Chimney Swift (Chaetura pelagica): revise global status?

Chimney Swift (Chaetura pelagica) is a migratory species, breeding in eastern North America from southern Canada to the Gulf Coast states of U.S.A., and occasionally in California and Arizona. It winters in north-western South America, and while the exact range is uncertain it is thought to occur in Colombia, eastern Ecuador, Peru, north-west Brazil and northern Chile (see Chantler and Boesman 2018).

When breeding the species is commonly associated with urban environments, because of its nature of nesting in chimneys, although it will use other nesting sites such as in hollowed out tree trunks, and will forage over a range of habitat types (see Chantler and Boesman 2018). Its association with chimneys may have historically allowed the population to expand, but in recent times the number of available chimneys has decreased as a result of the demolition of old buildings, the capping of old chimneys, and even through chimney sweeps removing nests from chimneys (despite the species being protected by federal law) (see COSEWIC 2007, Steeves et al. 2014, Chantler and Boesman 2018). Logging of old-growth forest may also reduce the number of breeding sites for the species (see Steeves et al. 2014). Additionally, the use of DDT in the 1950s to control insect populations may have caused a shift in Chimney Swift diet, although the long term impact of this on the species is uncertain (Nocera et al. 2012, Steeves et al. 2014). The key threat though is thought to be the ongoing loss of potential nesting sites (although this may not be the case for all populations; Fitzgerald et al. 2014), and the species is currently listed as having undergone a moderately rapid decline, such that it is listed as Near Threatened (see BirdLife International 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, Chimney Swift 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 that between 1970 and 2014 the species underwent a population reduction of 67%, which would equate to a decrease of 33.3% over three generations (c.16 years). Partners in Flight also gives the species a half-life of 27 years, which would equate to a population reduction of 33.8% over three generations.

Short term data (2005-2015) from Sauer et al. (2017) shows an annual decline of 2.71% (2.32-3.09%) for the species. This would equate to a reduction of 35.7% (31.4-39.6%) over three generations. Sauer et al. (2017) do also show year by year records, and so we can extrapolate trends for any three generation period. Three generations ago is approximately 2002. Therefore, we can extrapolate the trends between 2002 and 2015 to 2018 in order to estimate the population trend over the past three generations. Between 2002 and 2015 the population has been, in general, decreasing with a significant, estimated annual decrease of 2.68% (2.38 to 3.00%) (Sauer et al. 2017). This would equate to a reduction of 35.3% (32.1-38.7%) over three generations. The threshold reduction size for listing as Vulnerable is 30% over three generations, and so the species warrants listing as Vulnerable under criteria A2acd+3cd+4acd.

 

Criterion B – The species’s range is far too large to warrant listing under this criterion (Extent of Occurrence [breeding] = 8,580,000km2; Extent of Occurrence [non-breeding] = 5,380,000km2).

 

Criterion C – Rosenberg et al. (2016) estimate the population size to be 7,700,000 mature individuals. This is 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, Chimney Swift potentially warrants uplisting to 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.

 

References

BirdLife International. 2018. Species factsheet: Chaetura pelagica. Downloaded from http://www.birdlife.org on 07/03/2018.

Chantler, P.; Boesman, P. 2018. Chimney Swift (Chaetura pelagica). 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/55310 on 7 March 2018).

COSEWIC. 2007. Assessment and Status Report on the Chimney Swift Chaetura pelagica in Canada.

Fitzgerald, T. M.; van Stam, E.; Nocera, J. J.; Badzinski, D. S. 2014. Loss of nesting sites is not a primary factor limiting northern Chimney Swift populations. Population Ecology 56 (3): 507-512.

Nocera, J. J.; Blais, J. M.; Beresford, D. V.; Finity, L. K.; Grooms, C.; Kimpe, L. E.; Kyser, K.; Michelutti, N.; Reudink M. W.; Smol, J. P. 2012. Historical pesticide applications coincided with an altered diet of aerially foraging insectivorous Chimney Swifts. Proceedings of the Royal Society B: Biological Sciences 279 (1740): 3114-3120.

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.

Steeves, T. K.; Kearney-McGee, S. B.; Rubega, M. A.; Cink, C. L.; Collins, C. T. 2014. Chimney Swift (Chaetura pelagica), 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.646.

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