Dendrohyrax validus 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Hyracoidea Procaviidae

Scientific Name: Dendrohyrax validus True, 1890
Common Name(s):
English Eastern Tree Hyrax
Taxonomic Notes: Shoshani (2005) included Dendrohyrax validus as a synonym of Dendrohyrax arboreus. The validity of D. validus has been questioned by some authors (e.g., Bothma 1971), but has been retained as distinct by others (Meester et al. 1986, Schlitter 1993, Roberts et al. 2013), which is the treatment followed here. The call of D. validus is very characteristic and distinct from D. arboreus. It helped finding a new subpopulation on the Kenya coast, see Seibt et al. (1977) and Hoeck (1978).

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2015
Date Assessed: 2014-02-03
Assessor(s): Hoeck, H., Rovero, F., Cordeiro, N., Butynski, T., Perkin, A. & Jones, T.
Reviewer(s): Taylor, A.
Contributor(s): Hoffmann, M.
Facilitator/Compiler(s): Koren, L.

In 2008 this species was listed as Least Concern in view of its presumed large population and local abundance. However, since then new data and range analysis show that area of occupancy (AOO) may be as low as 3,078 km2, viable habitat is severely fragmented and a population decline is inferred over the last 1-2 decades (approximately three generations) due to hunting and habitat loss / degradation / fragmentation across a large portion of its AOO (which mainly falls within Forest Reserves in the Eastern Arc Mountains and coastal forests that are not adequately protected). This species is only locally abundant at a small number of well protected sites, but sufficient data to quantify population size are currently unavailable. Therefore the species is uplisted to Near Threatened because it almost qualifies for listing as threatened under criterion B2ab(ii,iii,v). When future surveys rectify this shortcoming, the status could be reviewed.

Previously published Red List assessments:

Geographic Range [top]

Range Description:This species has a restricted and patchy geographic range, being limited to montane forests of Mt Kilimanjaro and Mt Meru, the Eastern Arc Mountains, and coastal forests of Tanzania, southern Kenya and offshore islands, including Pemba, Zanzibar and Tumbatu (Roberts et al. 2013).
Countries occurrence:
Kenya; Tanzania, United Republic of
Additional data:
Estimated area of occupancy (AOO) - km2:3078-4250
Number of Locations:26
Upper elevation limit (metres):3070
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Locally abundant. They are rarely seen, but can frequently be heard calling and are camera trapped regularly in areas of high abundance in the Udzungwa Mountains (F. Rovero, pers. comm.). Based on Circular Plot Counts of calls, densities of up to 17 individuals/ha have been estimated in undisturbed, closed-canopy forest on the Udzungwa Mts (Topp- Jørgensen and Pedersen 2001). Extensive camera trap data from the Udzungwa Mountains and other blocks in the Eastern Arc indicate that relative high abundance, as estimated by the camera trap rate (number of images/camera days deployed), is only found in very well protected and montane forests, particularly Mwanihana and Ndundulu-Luhomero, while trap rates are much lower in disturbed forests as well as in the few other blocks within the Eastern Arc Mountains where it has been camera trapped (F. Rovero and T. Jones unpubl. data). Thus, a number of surveys conducted in the Udzungwa Mountains during 2005-2009 found that camera trap rates ranged from 0.88-1.40 for Mwanihana and Ndundulu Luhomero (survey effort of 639-1800 camera-days) while it was never camera trapped in the heavily hunted and disturbed Uzungwa Scarp Forest Reserve, despite 354 camera days deployed (F. Rovero and T. Jones unpubl. data). A database of >7,500 images from camera trap surveys for several sites in the Eastern Arc Mountains conducted during 2005-2009 and hosted by MUSE – Museo delle Scienze (Italy) only contains two records of tree hyrax from other sites than Udzungwa, i.e. Kanga forest (Nguru South Mountains) and Kilindi forest (Nguu, or Nguru North Mountains), translating into trap rates of 0.16-0.37. This may partly indicate that in disturbed sites this species albeit present rarely come to ground.

The local abundance and habit to travel on the ground is well shown by a systematic camera trap study in Mwanihana forest, eastern Udzungwa, deploying 60 camera trap stations within 120 km2 (1800 camera days). The study found tree hyrax seventh-ranked in order of occupancy in a checklist of 26 medium-to-large mammals, with a remarkable occupancy of 0.48 (detection probability of 0.11). Occupancy modelling with habitat covariates indicates that its occupancy increases with distance from large rivers; moreover, its detection probability increases with distance from forest edge, which may reflect shyness of this species near disturbed/more open forest areas (F. Rovero, E. Martin, unpubl. data).

Old estimates from Mt Kilimanjaro in the 1970s were 8-70/ha (Kundaeli 1976), but upper limit appears be grossly overestimated (Topp-Jørgensen et al. 2008).

Remains abundant in patches of suitable forest on Pemba Island, Tanzania, although the area of forest on Pemba has been greatly reduced over the past century (T. Butynski and Y. de Jong, pers. comm.). A recent survey of Pemba found hyrax in Ngezi forest in 2012 (A. Perkin pers. comm.).

Current Population Trend:Decreasing
Additional data:
Continuing decline of mature individuals:Yes
Population severely fragmented:Yes

Habitat and Ecology [top]

Habitat and Ecology:

Occurs in moist lowland and montane forest, from sea level to 3,070 m (Roberts et al. 2013). The species is susceptible to habitat disturbance and to hunting. In the Udzungwa Mts, logging has a significant impact on population numbers, especially where hunting also occurs (Topp- Jørgensen et al. 2008; In disturbed forests, individuals call less frequently and are rarely observed in the day as compared to undisturbed and non-hunted forests (Topp- Jørgensen et al. 2008). Overall, high population densities (i.e., based on calling frequency) appear to be linked to isolated, undisturbed forest patches. This would agree with the findings of Kundaeli (1976) on Mt Kilimanjaro: highest densities were estimated at an elevation of 2,310 m, where disturbance from logging and hunting was low. Ecology and behaviour are reviewed in detail in Roberts et al. (2013). 

Continuing decline in area, extent and/or quality of habitat:Yes
Movement patterns:Not a Migrant

Use and Trade [top]

Use and Trade:

Hyrax skins are locally traded in secret to make traditional blankets and bags in the communities around Mt. Kilimanjaro.

Threats [top]

Major Threat(s):

The main threats to this species are severe forest loss, degradation, fragmentation (mainly due to logging and burning), and hunting. Hunting occurs in all areas it is found apart from the most protected and remote forests (Mt. Kilimanjaro in the Udzungwa Mountains National Park). Although individuals can persist in closed-canopy forests of less than 1 km², logging, including selective logging of large trees, removes shelter trees, destroys arboreal pathways, and makes animals more vulnerable and prone to ground trapping (Roberts et al. 2013). Eastern Tree Hyraxes are hunted for their meat and skins. Skins are used to make blankets or karosses, which can still be found for sale in Arusha and Moshi, dating back to the 1970s when commercial exploitation was quite severe (Kundaeli 1976b). Hyraxes are trapped using snares set at the head of runnels (pathways through the undergrowth) near the base of a tree or in rocky outcrops. They may also be clubbed, speared, or run down by dogs having been ’smoked out’ or following the felling of a den tree (a common method employed in the Udzungwa Mts; Topp- Jørgensen et al. 2008).  Hunting for hyrax with dogs also occurs in a number of other Eastern Arc Mountains, such as the East Usambaras (N. Cordeiro pers. comm.), Pemba and Zanzibar Islands, Kilindi, Rubeho, Uluguru, Mahenge and Nguru Mountains (A. Perkin pers. obs). 

Conservation Actions [top]

Conservation Actions:

Occurs in a number of protected areas across its range, including Udzungwa Mts National Park, Kilombero Nature Reserve, Kilimanjaro and Arusha National Parks and eight Nature Reserves in the Eastern Arc Mts: Kilombero and Uzungwa Scarp in Udzungwa Mts, Amani and Nilo in East Usambaras, Mkingu in Ngurus, Uluguru in Ulugurus, Magamba in West Usambaras, and Chome in South Pares, as well as Jozani-Chwaka Bay Nature reserve on Zanzibar and Ngezi Vumawimbi Nature Forest Reserve on Pemba. The species also occurs in numerous forest reserves in the Eastern Arc Mts and coastal forests of Tanzania, such as Kilindi, Kanga and Nguru North Forest Reserves (Cordeiro et al. 2005, Roberts et al. 2013).

Citation: Hoeck, H., Rovero, F., Cordeiro, N., Butynski, T., Perkin, A. & Jones, T. 2015. Dendrohyrax validus. The IUCN Red List of Threatened Species 2015: e.T136599A21288090. . Downloaded on 19 August 2018.
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