Phenotypic variation and vocal divergence reveals a species complex in White-eared Ground-sparrows (Cabanis) (Aves: Passerellidae)

Luis Andres Sandoval Vargas
Pierre-Paul Bitton
Alana D. Demko
Stéphanie M. Doucet, University of Windsor
Daniel J. Mennill, University of Windsor

LS was supported by scholarships and grants from the Ministerio de Ciencia y Tecnología (MICIT) and the Consejo Nacional para Investigaciones Científicas y Tecnológicas (CONICIT) of Costa Rica, the Government of Ontario, the University of Windsor, and the Visiting Scholar program of the Field Museum of Natural History. PPB and ADD were supported by scholarships from the Natural Sciences and Engineering Research Council of Canada (NSERC) and Ontario Graduate Scholarships (OGS). SMD and DJM were supported by Discovery Grants, an Accelerator Grant, and Research Tools and Instrument Grants from NSERC, as well as grants from the Canada Foundation for Innovation and the Government of Ontario.


The taxonomy of the genus Melozone has recently been analyzed from genus to subspecies level, leading to a significant revision of our understanding of this group of birds. Previous studies quantified differences in phenotypic traits, behavior, and genotypes, to provide a better understanding of the underappreciated diversity within Melozone and the relationship between species within this genus. Yet the relationship between the subspecies of White-eared Ground-sparrows, Melozone leucotis, has not received thorough taxonomic scrutiny. In this study, we evaluate the taxonomic status of the three recognized subspecies of M. leucotis using multiple morphometric characteristics, plumage color features, and vocalizations. We measured plumage patterns and reflectance from museum specimens, morphometric features from museum specimens and live birds, and vocal characteristics from sound recordings. We observed substantial variation between subspecies in plumage, morphometry, and voice, especially between northern and southern birds. The phenotypic and vocal differences exhibited by M. l. occipitalis (from Chiapas, Mexico; Guatemala; and El Salvador) suggest that its taxonomic relationship with the M. l. leucotis and M. l. nigrior complex (from Costa Rica and Nicaragua, respectively) needs to be reevaluated, because these two groups are highly diagnosable from one another. Additionally, M. l. occipitalis is geographically isolated from the other two subspecies, reducing the probability of contact by natural causes in the near future. Based on the clear differences in voice, plumage, and morphometric features reported here, we propose that M. l. occipitalis be recognized as a distinct species, M. occipitalis (Salvin's Ground-sparrow), diagnosed on the basis of its longer tail, longer bill, duller plumage, and songs with a lower frequency of maximum amplitude.