- the very small overall range (270km²) of the wrens habitat
- living on islands with a high susceptibility to invasion by rats
Under threat predominantly from the potential
- introduction of mammalian predators to islands where it breeds
- the loss of its natural tussac habitat by burning and livestock grazing
- cannot survive on islands in the presence of rats
- may co-exist with a few domestic cats on larger islands
- feral cats and rats have probably already destroyed whole populations
- Troglodytes aedon
- T. brunneicollis
- T. musculus
- T. tanneri
- T. beani
- Crown and nape grey-brown, becoming browner on the back and shoulders and brighter rusty-brown on the rump.
- Primaries and secondaries blackish-grey on inner webs, the outer webs with warm brown transverse bars, forming alternating ‘black and brown’ bars visible on the closed wing.
- Rectrices warm brown, with narrow blackish bars across the entire tail.
- Lores, cheeks and ear-coverts unmarked grey-brown; chin and throat lighter grey-brown.
- Chest and belly unmarked grey-brown; flanks and undertail coverts rusty-brown.
- Iris brown; bill blackish; legs dark brown.
A dark wren with uniformly dark chestnut-brown upperparts, pale greyish-buff underparts and greyish head. Wings and tail barred blackish and pale buff. Slender backish bill.Similar in appearance to Northern and Southern house wrens (Troglogytes aedon and T. musculus), though distinguished by its larger size, generally greyer plumage and very different ecology.
The only other wren present on the Falkland Islands is the Sedge Wren (Cistothorus platensis), which is smaller, shorter-billed, paler, and with obvious black and buff striations on the shoulders
- Length: 12 – 13 cm long (bill tip to tail tip)
- Weight: 19.1g (mean), 17g - 20g (min-max)
- Song heard between late August and mid-April.
- Strongly territorial during breeding and faithful to territory from year to year.
- The nest is a domed ball made of grasses with an entrance hole 6cm to 8cm wide near the top. It is lined with soft feathers of several species and is usually well hidden in tussac stems, a tussac pedestal or in a rock crevice between ground level and 60 cm above ground.
- Three to four pinkish eggs, covered with tiny red or light brown spots, are laid between early October and December. Two broods are probably reared in a season.
Habitat and Ecology
Endemic to the Falkland Island archipelago were it is only found on small offshore, predator-free islands.
Associated with tussac grass (Parodiochloa flabellata), a very tall and dense Falkland plant.Optimum habitat is dense tussac-grassland growing from the high-water mark behind boulder beaches with accumulated dead kelp in which invertebrates thrive.It also occurs in rushes and among rock outcrops up to 1 mile from coastal tussac.
Surveys in 1998/1999 estimated the total population at 4,500 – 8,000 pairs.
Life History and Behavior
Sedentary.No evidence of movement other than possibly between closely adjacent islands.
Feeds on invertebrates for which it forages in tussac grass, around and under boulders and among washed-up kelp on beaches.Food items include:
- Small insects
- Moth larvae
Molecular Biology and Genetics
Barcode data: Troglodytes cobbi
No available public DNA sequences.
Download FASTA File
Statistics of barcoding coverage: Troglodytes cobbi
Public Records: 8
Specimens with Barcodes: 8
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
Classified as ‘Vulnerable’ due to its very small overall range (270km²) and the high susceptibility of islands on which it occurs to invasion by rats.
Under threat predominantly from the potential introduction of mammalian predators to islands where it breeds. Also threatened by the loss of its natural tussac habitat by burning and livestock grazing.It cannot survive on islands in the presence of rats, but may co-exist with a few domestic cats on larger islands. However, feral cats and rats have probably already destroyed whole populations.
Population currently thought to be stable.
Rat eradication on suitable islands is the most important conservation strategy.
In 1998, Double and Outer Islands, off Spring Point, West Falkland, were acquired by Falklands Conservation (Woods 2000), and rat eradication started in 2000, covering these islands and two others, Top and Bottom Islands at Port William (R. Ingham in litt. 2000). In total, rats have now been eradicated from 22 islands (G. Munro in litt. 2007). Of the remaining islands within the range, 162 are known to have no introduced land predators, 75 have confirmed rats and/or mice present and a further 553 have not been surveyed (most of them are small or tiny islands) (N. Huin in litt. 2007). Conservation Actions Proposed
A conservation action plan has been produced (Woods and Otley 2008). Continue surveys to monitor population trends. Conduct ecological studies in order to understand the necessary conditions for the species's conservation (Woods and Woods 1997). Eradicate rats from selected small islands covered with mature tussock-grass to encourage recolonisation (Woods and Woods 1997, R. W. Woods in litt. 1999).
Cobb's wren (Troglodytes cobbi) is a fairly small (12-13.5 cm) wren which is endemic to the Falkland Islands. It was formerly classified as a subspecies of the house wren (Troglodytes aedon) but is now commonly considered to be a separate species due to differences in plumage, voice, ecology and morphology.
The plumage is brown, greyer on the head and breast and more rufous on the tail. There are dark bars on the flight feathers and tail. The bill is long, blackish and slightly curved. The main confusion species is the sedge wren which is smaller with a shorter bill, buff eyestripe and dark streaks on the back and head. Cobb's wrens have a number of buzzing calls and their song is a series of jumbled trills and whistles. The song can be heard from August to February and varies between individuals with different males having different song patterns.
The birds typically inhabit dense stands of tussac grass near the coast. They are often found on beaches searching among kelp and debris to find small invertebrates such as insects and amphipods. They are tame and can often be approached closely. When disturbed they prefer to slip away like a mouse between boulders or tussac clumps rather than fly.
The nest is a ball of grass lined with feathers and tussac root fibres. It is built on or near the ground among tussac or in a rock crevice. The eggs are pinkish with small reddish spots, three or four are laid in a clutch. The eggs are laid from early October to December and two broods are probably raised during the breeding season.
Status and conservation
This wren is restricted to small rat-free islands with a population of only 4,500-8000 pairs (1997/1998 estimate). The species is considered to be vulnerable to extinction as it is fragmented into small populations which could disappear if their islands were colonized by rats or cats. The birds' habit of feeding and breeding at ground level makes them very vulnerable to predation unlike the sedge wren which lives higher up and can coexist with predators.
- BirdLife International (2012). "Troglodytes cobbi". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
- Beolens, Bo; Watkins, Michael (2003). Whose Bird? Men and Women Commemorated in the Common Names of Birds. London: Christopher Helm. p. 85.
- Birdlife International (2006) Cobb's Wren - Birdlife Species Factsheet, retrieved 24/10/06
- David Brewer (2009). "Cobb’s Wren Troglodytes cobbi foraging in penguin burrows". Cotinga 31: 88.
- Alvaro Jaramillo, Peter Burke & David Beadle (2003) Field Guide to the Birds of Chile including the Antarctic Peninsula, the Falkland Islands and South Georgia, Christopher Helm, London
- Robin W. Woods (1988) Guide to Birds of the Falkland Islands, Anthony Nelson, Oswestry
- South American Classification Committee (November 19, 2012). "Proposal (#526) to South American Classification Committee – Split Troglodytes cobbi from T. aedon". Retrieved December 10, 2012.
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