Status and Breeding Ecology of the Arizona Grasshopper Sparrow

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The Arizona Grasshopper Sparrow (Ammodramus savannarum ammolegus) is a disjunct race that breeds in desert grasslands of southeastern Arizona, extreme southwestern New Mexico, and adjacent parts of northern Sonora and Chihuahua, Mexico.

Janet Ruth releasing a color-banded male Grasshopper Sparrow. Photo by Noel Snyder.

Janet Ruth releasing a color-banded male Grasshopper Sparrow. Photo by Noel Snyder. Public domain.

This subspecies was only recently documented as breeding in the Animas Valley of New Mexico. Partners in Flight and the U.S. Fish and Wildlife Service both consider it a subspecies of conservation concern for desert grassland habitats. Concerns regarding this subspecies focus on the apparent extreme fluctuations in a relatively small breeding population, the effects of habitat loss due to suburban development, the effects of habitat modification due to management practices such as fire and intensive grazing, and limited information about its breeding ecology. This task will provide valuable information to managers by addressing research needs identified in the Partners in Flight Bird Conservation Plans for Arizona and New Mexico. The initial phase of this research involved the repetition of historical roadside breeding-bird surveys of abundance and distribution that were conducted in 1982 and 1987 in order to compare abundance and distribution over this time period. These comparisons showed that the Sonoita and San Rafael Valleys in Arizona and the Animas Valley in New Mexico continue to support the primary population centers for this subspecies. A pattern of increasing numbers of singing males was documented from 1982–1987 from the historical surveys, and a subsequent decline to intermediate numbers (higher than 1982 but lower than 1987) was documented in 2004–2005. Small populations remain in other grassland valleys in southeastern Arizona. A second phase of this task was initiated in 2009 with Arizona Grasshopper Sparrow breeding ecology studies to map territories, measure territory vegetation, band individuals, and search for and monitor nests on two sites within the core breeding range in the Sonoita Valley.