Archived 2018 topic: Rufous Hummingbird (Selasphorus rufus): revise global status?

Currently listed as Least Concern (BirdLife International 2018), Rufous Hummingbird (Selasphorus rufus) breeds in second growth forests of south-east Alaska, western Canada and north-west U.S.A.; in winter it migrates to the Gulf Coast of U.S.A., southern California and throughout Mexico (Powers et al. 2018). The threats to the species are difficult to establish, but declines have continued for some time (see Sauer et al. 2017), and it appears that they will continue into the future.

The species benefits from some forest degradation, as it may increase the availability of certain food flowers (see Healy and Calder 2006), and artificial feeders can also help increase abundance (Healy and Calder 2006, Powers et al. 2018). However, while the species may tolerate some forest degradation, habitat destruction could impact the species (Rosenberg et al. 2016, Powers et al. 2018), and given it is typically found in cooler climates, climate change could prove to be a key threat (Rosenberg et al. 2016).

Following the publication of Partners in Flight 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 Categories and Criteria. As the data presented come from long-term trends (Partners in Flight trends come from between 1970 and 2014), where possible we have also used data from the North American Breeding Bird Survey (Sauer et al. 2017) to collate more recent trends. Having completed this review, Rufous Hummingbird appears to warrant a change in Red List status. Therefore, we present here our reassessment for the species against all criteria.

 

Criterion A – Rosenberg et al. (2016) show a population reduction of 60% between 1970 and 2014, which roughly equates to a reduction of 25.4% over three generations (14.1 years). Short term data from Sauer et al. (2017) also suggest that the reduction is not only historical. Between 2005 and 2015 the species showed annual declines of 2.07% (0.93-3.28%), which roughly equates to a reduction of 25.5% over three generations (12.3-37.5%). Sauer et al. (2017) present year by year records, and so we can extrapolate trends for any three generation period. Three generations ago was approximately 2004. Therefore, we can extrapolate the trends between 2004 and 2015 to 2018 in order to estimate the population trend over the past three generations. Between 2004 and 2015 the population has been, in general, decreasing with a significant, estimated annual decrease of 2.23% (1.21 to 3.40%) (Sauer et al. 2017). This would equate to a reduction of 27.2% (15.8-38.6%) over three generations, approaching the threshold for Vulnerable.

Looking through the Sauer et al. data, year by year we can see that the rate of decline slows after 2006, such that they would no longer approach the threshold for Vulnerable. However, Partners in Flight also gives the species a future half-life of 34 years, which would equate to a decrease of 25.0% over three generations (Rosenberg et al. 2016). Therefore, the species likely does approach the threshold for Vulnerable, and warrants listing as Near Threatened, precautionarily 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] = 2,780,000km2; Extent of Occurrence [non-breeding] = 3,600,000km2).

 

Criterion C – Rosenberg et al. (2016) estimate the population size to be 19,000,000 mature individuals. Therefore, 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, Rufous Hummingbird potentially warrants listing as Near Threatened. 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: Selasphorus rufus. Downloaded from http://www.birdlife.org on 06/03/2018.

Healy, S.; Calder, W. A. 2006. Rufous Hummingbird (Selasphorus rufus), 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.53.

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

Powers, D. R.; Boesman, P.; Kirwan, G. M. 2018. Rufous Hummingbird (Selasphorus rufus). 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/55674on 6 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.

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2 Responses to Archived 2018 topic: Rufous Hummingbird (Selasphorus rufus): revise global status?

  1. James Westrip (BirdLife) says:

    Tim Meehan has kindly provided analyses of Christmas Bird Count data. Taken from long-term trends (1966-2017), these data suggest an annual increase of 3.88% (1.77-5.91% annual increase) in this species. This would equate to an increase of 70.93% (28.11-124.76%) over three generations.

  2. James Westrip (BirdLife) says:

    Preliminary proposals

    Based on available information, our preliminary proposal for the 2018 Red List would be to adopt the proposed classifications outlined in the initial forum discussion.

    There is now a period for further comments until the final deadline in mid-July, 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 those in the initial proposal.
    The final 2018 Red List categories will be published on the BirdLife and IUCN websites in November, following further checking of information relevant to the assessments by both BirdLife and IUCN.

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