Knysna Warbler (Bradypterus sylvaticus) - BirdLife species factsheet

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VU	Knysna Warbler Bradypterus sylvaticus

2010 IUCN Red List Category (as evaluated by BirdLife International - the official Red List Authority for birds for IUCN): Vulnerable

Justification This rarely seen species is classified as Vulnerable because it has a small, severely fragmented range and population, which are suspected to be undergoing a continuing decline owing to the loss and degradation of suitable habitat. In 1992, it was reported to be extremely numerous and under no threat, but recent information indicates otherwise.

Family/Sub-family Sylviidae

Species name author Sundevall, 1860

Taxonomic source(s) Dowsett and Forbes-Watson (1993), Sibley and Monroe (1990, 1993)

Identification 14-15 cm. Medium-sized, drab, brown warbler. Paler brown underparts. Pinkish-brown bill. Olive-brown legs. Similar spp. Difficult to separate from African Scrub-warbler B. barratti, which has spotted throat and longer tail. Voice Song is an accelerating trill.

Population estimate	Population trend	Range estimate (breeding/resident)	Country endemic?
2,500	decreasing	8,800 km²	Yes

Range & population Bradypterus sylvaticus is endemic to South Africa, being restricted to remnant forest patches in coastal regions of the Eastern and Western Cape. The population is highly fragmented, with four main isolated subpopulations. These are concentrated upon: the coast between Port St Johns and Dwesa Nature Reserve, the Southern Cape, from Tsitsikamma to Sedgefield, the south slopes of the Langeberg Mountains, near Swellendam, and the east slopes of Table Mountain. It also formerly occurred around Durban. Estimates of a population of hundreds of thousands in 1992 have been revised by the paucity of atlas records, which strongly suggest that it is far rarer, and probably numbers c.2,500 individuals. Some of the atlas data may, however, be misleading as the area between Durban and East London in the former Transkei was not well covered, giving the impression of a discontinuous distribution¹.

Important Bird Areas Click here to view map showing IBAs where species is recorded and triggers any of the IBA criteria.

Ecology: It typically occurs in thick, tangled vegetation along the banks of watercourses, or covering drainage lines in fynbos forest patches, or on the edges of afromontane forest. It occurs at the base of vegetation, and appears to frequently forage on the ground. It has adapted well to thickets of non-native brambles Rubus. Despite this, there are absolutely no records of range extension, suggesting that it either has very poor dispersal ability or very poor reproductive capacity.

Threats Habitat loss, which resulted in the demise of the Durban population, is the primary threat and is largely a result of clearance of coastal forests. Burning of fire-breaks adjacent to forests is also causing habitat loss, and may prevent uncontrollable wildfires - like those recently on the Cape Peninsula - which could burn substantial areas of habitat. Removal of non-native brambles, the subject of several eradication campaigns, may ironically have negative impacts. Inbreeding depression may become a problem, particularly in the tiny, fragmented Eastern Cape subpopulation.

Conservation measures underway The Table Mountain subpopulation falls within the boundaries of the Cape Peninsula Protected Natural Environment, but a large proportion occurs in suburbia. It is also frequently recorded in the Tsitsikamma National Park, and the scarce Eastern Cape population probably occurs at Dwesa and Cwebe Nature Reserves.

Conservation measures proposed Conduct thorough surveys of singing males in the breeding season to clarify distribution and abundance. Conduct research into its habitat preferences, reproductive capacity and dispersal. Assess genetic divergence between the widely separated Eastern and Southern Cape races. Preserve suitable native habitat. Prevent clearance of non-native brambles, if this will negatively affect core populations.

References Barnes (2000). 1. N. Smith in litt. (2007).

Text account compilers Jonathan Ekstrom (BirdLife International), John Pilgrim (BirdLife International), Joe Taylor (BirdLife International)

Contributors Neil Smith (BirdLife South Africa)

IUCN Red List evaluators Stuart Butchart (BirdLife International), Joe Taylor (BirdLife International)

Recommended citation BirdLife International (2010) Species factsheet: Bradypterus sylvaticus. Downloaded from http://www.birdlife.org on 2/9/2010

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

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