Effects of Livestock Grazing on Mearns Quail in Southeastern Arizona

Abstract

Grazing by domestic livestock does not limit production of food supplies for Mearns quail (Cyrtonyx montezumae mearnsi) in southeastern Arizona. Nevertheless, grazing available forage in excess of 55% by weight can nearly eliminate local quail populations by removing their escape or hiding cover just prior to the nesting season. This eliminates the breeding population itself. The 46 to 50% level of utilization by weight appears to be marginal for maintaining optimum quail populations. The Mearns quail is the northernmost of three subspecies collectively known as montezumae quail. These are endemic to the pine-oak vegetation zone of Mexico with the range of C.m. mearnsi subspecies extending into portions of southern Arizona, New Mexico, and west Texas (Leopold and McCabe 1957). Arizona's population is distributed from the Mexican border north to the Mogollon Rim and from the Baboquivari Mountains east to New Mexico (Fowler 1903 in Bishop 1964, Yeager 1966). Major populations are located in the southeastern corner of the state in the oak woodland and grassland described by Lowe (1964). In 1960 the Mearns quail was legally hunted for the first time in Arizona, and since then has become a focal point for attention from preservationists and hunters alike. The limited amount of literature on the species frequently refers to the negative effect that livestock grazing has on quail densities. However, no previous investigator brought quantitative evidence to bear on the subject, and there was a lack of agreement among investigators on how grazing actually limited populations. Leopold and McCabe (1957) felt that grazing depleted the birds' food supply. Ligon (1927) felt the problem was related to cover removal. It is the intent of this paper to explain the mechanics of the relationship between livestock grazing and quail densities and to estimate the level of grazing intensity that is limiting to local quail populations.