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
Distribution and populationTurdus helleri
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.
is confined to four tiny forest patches in the Taita Hills, southern Kenya
: Mbololo (c.200 ha), Ngangao (c.92 ha), Chawia (c.50 ha) and Yale (2 ha) (Brooks 1997, Brooks et al
. 1998, L. Bennun in litt.
1999, Waiyaki and Samba 2000)
. Although there have been reported sightings at Mt Kasigau, 50 km south-east of the Taita Hills, survey work in 1998 did not record the species there (Brooks 1997, Barnes et al.
. Research in 1997 indicated a total population of c.1,350 birds, with c.1,060 in Mbololo, 250 in Ngangao and 38 in Chawia (Galbusera et al
. 2000, Waiyaki and Samba 2000, Waiyaki et al.
, although the effective population size is likely to be lower owing to a male-biased sex ratio. In 2009 surveys confirmed continued presence of the species in Mbololo and Ngangao fragments (M. Githiru in litt.
2008, 2009, 2010)
. Population justification
Waiyaki and Samba (2000) estimate the population to number 1,400 individuals, roughly equivalent to 930 mature individuals. Trend justification
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. Ecology
It is confined to montane cloud-forest (Waiyaki and Samba 2000)
, not venturing into secondary growth, scrub or cultivated areas (Zimmerman et al
, 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
. 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
. Orange Ground-thrush Zoothera gurneyi
often occurs in exactly the same areas as T. helleri
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). 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).Conservation 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)
. Conservation 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.
. Further develop sustainable forest-use schemes, based on ecotourism and harvesting forest products (Brooks 1997, L. Bennun in litt.
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. 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.
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.
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.
Further web sources of information
Alliance for Zero Extinction (AZE) species/site profile. This species has been identified as an AZE trigger due to its IUCN Red List status and limited range.
Click here for more information about the Alliance for Zero Extinction (AZE)
Species Guardian Action Update
View photos and videos, and hear sounds of this species from the Internet Bird Collection
Text account compilers
Bird, J., Ekstrom, J., Evans, M., Shutes, S., Starkey, M., Symes, A.
Bennun, L., Githiru, M., Lens, L.
IUCN Red List evaluators
Butchart, S., Taylor, J.
BirdLife International (2013) Species factsheet: Turdus helleri. Downloaded from
http://www.birdlife.org on 11/12/2013.
Recommended citation for factsheets for more than one species: BirdLife International (2013) IUCN Red List for birds. Downloaded from
http://www.birdlife.org on 11/12/2013.
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