How mother bats save energy

WASHINGTON - A new study has shown that pregnant and lactating wild female bats can profit energetically from clustering when temperatures drop, which suggests that they have a flexible temperature regulation strategy.

According to a report in the journal Springer, the study was carried out by Iris Pretzlaff, from the University of Hamburg in Germany, and colleagues.

When energy demands are high, such as during pregnancy and lactation, female bats need to efficiently regulate their body temperature to minimize energy expenditure.

In bats, energy expenditure is influenced by environmental conditions, such as ambient temperature, as well as by social thermoregulation - clustering to minimize heat and energy loss.

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 reproductive cycle - pre-lactation, lactation, and post-lactation.

They collected data from two maternity colonies roosting in deciduous forests near W|rzburg in Germany, predominantly in bat boxes.

The researchers measured ambient temperature over those three periods as well as the bats’ metabolic rate by using respirometry (measuring the rate of oxygen consumption).

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.

According to the researchers, “We were able to demonstrate on wild Bechstein’s bats, during different reproductive periods, the significance of behavioral and physiological flexibility for ptimal thermoregulatory behavior.” (ANI)