CR
Bahama Oriole Icterus northropi



Justification

Justification of Red List Category
This newly-split species is listed as Critically Endangered because its extremely small population, which is believed to form a single subpopulation, is suspected to be in decline owing to the effects of introduced species, as well as infrastructural and agricultural development.

Population justification
The global population has been estimated at c.140-260 individuals based on recent breeding season surveys. This is roughly equivalent to 93-180 mature individuals.

Trend justification
Comprehensive population studies have not been carried out. The species's population is suspected to be in decline owing primarily to the impacts of the Shiny Cowbird Molothrus bonariensis on breeding success and lethal yellowing on the availability of suitable coconut palm habitat. 

Distribution and population

Icterus northropi was recently split from I. dominicensis following studies into the morphology, life history, vocalisations and genetics of the dominicensis group (Price and Hayes 2009, Sturge et al. 2009). It is endemic to the Andros group in The Bahamas, including North Andros, South Andros and Mangrove Cay. It formerly occurred on Abaco, but disappeared for unknown reasons in the early 1990s (M. Price in litt. 2010, 2011). In 1997, a liberal estimate was put forward of 150-300 individuals on North Andros and South Andros (Price and Hayes 2009); however, more recent surveys recorded a total of 81 individuals on North Andros, 22 on Mangrove Cay, and 24 on South Andros. Assuming 50-100% detectability, total numbers are estimated at 127-254 (M. Price in litt. 2010, 2011). These surveys did not extend to the interior (pine forest) and western side (mangrove) of Andros; the species is thought to be rare in these habitats (Currie et al. 2005, M. Price in litt. 2010, 2011, W. K. Hayes in litt. 2011), although the preliminary results of a further study underway in 2016 suggest that the population may be higher than previously thought (S. Cant-Woodside in litt. 2016). Habitat on Wood Cay may be suitable, but other cays within and around Andros are thought likely to be too small to support populations. Results of a genetic study have found some evidence for genetic differences between Bahama Orioles from North Andros and those from the southern islands of Mangrove Cay and South Andros (Price et. al. 2015), which suggests that dispersal among islands may be limited.

Ecology

This species inhabits open forests and edge habitats. The planting of coconut palms in residential areas has allowed the species to spread into human settlements, although the species is not reliant on coconut palms for nesting (Price et. al. 2011, S. Cant-Woodside in litt. 2016). It also makes use of coppiced broadleaved woodland, including areas of mixed pine and coppice (Currie et al. 2005, M. Price in litt. 2010, 2011). It feeds primarily on insects and fruit (Jaramillo and Burke 1999). The species nests in palms (Price et al. 2011), in May and June (Jaramillo and Burke 1999).

Threats

Perhaps the two most significant threats are brood parasitism by the Shiny Cowbird Molothrus bonariensis, which arrived in the 1990s, and lethal yellowing, which has destroyed entire communities of coconut palm within the last five years, such as that of Staniard Creek, which has suffered 97% mortality. In 2009, the species was completely absent from this settlement, where they were formerly common. Lethal yellowing appears not to have reached South Andros or Mangrove Cay, as they had very healthy palm populations in 2009, and there appears to be a much higher density of orioles on these islands than on North Andros (M. Price in litt. 2010, 2011). The cowbird population does not appear to be increasing (W. K. Hayes in litt. 2011). On South Andros, the coppiced habitats that the species favours are threatened by major road and agricultural developments (M. Price in litt. 2010, 2011, W. K. Hayes in litt. 2011). Additional potential threats include forest fires, logging, introduced diseases, invasive species (in particular rats Rattus spp. and feral cats Felis catus), and the potential effects of climate change in terms of sea-level rise and changes in habitat distributions (Price and Hayes 2009).

Conservation actions

Conservation Actions Underway
The species is the subject of ongoing research (M. Price in litt. 2010, 2011).

Conservation Actions Proposed
Study habitat use by the species throughout the year and in relation to its life history. Carry out further survey work to confirm the population size. Monitor population trends. Initiate a citizen science programme focussed on the species and involving local schools. Protect coppiced habitats and encourage the practice to increase extent of such habitats. Plant disease-resistant cultivars of coconut palm on North Andros to replace those already lost (M. Price in litt. 2010, 2011). Examine the feasibility of translocating the species to Abaco, from which it has been extirpated (Price et al. 2011) and establish a captive breeding programme to support future reintroductions/ population supplementations.

Identification

20-22 cm. A slender-billed oriole with an obviously decurved culmen. Head and body black with yellow underparts from the pectoral line back to the undertail coverts. There is a brown or greenish wash to the back. On the upperparts the lower back, rump and uppertail coverts are yellow. The wing linings are also yellow. The greater coverts, remiges and rectrices have white tips and fringing. Females are similar to males but have a duller, paler back. Juveniles and immatures have olive to olive-grey upperparts and greenish-yellow underparts and rump. They acquire more black plumage with age, first on the lores and throat. Bill black with bluish-grey basal half to lower mandible; legs grey-blue; iris dark brown. Similar spp Unlikely to be confused with any other species in its range. Voice Calls include a hard keek or check.

Acknowledgements

Text account compilers
Sharpe, C J, Symes, A., Taylor, J., Khwaja, N. & Wheatley, H.

Contributors
Hayes, W., Price, M. & Cant-Woodside, S.


Recommended citation
BirdLife International (2017) Species factsheet: Icterus northropi. Downloaded from http://www.birdlife.org on 21/10/2017. Recommended citation for factsheets for more than one species: BirdLife International (2017) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 21/10/2017.