This is part of a consultation on the Red List implications of extensive changes to BirdLife’s taxonomy for passerines
Lynx Edicions and BirdLife International will soon publish the second volume of the HBW-BirdLife Illustrated Checklist of the Birds of the World, building off the Handbook of the Birds of the World series, and BirdLife’s annually updated taxonomic checklist.
The new Checklist will be based on the application of criteria for recognising species limits described by Tobias et al. (2010). Full details of the specific scores and the basis of these for each new taxonomic revision will be provided in the Checklist.
Following publication, an open and transparent mechanism will be established to allow people to comment on the taxonomic revisions or suggest new ones, and provide new information of relevance in order to inform regular updates. We are also actively seeking input via a discussion topic here regarding some potential taxonomic revisions that currently lack sufficient information.
The new Checklist will form the taxonomic basis of BirdLife’s assessments of the status of the world’s birds for the IUCN Red List. The taxonomic changes that will appear in volume 2 of the checklist (for passerines) will begin to be incorporated into the 2016 Red List update, with the remainder to be incorporated into subsequent Red List updates.
Preliminary Red List assessments have been carried out for the newly split or lumped taxa. We are now requesting comments and feedback on these preliminary assessments.
Red-bellied Pitta is being placed in the genus Erythropitta Bonaparte, 1854, and split into twelve species: Erythropitta erythrogaster, E. inspeculata, E. caeruleitorques, E. palliceps, E. celebensis, E. rufiventris, E. rubrinucha, E. macklotii, E. meeki, E. gazellae, E. splendida and E. novaehibernicae, following the application of criteria set out by Tobias et al. (2010). Sula Pitta E. dohertyi (BirdLife species factsheet) is also recognised as a split from E. erythrogaster by this assessment: it is retained as a separate species with its present status of Near Threatened.
Prior to this taxonomic change, Pitta erythrogaster (BirdLife species factsheet) was listed as being of Least Concern, on the basis that it was not thought to approach the thresholds for Vulnerable under any of the IUCN criteria.
Long recognised as a highly polytypic bird, the pre-split taxon was characterised as a bird of predominately lowland forest, particularly associated with volcanic soils on Sulawesi, but occurring in evergreen forest, secondary forest, edge, riparian woodland and old plantations (Erritzoe 2016). The species was generally considered tolerant of modified habitats, even occurring in small thickets within agriculture and in heavily degraded forest (Erritzoe 2016). The generation length of the pre-split taxon was set at 4.2 years, and in the absence of information pertaining to the newly split species this figure is used for the newly-defined species. Population densities vary dramatically for the two areas from which they have been reported: on the island of Sangihe 2.8 individuals/km2 was reported in secondary forest around the Sahendaruman Crater (P. caeruleitorques: Riley 2002) and in the Brown River region of Papua New Guinea (P. macklotii) 30 individuals/km2 were reported in primary lowland forest (Bell 1982).
E. meeki is restricted to Rossel Island in the Louisiade Archipelago, Papua New Guinea with a provisional EOO of 409 km2. The island retains significant forest cover although small-scale clearance is occurring in lowland areas, with less than 5% forest loss over the period 200-2014 (data from Hansen et al. 2013).
However, there do not appear to be any records of this species since Albert S. Meek collected the type specimen in 1898 (Mayr 1941). Were it to be known to be extant and present in similar densities to the pre-split species, then it is likely that the species would qualify as Endangered under category C2a(ii), on the basis of the single subpopulation, estimated small population size and inferred ongoing population decline.
But with no information on even whether the species is still present on the island, this species must initially be listed as Data Deficient.
If anyone has been to Rossel Island recently and searched for any Erythropitta, please let us know!
E. caeruleitorques is restricted to Sangihe Besar, Sangihe, Indonesia, where it is common in a restricted area on the western slopes of Gunung Awu and present at low density around the Sahendaruman crater in the south of the island with records up to c600 m above sea level (Riley 1997, R. Martin in litt. 2016). Both Gunung Awu and the Sahendaruman Crater are designated as Protection Forest intended to prevent landslips and maintain water supply. Approximately one third of the area of Protection Forest around Sahendaruman is forested, and much of what remains lies above 650 m in altitude. The EOO for the newly defined species has been calculated as 805 km2, and on the basis of this the population is likely to fall in the band 150-700 mature individuals from an estimated population density of 2.8 individuals/km2 (Riley 2002).
The proposal is to list the species as Endangered under category C2a(i,ii), with the species also qualifying as Vulnerable under B1 + B2ab(iii,v) and D1.
E. palliceps (as defined following the taxonomic change) is found on the islands of Siau, Tagulandang and Ruang, Indonesia (Erritzoe 2016, J. Kelly in litt. 2016). It is frequently encountered in secondary forest on Tagulandang, but is apparently scarcer on Siau (J. Kelly in litt. 2016). There are no protected areas on these islands. The maximum Extent of Occurrence (EOO: a Minimum Convex Polygon incorporating the entire extent of the species known occurrence) of the newly defined species is 887 km2, but the total area of land within this is only approximately 170km2. Siau has very little natural habitat remaining and even secondary growth is highly limited by the wholesale and long-standing conversion of forest to plantation agriculture, principally for nutmeg. The frequent eruptions of Mount Karangetang have also left much of the northern half of the Siau devoid of suitable habitat. There is more secondary habitat remaining on Tagulandang (J. Kelly in litt. 2016), though this is restricted to the steeper slopes.
The population size is estimated to number 95-1,020 individuals based on an assessment of known records, descriptions of abundance and range size. This is consistent with recorded population density estimates for the pre-split species, and the fact that only a proportion of the estimated Extent of Occurrence is likely to be occupied. This estimate is equivalent to 167- 666 mature individuals, rounded here to 150 – 700 mature individuals.
The majority of habitat clearance on Siau took place some considerable time ago, certainly well before the previous three generations (12.6 years) applicable to this taxon. However small-scale rotational clearance of secondary regrowth occurs on a regular basis, and this is likely to contribute to a continuing slow decline in the extent of habitat available on the island. On Tagulandang there is similar ongoing small-scale clearance for agriculture (J. Kelly in litt. 2016). No information is available for Ruang. The population size is therefore suspected to be declining, but there is no evidence to assess the rate of this decline.
On the precautionary basis that there are likely to be fewer than 250 mature individuals in each subpopulation and there is an inferred ongoing population decline, the species is proposed for listing as Endangered under category C2a(i). In addition, an accurate population assessment may demonstrate that the population of the species is below 250 mature individuals, in which case P. palliceps would also qualify as Endangered under category D.
Further information is required on threats and whether the suspected population decline has the potential to exceed 20% in two generations or 8.4 years, in which case the species could additionally be listed as Endangered under category C1.
If there is evidence for additional threats that would indicate that the number of locations* in which the species occurs was fewer than 5 then the species would also qualify for listing as Endangered under category B1ab(ii,iii,v) + B2ab(ii,iii,v).
E. inspeculata (as defined following the taxonomic change) is found on the island of Karakelang in the Talaud Islands, Indonesia (R. Martin in litt. 2016). Commonly encountered on Karakelang, the species is found in all forested habitats including rarely in plantations, but occurs at much higher density in primary forest (R. Martin in litt. 2016). It is found in both the Northern and Southern Wildlife Reserves on Karakelang, which total 24,669 hectares (UN Protected Planet). The EOO for the newly defined species has been calculated as 1,219 km2. Given the restricted range of the species and preference for forest, it is suspected that the population is below 10,000 mature individuals, with all individuals considered to be in the one subpopulation.
Karakelang still retains a large area of good quality lowland forest, although clearance for small-scale agriculture and selective logging continues even within the Wildlife Reserves. This is especially the case in the southern reserve where approximately 12% of the forest area has been lost during the past 15 years, compared with around 4% in the northern reserve (R. Martin in litt. 2016). Outside of the reserves the rate of loss is lower, given that most areas are already used for agriculture.
On the basis that the number of mature individuals is likely to be under 10,000 and an inferred continuing decline in the extent of available habitat and therefore in population size, it is proposed that E. inspeculata is listed as Vulnerable, under Category C2a(ii). Should there be evidence to suggest that the number of mature individuals exceeds 10,000 then the species may be considered as Near Threatened under Category C2a(ii).
E. splendida is restricted to the Tabar Islands, to the north of New Ireland, Papua New Guinea and is thought to occur on at least the three larger islands. The EOO for the newly-defined species is 546km2. Dutson (2011) considered it to have a small population which may be threatened by habitat loss, however it has been mentioned that it is still common on the islands (Erritzoe 2016). There is little information relating to the condition of the habitat on Tabar, although there is a 2,560 ha mining lease in place (St. Barbara Ltd. 2016), with further mining activity apparently ongoing on Tatau (data from Hansen et al. 2013). Therefore a continuing decline in habitat extent and quality within the range of the newly defined species is suspected, though the rate of that decline is unknown. Data from the Global Forest Watch project (Hansen 2013) indicate that forest loss in the period 2000-2014 on these islands has been around 5% of the total island area.
The population here is tentatively estimated to fall within the band 1,000 to 2,499 individuals based on an assessment of known records, the description of the species as common and range size. This is consistent with recorded population density estimates for the pre-split species, with 30 individuals per km2 giving an estimate of 3276 individuals and 2.8 individuals per km2 giving an estimate of 306 individuals, where 20% of the EOO is considered likely to be occupied. This estimate is equivalent to 667 to 1,666 mature individuals, rounded here to 600-1,700 mature individuals.
On the assumptions that there is more than one subpopulation (i.e. the populations on each of the three larger islands are distinct subpopulations), there are likely to be fewer than 1,000 mature individuals in each of these subpopulation and that there is an inferred ongoing population decline due to habitat conversion and degradation, then the species is proposed to qualify as Vulnerable under category C2a(i).
If there are likely to be fewer than 250 mature individuals in each subpopulation then the species would qualify as Endangered under the same category. Equally, if in fact the species were shown to operate as a single subpopulation then it would be eligible for listing as Endangered under category C2a(ii).
Any additional information is sought for this species.
E. novaehibernicae (as defined following the taxonomic change, and incorporating extima) is found throughout New Ireland and on Djaul Island and New Hanover, Papua New Guinea. The newly-calculated EOO for the species is 27,995km2. Forest loss is ongoing throughout the range, with 21% of forest area lost between 1972 and 2002, and a further 31% of forest degraded over the same period (Shearman et al. 2008). Forest loss is ongoing, and suggests that the population size may be declining by a rate that approaches the thresholds for Vulnerable (30-49% over three generations for a population reduction suspected in the past, the future, and/or where the time period includes both the past and the future).
On this basis it is proposed that E. novaehibernicae is listed as Near Threatened as it is suspected to approach the thresholds for listing as Vulnerable under category A2c + A3c + A4c.
Least Concern proposals:
E. rubrinucha (as defined following the taxonomic change, and incorporating piroensis) is restricted to Buru, Ambon and Seram in the south Moluccas. The EOO of newly defined species does not approach the geographic range thresholds for listing as Vulnerable, and the rate of habitat loss across the range is not sufficient to suspect a population decline close to 30% within the 3 previous generations, currently or for the next three generations. Therefore the species is proposed as Least Concern.
E. gazellae is restricted to New Britain, Papua New Guinea. The EOO of newly defined species does not approach the geographic range thresholds for listing as Vulnerable. Buchanan et al. (2008) used remote sensing to evaluate the high rate of forest loss on New Britain, however for this species (generation length 4.2 years, elevation range 0-2100 m) the estimated rate of habitat loss would be 13% over three generations and so would still not approach the thresholds for listing under category A, population decline. Consequently this taxon is proposed as Least Concern.
E. rufiventris (as defined following the taxonomic change, and incorporating cyanonota and bernsteini) is restricted to the north Moluccas, being found on the islands of Morotai, Halmahera, Ternate, Obi, Bacan, and Gebe Island. The species is not believed to approach any thresholds for listing as Vulnerable, and is consequently proposed as Least Concern.
E. macklotii (as defined following the taxonomic change, and incorporating digglesi, habenichti, loriae, oblita, finschii and extima) is found throughout mainland Papua New Guinea, and also on the West Papuan Islands, the D’Entrecasteaux Archipelago and north-east Australia. The species is not believed to approach any thresholds for listing as Vulnerable, and is consequently proposed as Least Concern.
E. erythrogaster (as defined following the taxonomic change) is found throughout the Philippine Islands, including Palawan and Balabac. The species is not believed to approach any thresholds for listing as Vulnerable, and is consequently proposed as Least Concern.
E.celebensis (as defined following the taxonomic change) is found throughout Sulawesi, including Manterawu, Togian and Buton. The species is not believed to approach any of the thresholds for listing as Vulnerable, and is consequently proposed as Least Concern.
*Note that the term ‘location’ defines a geographically or ecologically distinct area in which a single threatening event can rapidly affect all individuals of the taxon present. The size of the location depends on the area covered by the threatening event and may include part of one or many subpopulations. 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).
Comments are invited on these proposed categories and further information would be welcomed.
Buchanan, G.M., Butchart, S.H.M., Dutson, G., Pilgrim, J.D., Steininger, M.K., Bishop, K.D. and Mayaux, P. 2008. Using remote sensing to inform conservation status assessment: estimates of recent deforestation rates on New Britain and the impacts on endemic birds. Biological Conservation 141: 56-66.
Dutson, G. 2011. Birds of Melanesia. Christopher Helm, London.
Erritzoe, J. (2016). Red-bellied Pitta (Pitta erythrogaster). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/57572 on 2 August 2016).
IUCN (2001) IUCN Red List Categories and Criteria: Version 3.1. Gland, Switzerland and Cambridge, UK: IUCN Species Survival Commission.
IUCN (2012) IUCN Red List Categoriesand Criteria: Version 3.1. Second edition. Gland, Switzerland and Cambridge, UK: IUCN. Available at www.iucnredlist.org/technical-documents/categories-and-criteria
Mayr, E. 1941. List of New Guinea birds : a systematic and faunal list of the birds of New Guinea and adjacent islands.. Amer. Mus. Nat. Hist., New York. Accessed via Biodiversity History Library http://biodiversitylibrary.org/page/42702990. Accessed 8th September 2016.
Riley, J. 1997. The birds of Sangihe and Talaud, North Sulawesi. Kukila 9:3–36
Riley, J. 2002. Population sizes and the status of endemic and restricted-range bird species on Sangihe Island, Indonesia. Bird Conservation International 12: 53-78.
Shearman, P.L., Bryan, J.E., Ash, J., Hunnam, P., Mackey, B., Lokes, B. 2008. The State of the Forests of Papua New Guinea: Mapping the extent and condition of forest cover and measuring the drivers of forest change in the period 1972-2002. University of Papua New Guinea.
St. Barbara Ltd. 2016. “Our Operations/Simberi” http://www.stbarbara.com.au/our-operations/simberi/ Accessed 5 August 2016.