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.
Dark-eyed Junco Junco hyemalis is being split into J. hyemalis and J. insularis, following the application of criteria set out by Tobias et al. (2010).
Prior to this taxonomic change, J. hyemalis was listed as Least Concern, on the basis that it did not approach the threshold for Vulnerable under any criterion. J. hyemalis (as defined now following the taxonomic change) is found across much of North America for at least part of the year with a very large population size estimate. The population trend appears to be stable (Butcher and Niven 2007) and so this species warrants listing as Least Concern.
J. insularis is found only on Guadalupe Island off the coast of Baja California, Mexico, where it is confined to remnant forest in the north of the island (Howell and Webb 1995). It had been threatened by intense grazing by goats, with the largest remaining tract of remnant forest being only c.1 km of cypress by 1988 (BirdLife International 2000). However, numbers have increased in recent years (P. Salaman in litt. 2007) from only 50-100 birds in 1995 (Howell and Webb) owing to habitat management and the culling of goats. Threats may remain though, as feral cats were common in 1988 and presumably prey upon this species (BirdLife International 2000). As the population is increasing it may no longer qualify as Critically Endangered (BirdLife International 2000), as it did prior to being lumped with J. hyemalis, though we request any further information as to whether there has been any habitat declines which would then qualify the species as Critically Endangered under criterion B1ab. Depending on the rate of population increase the species does likely qualify as Endangered under criterion D (<250 mature individuals). However, if there is further information to suggest the population may be larger than this the species will qualify as Vulnerable under criteria D1+2.
Comments are invited on these proposed categories and further information would be welcomed.
BirdLife International 2000. Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International.
Butcher, G. S. and Niven, D. K. (2007) Combining data from the Christmas bird count and the breeding bird survey to determine the continental status and trends of North American birds. National Audubon Society.
Howell, S. N. G. and Webb, S. 1995. A guide to the birds of Mexico and northern Central America. Oxford University Press, Oxford.
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.