaillard, Colette Trouvé, Dominique Besson, Olivier Chastel, and Henri Weimerskirch. Proc Natl Acad Sci USA, Online on the PNAS website on 22 March 2010.

add to favorites email to friend print save as pdf

Related Stories

'Nervous' birds take more risks

Oct 26, 2007

Scientists have shown that birds with higher stress levels adopt bolder behaviour than their normally more relaxed peers in stressful situations. A University of Exeter research team studied zebra finches, which had been ...

A young brain for an old bee

Jul 01, 2009

Scientists have found that by switching the social role of honey bees, aging honey bees can keep their learning ability intact or even improve it. The research team is hoping to use them as a model to study ...

Turtles are loyal in feeding as well as in breeding

Apr 25, 2007

A research team led by the Dr Annette Broderick of the University of Exeter’s School of Biosciences has discovered that, after laying their eggs, sea turtles travel hundreds of miles to feed at exactly the same sites. The ...

Seabird's ocean lifestyle revealed

Jan 21, 2009

(PhysOrg.com) -- An important British seabird has been tracked for the first time using miniature positioning loggers. The results are giving a team led by Oxford University zoologists information that could ...

Recommended for you

Research helps steer mites from bees

Sep 19, 2014

A Simon Fraser University chemistry professor has found a way to sway mites from their damaging effects on bees that care and feed the all-important queen bee.

Bird brains more precise than humans'

Sep 19, 2014

(Phys.org) —Birds have been found to display superior judgement of their body width compared to humans, in research to help design autonomous aircraft navigation systems.

User comments : 0