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|BirdLife Species Guardian||Mwangi Githiru|
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This species is considered Critically Endangered because it has a tiny occupied range of c. 3.5 km2, within which its montane forest habitat has been severely fragmented and continues to decline in both extent and quality.
Turdus olivaceus (Sibley and Monroe 1990, 1993) has been split into T. helleri on the basis of its highly distinct plumage pattern, and reportedly different voice (following Collar and Stuart 1985), T. ludoviciae on the basis of its extremely distinct plumage pattern following Collar et al. (1994) and T. olivaceus (with species limits accordingly revised).
20-22 cm. Medium-sized thrush of montane forest. Dark upperparts, head and breast. White underparts. Rich rufous flanks. Bright orange bill and eye-ring. Voice Thought to resemble Olive Thrush T. olivaceus. Hints Shy, keeps well hidden in dense thickets and undergrowth, where spends much time foraging in leaf-litter.
The population is suspected to be in decline as the species's montane forest habitat has been severely fragmented and continues to decline in both extent and quality, however the rate of decline has not been quantified.
It is confined to montane cloud-forest (Waiyaki and Samba 2000), not venturing into secondary growth, scrub or cultivated areas (Zimmerman et al. 1996), although the areas where it occurs have been heavily logged in the past (Brooks 1997). Despite much research, very few inter-fragment movements have been recorded (Waiyaki and Samba 2000). It prefers well-shaded areas with a dense understorey, high litter-cover and little or no herbaceous cover (Waiyaki and Samba 2000), and consequently is found at greater density in Mbolobo, the least disturbed forest area, and is rarest in Chawia, which has a more open canopy and a very shrubby understorey (Brooks 1997, Waiyaki and Samba 2000, Waiyaki et al. 2001). It rarely ascends more than 2 m above ground (Zimmerman et al. 1996). The diet is predominantly fruit (Brooks 1997). It is monogamous and terrestrial, with overlapping home ranges (Waiyaki and Samba 2000) and breeding between January and July. The clutch-size is 1-3 (Urban et al. 1997). Orange Ground-thrush Zoothera gurneyi often occurs in exactly the same areas as T. helleri (Brooks 1997).
Most indigenous forest has been cleared in the Taita Hills for cultivation or reforestation with non-native timber, and the remaining tiny area is under serious threat from both clearance and degradation (Brooks et al. 1998, Mulwa 1998, L. Bennun in litt. 1999), although habitat quality in the largest two fragments remains good (Waiyaki and Samba 2000, Rogers et al. 2008). A highly male-biased sex ratio in Chawia (only 10% of birds were female) might have significant negative consequences for the subpopulation's long-term survival (Lens et al. 1998, Waiyaki and Samba 2000, Waiyaki et al. 2001). The species's reproductive rate may thus be lower than expected (Lens et al. 1998). Inbreeding is a concern due to a lack of movement of individuals between forest fragments (Collar 2005). Where habitat disturbance leads to deteriorations in body condition, the long-term survival of sub-populations may be put at risk (Lens et al. 2001). Other threats include fire, nest predation and climate change
Conservation and Research Actions Underway
The Forest Department is now safeguarding the remaining forest fragments of the Taita Hills, which have been designated as an IBA. At present, efforts are being undertaken (ban of cattle grazing, enrichment planting with seedlings) to restore indigenous forest fragment Chawia; while it remains to be seen what affect this has on the thrush population, unringed juveniles have been seen. An ongoing collaborative research project includes a large ornithological component, which aims to provide the necessary ecological data to plan conservation policies for this and other endemic species in the area. As part of the BirdLife Preventing Extinctions programme for this species and Taita Apalis, Species Guardian Mwangi Githiru has begun to implement the following actions: 1. Tree nurseries are being established by local community-led Environmental Committees. Indigenous trees will be used to restore degraded habitat and enhance the connectivity of scattered forest fragments, whilst on adjacent agricultural land fast-growing non-native species will be planted to provide a buffer zone. 2. Income-generating activities, including bee-keeping and butterfly-rearing have been initiated and farmers have been educated in environmentally responsible agriculture practices. 3. In order to secure the long-term survival of the Chawia population a translocation project is being developed. 4. Nature Kenya has initiated the development of local capacity through catalyzing the formation of a Site Support Group (SSG) with the aim of enabling local people to constructively engage in conservation of the IBA (M. Githiru in litt. 2008, 2009, 2010). A Darwin Initiative project has been set up in the Taita Hills and as part of this an Internatonal Species Action Plan is being developed (A. Ward-Francis in litt. 2014).
Conservation and Research Actions Proposed
Continue to remove non-native trees from within indigenous forest (Brooks 1997), and continue to reforest cleared areas with native trees (Brooks 1997, L. Bennun in litt. 1999). Further develop sustainable forest-use schemes, based on ecotourism and harvesting forest products (Brooks 1997, L. Bennun in litt. 1999) and outreach programmes to local communities (Brooks 1997, L. Bennun in litt. 1999, M. Githiru in litt. 2008, 2009, 2010). Strengthen the population at Chawia through carefully managed translocations (M. Githiru in litt. 2008, 2009, 2010).
Related state of the world's birds case studies
Barnes, J.; Barnes, R.; Burston, P.; Githiru, M.; Leckie, J.; Mulwa, R.; Pilgrim, J. 1999. Project Kasigau '98.
Brooks, T. 1997. Threatened birds of Kenya 9: Taita Thrush. Kenya Birds 5(2): 102-104.
Brooks, T.; Lens, L.; Barnes, J.; Barnes, R.; Kageche Kihuria, J.; Wilder, C. 1998. The conservation status of the forest birds of the Taita Hills, Kenya. Bird Conservation International 8: 119-139.
Collar, N. 2005. Taita Thrush (Turdus helleri). In: J. del Hoyo, A. Elliott, J. Sargatal, D.A. Christie and E. de Juana (eds), Handbook of the Birds of the World Alive, Lynx Edicions, Barcelona.
Collar, N. J.; Crosby, M. J.; Stattersfield, A. J. 1994. Birds to watch 2: the world list of threatened birds. BirdLife International, Cambridge, U.K.
Collar, N. J.; Stuart, S. N. 1985. Threatened birds of Africa and related islands: the ICBP/IUCN Red Data Book. International Council for Bird Preservation, and International Union for Conservation of Nature and Natural Resources, Cambridge, U.K.
Galbusera, P.; Lens, L.; Schenck, T.; Waiyaki, E.; Matthysen, E. 2000. Genetic variability and gene flow in the globally, critically-endangered Taita Thrush. Conservation Genetics 1: 45-55.
IUCN. 2015. The IUCN Red List of Threatened Species. Version 2015-4. Available at: www.iucnredlist.org. (Accessed: 19 November 2015).
Lens, L.; Bennun, L. A.; Duchateau, L. 2001. Landscape variables affect the density of Sharpe's Longclaw Macronyx sharpei, a montane grassland specialist. Ibis 143: 674-676.
Lens, L.; Galbusera, P.; Brooks, T.; Waiyaki, E.; Schenck, T. 1998. Highly skewed sex ratios in the critically endangered Taita thrush as revealed by CHD genes. Biodiversity and Conservation 7(7): 869-873.
Mulwa, R. 1998. An ornithological survey of Mt Kasigau Forest with particular emphasis on Taita White-eye Zosterops poliogaster silvanus in Taita Tareta District, Kenya. In: Bytebier, B. (ed.), Taita Hills Biodiversity Project Annual Report Second Year (November 1997--October 1998), pp. Appendix 10.2.9. National Museums of Kenya, Nairobi.
Rogers, P. C.; O'Connell, B.; Mwang'ombe, J.; Madoffe, S.; Hertel, G. 2008. Forest health monitoring in the Ngangao Forest, Taita Hills, Kenya: a five year assessment of change. Journal of East African Natural History 97(1): 3-17.
Sibley, C.G. and Monroe, B.L. 1990. Distribution and Taxonomy of Birds of the World. Yale University Press, New Haven, USA.
Sibley, C.G. and Monroe, B.L. 1993. A supplement to 'Distribution and Taxonomy of Birds of the World'. Yale University Press, New Haven, USA.
Urban, E. K.; Fry, C. H.; Keith, S. 1997. The birds of Africa vol. V. Academic Press, London.
Waiyaki, E.; Samba, D. 2000. Status and ecology of the critically endangered Taita Thrush Turdus helleri.
Waiyaki, E.; Samba, D.; Lens, L. 2001. Status and ecology of the critically endangered Taita Thrush, Turdus helleri. Ostrich: 198.
Zimmerman, D. A.; Turner, D. A.; Pearson, D. J. 1996. Birds of Kenya and northern Tanzania. Helm, London.
Text account compilers
Bird, J., Ekstrom, J., Evans, M., Shutes, S., Starkey, M., Symes, A. & Wright, L
Bennun, L., Githiru, M., Lens, L. & Ward-Francis, A.
IUCN Red List evaluators
BirdLife International (2016) Species factsheet: Turdus helleri. Downloaded from http://www.birdlife.org on 08/02/2016. Recommended citation for factsheets for more than one species: BirdLife International (2016) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 08/02/2016.
This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.
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Additional resources for this species
|Current IUCN Red List category||Critically Endangered|
|Species name author||(Mearns, 1913)|
|Population size||930 mature individuals|
|Distribution size (breeding/resident)||150 km2|
|Links to further information|
|- Additional Information on this species|