This little-known bird, endemic to Mexico (3), has a dull brown plumage with a distinctive head pattern. The head is steely-grey with a rufous crown and brownish markings behind and below the eye (2). Upperparts are otherwise sandy grey-brown streaked with dark brown, while underparts are buff, and the bill is pink (2).
While nesting Worthen’s sparrows appear to be rather thinly dispersed, birds in the non-breeding season have been observed congregating into single-species flocks of up to 70 individuals, occasionally in the company of other bird species (4).
Nests of three to four eggs have been found from May to July (2), with nesting males observed performing territorial songs (4).
Once extending across Mexico north into the U.S., Worthen’s sparrow has suffered a major decline and recent breeding records only exist from north-east Mexico at Tanque de Emergencia in Coahuila (100-120 individuals found in January 1998) and Las Esperanzas in Nuevo León (2).
Worthen’s sparrow is dangerously close to extinction, with just 100 to 120 individuals estimated to survive today. The species’ range has greatly retracted due to habitat loss, with open shrub-grassland having been widely destroyed by agriculture and grazing, and it seems unlikely that large tracts of habitat remain near the two currently known sites (2).
The north side of the valley at Tanque de Emergencia is managed using a rotational grazing regime that ensures that the grass always remains high in several pastures, preserving suitable habitat for Worthen’s sparrow. It would greatly benefit this rare bird if such regimes were implemented elsewhere within its range (2).
Behrstock, R.A., Sexton, C.W., Lasley, G.W., Eubanks, T.L. and Gee, J.P. (1997) First nesting records of Worthen's Sparrow Spizella wortheni for Nuevo León, Mexico, with a habitat characterisation of the nest site and notes on ecology, voice, additional recent sightings and leg coloration. Cotinga (Journal of the Neotropical Bird Club), 8: 27 - 33. Available at: http://www.neotropicalbirdclub.org/contents.asp?IssueID=8
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