17 Mar 2017

New hope for critically endangered Tanzanian tailorbird

The Long-billed Forest-warbler, endemic to Tanzania, is thriving in its natural habitat.

Field team Victor and Martin collecting tailorbird data © Norbert Cordeiro
Field team collecting tailorbird data © Norbert Cordeiro
By N.J. Cordeiro, L. Borghesio, K. Ndang’ang’a, Jude Fuhnwi

One of the world’s rarest birds appears to occur in slightly higher numbers than previously thought. The bird is also responding positively to conservation efforts that involve working with farmers to allow re-growth of vegetation necessary for the birds. This has offered the opportunity for the bird to recolonise some areas, in what bird conservation experts say provides new hope for the species’ small population found only in Tanzania, East Africa.

About 100 – 200 pairs of the Long-billed Forest-warbler Artisornis moreaui (previously also known as Long-billed Tailorbird) are present in the East Usambara Mountains in north-eastern Tanzania, the only place where the species is found, according to annual surveys. Intensive research and conservation work had previously focused on Amani Nature Reserve. However, recent emphasis in Nilo Nature Reserve, a protected area found north of the Amani Nature Reserve, has resulted in more records. Surveys were done by the BirdLife Species Guardian, the local field team and other experts from the University of Dar es Salaam. This new figure represents more than 50% of population assessment made in 2000, when only 150 – 200 individuals were estimated to be in the Amani Nature Reserve.

BirdLife supports conservation of the tailorbird on farms bordering the forest, where the land is leased and vegetation allowed to regenerate naturally without disturbance. These farm plots started as an experiment in 2012 by Nsajigwa Kyonjola, a masters student of the University of Dar es Salaam and was supported in part by the African Bird Club. Results after four years of natural regeneration on these farm plots show that the tailorbird has colonised 50% of these restored plots. 

This enigmatic Long-billed Forest warbler prefers relatively open parts of the forest like canopy gaps, stream lines and forest edges above 800m for habitat. It is not found outside the forest.

Heavy pressure from illegal mining in and around Amani Nature Reserve since the discovery of gold in 2003 has negatively impacted forest edges and streams in several areas, forcing this bird to abandon territories in chronically disturbed forest tracts. Discovery of new territories in the nearby Nilo Nature Reserve has therefore raised hopes for this species listed on the IUCN Red List as critically endangered. The remoteness of Nilo Nature Reserve and a low human population density has reduced encroachment and disturbance by local communities, allowing the birds to flourish in a natural habitat.

Results from surveys and monitoring visits in the past years show that higher numbers of the tailorbird are found in less disturbed forest tracts at the Nilo Nature Reserve unlike in the Amani reserve where humans are very active with continued illegal mining for gold being a major threat. This has currently positioned the Nilo protected area as a very important site for the conservation of this species in Tanzania.

Illegal mining puts pressure on forest habitat in Amani Nature Reserve © Chris Magin

Experts from BirdLife, with support from local conservation practitioners, have carried out intensive field work to establish and map the distribution of this rare species, in order to improve its conservation. The field team works closely with local communities and educate people living around protected areas of the impact their activities have on site management and conservation efforts.

Local conservationists, Victor Mkongewa and Martin Joho have been collecting data on the species and engaging villagers in their hometown, Amani, to conserve the tailorbird. In January 2017, the duo were accompanied by BirdLife Species Guardian, Professor Norbert Cordeiro and Botanist of the University of Dar es Salaam, Professor Henry Ndangalasi among others, on a challenging trip to a remote part of East Usambara Mountains to reassess the population of tailorbirds and continue with awareness campaigns.

“We delivered the message of conservation to farmers and other villagers, explaining the major threats to the conservation of birds and their habitats. We talked about habitat loss and fragmentation caused by human activities like illegal harvesting of timber, gold mining and fire. Many of them are absolutely awakened,” explained Victor.

According to him, their journey into the forested area was full of natural obstructions through steep and sometimes slippery terrain, as well as a barrier set by a fallen large tree that made it difficult for the team to access with a Land rover vehicle.

“We relied on commercial motorbikes that transported team members and their heavy camping supplies on multiple trips,” he added.

When the experts finally entered the thick, dark forest, enveloped by massive 40 - 60 m canopy emergent trees, they were happy to see that the condition of the forest and tailorbird population looked quite intact, with no logging threats observed at census sites. All 17 tailorbird territories previously identified between 2009 and 2016 were all relocated with ease.

With more funding in 2017, the team can proceed to marking and radio-tracking of tailorbirds to evaluate the impact of human-caused disturbances on their preservation and ecology. This will entail capturing the birds in mist-nets - which are special nets to trap birds - and tagging by placing a transmitter on the bird in order to use a radio receiver and antenna to monitor the tagged birds. Also, additional funds could be instrumental in allowing regeneration of good tailorbird habitat in much larger areas beyond the successful work done within experimental plots.