Turner's Eremomela (Eremomela turneri) is an Endangered (IUCN, 2008) forest canopy bird found in the South Nandi forest in Kanya's Rift Valley province, Kakamega forest (Western province) as well as in western Uganda (Bennun and Njoroge, 1999) and the Democratic republic of Congo. The bird is thus restricted to the Guinea-Congolean forest habitat biome extending westwards of Kenya to central Africa. South Nandi forest is however the main global stronghold for the species (Kosgey, 1998). The forest is of middle-altitude, halfway between the lowland forest of the neighbouring Kakamega forest in western and the highland forests of central Kenya. The forest's biodiversity also reflect such transitory qualities (Bennun and Njoroge, 1999). It is also one of Kenya's Key Important Bird Areas chiefly because of the presence of T. Eremomela but also 8 other regionally-threatened bird species. The forest's fairly rich soils and mild climate have proved considerably attractive to human encroachment with the effect that the local population has grown tremendously over the past three decades. The main conservation challenge for Turner's Eremomela appears to be reduction and modification of its habitat due to human encroachment.
My our earlier survey (June, 2009) suggested a rather insignificant population growth for T. Eremomela (1.11 bird/ha) when compared to previous studies conducted by Kosgey et al, (1998) ten years ago. Our preliminary presumption for this is anthropogenic impact on suitable habitat for the species, especially since tree logging had an overall negative relationship with its density.
In this latest study however, we sought to repeat the same survey of T. Eremomela and other birds but on the southern and western side of the forest and to attempt sampling and observing birds around the edge of the forest to assess how far the forest birds disperse towards the edge of the neighbouring Kakamega forest.
Results revealed a higher anthropogenic-impact effect and lower habitat suitability for T. Eremomela in the western end of the forest compared to the earlier study in the eastern end. The encounter rate of T. Eremomela was only 19% of that in the eastern side of the forest. Lower bird species diversity index coupled with higher overall bird density in the western side also suggested higher species dominance than in the eastern side and thus tending towards favouring a few species of generalist.
Although no evidence was found of understorey forest birds dispersing between Kakamega and South Nandi forests, a number of large frugivores and raptors were observed doing so on diverse occasions. Further, many forest-associated birds were encountered on trees or hedges on farmland between the two forests, suggesting a potential for a strategy to aid inter-forest bird dispersal through gradual on-farm tree planting and hedge maintenance to serve as dispersal corridors. Such a process if embarked on and sustained for a number of years, might facilitate reconnection of the two forests that were actually one at some point in time in the past, assuming no adverse anthropogenic interventions. Our immediate recommendation is to step up the ongoing restoration programme for degraded forest sections through reforestation and to halt any further illegal logging while also regulating human access to the forest. This is to ensure that the relatively less-impacted sections of the forest in the eastern end where more specialist birds such as Eremomola turneri are still found, are safeguarded.