Archived 2016 topics: Savannah Sparrow (Passerculus sandwichensis) is being split: list P. sanctorum as Near Threatened?

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.

Savannah Sparrow Passerculus sandwichensis is being split into P. sandwichensis, P. guttatus, P. rostratus and P. sanctorum, following the application of criteria set out by Tobias et al. (2010).

Prior to this taxonomic change, P. sandwichensis was listed as Least Concern, on the basis that it did not approach the threshold for Vulnerable under any criterion. P. sandwichensis (as now defined following the taxonomic change), P. guttatus and P. rostratus all do not appear to globally approach the threshold for Vulnerable under any criterion, and so it is proposed that they be listed as Least Concern.

P. sanctorum is found only on the San Benito islands off the western coast of Baja Califonia, Mexico, in xeric scrub habitats (Rising 2016). It is abundant on these islands (Rising 2016) and is not expected to meet the threshold for Vulnerable under any criterion. However, Cedros Island cactus mouse, Peromyscus eremicus cedrosensis, has become invasive on at least one island (Aguirre-Muñoz et al. 2011), and could be affecting this species. At the moment there is no evidence to suggest that there has been any significant effect of the introduction of the mice on this species and it may warrant listing as Least Concern. However, given its highly restricted range on only three islands this species may be precautionarily listed as Near Threatened under criterion D2 because of the possible effect that mice could have within its highly restricted range.

Comments are invited on these proposed categories and further information would be welcomed.

References:

Aguirre-Muñoz, A., Samaniego-Herrera, A., Luna-Mendoza, L., Ortiz-Alcaraz, A., Rodríguez-Malagón, M., Méndez-Sánchez, F., Félix-Lizárraga, M., Hernández-Montoya, J.C., González-Gómez, R., Torres-García, F., Barredo-Barberena J.M. and Latofski-Robles, M. 2011. Island restoration in Mexico: ecological outcomes after systematic eradications of invasive mammals. Pp. 250-258 In: Veitch, C. R., Clout, M. N. and Towns, D. R. (eds.). Island invasives: eradication and management. IUCN, Gland, Switzerland.

Rising, J. 2016. San Benito Sparrow (Passerculus sanctorum). 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/61921 on 6 October 2016).

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.

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One Response to Archived 2016 topics: Savannah Sparrow (Passerculus sandwichensis) is being split: list P. sanctorum as Near Threatened?

  1. James Westrip (BirdLife) says:

    Based on available information, our preliminary proposal for the 2016 Red List would be to list:

    P. sandwichensis, P. guttatus and P. rostratus as Least Concern.

    P. sanctorum as Near Threatened under criterion D2.

    There is now a period for further comments until the final deadline of 28 October, 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 2016 Red List categories will be published on the BirdLife and IUCN websites in early December, following further checking of information relevant to the assessments by both BirdLife and IUCN.

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