Grey-crested helmet-shrike (Prionops poliolophus)
| French: | Bagadais à huppe grise |
|---|
| Kingdom | Animalia |
|---|---|
| Phylum | Chordata |
| Class | Aves |
| Order | Passeriformes |
| Family | Malaconotidae |
| Genus | Prionops (1) |
| Size | Length: 24 - 26 cm (2) |
| Weight | c. 49 g (3) |
Classified as Near Threatened (NT) on the IUCN Red List (1).
Helmet-shrikes are small to medium-sized birds with characteristic hooked beaks and bristled foreheads (4). The grey-crested helmet-shrike is boldly marked with black and white and has a yellow eye, an obvious long grey crest on the head in adults, and a large white wing stripe. It resembles the much more common white-crested helmet-shrike, Prionops plumatus, but is larger and lacks the yellow eye wattle of this species. Calls include various churring and clicking sounds as well as bill snapping (2).
The grey-crested helmet-shrike has a fairly restricted range, being found only in areas of southern Kenya and northern Tanzania (2) (4) (5). Most breeding records for the species are from the woodlands surrounding Lake Naivasha in Kenya, where a recent study has been undertaken (5) (6) (7).
Open woodland, riparian woodland and wooded grassland, at elevations up to 2,200 metres (2) (5).
The grey-crested helmet-shrike is a highly social species, living in permanent groups of up to 12 to 17 individuals (2) (5). Groups defend territories and are co-operative breeders, with all members of the group, including juveniles, helping to build the nest, incubate the eggs, and brood and feed the young. Nesting usually takes place between April and May, the cup-shaped nest being built in dense vegetation, which may help to conceal it (2) (5) (6). The framework of the nest is typically built from tree bark, and the cup is lined and plastered to a smooth finish with cobwebs, which are also used to bind the nest to the branch. Three to four eggs are usually laid, though more than one clutch may be laid in the same nest, and all group members help with incubation, which lasts for 16 to 18 days (6) (7). Nesting success is thought to be low due to nest predation (5) (6), but re-nesting may occur when a clutch is lost, the group moving to a new tree to build a new nest some distance away (6) (7).
Little other information is available on the ecology of the grey-crested helmet-shrike, but, like other helmet-shrikes, it is likely to feed on insects (4), including insect larvae, grasshoppers and praying mantises (6).
The main threat to the grey-crested helmet-shrike is habitat loss and degradation due to increasing densities of livestock and conversion of woodlands for agriculture, settlement and urban development (2) (5). As a result, the species is thought to be undergoing a reasonably rapid and ongoing population decline (2).
There is still a lack of adequate information about the ecology and conservation status of the grey-crested helmet-shrike, but it is thought that measures to combat habitat destruction will be needed if the species is to survive (5). The grey-crested helmet-shrike is found in the Serengeti National Park, Tanzania and Lake Nakuru National Park, Kenya (2) (8), and may be found in buffer zones of the Masai Mara Game Reserve in Kenya, but its range is thought to be peripheral to most protected areas (2). Conservation measures proposed include nationwide surveys to assess the species’ overall distribution and population size, detailed studies into its ecology and habitat requirements, and monitoring the extent of habitat loss, as well as increasing the area of suitable habitat that has protected status (2).
For more information on the grey-crested helmet-shrike, see:
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BirdLife International:
http://www.birdlife.org/datazone/species/index.html?action=SpcHTMDetails.asp&sid=6201&m=0
Authenticated (23/02/09) by Philista Malaki, National Museums of Kenya, Nairobi, Kenya.
http://www.museums.or.ke/
- Co-operative breeders: in birds, species in which three or more individuals contribute towards raising a single brood at a single nest site. Non-parental helpers at the nest assist with the feeding and raising of young birds.
- Incubation: the act of incubating eggs, that is, keeping them warm so that development is possible.
- Larvae: stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
- Riparian: relating to the banks of watercourses.
- Territory: an area occupied and defended by an animal, a pair of animals or a colony.
- Wattle: a fleshy organ that hangs from the bill, throat or eye of some bird species.
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IUCN Red List (December, 2008)
http://www.iucnredlist.org/ -
BirdLife International (December, 2008)
http://www.birdlife.org/datazone/species/index.html?action=SpcHTMDetails.asp&sid=6201&m=0 - Dunning Jr, J.B. (2007) CRC Handbook of Avian Body Masses. Second Edition. CRC Press, Boca Raton, Florida.
- Alden, P.C., Estes, R.D., Schlitter, D. and McBride, B. (1996) Collins Guide to African Wildlife. HarperCollins Publishers, London.
- Malaki, P., Muchane, M. and Balakrishnan, M. (2006) Population status and behaviour of the grey-crested helmet-shrike in Naivasha, Kenya. Journal of Ornithology, 147: 206 - 207.
- Malaki, P., Muchane, M. and Balakrishnan, M. (2008) Notes on the nesting and breeding behaviour of the grey-crested helmet-shrike Prionops poliolophus around Lake Naivasha, Kenya. Scopus, 28: 41 - 45.
- Malaki, P. (2004) Population status and behaviour of the grey-crested helmet-shrike in Naivasha, Kenya. MSc Thesis, Addis Ababa University, Addis Ababa, Ethiopia.
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WWF Ecoregion Profile: Serengeti volcanic grasslands (January, 2009)
http://www.nationalgeographic.com/wildworld/profiles/terrestrial/at/at0714.html