Biology ETDs

Publication Date



Horned Larks, Eremophila alpestris, were collected from eight stations in New Mexico in order to investigate geographic variation in size of certain skeletal elements and in back coloration of males. Size of many mensural characters appears to increase clinically to the north; but, the effects of latitude (presumably an example of Bergmann’s Role) are often modified by local ecological conditions, notably altitude. Those characters not demonstrating this are, in general, disassociated from the main metabolic mass of the birds. Females seem more affected by the above than males. Back coloration was found to vary in much the same manner as described by previous workers. A radial increase in paleness from dark Catron and Socorro County birds and a south-north cline from red to yellowish were indicated New Mexico apparently contains one relatively well marked race, E.a. adusta, in its southwestern corner; the remainder of the state appears to lie in a broad area of integradation between the nominal races E.a. occidentalis and E.a. leuclaema. Within this zone of integradation some local differentiation in size, seemingly correlated with the relative xerosity of the different habitats, is evident. Thus larks from the Rio Grande Valley of Bernalillo County are somewhat smaller than birds from the more southerly, but higher and cooler areas in Socorro and Catron counties. Similarly, females of Socorro County are apparently smaller than females from the more mesic collecting station in Catron County and females of San Juan County are smaller than birds from the cooler and moister Great Plains of Harding County.



Document Type


Degree Name


Level of Degree


Department Name

UNM Biology Department

First Committee Member (Chair)

James Smith Findley

Second Committee Member

Howard J. Dittmer

Third Committee Member

William Jacob Koster

Included in

Biology Commons