Long-billed Forest-warbler Artisornis moreaui


Justification of Red List Category
This species can now be found reliably in parts of the East Usambara plateau, Tanzania. Its low population density and the small area of suitable habitat indicate that its total population is extremely small. Given that much of its habitat is being altered rapidly and is becoming increasingly fragmented, the species is likely to be undergoing a continuing decline, at least in some parts of its global range. Over 90% of its very small global population has been suspected to be confined to one subpopulation (Amani Nature Reserve), and on this basis it is considered Critically Endangered, however recent research suggests that total numbers, while still small, are larger than previously thought, and that Mt Nilo holds a significant proportion of the population. If this is confirmed the species is likely to warrant downlisting.

Population justification
Cordeiro (2000) estimated 150-200 in Amani Nature Reserve. The populations on Mount Nilo and the Njesi Plateau are unknown, but may be small, so the global estimate is placed precautionarily in the band 50-249 individuals. This equates to 33-166 mature individuals, rounded here to 30-200 mature individuals.

Trend justification
This species is suspected to be declining in parts of its range owing to strong pressures that are impacting unprotected forests in parts of the East Usambaras, and recent disturbance within protected areas such as Amani Nature Reserve. Therefore, we employ a negative population trend overall (though this may be slight). If further research confirms that the species's global population size is stable it may warrant downlisting in the future.

Distribution and population

This species occurs at low density in the East Usambaras in Tanzania, where only c.110 km2 of suitable habitat remains. In the East Usambaras it is more common than previously suggested (Cordeiro 2000), but still somewhat local and infrequent. Indeed, intensive surveys during 2014 discovered 17 more territories (Torto 2015). Recent records from Mt Nilo were followed by the discovery of territories around Zirai in May 2009, and later surveys located a total of 10 territories in Nilo Nature Reserve, in the areas of Nkombola, Kweng'wiza, Kilangangua and Kiziga and northward to Lutindi (Kyonjola and Njilima 2010). Mt Nilo covers 43.6 km2 and may hold up to 75% of the total East Usambaras population, which has been estimated to number at least 371 individuals but these numbers have yet to be confirmed. The species occurs over ten broad localities near Amani (Cordeiro 1998, Baker and Baker 2001). Amani Nature Reserve was conservatively estimated to hold 150-200 individuals in 2000 (Cordeiro 2000), and surveys in 2008-2009 found around 80 territories at Amani and in the surrounding area. Given that it is uncommon, elusive and exists at low densities, it may yet be found in other forests of the Eastern Arc (Baker and Baker 2001) now that the microhabitats and vocalisations are known (Cordeiro 2000, McEntree et al. 2005).


In the East Usambaras, its primary habitat is forest edge and large canopy gaps (Cordeiro 2000). It has been found in submontane and montane forest (Baker and Baker 2001), chiefly in open forest edge-type habitat with a high density of vines and climbers (Cordeiro 2000, McEntree et al. 2005) such as clearings and drainage lines (Ryan et al. 1998), in addition to glades on the edge of, or deep inside forest (Cordeiro 2000, McEntree et al. 2005, Borghesio unpubl. data). It can also be found in degraded forest (Baker and Baker 2001, Kyonjola and Njilima 2010), in habitats buffering tea plantations (e.g. secondary Lantana growth and Eucalypt plantations) (Cordeiro 2000, Borghesio unpubl. data), but never far from indigenous forest, as none of >80 currently known territories is more than 100 m from forest edge (Borghesio unpubl. data). However forest areas consistently disturbed by humans, such as agricultural fields that are burned or weeded regularly, are clearly not favoured (Cordeiro 2000). 

Its preference for early successional habitats may mean it is dependent on some form of recurrent disturbance to create forest gaps (Borghesio et al. 2008). It is often absent from large areas of apparently suitable habitat. It forages alone but can sometimes be found in mixed-species parties in the lower and middle storeys (up to 18 m) (Cordeiro 2000, Borghesio unpublished data), preferring the tangled vegetation nearer the ground where it searches foliage for invertebrates (Cordeiro 1998) avoiding sunlit places (Urban et al. 1997, McEntree et al. 2005). It is apparently territorial; one probable male colour-ringed in 2000 has maintained the same territory at the headquarters of Amani Nature Reserve up to 2007 (Cordeiro unpubl. data). Its breeding ecology remains poorly known (Urban et al. 1997). In an initial population assessment, 26% of records were of pairs (Cordeiro 2000).


Despite favouring some open forest-edge habitats, it remains vulnerable to forest destruction, especially as it may not cross open spaces easily (Urban et al. 1997). Although the extent of protected forest in the East Usambaras has recently been increased, there is heavy pressure on most unprotected forest and along forest edges, especially for mining, pole-cutting, cultivation and firewood-collection (Evans 1997, Kessy 1998, Doggart et al. 2004). As this forest becomes depleted, pressure on smaller forest reserves is likely to increase (Evans 1997, Kessy 1998). In addition, the harvesting of plants for medicinal purposes may cause some disturbance, clearance of vegetation along powerlines has resulted in the loss of some territories. Introduced species, such as the tree Maesopsis eminii, appear to reduce habitat suitability (Kyonjola and Njilima 2010) as it closes up canopy gaps, the preferred habitat of A. moreaui (A. Ward-Francis in litt. 2016). Having a montane distribution that is close to the maximum altitude within its range, this species is potentially susceptible to climate change (BirdLife International unpublished data).

Conservation actions

Conservation and Research Actions Underway
The BirdLife International project staff in Tanzania are working on a collaborative project with the Species Guardian and the RSPB to conserve endemic and threatened biodiversity in the East Usambaras, focusing on this species, through the BirdLife Preventing Extinctions programme.

As part of this programme the following actions are underway, delivered by a team of local staff: 1. Extensive surveys have been carried out in the Amani Nature Reserve and its immediate vicinity, and have been extended towards the eastern and northern parts of the East Usambaras to cover the Derema Corridor as well as the Ngua and Ndola areas. Each known territory of the Long-billed Forest-warbler (Tailorbird) is being monitored every two months. 2. Implementation of an education and awareness scheme for local landowners and other key stakeholders is in development. Educational materials including posters, calendars and leaflets are being developed in both English and Swahili. 3. Work is currently underway to identify key conservation areas for the species and to prioritise these sites for establishing or trialling forest protection and restoration management agreements. After 4 years, the species has been recorded in forest edge farm agreements, established through the project, which are working to improve edge habitat quality for the species (A. Ward-Francis in litt. 2016).

In 2016, the key action to be developed was a plan for removal of the invasive tree, Maesopsis, working with private land owners in order to underpin the wider application of successful interventions (A. Ward-Francis in litt. 2016).

Conservation and Research Actions Proposed
Evaluate the effectiveness of selected forest-management techniques that could benefit this species (Baker and Baker 2001, Cordeiro 2000). Consider methods to reduce disturbance in and around tea plantations (Cordeiro 2000). Conduct ecological surveys to understand why it is apparently so rare and thinly distributed (Baker and Baker 2001). Test techniques to control the expansion of Maesopsis eminii in indigenous forest and to restore heavily invaded forest tracts (L. Borghesio in litt. 2012). Engage stakeholders on the Amani Plateau in forest management and raise awareness of this species's status. Sensitize local farmers to conserve patches of bushy and regenerating vegetation in farms located along forest edges in Amani, Derema and Nilo.


10 cm. Small, rotund warbler of forest edge and canopy gaps. Overall greyish, slightly paler below. Warm brownish tinge on face and crown (can be absent). Very long, black bill. Very rounded head, with filoplumes extending over to the back of the head. Long tail invariably cocked when excited. Similar spp. African Tailorbird O. metopias has much shorter bill and more extensive russet wash on face and breast. Voice Repeated, Apalis-like but more metallic peedoo peedoo. Hints Very secretive, extremely inconspicuous, best located by call (Baker and Baker 2001). Most reliable site is near Amani in East Usambara Mountains, Tanzania.


Text account compilers
Ekstrom, J., Symes, A., Wheatley, H., Bird, J., Taylor, J., Wright, L, Evans, M., Ashpole, J, Shutes, S., Westrip, J., Starkey, M.

Borghesio, L., Cordeiro, N., John, J., Spottiswoode, C. & Ward-Francis, A.

Recommended citation
BirdLife International (2021) Species factsheet: Artisornis moreaui. Downloaded from on 26/09/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from on 26/09/2021.