Mother bats expert at saving energy

Feb 10, 2010
Bat in flight.

In order to regulate their body temperature as efficiently as possible, wild female bats switch between two strategies depending on both the ambient temperature and their reproductive status. During pregnancy and lactation, they profit energetically from clustering when temperatures drop. Once they have finished lactating, they use torpor - temporary hibernation - to a greater extent, to slow their metabolic rate and drop their body temperature right down so that they expend as little energy as possible.

These findings by Iris Pretzlaff, from the University of Hamburg in Germany, and colleagues, were just published online in Springer's journal Naturwissenschaften - The Science of Nature.

When energy demands are high, such as during pregnancy and lactation, female bats need to efficiently regulate their body temperature to minimize . In bats, energy expenditure is influenced by environmental conditions, such as ambient temperature, as well as by social thermoregulation - clustering to minimize heat and . Torpor, another common temperature regulation strategy, has disadvantages for reproductive females, such as delayed offspring development and compromised milk production.

Pretzlaff and team investigated, for the first time in the wild, the thermoregulation strategies used by communally roosting Bechstein's bats during different periods of their - pre-lactation, lactation, and post-lactation. They collected data from two maternity colonies roosting in deciduous forests near Würzburg in Germany, predominantly in bat boxes. The authors measured ambient temperature over those three periods as well as the bats' by using respirometry (measuring the rate of ).

They found that the bats' metabolic rate was strongly influenced by the ambient temperature. However, by roosting in groups (social thermoregulation), the bats were able to regulate their body temperature more effectively, despite changes in daily ambient temperature.

The bats also used torpor to minimize energy expenditure, particularly post-lactation - more than twice as often than during the other two periods. This suggests that they predominantly use torpor once they can afford to do so without compromising offspring development and milk production. They also formed much smaller groups post-lactation when temperatures were lower because roosting in smaller groups reduces the risk of disturbances by conspecifics. This resulted in longer torpor bouts and therefore longer periods of energy saving.

The authors conclude: "We were able to demonstrate on wild Bechstein's , during different reproductive periods, the significance of behavioral and physiological flexibility for optimal thermoregulatory behavior. Our study also highlights the importance of field studies, where the animals can use their behavioural and physiological repertoire, which is often not possible under the generally more controlled regimes in laboratory studies."

Explore further: Female color perception affects evolution of male plumage in birds

More information: Pretzlaff I et al (2010). Communally breeding bats use physiological and behavioural adjustments to optimize daily energy expenditure. Naturwissenschaften. DOI:10.1007/s00114-010-0647-1

Related Stories

Team offers first look at how bats land (w/Video)

Mar 20, 2009

People have always been fascinated by bats, but the scope of that interest generally is limited to how bats fly and their bizarre habit of sleeping upside down. Until now, no one had studied how bats arrive ...

Bats recognize the individual voices of other bats

Jun 05, 2009

Bats can use the characteristics of other bats' voices to recognize each other, according to a study by researchers from the University of Tuebingen, Germany and the University of Applied Sciences in Konstanz, Germany. The ...

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

9 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

10 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.