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Vocalization Analyses of Nocturnal Arboreal Mammals of the Taita Hills, Kenya

Recent publication

By: Rosti, H., Pihlström, H., Bearder, S., Pellikka, P. & Rikkinen, J.  
Date: 13.12.2020  
Registered: Diversity 202012, 473.  

Open access article: https://www.mdpi.com/1424-2818/12/12/473  


This article describes vocal profiles for three nocturnal mammals in the Taita Hills. These are local tree hyrax (Dendrohyrax), dwarf galago (Paragalago), and small-eared greater galago (Otolemur garnettii). Our vocalization analyses compare calls in order to make taxonomic implications. This article also presents a review of the taxonomy for each of these species.  

The Taita Hills is part of Eastern Arch Mountains for which there is a very high rate of endemic fauna and flora. Almost all of the forests of the Taita Hills have been cleared for agriculture and tree plantations. The only two remaining forests are Mbololo (2 km2) and Ngangao (1 km2).

Tree hyrax (Dendrohyrax)

Tree hyrax calls in Taita Hills are different from those known for southern tree hyrax Dendrohyrax arboreus or eastern tree hyrax Dendrohyrax validus. This strongly suggest that species is new to science. Similar calls have been recorded from the East Usambara Mountains, located about 160 km south of the Taita Hills. Tree hyraxes eat leaves and are dependent on tree cavities for daytime resting sites. Populations in the Taita Hills are small and in danger of extinction due to loss of habitat. Photos and recordings of the Taita tree hyrax recordings here.


Adult female tree hyrax (Dendrohyrax sp.), Ngangao Forest, Taita Hills, southern Kenya.

Dwarf galagos (Paragalago cocos and sp.?)

Based on analyses of their vocalizations, the dwarf galago in Ngangao Forest is the Kenya coast dwarf galago (Paragalago cocos). This is interesting as P. cocos has previously been encountered only below 350 meters asl. The Ngangao population is almost extinct, with about 10 individuals. 

The dwarf galagos in Mbololo remains unidentified. They use screech calls as a contact call. Their warning calls resemble P. cocos, but not exactly. More information of this population is needed to confirm its taxonomic status. Dwarf galagos in Mbololo are very shy and difficult to record. Also, this forest is very moist, and the constant drizzle makes it difficult to obtain good recordings. There are several groups of dwarf galagos in Mbololo, but this population is small due to the small size of this forest.  Photos and recordings of P. cocos here.


Kenya coast dwarf galago (Paragalago cocos), Ngangao Forest, Taita Hills, southern Kenya.

Small-eared greater galago (Otolemur garnettii lasiotis)

The small-eared greater galago is common in Taita Hills, living in forests and villages. In Taita Hills, the small-eared greater galagos live in pairs, whereas in most other places this species is considered solitary. We compared trailing calls from Ngangao Forest to determine the subspecies of Otolemur. Our analyses confirmed that the subspecies in Taita Hills is the white-tailed small-eared galago(O. g. lasiotis).  Photos and recordings of O. g. lasiotis recordings here.


White-tailed small-eared greater galago (Otolemur garnettii lasiotis), Ngangao Forest, Taita Hills, southern Kenya.

Spectrograms and call analysis parameters are available in the article (pdf)  

Contact: hanna.z.rosti(at)helsinki.fi, https://animalstaita.com  

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