Currently listed as Least Concern (BirdLife International 2018), Lark Bunting (Calamospiza melanocorys) breeds from southern Canada through the Great Plains of U.S.A. to east New Mexico, northern Texas and west Oklahoma. It is present year-round in the southern part of its breeding range, but in the non-breeding season this becomes the northern part of its range, with the species also occurring south into northern Mexico, including Baja California (see Rising 2018). During the breeding season it is found in short-grass prairie, with scattered shrubs and bare ground, while in the non-breeding season it occupies desert scrub, weedy fields and open farmland (Rising 2018).
While the species remains common in parts of its range, it is thought to have undergone declines as a result of the degradation and loss of its habitat due to agricultural conversion, overgrazing and the absence of natural herbivores and fire regimes (see Shane 2000, Rising 2018). Pesticides for controlling grasshoppers can also have a serious impact on the species (see Shane 2000, Rising 2018).
Following the publication of Partners in Flight (PiF) Landbird Conservation Plan (Rosenberg et al. 2016) and The State of North America’s Birds 2016 (North American Bird Conservation Initiative 2016) we have reviewed the new information held in these publications, particularly regarding population trends. This has allowed us to reassess the species outlined in these publications against IUCN Red List Categories and Criteria. As the PiF data are long-term trends (1970-2014), where possible we have also used data from the North American Breeding Bird Survey (Sauer et al. 2017) to assess more recent trends over the period relevant to the Red List. Having completed this review, Lark Bunting appears to warrant a change in Red List status. Therefore, we present here our reassessment against all criteria for the species.
Criterion A – Rosenberg et al. (2016) suggest the species has undergone a population reduction of 86% between 1970 and 2014. Assuming a constant rate of decline this would equate to a reduction of 36.0% over 10 years. Short term trends from Sauer et al. (2017) instead show that the species may have undergone a non-significant annual increase of 1.43% (5.28% increase to 2.40% decrease) between 2005 and 2015. This equates to an increase of 15.3% (67.3% increase to 21.2% decrease) over 10 years. This suggests that declines may have been historical, and in fact the population may be doing better now.
However, Rosenberg et al. (2016) do predict a future half-life for the species of 16 years, and this would equate to a decline of 35.3% over 10 years. This would meet the threshold for Vulnerable, but the current trend from Sauer et al. (2017) does appear to contradict this. Therefore, we request any further comment and information about the current trends for this species, but in the absence of any information it may be precautionary to list the species as Near Threatened under criterion A3cd, as there is the potential for rapid future declines, but there is uncertainty over the rate of such declines.
Criterion B – The species’s range is far too large to warrant listing under this criterion (Extent of Occurrence [breeding/resident] = 2,010,000km2; Extent of Occurrence [non-breeding] = 2,520,000km2).
Criterion C – Rosenberg et al. (2016) estimates the population size to be 10,000,000 mature individuals. This is far too large to warrant listing under this criterion.
Criterion D – The species’s range and population size are far too large to warrant listing 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, Lark Bunting potentially warrants uplisting to Near Threatened or even Vulnerable. We welcome any comments or further information but 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 about the proposed listing.
BirdLife International. 2018. Species factsheet: Calamospiza melanocorys. Downloaded from http://www.birdlife.org on 12/03/2018.
North American Bird Conservation Initiative. 2016. The State of North America’s Birds 2016. Environment and Climate Change Canada, Ottawa, Ontario.
Rising, J. 2018. Lark Bunting (Calamospiza melanocorys). 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 https://www.hbw.com/node/61901 on 12 March 2018).
Rosenberg, K. V., Kennedy, J. A., Dettmers, R., Ford, R. P., Reynolds, D., Alexander, J. D., Beardmore, C. J., Blancher, P. J., Bogart, R. E., Butcher, G. S., Camfield, A. F., Couturier, A., Demarest, D. W., Easton, W. E., Giocomo, J. J., Keller, R. H., Mini, A. E., Panjabi, A. O., Pashley, D. N., Rich, T. D., Ruth, J. M., Stabins, H., Stanton, J. and Will., T. 2016. Partners in Flight Landbird Conservation Plan: 2016 Revision for Canada and Continental United States. Partners in Flight Science Committee.
Sauer, J. R.; Niven, D. K. ; Hines, J. E.; Ziolkowski, Jr, D. J.; Pardieck, K. L.; Fallon, J. E.; Link, W. A. 2017. The North American Breeding Bird Survey, Results and Analysis 1966 – 2015. Version 2.07.2017 USGS Patuxent Wildlife Research Center, Laurel, MD.
Shane, T. G. 2000. Lark Bunting (Calamospiza melanocorys), version 2.0. In: Rodewald, P. G. (ed.). The Birds of North America. Cornell Lab of Ornithology, Ithaca, New York, U.S.A. https://doi.org/10.2173/bna.542.