Turner's Eremomela

Turner's eremomela (''Eremomela turneri'') is a species of bird formerly placed since 1990 in the "Old World warbler" (Sylviidae) assemblage. It was since definitely placed in the family Cisticolidae in 2008 after multiple genetic analysis.

It is found in Democratic Republic of the Congo, Kenya and Uganda.
Its natural habitats are subtropical or tropical moist lowland forests and subtropical or tropical moist montane forests.
It is threatened by habitat loss.

Description

Turner's eremomela is a small, discreet bird being only 9 centimetres long and weighting 6 to 9 grams. It does not exhibit a sexual dimorphism. All adults have pale grey underparts, rear of the head, back. The upper wings are slightly darker grey. They are easily distinguishable by a bright rufous forehead which extends to the top of the head. Under their dark eye streak, they have a white throat and a darker band right underneath. Unlike the adults, juveniles are a duller olive-brown above and pale yellow below. They also do not have the rufous forehead or the throatband.

This species is very similar to the Rufous-crowned Eremomela. Turner's eremomela is smaller overall and has less rufous present on the head.

Taxonomy

Turner's eremomela was first officially described by Van Someren in 1920, along with many other new African birds. This species is now a member of the family Cisticolidae. It was once considered part of the rufous-crowned eremomela species, but was recognized as a separate species when areas of overlap between the two were discovered in the Congo Rainforest. Depending on the assessement technique used, it is still debated whether the closer sister genus is ''Prinia'' or ''Apalis'', both also originally classified in the "Old world Warbler" assemblage.

Regional Variation

Two subspecies are currently recognized.

The nominate ''E. t. turneri'' is named for Henry John Allen Turner, a settler in Kenya of British origin. The western ''E. t. kalindei'' is named for Kalinde Musiko, a Congolese hunter who collected birds on behalf of Alexandre Prigogine and Musée du Congo belge.

Distribution and Habitat

Found in several small patches of Central and East Africa, Turner's eremomela's distribution is quite patchy and not very well known. It is estimated they occupy only about 1 400 km2 in 11 to 20 distinct locations, over a total extent of 39 100 km2. In Kenya they are currently present in Kakamega and Nandi Forests, with the type specimen for this species collected in the Yala River, in western Kenya. This species is also found in the south-eastern corner of the equatorial forest belt in Central-Eastern Democratic Republic of Congo. It is a native species to all these regions and has not been introduced or is considered invasive anywhere.

It is a sedentary species, it does not migrate between areas with the seasons. Therefore, it heavily relies on its current distribution and habitat for survival. However, its area of occupancy is continually declining.

Turner's eremomela occupies the canopy of large trees in lowland to mid-altitude forests, and is a specialist of this habitat. In Kenya, the rainforest fragments they inhabit are between 1500 and 1700 meters of elevation. But in the Democratic Republic of Congo, these altitudes are lower. Overall, this species' elevation limits have been recorded to be from 470 meters to 1900 meters. They are usually found in the open parts of the forest: clearings, edges, along streams and can live in isolated mature trees outside of the forest. However, it is sometimes also in the closed primary forest, more dense areas.

Behaviour

Being almost always observed in groups, Turner's eremomela is a social species. Most of the time, these groups are composed of around 4 individuals but some of up to 15 have been recorded in the Democratic Republic of Congo.

Vocalisations

Like most rainforest species, Turner's eremomela is shy and difficult to spot in the dense canopy. Flocks are more easily heard than seen: a series of very high “titititititititi”, followed by louder “si-si-chick” or “weet-su-sweet”.

Diet

In local itinerant groups of between 3 and 10 individuals, these insectivorous birds search together for arthropods and caterpillars in mature tree canopies. Turner's eremomela is often seen joining larger mixed feeding flocks composed of several other Sylviid species. These 'bird-parties' are very common in the Cisticolidae family, and this species is often seen feeding alongside the Buff-throated Apalis, it shares its range with. In their area of overlap, Turner's eremomela and the Rufous-crowned eremomela do not feed in the same areas of the trees.

Breeding

Little is known on the breeding behaviour of Turner's eremomela and its early years. It is estimated that one generation last about 3.6 years.

Conservation

Population status

Turner's eremomela has changed IUCN categories a few times in the past years: starting as Threatened in 1988, it vas moved to Vulnerable from 1994 to 1996. In the year 2000 it was re-assessed to being fully Endangered. These critical conservation statuses may stem from the lack of data or accurate mathematical calculations until its final assessment in August 2019. Today, the population of Turner's eremomela is estimated at around 14 000 birds in Nandi forest and another 4 300 in Kakamega forest. With abundance estimation, this would place the population at between 20 and 50 thousand individuals in total and around 13 000 to 34 000 mature individuals. Although this number is important, it seems to be continually decreasing due to the threats this species' habitat faces, justifying its conservation status as near threatened.

Threats

The more restricted the range of a species is, the more it is vulnerable to perturbations. This is the case for Turner's eremomela where the main threat to its population is a significant loss of habitat. Their native rainforests are destroyed by cultivation encroachment, illegal charcoal production, grazing and logging.Kagombe, J. 2015. North and South Nandi Forest forests strategic Ecosystem Management Plan 2015 -2040. Kenya Forest Service, Nairobi. Especially in the species' stronghold, Nandi Forest, commercial logging,'' is largely targeted by this illegal activity. The deforestation doesn't only cause habitat loss, but also changes canopy structure and accelerates habitat fragmentation of this gregarious species.

Overall, non-timber crops, small-holder farming, livestock ranching and farming, logging and wood harvesting are the main causes of the ongoing destruction of Turner's eremomela's habitat. This restricts even more the already very small and patchy range of the species.

Conservation measures

A few conservation measures are in place to help Turner's eremomela and other threatened birds in these areas. The measures, of course, are focused on the habitat, the forests they inhabit. The northern part of Kakamega forest was designated as a national reserve. This makes it better protected and completely bans logging activities. Educating the local population on the importance of conservation work is crucial to ensure these efforts will be carried on by future generations. Thus, a small group of local guides have started educational programs around Kakamega and are working towards replicating them around Nandi forest.

Other actions have been proposed to the same ends. They include more thorough and large scale protection of the forest patches this species lives in. A better study of the species, from its life history and ecology to actual, precise status and distribution would help understand its needs and inform useful measures. Finally, efficiently enforcing the logging bans, especially on indigenous trees, present both and Kenya and Democratic Republic of Congo would be hugely beneficial to all remaining rainforest birds that need these pristine, undisturbed habitats.

However, it is important to remember that Turner's eremomela is very specialised and restricted in its habitat and diet. Therefore, simply having a contiguous, closed-canopy forest is not enough if it mostly composed of non-native trees. These will not support the desired prey items or provide suitable habitat. It is important to try to re-create its original habitat conditions as much as possible.

References

External links

BirdLife Species Factsheet.

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Turner's eremomela
Birds of Central Africa
Birds of East Africa
Turner's eremomela
Taxonomy articles created by Polbot