EPOW - Ecology Picture of the Week

The Bizarre Song of the Southern Tree Hyrax

Southern Tree Hyrax (Dendrohyrax arboreus), Family Procaviidae
Kenya, Africa

Explanation:  Hyraxes are bizarre animals.  Some half-dozen species variously inhabit cliffs, rocky outcrops, and trees throughout sub-Sarahan Africa.  They look like giant rodents, which they are not, or like overgrown guinea pigs.  And they are most closely related to elephants!

The southern tree hyrax likes to hide in tree cavities during the daytime, as shown in this week's main photo above.  At night, they emerge to feed on leaves, fruits, and twigs.  They are mainly arboreal, sticking to the tree canopies, and do not do well on the ground.

But perhaps most bizarre about this species is the male's territorial song.  It sound like ... well, listen for yourself.  Picture yourself in a woodland opening in eastern Africa, well after sunset, in an enveloping darkness.  It is quiet except for a few insects.  Suddenly the night is shattered by this ... song.  

I recorded the following song in Kenya at night, and I produced this sound spectrogram of the recording.  Click on the spectrogram to hear the song:

and click here to see a larger version of the spectrogram image. 

And here is a zoom into just one of the "notes" of this odd song:

Their calls can be used as indicators of abundance and disturbance, particularly effects of disrupting contiguous tree canopies upon which they are highly dependent.  

Information:
     Topp-Jorgensen, J.E., A.R. Marshall, H. Brink, U.B. Pedersen.  2008.  Quantifying the response of tree hyraxes (Dendrohyrax validus) to human disturbance in the Udzungwa Mountains, Tanzania.  Tropical Conservation Science 1:63074.