St Lucia Oriole (Icterus laudabilis): request for information

BirdLife species factsheet for St Lucia Oriole

St Lucia Oriole (Icterus laudabilis) is endemic to St Lucia in the Lesser Antilles. It inhabits secondary and primary forest, dry scrubland and agricultural areas near settlements, but appears to prefer moist highland forest (Keith 1997, Raffaele et al. 1998, Fraga 2020). The species has been described as scarce, but still widespread (Keith 1997). The population size has been placed in the band 1,000-2,499 mature individuals (H. Temple in litt. 2005), but it is possible that the population now is smaller than previously thought.

The species appears to be in decline. It has been hypothesised that the species is suffering from nest parasitism by Shiny Cowbird (Molothrus bonariensis), pesticide use in agriculture, as well as habitat degradation through feral pigs and habitat loss for infrastructural developments (Keith 1997, Raffaele et al. 1998, H. Temple in litt. 2005, Daltry et al. 2009, Toussaint et al. 2009, P. Haynes in litt. 2016). However, the impact of these threats on the population size is not clear. In any case, St Lucia Oriole has reportedly become less numerous and more local since 1935 (Keith 1997, Raffaele et al. 1998). During a comprehensive survey in 2009, the species has only been recorded in low numbers at few sites (Toussaint 2009) and is now very difficult to find (Aley 2018, J. Mortensen and A. Toussaint per G. Young in litt. 2020).

St Lucia Oriole has been considered Near Threatened, approaching the threshold for listing as threatened under Criterion D1+2 (BirdLife International 2020). However, new information regarding the population trend suggest that the species may warrant a change in Red List status. Therefore, we have fully reviewed the species here against all criteria.

Criterion A – Thepopulation is thought to be in decline, but the trend is difficult to quantify. In recent years, evidence for declines has become prevalent as the species appears to be increasingly difficult to record. The rate of decline has not been quantified. Given its small population size and the fact that the species is still observed, it is likely that declines are slow to moderate, rather than steep. The timeframe relevant for Criterion A is three generation lengths (10.2 years; Bird et al. 2020*), and any rates of decline therefore have to be quantified for the period between c. 2010 and 2020, or projected to 2030. In order to assess the species against Criterion A, we are asking for information on the population trend. What is the likely rate of decline since 2010?

Criterion B – The species’s range is confined to one island, where it is thought to be relatively evenly distributed (Toussaint et al. 2009, eBird 2020). The newly calculated EOO (Extent of Occurrence) and maximum Area of Occupancy (AOO), as calculated by a 4 km2 grid over the area of mapped range, both amount to 708 km2.  This value meets the thresholds for Endangered under Criterion B1 (EOO < 5,000 km2) and for Vulnerable under Criterion B2 (AOO < 2,000 km2). However, in order to be listed under these criteria, at least two further conditions have to be met.

St Lucia Oriole is found throughout its range and forms one subpopulation. As such, it is not severely fragmented sensu IUCN (IUCN Standards and Petitions Committee 2019). Potential threats to the species include cowbird parasitism, pesticide use, as well as habitat loss and degradation. However, currently, we have no information on the impacts of these threats on the population size and the extent to which they drive a population decline. It is therefore not possible to assess whether any of these threats can extirpate large parts of the population within the next generation (3.4 years), and consequently we cannot quantify the number of locations**, as defined by the most serious plausible threat. It is therefore currently unclear whether the species meets condition a.

We assume that the above mentioned threats (cowbird parasitism, pesticide use and habitat loss) are causing the apparent population decline, and therefore we can infer a continuing decline in area, extent and quality of habitat. St Lucia Oriole thus meets condition b(iii). Moreover, from a declining number of records during ornithological surveys we can tentatively infer a continuing population decline; hence condition b(v) is met. There is no evidence of extreme fluctuations in the distribution range or population size, and condition c is not met.

Overall, while EOO and AOO are small, we currently do not have sufficient information to assess whether St Lucia Oriole qualifies for listing as threatened under Criterion B. We are therefore asking for up-to-date information regarding the threats the species is facing and their potential impacts on the population size in order to accurately quantify the number of locations* of occurrence.

Criterion C – The population is thought to number 1,000-2,499 mature individuals, but this may be an overestimate. Nevertheless, the number meets the threshold for listing as Endangered under Criterion C, but to be listed under this criterion, further conditions must be met.

From the declining number of observational records, it is tentatively inferred that the population is in continuing decline. All individuals are thought to belong to the same subpopulation. Therefore, St Lucia Oriole qualifies as Endangered under Criterion C2a(ii).

Criterion D – The population size is estimated at a maximum of 1,000-2,499 mature individuals, and it is possible that the true population size is below this number. Assuming that the latter is the case, the species would meet the threshold for listing as threatened under Criterion D1, but this requires confirmation. We urgently seek up-to-date information regarding the population size of St Lucia Oriole.

The AOO is too large to meet or approach the threshold for listing as threatened; it therefore depends on the number of locations** of occurrence whether the species additionally qualifies for listing as threatened under Criterion D2. Based on currently available information, the number of locations* cannot be determined; therefore we are asking for recent information on threats the species is facing and their potential impacts on the population size.

Criterion E – To the best of our knowledge, there has been no quantitative analysis of extinction risk conducted for this species. Therefore, it cannot be assessed against this criterion.

Hence, based on currently available information it appears that the species warrants listing as Endangered under Criterion C2a(ii), but it is possible that it also qualifies for listing as threatened under additional criteria. Therefore, up-to-date information is urgently sought regarding the population size and trend of St Lucia Oriole as well as the intensity and impact of threats the species is facing.

Please note that this topic is not designed to be a general discussion about the ecology of the species, rather a discussion of the species’ Red List status. Therefore, please make sure your comments are relevant to the species’ Red List status and the information requested. By submitting a comment, you confirm that you agree to the Comment Policy.

*Bird generation lengths are estimated using the methodology of Bird et al. (2020), as applied to parameter values updated for use in each IUCN Red List for birds reassessment cycle. Values used for the current assessment are available on request. We encourage people to contact us with additional or improved values for the following parameters; adult survival (true survival accounting for dispersal derived from an apparently stable population); mean age at first breeding; and maximum longevity (i.e. the biological maximum, hence values from captive individuals are acceptable).

**The term ‘location’ refers to a distinct area in which a single threatening event can rapidly affect all individuals of the taxon present, with the size of the location depending on the area covered by the threatening event. Where a taxon is affected by more than one threatening event, location should be defined by considering the most serious plausible threat (IUCN 2001, 2012).

An information booklet on the Red List Categories and Criteria can be downloaded here and the Red List Criteria Summary Sheet can be downloaded here. Detailed guidance on IUCN Red List terms and definitions and the application of the Red List Categories and Criteria can be downloaded here.

References

Aley, P. 2018. St Lucia – 27th August – 3rd September 2018. http://www.surfbirds.com/trip_report.php?id=2894 (Accessed 08 April 2020).

Bird, J. P.; Martin, R.; Akçakaya, H. R.; Gilroy, J.; Burfield, I. J.; Garnett, S.; Symes, A.; Taylor, J.; Šekercioğlu, Ç.; Butchart, S. H. M. 2020. Generation lengths of the world’s birds and their implications for extinction risk. Conservation Biology online first view.

BirdLife International. 2020. Species factsheet: Icterus laudabilis. http://www.birdlife.org (Accessed 08 April 2020).

Daltry, J.C. 2009. Biodiversity Assessment of Saint Lucia’s Forests, With Management Recommendations. Technical Report No. 10 to the National Forest Demarcation and Bio-Physical Resource Inventory Project, FCG International Ltd, Helsinki, Finland.

eBird. 2020. eBird: An online database of bird distribution and abundance [web application]. eBird, Cornell Lab of Ornithology, Ithaca, NY, USA. http://www.ebird.org (Accessed 08 April 2020).

Fraga, R. 2020. St Lucia Oriole (Icterus laudabilis), version 1.0. In: del Hoyo, J.; Elliott, A.; Sargatal, J.; Cristie, D. A.; de Juana, E. (eds.). Birds of the World. Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.stlori1.01 (Accessed 08 April 2020).

IUCN. 2001. IUCN Red List Categories and Criteria: Version 3.1. IUCN Species Survival Commission. IUCN, Gland, Switzerland and Cambridge, U.K.

IUCN. 2012. IUCN Red List Categories and Criteria: Version 3.1. Second edition. IUCN Species Survival Commission. IUCN, Gland, Switzerland and Cambridge, U.K. www.iucnredlist.org/technical-documents/categories-and-criteria.

IUCN Standards and Petitions Committee. 2019. Guidelines for using the IUCN Red List Categories and Criteria. Version 14. http://www.iucnredlist.org/documents/RedListGuidelines.pdf.

Keith, A. R. 1997. The birds of St Lucia, West Indies: an annotated check-list. British Ornithologists Union, Tring, UK.

Raffaele, H.; Wiley, J.; Garrido, O.; Keith, A.; Raffaele, J. 1998. Birds of the West Indies. Christopher Helm, London, UK.

Toussaint, A.; John, L.; Morton, M. 2009. The Status and Conservation of Saint Lucia’s Forest Birds. Technical Report No. 12 to the National Forest Demarcation and Bio-Physical Resource Inventory Project, FCG International Ltd, Helsinki, Finland.

This entry was posted in Americas, Caribbean and tagged , . Bookmark the permalink.

2 Responses to St Lucia Oriole (Icterus laudabilis): request for information

  1. Red List Team (BirdLife International) says:

    The window for consultation is now closed. We will analyse and interpret the new information and post a preliminary decision on this species’s Red List status on this page in early July.

    Thank you,
    BirdLife Red List Team

  2. Red List Team (BirdLife International) says:

    Preliminary proposal

    Evidence suggests that the species is undergoing a rapid population decline. However, uncertainties and a lack of information surrounding the rate of decline and the threats that the species is facing does not allow a detailed assessment against Criteria A and B.

    Based on available information, our preliminary proposal for the 2020 Red List would be to list St Lucia Oriole as Endangered under Criterion C2a(ii).

    There is now a period for further comments until the final deadline in mid-July, after which the recommended categorisations will be put forward to IUCN.

    Please note that we will then only post final recommended categorisations on forum discussions where these differ from those in the initial proposal.

    The final 2020 Red List categories will be published on the BirdLife and IUCN websites in December 2020/January 2021, following further checking of information relevant to the assessments by both BirdLife and IUCN.

Leave a Reply

You have to agree to the comment policy.

All comments must follow the rules of usage.

This site uses Akismet to reduce spam. Learn how your comment data is processed.