|Scientific Name:||Rhynchocyon petersi Bocage, 1880|
|Taxonomic Source(s):||Corbet, G.B. and Hanks, J. 1968. A revision of the elephant-shrews, family Macroscelididae. Bulletin of the British Museum of Natural History (Zoology) 16: 1-111.|
|Taxonomic Notes:||In the past the single family was included in the order Insectivora, but now the family is in the monophyletic order Macroscelidea and the newly created super-cohort Afrotheria. Currently, there are 19 living species recognized in four genera. The soft-furred sengis or elephant-shrews include three genera: Petrodromus is monospecific, Macroscelides contains three species, and Elephantulus contains 11 species. The four species of giant sengis belong to the genus Rhynchocyon. The common name "sengi" is being used in place of elephant-shrew by many biologists to try and disassociate the Macroscelidea from the true shrews (family Soricidae) in the order Soricomorpha. See the Afrotheria Specialist Group web site and www.sengis.org for additional information.|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor(s):||Hoffmann, M., Burgess, N. & Rovero, F.|
|Contributor(s):||Butynski, T., Howell, K., Nowak, K., Perkin, A., Rathbun, G.B. & Stanley, W.|
The Black and Rufous Sengi has a distribution restricted to the Eastern Arc Mountains and coastal forests of Tanzania, south-eastern Kenya, as well as Zanzibar and Mafia. Although restricted in range, extent of occurrence, based on current known range, considerably exceeds the threshold of 20,000 km² to warrant listing as Vulnerable under criterion B1. Estimated area of occupancy (AOO), based on a summation of occupied forest patches within the current known range, suggests an area of occupancy between ~3,000 and 5,000 km², although there is uncertainty with this figure. If estimated AOO is indeed at the very lower end of this range, then combined with severe fragmentation and an inferred continuing decline, the species could warrant listing as Near Threatened based on approximating listed as VU under criterion B2; however, if it is higher, then the species would be listed as Least Concern.
In terms of criterion A, it is highly unlikely, based on an estimated rate of forest loss of perhaps 10-15% across the range of the species (and considering too that it shows at least some adaptability to modified habitats), that the species could conceivably have undergone a decline exceeding 30% in the past 10 years (and hence be listed as Vulnerable). A decline exceeding 20% over the past 10 years (which would be sufficient for listing as Near Threatened), accounting also for the loss of some individuals to hunting, is more feasible (especially in the coastal forests of East Africa), albeit highly precautionary. In summary, two categories seem most relevant: Least Concern and Near Threatened. A listing of Near Threatened seems overly precautionary as it would suggest that AOO is at most 3,000 km² (when this is the lower end of the estimate) or a decline exceeding 20% over 10 years due to a combination of hunting and habitat loss. Hence, the species is here listed as Least Concern, albeit noting that while it doesn't currently meet or approximate listing in a threatened category, the species is nonetheless declining and is a priority for further monitoring.
|Previously published Red List assessments:|
|Range Description:||An East African endemic ranging in coastal forests from about 3°60’S in south-eastern Kenya to about 7°40’S in Tanzania, just north of the Rufiji River, and in the Eastern Arc Mountains, where it is reliably recorded from North and South Pare (Stanley et al. 1996, Cordeiro et al. 2005, Stanley et al. 2007), West and East Usambara (Stanley et al. 2011), Nguu (Cordeiro et al. 2005), Nguru (Owen et al. 2007), and the Uluguru mountains (e.g., Swynnerton & Hayman 1951). Records from Mahenge (Rovero et al. 2014, based on Owen et al. 2007) likely refer to Chequered Giant Sengi Rhynchocyon cirnei. Absent from the Udzungwa Mountains (where Rhynchocyon udzungwensis occurs), but recorded from northern Selous Game Reserve. The westernmost record of the species appears to be that of a specimen from “Kibaya” mentioned by Swynnerton and Hayman (1951). Corbet and Hanks (1968) presumed this to be an isolated forest habitat, and it is a priority for further survey work. Populations occur along the coast in small and fragmented forests from about the Rabai Hills and Diani Forest, Kenya, south to the Rufiji River, Tanzania. Some surveyors report records from south of the Rufiji River (e.g., Howell et al. 2012, from Kiwengoma, Ruawa and Kichi Hills) , but these are all considerably south of the Rufiji and presumably refer to Chequered Giant Sengi (specifically, the form R. c. macrurus, in which the chequered pattern is obscured by dark pelage in individuals near the coast). Also occurs widely on the islands of Zanzibar (= Unguja) (Pakenham 1984), including Uzi Island in the south, and Mafia (Kock and Stanley 2009), but absent from Pemba.|
Native:Kenya; Tanzania, United Republic of
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||A relatively rare species with a fragmented and restricted distribution. Densities from transect surveys of nests range from 19/km² in the 143-km² Chome Forest Reserve in South Pare (Coster and Ribble 2005) up to 79/km² in the now largely destroyed Pugu Forest Reserve on the Tanzania coast (Hanna and Anderson 1994). In Nguru South Forest Reserve, this species had the highest recorded encounter rate from camera trapping, although in Kanga Forest Reserve (also in the Ngurus), they were recorded at low abundances, only once through camera-trapping (Owen et al. 2007). F. Rovero (pers. comm. 2015) observed R. petersi along the northern bank of the Rufiji approximately 150 km west of the coast by the Selous Game Reserve border, where they appeared very common. It is reported to be widespread and common on Mafia at least (Kock and Stanley 2009).|
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||Relatively little is known about the biology of the Black and Rufous Sengi because no detailed field studies have been completed. It occupies evergreen and semi-deciduous forests, dense woodlands, coral rag scrub, and abandoned and overgrown agricultural lands with closed canopies where a thick layer of leaf litter accumulates (Corbet and Hanks 1968). In recent years, these habitats have become increasingly fragmented, isolated, and small. However, they do seem able to persist in some areas where non-intensive agriculture is practised, provided there is good cover nearby. K. Howell (pers. comm. 2015) observed them in cashew nut plantation leaf litter near the Mafia Island airport. On Zanzibar, they favour the coral rag forests in the eastern half of the island (Siex & Delgado 2008) and are reported as common in Kiwengwa-Pongwe Forest Reserve in north-eastern Unguja where it has been observed to tolerate association with Red-capped Robin-chats (Cossypha natalensis) that follow it as it rummages in the leaf litter in coral rag forest, and where it also forages in exotic tree plantations of Casuarina equisitifolia, to the east of the reserve, suggesting an ability to use this homogenous habitat (K. Nowak, pers. obs. 2003-2005). They are recorded from around sea level to 2,020 m in Nguru South Forest Reserve (Owen et al. 2007).|
Like other members of the genus, the species is completely terrestrial and diurnal with very keen senses. Like other sengis, the Black and Rufous Sengi has a propensity to quickly flee any disturbance in a highly cursorial gait (Allen and Loveridge 1927). It feeds on forest floor invertebrates. Most often only brief sightings of lone individuals are made, although it is probably monogamous like the Golden-rumped Sengi (Rhynchocyon chrysopygus). Most aspects of its natural history are probably similar to the Golden-rumped Sengi (Rathbun 1979).
|Continuing decline in area, extent and/or quality of habitat:||Yes|
|Use and Trade:||There is some limited and localized hunting of this species for food, both on the mainland and also on Zanzibar.|
|Major Threat(s):||Fragmentation and degradation of forested habitats due to urban and agricultural expansion is the major threat to this sengi (Nicoll and Rathbun 1990). Use of timber for woodcarving, firewood, and charcoal production, and hunting for food, are also threats, with charcoal production being the largest threat near towns. Given the life history similarities between the Golden-rumped Sengi and the Black and Rufous Sengi (Rathbun 1979), it is very likely that the latter is experiencing overall population declines due to habitat loss and degradation (Hanna and Anderson 1994). Although some hunting does take place, it does not appear to be a major threat to the species.|
Not included on the CITES Appendices.
Numerous relatively small blocks of forest are designated as forest reserves in Kenya and Tanzania, and these offer a minimal level of theoretical protection of habitat for this sengi. Populations also occur in the Selous Game Reserve and Saadani National Park along the coast (they are considered especially common in the 20-km² Zaraninge Forest within Saadani), which are much better managed.
In 2000, Black and Rufous Sengis from Tanzania were imported to North American zoos, where they have successfully bred. In the future, the husbandry methods developed may be useful in captive breeding and reintroduction programs (see back issues of Afrotherian Conservation, Newsletter of the IUCN-SSC Afrotheria Specialist Group for further information). In order to more accurately assess the conservation status of this sengi, data on the conservation status of occupied forests needs to be assembled and the likely area of these occupied forests calculated. A focused study of the life history of this species is also needed, including density estimates. Lastly, the taxonomic status of the populations on the Tanzanian islands, as well as isolated montane populations on the mainland, using molecular genetics, is needed.
|Citation:||Hoffmann, M., Burgess, N. & Rovero, F. 2016. Rhynchocyon petersi. The IUCN Red List of Threatened Species 2016: e.T19708A21286959.Downloaded on 18 March 2018.|
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