EPOW - Ecology Picture of the Week

Alarm Call at Night

Chital (Spotted Deer) (Axis axis), Family Cervidae
Corbett National Park, India

Explanation:  Spots have advantages!  This is a small herd of spotted deer, also known as chital or axis deer, quietly browsing in the dense grassland of Corbett National Park, northern India.  

Their spots provide a nice camouflage in the dappled shadows and visual confusion of dense vegetation, helping the deer avoid detection by predators.

But what happens at night when their main predator here, Bengal tigers, are on hungry prowls?

In the dead of night (so to speak), when Chital detect the presence of a predator, they will issue a loud barking alarm call to warn others of their herd. 

In northern India, late one night, I ventured into the teak forests there and recorded chital alarm calls:

Just by their calls, I could follow the path that the invisible tiger took that night, as further deer took up the call as they too detected the predator.

Chital are widespread throughout India and often the prey of tigers, leopards, and other predators (Andheria et al. 2007, Bagchi et al. 2003, Biwas and Sankar 2002).  

In South India, tigers tend to take smaller prey, such as chital and wild boar, rather than livestock (Reddy et al. 2004).

Sometimes alarm calls are shared among species.  Langurs, safe in the trees, will often issue a similar barking alarm call if they spot a predator, and chital and other species will take notice.  In Madagascar, ringtail lemurs will respond to alarm calls issued by Verreaux's sifakas (Oda and Masataka 1996).  Other examples are also found in nature.  Call it mutualism, whereby one species benefits from the behavior of another ... and it makes sense in dense jungles where predators also hide among the dappled shadows ...

  
Information:
     Andheria, A.P., K.U. Karanth, and N.S. Kumar.  2007.  Diet and prey profiles of three sympatric large carnivores in Bandipur Tiger Reserve, India.  Journal of Zoology 273(2):169-175.
     Bagchi, S., S.P. Goyal, K. Sankar.  2003.  Prey abundance and prey selection by tigers (Panthera tigris) in a semi-arid, dry deciduous forest in western India.  Journal of Zoology 260(3):285-290.
     Biwas, S., and K. Sankar.  2002.  Prey abundance and food habit of tigers (Panthera tigris tigris) in Pench National Park, Madhya Pradesh, India.  Journal of Zoology 256(3):411-420.
     Oda, R.,, and N. Masataka.  1996.  Interspecific responses of ringtailed lemurs to playback of antipredator alarm calls given by Verreaux's sifakas.  Ethology 102(3):441-453.
     Reddy, H.S., C. Srinivasulu, and K.T. Rao.  2004.  Prey selection by the Indian tiger (Panthera tigris tigris) in Nagarjunasagar Srisailam Tiger Reserve, India.  Mammalian Biology - Zeitschrift für Säugetierkunde 69(6):384-391.