Moluccan Woodcock (Scolopax rochussenii): revise global status?

BirdLife species factsheet for Moluccan Woodcock

This discussion was first published as part of the 2020 Red List update. At the time a decision regarding its status was pended, but to enable potential reassessment of this species as part of the 2021 Red List update this post remains open and the date of posting has been updated.

Moluccan Woodcock (Scolopax rochussenii) is endemic to the islands of Obi and Bacan in Indonesia. It inhabits a variety of forests, including primary lowland forest, selectively logged and secondary forest as well as swamp forest, where it is strongly associated with rivers and streams (Cottee-Jones et al. 2013). Despite being tolerant of low levels of habitat degradation, the species seems to avoid heavily disturbed areas and agricultural zones (Cottee-Jones et al. 2013, Thibault et al. 2013). A species distribution model based on results from a field survey estimated a population size of c. 19,000 mature individuals (Cottee-Jones et al. 2013). The species is undergoing a decline caused by logging, agricultural encroachment and gold mining.

Moluccan Woodcock has been considered Endangered under Criterion B1ab(ii,iii,v) (BirdLife International 2020). However, this is no longer tenable because this was based on an Extent of Occurrence (EOO) value calculated as the ‘area of mapped range’. This is no longer appropriate and the EOO should be calculated using a Minimum Convex Polygon (see IUCN 2001, 2012, Joppa et al. 2016), as EOO is a measure of the spatial spread of areas occupied by a species, not the actual area it occupies. The resulting EOO value now exceeds the thresholds required to maintain the species’s current listing. Therefore, we have fully reviewed the species here against all criteria.

Criterion A – The population trend for this species has not been directly estimated. The only known threat is habitat loss, and over the last three generations (11.1 years, Bird et al. 2020)*, forest loss has been low within its mapped range (<5%; Tracewski et al. 2016, Global Forest Watch 2020). However, Moluccan Woodcock is highly forest-dependent and avoids disturbed areas; as such, rates of population decline may be exacerbated by additional effect of forest degradation, and larger than rates of forest loss alone. Nevertheless, population declines are considered unlikely to exceed 10% over three generations. Moluccan Woodcock is therefore assessed as Least Concern under Criterion A.

Criterion B – The newly calculated Extent of Occurrence (EOO) for this species is 6,100 km2. The maximum Area of Occupancy (AOO), as calculated from a 4 km2 grid over the area of mapped range, is 2,300 km2. As such, the EOO meets the threshold for listing as Vulnerable under Criterion B1, while the AOO approaches it under Criterion B2. However, in order to be listed under these criteria, further conditions have to be met.

During a field survey, the species was recorded from a larger number of sites than previously known (11 sites; Cottee-Jones et al. 2013). As the primary threat is habitat loss to agriculture and mineral mining, the number of locations** of occurrence is assessed as 6-10, meeting subcriterion a at the level of Vulnerable. With the population estimate derived from a habitat-based species distribution model (Cottee-Jones et al. 2013), the observation that the extent of suitable habitat is declining allows the inference that the number of territories calculated in this way has reduced, and that the species is undergoing a continuing decline in population size. Thus, subcriterion b(ii,iii,v) is met. Overall, Moluccan Woodcock warrants a listing as Vulnerable under Criterion B1ab(ii,iii,v). The species additionally qualifies as Near Threatened, approaching the threshold for listing as threatened under Criterion B2ab(ii,iii,v).

Criterion C – The global population is tentatively placed in the band 10,000-19,999 mature individuals. Under the very precautionary assumption that the true population size is closer to the lower end of the estimate, this would approach the threshold for listing as threatened under Criterion C. In order to be listed under this criterion, further conditions have to be met though.

The estimate of the population size from a habitat-based species distribution model (Cottee-Jones et al. 2013) allows to infer a continuing decline in the number of mature individuals, meeting subcriterion 2. Even though we have no information on the subpopulation structure, we can tentatively assume that the species forms two disconnected subpopulations on Obi Island and on Bacan Island. This suggests that the largest subpopulation contains considerably more than 1,000 mature individuals, and neither condition a(i) nor a(ii) are met. There is no evidence that the population is undergoing severe fluctuations, and condition b is not met. Overall, Moluccan Woodcock does not meet enough conditions to warrant listing as Near Threatened under Criterion C; it is therefore considered Least Concern under this criterion.

Criterion D – The global population and range are too large to warrant listing as threatened under Criterion D, and therefore Moluccan Woodcock is considered Least Concern under this criterion.

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.

Therefore, it is suggested that Moluccan Woodcock (Scolopax rochussenii) be listed as Vulnerable under Criterion B1ab(ii,iii,v).We welcome any comments to the proposed listing.

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

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: Scolopax rochussenii. http://www.birdlife.org (Accessed 19 May 2020).

Cottee-Jones, H. E.; Mittermeier, J. C.; Redding, D. W. 2013. The Moluccan Woodcock Scolopax rochussenii on Obi Island, North Moluccas, Indonesia: a ‘lost’ species is less endangered than expected. Forktail 29: 88-93.

Global Forest Watch. 2020. Interactive Forest Change Mapping Tool. http://www.globalforestwatch.org (Accessed 18 February 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.

Joppa, L. N.; Butchart, S. H. M.; Hoffmann, M.; Bachman, S. P.; Akçakaya, H. R.; Moat, J. F.; Böhm, M.; Holland, R. A.; Newton, A.; Polidoro, B.; Hughes, A. 2016. Impact of alternative metrics on estimates of extent of occurrence for extinction risk assessment. Conservation Biology 30: 362-370.

Thibault, M.; du Rau, P. D.; Pineau, O.; Pangimangen, W. 2013. New and interesting records for the Obi archipelago (north Maluku, Indonesia), including field observations and first description of the vocalisation of Moluccan Woodcock Scolopax rochussenii. Bulletin of the British Ornithologists Club 133(2): 83-115.

Tracewski, Ł.; Butchart, S. H. M.; Di Marco, M.; Ficetola, G. F.; Rondinini, C.; Symes, A.; Wheatley, H.; Beresford, A. E.; Buchanan, G. M. 2016. Toward quantification of the impact of 21st-century deforestation on the extinction risk of terrestrial vertebrates. Conservation Biology 30: 1070-1079.

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6 Responses to Moluccan Woodcock (Scolopax rochussenii): revise global status?

  1. James Eaton says:

    The swampy lowland forest mentioned in Cottee-Jones et al. 2013 (plate 2, and on figure one, the northern localities) has been bulldozed already (this began in late 2016), from my first visit here in early 2016, recording several displaying woodcocks, to just one in March 2017. The same is happening along much of northern Obi, as the push for improving infrastructure in eastern Indonesia has gathered pace. Google earth imagery shows how the eastern side of Obi has also changed considerably, and the island is also home to a huge mine on the west side of the island, which has decimated the habitat there (See google earth again).
    Away from this swampy forest habitat, I’ve found the woodcock to be rare, and largely absent.

    James

  2. Red List Team (BirdLife International) says:

    Global Forest Change data on tree cover loss up to 2019 have now been released and made available via Global Forest Watch. Based on these data, over three generations (11.1 years) approximately 4.3% of tree cover with 75% canopy cover was lost from within the species’s range (Global Forest Watch 2020).

  3. Red List Team (BirdLife International) says:

    Many thanks to everyone who has contributed to this discussion. We greatly appreciate the time and effort invested by so many people in commenting. 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 once again,
    BirdLife Red List Team

  4. Red List Team (BirdLife International) says:

    Preliminary proposal

    Based on available information, our preliminary proposal for the 2020 Red List would be to adopt the proposed classifications outlined in the initial forum discussion.

    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 the initial proposal.

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

  5. Based on our fieldwork on this species in 2012 (Cottee-Jones et al. 2013, already cited here), Cottee-Jones and I concluded that the woodcock should be downlisted from Endangered to Vulnerable. That study was 8 years ago now, however, and as James points out there seems to have been substantial habitat loss since then. We did find the woodcock in Obi’s central highlands, but same as James, found that it was less common there and most of the population probably relies on lowland swampy areas, which are more threatened by land use change.

    More importantly, unless I’ve missed some recent reports, the occurrence of this species on Bacan is based on a single record from 1902. Several notable ornithologists and collectors, including Wallace, spent long periods of time on Bacan and did not find any woodcock there. Absent additional evidence, this single record could be due to a location error by the collector or a population that was once on Bacan and has now gone extinct (though this would not explain why collectors visiting before 1900 failed to find it). Unless/until it is confirmed that the species definitely occurs on Bacan, I would consider the occurrence of the woodcock on Bacan unconfirmed and would not include Bacan in the population and distribution estimates.

    I imagine the species probably still qualifies as Vulnerable overall, but having it be Least Concern under Criteria C based on an assumed population in Bacan does not seem correct (again, unless there are recent confirmed records from there that I have yet to hear about!).

  6. Red List Team (BirdLife International) says:

    Recommended categorisations to be put forward to IUCN

    Based on the information received through this forum process, our proposal for the 2020 Red List is to pend the decision on this species and keep the discussion open until 2021, hence there will be no new assessment for this species in the 2020 update.

    Many thanks for everyone who contributed to the 2020 GTB Forum process. 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.

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