Justification This species has always had an extremely small range, but recent volcanic eruptions have caused an extremely rapid population decline and extirpated it from all but two disjunct areas. Deposits of volcanic ash have seriously damaged the habitat of the remaining population, and further deposits or an increased frequency of hurricanes could have devastating effects. The future of this species in the wild is extremely uncertain, and it consequently qualifies as Critically Endangered.

Family/Sub-family Icteridae

Species name author Lawrence, 1880

Taxonomic source(s) AOU checklist (1998 + supplements), Sibley and Monroe (1990, 1993), Stotz et al. (1996)

Identification 20-22 cm. Medium-sized, black-and-yellow icterid. Adult male, mostly black with yellowish lower back, rump, shoulder, lower breast, belly and undertail. Female, dull yellowish-green above and yellowish below. Immature duller. Voice Loud whistles and harsh chuur.

Population estimate

Population trend

Range estimate (breeding/resident)

Country endemic?

520 - 5,200

decreasing

10 km²

Yes

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

Ecology: It occurs in most forest types between c.150-900 m, but reaches highest densities in wetter, higher altitude forests, and is absent from areas of very dry forest^4,5. It is found in all successional stages, and sometimes at the edges of cultivated areas and banana plantations but appears to be an obligate forest species⁴. Nesting occurs in March-August, but the exact timing probably depends on the rainy season^2,5. Nests are mainly suspended from the leaves of Heliconia caribbaea, although banana and other broad-leaved trees are also used⁴. Its clutch-size is typically two or three. Unsuccessful pairs may attempt up to five clutches; successful pairs can very rarely rear three broods per year⁴. It forages at all levels, but particularly in the understorey, feeding mainly on insects, but occasionally also on fruit and possibly nectar⁴.

Threats Volcanic eruptions in 1995-1997 all but extirpated the species from the Soufrière and South Soufrière hills. Although volcanic activity was reduced in 1998-2000, the population continued to decline^4,10. Potential causes are low insect availability¹³ and/or chronic ill-health of birds resulting from ash fall on remaining forest, and other unknown and indirect knock-on effects of volcanic activity⁴. Research into reproductive success, using nest cameras, has also revealed high rates of nest predation by rats and native Pearly-eyed Thrashers Margarops fuscatus, both of which occur at high but fluctuating densities^4,7,8. In 2001 and 2003, drought appeared to cause reduced laying frequency and clutch-size, and this may be an increasing problem now that that species is confined to lower, drier areas⁴. Conversely, excessive rainfall can also have a negative impact. A feral pig population is spreading fast and could cause serious damage to the forest habitat if not eradicated. Having a montane distribution that is close to the maximum altitude within its range, this species is also potentially susceptible to climate change¹⁵. Despite being previously proposed as a threat, there is no nest parasitism by Shiny Cowbird because this species does not currently occur on Montserrat^2contra6.

Conservation measures underway There is a comprehensive programme to monitor the population and breeding success^3,4, and in 2001 a new research programme into the causes of the continuing decline was begun⁷. During 2003, preliminary tests of management interventions were made, aimed at boosting reproductive success⁴. In June 1999, eight birds were taken to Jersey Zoo to enable the development of husbandry techniques; initial attempts at captive breeding proved successful^4,9 and captive birds are now also present at several other locations in the UK, but there are currently no plans to augment the wild population with birds from captive stock¹². The Centre Hills has been designated a protected area and development is not permitted within its marked boundaries². A Species Action Plan was published in 2005. Experimental rat control in the Centre Hills commenced in 2006 and work to compare nest success in an area with experimental rat control with nest success in adjacent areas with high rat density was scheduled for 2008¹². A pig eradication programme is also planned for the island.

Conservation measures proposed Continue the existing programme and research into the causes of the decline. Develop potential management interventions to boost reproductive success⁴. Continue the close monitoring of the population⁴. Investigate the reasons for the high densities of nest predators in the Centre Hills⁴.

References 1. Arendt et al. (1999). 2. P. Atkinson in litt. (1998, 1999). 3. Gibbons et al. (1998). 4. G. Hilton in litt. (2000, 2003). 5. Jaramillo and Burke (1999). 6. Raffaele et al. (1998). 7. Cotinga 17 (2002): 7. 8. Bowden et al. (2001). 9. Owen (2000). 10. Hilton et al. (2003). 11. Anon (2006). 12. G. Hilton in litt. (2007, 2008). 13. Marske et al. (2007). 14. Bierley et al. (in prep.). 15. BirdLife International (unpublished data).

Further web sources of information

Alliance for Zero Extinction (AZE) species/site profile. This species has been identified as an AZE trigger due to its IUCN Red List status and limited range.

RSPB International Research - Montserrat Oriole

Text account compilers Jeremy Bird (BirdLife International), Rob Calvert (BirdLife International), Isabel Isherwood (BirdLife International), Rob Pople (BirdLife International - European Division), Andy Symes (BirdLife International), David Wege (BirdLife International)

Contributors Phil Atkinson (British Trust for Ornithology), Geoff Hilton (Royal Society for the Protection of Birds)

IUCN Red List evaluators Stuart Butchart (BirdLife International), Rob Calvert (BirdLife International), Andy Symes (BirdLife International)

Recommended citation BirdLife International (2010) Species factsheet: Icterus oberi. Downloaded from http://www.birdlife.org on 6/9/2010

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.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums