Seals gamble with their pups' futures

Nov 20, 2012
This shows a grey seal mother and pup "playing." Credit: Durham University

Some grey seal mums adopt risky tactics when it comes to the future of their young, a strategy that can give their pup a real advantage, according to scientists.

Researchers from Durham University, UK, and the University of St Andrews, looking at colonies in Scotland, found that some seal mothers are flexible in the they adopt and 'gamble' on the outcome of their actions, whilst other play it safe and steady.

The study is the first to demonstrate how variation in in large marine mammals in the wild can persist, rather than a single, successful, dominating the population.

The research shows that some seal mothers have a very fixed approach to looking after their , and tend to behave in a similar fashion whatever the local conditions on the breeding colony are; whether they are in a crowded and busy location, or in a less disturbed situation. These mums tend to achieve average success in terms of their pups' (crucial to the future of the pup), so that, by-and-large, they generally do well. These mums seem to have a 'play it safe' approach to life.

Some seal mothers have a very different approach. These mums are more flexible and try to adjust their mothering behaviour according to the local conditions. In potentially unpredictable situations, this can be risky; sometimes they get it right and their pups fare very well, but other times they might get it wrong and their pups do rather badly.

The findings, published in the journal , show that individual animals can differ markedly in their ability to adjust their behaviour to their local and that large variations in behavioural strategies can persist within a species.

According to the researchers, the results for both extremes of personality show how different types can be maintained by selection. This retains behavioural within a species, potentially making the species more resilient to environmental change.

The results are relevant to environment and conservation policies that use a one-size-fits-all approach, as these may need to be re-evaluated to take into account individual differences in animal personality, the researchers say.

Lead author, Dr Sean Twiss, School of Biological and Biomedical Sciences, Durham University, said: "Some mums have a very fixed way of caring for their pups, come what may, whilst others are more flexible. "Seals that 'gamble' and try to fit their behaviour to their immediate surroundings can do very well, if they get it right! However, being flexible can be risky - a mum might 'mis-judge' the conditions and fail to match her behaviour to the prevailing conditions.

"In either resting or disturbed situations, seal mums behaved in very individual ways, some showing high levels of maternal attentiveness, others showing low levels. Some behaved the same when disturbed as they did at rest while other individuals changed their behaviour dramatically when disturbed."

These differences in mothers' behaviour, either fixed or flexible, can have profound effects on their pups. After about 2 weeks of being looked after by their mothers, all pups are left to fend for themselves, and have to teach themselves to feed. The fatter a mum leaves her pup, the more time the pup has to learn, and its chances of surviving are better.

The scientists observed seals on the Scottish island of North Rona during the breeding season over two years. The team observed seals in their natural habitat to analyse responses to unusual stimuli (disturbances) and to assess seal behaviour at rest.

Co-author Dr Paddy Pomeroy said: "What's really interesting about these short term tests is the way behavioural types map onto individual measures of reproductive success. If more flexible mothers are better and worse pup rearers, one of our next tasks will be to see how breeding successes and failures are apportioned over lifetimes, which can only be done in this type of study."

Explore further: The influence of the Isthmus of Panama in the evolution of freshwater shrimps in America

More information: dx.plos.org/10.1371/journal.pone.0049598

add to favorites email to friend print save as pdf

Related Stories

Seal study shows diverse parenting styles

Dec 08, 2011

To most of us, one seal seems much like another. But a new study shows they have varied personalities that lead to distinctive approaches to parenting.

Memory of mum's voice remains strong for young sea lions

May 27, 2010

(PhysOrg.com) -- Young sea lions are able to recognise their mother's voices long after they've been weaned, a new Macquarie University study has found. The research provides rare evidence of the long-term ...

Harp seals on thin ice after 32 years of warming

Jan 04, 2012

Warming in the North Atlantic over the last 32 years has significantly reduced winter sea ice cover in harp seal breeding grounds, resulting in sharply higher death rates among seal pups in recent years, according to a new ...

Recommended for you

Dogs hear our words and how we say them

7 hours ago

When people hear another person talking to them, they respond not only to what is being said—those consonants and vowels strung together into words and sentences—but also to other features of that speech—the ...

Amazonian shrimps: An underwater world still unknown

8 hours ago

A study reveals how little we know about the Amazonian diversity. Aiming to resolve a scientific debate about the validity of two species of freshwater shrimp described in the first half of the last century, ...

Factors that drive sexual traits

9 hours ago

Many male animals have multiple displays and behaviours to attract females; and often the larger or greater the better.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.