Eavesdropping: a BAT behaviour?
Bats,Nycatalus noctula, are nocturnal creatures that live in complex environments. These bats have a wide Palaearctic spread and can found in many places, with Malaysia being the location closest to us. (Csorba et. al, 2008) The bats are capable of flight and utilise echolocation, the use of sound to locate objects, to aid in their hunt for prey and shelter.
Photo credit: Tigerhomes, The use of sound as a sensory guide
The Nycatalus notula are a species of cavity roosting bats. They seek shelter in tree cavities that have been created either by other animals, such as the woodpecker, or from broken branches or spaces beneath the trees’ bark. These cavities are important for the bat’s survival, especially during the breeding season. However, these cavities are limited and requires additional time and energy to locate them. In order to speed up the search process, the bats eavesdrop on other bats in the vicinity. Bats can transfer information about such cavities by using acoustic calls or simply by following the calls of bats in roosts. (Ireneusz & Kamil, 2012) It has been discovered that they can pick up calls from other bats up to 170 metres away. (Furmankiewicz et. al, 2011)
In a recent study by Ireneusz & Kamil (2012), the positive effect of eavesdropping on search success was clearly seen with increased group size. In an area with little trees, bats became more sensitive to calls of other bats and they focused less on inspecting trees for cavities.
It is interesting to observe the emergence of such compensatory strategies to overcome perceptual and environmental hardships. Perhaps, different strategies are being employed depending on the bat’s habitats. Now, who said that eavesdropping was a bad thing?
References
Ruczyński, I., & Bartoń, K. A. (2012). Modelling Sensory Limitation: The Role of Tree Selection, Memory and Information Transfer in Bats’ Roost Searching Strategies. PloS one, 7(9), e44897.
Bat Radar – Echolocation, Vision & Habitat, Tigerhomes (accessed on 9 Apr 2013) URL: http://www.tigerhomes.org/animal/the-bat-radar-vision.cfm
Csorba, G., Bates, P., Stubbe, M., Hutson, A.M., Aulagnier, S. & Spitzenberger, F. 2008. Nyctalus noctula. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2.
URL: http://www.iucnredlist.org/details/14920/0 (accessed on 9 Apr 2013)
Furmankiewicz J, Ruczyński I, Urban R, Jones G (2011) Social Calls Provide Tree-dwelling Bats with Information about the Location of Conspecifics at Roosts. Ethology 117: 480–489