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Climate change may make habitats become unsuitable in large parts of the range of Worthen's Sparrow

Worthen’s Sparrow Spizella wortheni, © Fernando Cerra

 Worthen’s Sparrow has an extremely small and declining range and population in north-east Mexico, where its shrub-grassland habitat is threatened by agriculture and grazing. Climate change modelling shows that much of the remaining habitat may become unsuitable in just 50 years. Populations at the south-western edge of the species’s distribution may be the most viable in the long term.


(a) Historic distribution of Worthen’s Sparrow based on specimen localities

 

Worthen’s Sparrow Spizella wortheni is currently listed as Endangered because it has an extremely small and declining range and population in north-east Mexico, threatened by continued degradation of its open shrub-grassland habitat by agriculture and grazing. Climate change modelling shows that much of the remaining habitat may become unsuitable in just 50 years.

 


(b) Current potential distribution of the species based on modelling of its ‘ecological niche’

This was determined by modelling the relationship between known localities (Navarro-Sigüenza et al. 2002, 2003; see figure a) and various climatic variables to generate a predicted potential distribution (Peterson et al. 2002; figure b). This was then combined with global climate change models to generate a predicted potential distribution in 2055 (Peterson et al. 2001, 2002; figure c). The modelled distributions for present and future were brought together to determine areas that are suitable now and likely to remain so (figure d).

 


(c) Potential distribution in 2055, based on modelled current distribution and global climate change models

Many of the sites from which the species is currently known are predicted to become unsuitable in future due to climate change. Assuming that Worthen’s Sparrow has minimal dispersal ability, this analysis points to the populations at the south-western edge of the species’s distribution as the most viable in the long term.

 

 

 


(d) Potential present and future distribution of the species


Related Species

References

Navarro-Sigüenza, A. G., Peterson, A. T. and Gordillo-Martinez, A. (2002) A Mexican case study on a centralised database from world natural history museums. CODATA J. 1: 45–53.
 
Navarro-Sigüenza, A. G., Peterson, A. T. and Gordillo-Martinez, A. (2003) Museums working together: the atlas of the birds of Mexico. Bull. Brit. Orn. Club 123A: 207–225.
 
Peterson, A. T., Ortega-Huerta, M. A., Bartley, J., Sánchez-Cordero, V., Soberón, J., Buddemeier, R. H. and Stockwell, D. R. B. (2002) Future projections for Mexican faunas under global climate change scenarios. Nature 416: 626–629.
 
Peterson, A. T., Sánchez-Cordero, V., Soberón, J., Bartley, J., Buddemeier, R. H. and Navarro- Sigüenza, A.G. (2001) Effects of global climate change on geographic distributions of Mexican Cracidae. Ecol. Model. 144: 21–30.
 
Peterson, A. T., Stockwell, D. R. B. and Kluza, D. A. (2002) Distributional prediction based on ecological niche modeling of primary occurrence data. Pp. 617–623 in J. M. Scott, P. J. Heglund and M. L. Morrison eds Predicting species occurrences: issues of scale and accuracy. Washington, DC, Island Press.

Acknowledgements

 Data and figures kindly provided by A. Townsend Peterson (University of Kansas Natural History Museum and Biodiversity Research Center, USA), Adolfo G. Navarro-Sigüenza (Universidad Nacional Autónoma de México), and Enrique Martínez-Meyer (Universidad Nacional Autónoma de México).

Compiled 2004

Recommended Citation:
BirdLife International (2004) Climate change may make habitats become unsuitable in large parts of the range of Worthen's Sparrow. Presented as part of the BirdLife State of the world's birds website. Available from: http://www.birdlife.org/datazone/sowb/casestudy/185. Checked: 21/10/2014