Eastern Meadowlark (Sturnella magna): revise global status?

Currently listed as Least Concern (BirdLife International 2018), Eastern Meadowlark (Sturnella magna) has a very large range from south-east Canada, though eastern and southern U.S.A., Mexico, Central America, Cuba and into northern South America from Colombia across to northern Brazil (see Fraga 2018). It inhabits grasslands and a range of pastureland habitats (Fraga 2018) and as such it can be impacted by agricultural practices. Degradation of land to intensive agriculture, as well as grazing and trampling by livestock may be contributing to declines, and early mowing can lead to the destruction of nests and/or the mortality of young and incubating adults (see Jaster et al. 2012). Pesticide use may also be impacting the species, and it is very sensitive to disturbance such that if a female is flushed from her nest she will likely abandon it (Jaster et al. 2012).

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, Eastern Meadowlark 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) put the population reduction between 1970 and 2014 at 77%. This would roughly equate to a decline of 35.7% over three generations (13.2 years). Partners in Flight also gives a half-life for the species of 23 years, which would roughly equate to a decline of 32.8% over three generations (Rosenberg et al. 2016). This appears to be an ongoing trend as short term (2005-2015) data shows an annual decline of 3.05% (2.29-3.56%) (Sauer et al. 2017), which would roughly equate to a reduction of 33.6% (26.3-38.0%) over three generations. This meets the threshold for Vulnerable (reduction of 30% over three generations), but while Rosenberg et al. (2016) state that their reduction figure relates to the global population*, the data from Sauer et al. (2016) only refer to U.S.A. and Canada subpopulations, and so we need to factor in the proportion of the species found elsewhere.

Using population size estimates from Partners in Flight (Rosenberg et al. 2016) approximately 65% of the global population is found in U.S.A. & Canada. If we assume here that the populations outside of U.S.A. & Canada are stable, then the overall rate of decline over 3 generations would be c.24% (c.18.5-c.28%) based on short-term trends from Sauer et al. (2017).

Therefore, even if the entire population outside of U.S.A. & Canada is stable the species is likely undergoing a moderately rapid decline, which could be approaching the threshold for Vulnerable under this criterion. If, however, the population trends from U.S.A. & Canada are representative of global trends, then it could meet the threshold for Vulnerable. We therefore request any further information regarding population trends from outside of U.S.A. & Canada, but in the absence of this it is proposed that the species is listed as Near Threatened under criteria A2ac+3c+4ac.

 

Criterion B – The species’s range is far too large to warrant listing under this criterion (Extent of Occurrence [breeding/resident] = 24,400,000km2; Extent of Occurrence [non-breeding] = 19,800,000km2).

 

Criterion C – Rosenberg et al. (2016) estimate the global population size to be 37,000,000 mature individuals. This is therefore far too large to warrant listing under this criterion.

 

Criterion D – The species’s population size and range 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, Eastern Meadowlark potentially warrants listing as Near Threatened, although we request further information about population trends throughout its range to see whether it could warrant listing under a higher threat level. 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.

 

*Note that while it is state to relate to the global population, the data appears to be derived from the North American Breeding Bird Survey and Christmas Bird Count, and as such range states not incorporated in these may not actually be represented (see Rosenberg et al. 2016 for details of how population reduction was calculated).

 

References

BirdLife International. 2018. Species factsheet: Sturnella magna. Downloaded from http://www.birdlife.org on 06/03/2018.

Fraga, R. 2018. Eastern Meadowlark (Sturnella magna). 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/62330 on 6 March 2018).

Jaster, L. A.; Jensen, W. E.; Lanyon, W. E. 2012. Eastern Meadowlark (Sturnella magna), 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.160.

North American Bird Conservation Initiative. 2016. The State of North America’s Birds 2016. Environment and Climate Change Canada, Ottawa, Ontario.

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.

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