Population
Estimated population is 100 - 120 (2010) and decreasing.
Status EN
Habitat destruction and degradation through conversion to agriculture and grazing is the main threat.
For more information see BirdLife International Species Factsheet.
Voice
A high, thin, fairly dry 'tssip' or 'tsip', sometimes repeated rapidly. Song is a dry, chipping trill of 2-3 second duration.
Worthen's Sparrow (Spizella wortheni) [XC324261]
by Andrew Spencer from San Rafael, Nuevo Le\u00f3n, Mexico (call)
Worthen's Sparrow (Spizella wortheni) [XC324255]
by Andrew Spencer from San Rafael, Nuevo Le\u00f3n, Mexico (dawn song)
Subspecies
Sometimes considered sister to Field Sparrow (Spizella pusilla) and has been considered conspecific, but Field Sparrow (Spizella pusilla) appears closer to Black-chinned Sparrow (Spizella atrogularis). Recently published molecular data indicate that it is sister to Brewer's Sparrow (Spizella breweri), suggesting that plumage similarities to Field Sparrow (Spizella pusilla) reflect convergence. Song is reminiscent of that of Chipping Sparrow (Spizella passerina), but molecular work suggests that the two are not sister-taxa. Subspecies browni known only from three specimens from type locality (near Sombrerete, in western Zacatecas).
The following 2 subspecies are recognised:
wortheni Ridgway, 1884 - South-eastern Coahuila and south-western Nuevo León, in north-eastern Mexico.
browni Webster, JD & Orr, 1954 - Western Zacatecas, in north-central Mexico.
Similar Species
Sympatric Aimophila spp. have different head patterns and darker bills.
References
See References.
BirdLife International Species Factsheet