Chapter 2: A historical perspective on the population decline of the cactus ferruginous pygmy-owl in Arizona

Abstract

The cactus ferruginous pygmy-owl (Glaucidium brasilianum cactorum) was discovered in the U.S. by Bendire in 1872 in the Tucson area (Coues 1872). During the next five decades, naturalists collected many specimens of this owl and typically described the subspecies as common or fairly common along some streams and rivers of central and southern Arizona. A common view among regional ornithologists is that the cactus ferruginous pygmy-owl’s Arizona population sharply declined around 1950 (see Monson and Phillips 1981). As a result of a petition (Galvin et al. 1992), the cactus ferruginous pygmy-owl became federally listed as Endangered in Arizona in 1997 (U.S. Fish and Wildlife 1997). In retrospect, however, many questions remain on the magnitude and timing of the population decline. In this chapter, we review early records of cactus ferruginous pygmy-owls from the published literature, U.S. Forest Service files, and museum specimen collections. Evidence of a sharp population decline dating back to the early 20th century exists for the Phoenix area, including the lower Salt River. Along the lower and middle Gila River Valley, a severe population decline is also apparent but its timing is uncertain. In southern Arizona, changes in the overall status of the owl are more difficult to detect in part due to the lack of baseline information. However, along Rillito Creek and the Santa Cruz River in particular, an early population decline is also probable. Along these two rivers, and along the Salt and Gila rivers, the owl’s population decline could have coincided with intensive woodcutting and the construction of the first dams, causing deforestation and reduced waterflow early in the 20th century. The current status of the cactus ferruginous pygmy-owl population in Arizona is also addressed in Chapter 3.

Parent Publication

• Ecology and conservation of the cactus ferruginous pygmy-owl in Arizona

Citation

Johnson, R. Roy; Cartron, Jean-Luc E.; Haight, Lois T.; Duncan, Russell B.; Kingsley, Kenneth J. 2000. Chapter 2: A historical perspective on the population decline of the cactus ferruginous pygmy-owl in Arizona. In: Cartron, Jean-Luc E.; Finch, Deborah M., tech. eds. Ecology and conservation of the cactus ferruginous pygmy-owl in Arizona. Gen. Tech. Rep. RMRS-GTR-43. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. p. 17-26