Tree hyrax

The tree hyrax or tree dassie is a small nocturnal mammal native to Africa. Distantly related to elephants and sea cows, it comprises the three species in the genus Dendrohyrax, one of only two genera in the family Procaviidae, which is the only living family within the order Hyracoidea.

Tree hyraxes[1]
Western tree hyrax, Dendrohyrax dorsalis
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Hyracoidea
Family: Procaviidae
Genus: Dendrohyrax
Gray, 1868
Species

The three species are:

The tree hyrax has four-toed front feet and three-toed back feet with rounded nails, and rubbery soles that help it climb.[6]

Colouring

Dependent on geographical location, their soft dense coats can range from a pale gray to light or dark brown. The variation is consistent with evolutionary development to aid with camouflage, so that in wetter regions with more verdant and abundant vegetation they are darker, and in more arid areas their colouring is lighter.

Habitat

The habitat of the tree hyrax is mostly in places where it is forested and has a mix of older and younger trees. It can be found in heights up to 4500 meters above sea level.

Despite being more common than its cousin the rock hyrax, the tree hyrax is much more difficult to spot, as it is both nocturnal and extremely shy.

Habitat assessment

Tree hyrax Dendrohyrax a nocturnal, arboreal folivore, which makes use of cavity-bearing trees as dens in forests where recent studies have found that forest fauna decreased due to the change in the structural nature of forests in Eastern Cape, South Africa. Studies which were used to study the specific habitat requirements of fauna in their forest, revealed that the tree hyrax was found to select for den trees with particular characteristics: seven tree species were selected as den trees, which were usually the tallest trees in the canopy 4–8 m. Den trees were usually only partly decayed, with multiple cavity entrances and trunk angles between 45 and 68 degrees. Cavity entrance and orientation did not appear to play a role in den tree selection by Dendrohyrax.[7]

Activity and calling patterns

Research has revealed that the hyrax was found to be active 16% of the time during which feeding was their most dominant activity. They mostly feed themselves on leaves of Hagenia abyssinica. Of the 16% active time, 4% of the time was used travelling between trees predominantly during daylight hours. They have calling behavior that is strongly prevalent in the dry season. The hyrax calls regularly in the early evening, and often a second time later at night; however during rains, their calls become infrequent.[8]

Diet

Tree hyrax diet is plant-based and varies depending on geographical location. In one South African forest, their principal food was Schotia latifolia , Cassine aethiopica, and Eugenia natalensis.[9]

Territorial call

Each of the three species of tree hyrax has a distinct territorial call.[10] In Dendrohyrax validus, it starts with a series of loud measured cracking sounds, sometimes compared to "a huge gate with rusted hinges being forced open". This is then followed by a series of "unearthly screams", ending in a descending series of expiring shrieks. Females also call, but lack the air pouches and enlarged larynx of the male, producing only a feeble imitation. On average there are two peak calling periods per night. Times vary, but the first period is often two to three hours after dark, and the second at some point after midnight.[6]

References
  1. Shoshani, J. (2005). Wilson, D.E.; Reeder, D.M. (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. pp. 87–88. ISBN 978-0-8018-8221-0. OCLC 62265494.
  2. Butynski, T.; Hoeck, H. & de Jong, Y.A. (2015). "Dendrohyrax arboreus". IUCN Red List of Threatened Species. 2015: e.T6409A21282806. doi:10.2305/IUCN.UK.2015-2.RLTS.T6409A21282806.en.
  3. Roberts, D.; Topp-Jorgensen, E.; Moyer, D. (2013). "Dendrohyrax validus, Eastern Tree Hyrax". In Kingdon, J.; Happold, D.; Hoffmann, M.; Butynski, T.; Happold, M.; Kalina, J. (eds.). Mammals of Africa, Volue 1: Introductory Chapters and Adfrotheria. A&C Black. pp. 158–161. ISBN 978-1-4081-8996-2.
  4. Hoeck, H.; Rovero, F.; Cordeiro, N.; Butynski, T.; Perkin, A.; Jones, T. (2015). "Dendrohyrax validus". IUCN Red List of Threatened Species. 2015: e.T136599A21288090. doi:10.2305/IUCN.UK.2015-2.RLTS.T136599A21288090.en.
  5. Butynski, T.; Dowsett-Lemaire, F.; Hoeck, H. (2015). "Dendrohyrax dorsalis". IUCN Red List of Threatened Species. 2015: e.T6410A21282601. doi:10.2305/IUCN.UK.2015-2.RLTS.T6410A21282601.en.
  6. Estes, Richard D. (1999). The Safari Companion. Chelsea Green Publishing Company. ISBN 1-890132-44-6.
  7. Gaylard, A.; Kerley, G. I. H. (2001). "Habitat assessment for a rare, arboreal forest mammal, the tree hyrax Dendrohyrax arboreus". African Journal of Ecology. 39 (2): 205–212. doi:10.1046/j.0141-6707.2000.301.x. ISSN 1365-2028.
  8. Milner, Jos M.; Harris, Stephen (1999). "Activity patterns and feeding behaviour of the tree hyrax, Dendrohyrax arboreus, in the Parc National des Volcans, Rwanda". African Journal of Ecology. 37 (3): 267–280. doi:10.1046/j.1365-2028.1999.00184.x. ISSN 1365-2028.
  9. Gaylard, Angela; Kerley, Graham I. H. (1997). "Diet of Tree Hyraxes Dendrohyrax arboreus (Hyracoidea: Procaviidae) in the Eastern Cape, South Africa". Journal of Mammalogy. 78 (1): 213–221. doi:10.2307/1382654. ISSN 0022-2372. JSTOR 1382654.
  10. "Hyrax vocalizations". Hyrax vocalizations. Retrieved 6 October 2019.
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