Archived 2014 discussion: New Zealand Dotterel (Charadrius obscurus) is being split: list C. obscurus as Endangered and C. aquilonius as Near Threatened?

The initial deadline for comments on this topic is 28 April 2014, and therefore later than for most other topics currently under discussion.

This is part of a consultation on the Red List implications of extensive changes to BirdLife’s taxonomy for non-passerines

Lynx Edicions and BirdLife International will soon publish 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.

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 1 of the checklist (for non-passerines) will begin to be incorporated into the 2014 Red List update, with the remainder, and those for passerines (which will appear in volume 2 of the checklist), 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.

New Zealand Dotterel Charadrius obscurus is being split into C. obscurus (Southern Red-breasted Plover) and C. aquilonius (Northern Red-breasted Plover), following the application of criteria set out by Tobias et al. (2010).

Southern Red-breasted Plover C. obscurus was once widespread on the South Island of New Zealand but now breeds only inland on Steward Island/Rakiura, mainly on subalpine herb-fields or rocky areas above the tree-line. During the non-breeding season all birds move to the coast where they feed on intertidal mudflats and beaches..

C. obscurus was extirpated from the South Island by about 1900 following introduction of stoats and other mustelids, and there was a rapid decline of the relict population on Stewart Island from the 1950s due to predation of adults by cats (and possibly rats). Males incubate at night, and are more vulnerable; a severe gender bias developed, with female-female pairs forming. The population was reduced to 18 male-female pairs by 1992, when cat and rat control was initiated. The population has since recovered, but its breeding range remains confined to Stewart Island, and it is conservation dependent (Dowding 2013).

Having reached a low of 62 birds in 1992, it has since responded well to management, with an estimated c.250 individuals in 2005 (Dowding and Davis 2007) and a post-breeding population which has fluctuated between 240 and 290 birds since 2005 (Dowding 2013).

This taxon was classified as Nationally Critical in New Zealand in 2012 on the basis that its population numbers <250 mature individuals but is not declining (Robertson et al. 2012). This would most closely correspond to a classification of Endangered under criterion D on the IUCN Red List. This taxon is listed as Conservation Dependent, occurring at a single location, and stable.

It is proposed that the newly-defined C. obscurus be listed as Endangered under criterion D1, since a population fluctuating between 240-290 individuals is assumed to contain fewer than 250 mature individuals.

Northern Red-breasted Plover C. aquilonius breeds on or near the coast of the North Island of New Zealand (mainly north of 39°S), where it typically breeds on sandy beaches and sandspits, some on shell banks in harbours, a few on gravel beaches. On beaches, they are usually clustered around stream-mouths. In urban areas (particularly Auckland) they often breed a short distance inland on short grass (golf courses, motorway verges, beside airport runways) or on bare ground (building sites, quarries).

It was estimated to number c.1,700 individuals, including c.700 breeding pairs, in October 2004 (Dowding and Davis 2007), and a total of 2,175 birds were counted in the 2011 breeding-season census (Dowling 2013).

Threats to C. aquilonius include predation by cats, stoats, hedgehogs and rats, flooding and crushing of nests, and disturbance during breeding caused by recreational use of beaches by people, vehicles and dogs (Dowding and Davis 2007). Protection programmes began in the 1980s, and normally include predator control, fencing of nesting areas, appointment of wardens to reduce disturbance, and advocacy. About 20-25% of the population is now managed, but effort and success vary between sites and years. The subspecies is conservation dependent – stable or declining where unmanaged, increasing where managed (Dowding 2013).

The taxon aquilonius was classified as Nationally Vulnerable in New Zealand in 2012 on the basis that its population lies within the band 1,000-5,000 mature individuals and is not declining (Robertson et al. 2012). It is listed as Conservation Dependent but increasing.

It is proposed therefore that C. aquilonius be classified as Near Threatened, approaching the threshold for classification as Vulnerable under criterion D1 (very small population).

Comments are invited and further information would be welcomed.

References

Dowding, J. E. and Davis, A. M. 2007. New Zealand dotterel (Charadrius obscurus) recovery plan, 2004-2014. Threatened Species Recovery Plan 58. Science & Technical Publishing, Department of Conservation, Wellington, New Zealand.

http://www.doc.govt.nz/documents/science-and-technical/tsrp58.pdf

Dowding, J. E. 2013. New Zealand dotterel. In Miskelly, C.M. (ed.) New Zealand Birds Online. www.nzbirdsonline.org.nz

Robertson, H. A., Dowding, J. E., Elliott, G. P., Hitchmough, R. A., Miskelly, C. M., O’Donnell, C. J. F., Powlesland, R. G., Sagar, P. M., Scofield, R. P., Taylor, G. A. 2013: Conservation status of New Zealand birds, 2012. New Zealand Threat Classification Series 4. 22 p. Department of Conservation, Wellington, New Zealand.

http://www.doc.govt.nz/Documents/science-and-technical/nztcs4entire.pdf

Tobias, J. A., Seddon, N., Spottiswoode, C. N., Pilgrim, J. D., Fishpool, L. D. C. and Collar, N. J. (2010) Quantitative criteria for species delimitation. Ibis 152: 724–746.

Related posts:

  1. New Zealand Grebe (Poliocephalus rufopectus): downlist to Near Threatened?
  2. Archived 2014 discussion: New Zealand Pigeon (Hemiphaga novaeseelandiae) is being split: list H. chathamensis as Vulnerable and H. novaeseelandiae as Near Threatened?
  3. Archived 2014 discussion: New Zealand Snipe (Coenocorypha aucklandica) is being split: list C. iredalei as Extinct, C. huegeli as Vulnerable and C. aucklandica as Near Threatened?
  4. Archived 2014 discussion: Northern Brown Kiwi (Apteryx mantelli) is being split: list both A. mantelli and A. rowi as Endangered?
  5. Archived 2011-2012 topics: St Helena Plover (Charadrius sanctaehelenae): downlist to Vulnerable?
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2 Responses to Archived 2014 discussion: New Zealand Dotterel (Charadrius obscurus) is being split: list C. obscurus as Endangered and C. aquilonius as Near Threatened?

  1. Andy Symes says:

    Preliminary proposals

    Based on available information, our preliminary proposals for the 2014 Red List would be to treat:

    C. obscurus as Endangered under criterion D

    C. aquilonius as Near Threatened, approaching the thresholds for classification as Vulnerable under criterion D1.

    There is now a period for further comments until the final deadline of 14 May, after which recommended categorisations will be put forward to IUCN.

    The final Red List categories will be published on the BirdLife and IUCN websites in mid-2014, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  2. Andy Symes says:

    Recommended categorisations to be put forward to IUCN

    Following further review, there have been no changes to our preliminary proposals for the 2014 Red List status of these species.

    The final categorisations will be published in mid-2014, following further checking of information relevant to the assessments by BirdLife and IUCN.

Comments are closed.