site selection by Cactus Ferruginous Pygmy-owls
in southern Arizona
The distribution and density of cactus ferruginous pygmy-owls (Glaucidium
brasilianum cactorum) may be limited by the availability of suitable
nesting habitat. Consequently, it is important to identify specific
structural characteristics used by pygmy-owls when selecting a place
to nest. Presently, large columnar cacti represent the primary known
cavity substrate used for nesting by pygmy-owls in Sonoran desertscrub.
Current data limitations preclude any credible prediction of potential
nesting habitat. This project proposes to identify habitats selected
by nesting pygmy-owls in Sonoran desertscrub habitat.
We will focus our survey efforts in those portions
of Pima and southern Pinal counties where nesting
pygmy-owls have been located in the past. Currently
most of the known nesting pygmy-owls occur
within the Sonoran desertscrub upland habitat
in the northern Tucson Basin and Altar Valley.
will characterize the structure and composition
of vegetation at known pygmy-owl nest sites.
Within a 15m diameter circular plot centered
on each identified nest we will measure density
of cacti and woody plants, non-herbaceous plant
species composition, index of vertical vegetation
density, tree crown diameter, and percent ground
cover. We will also measure the following physiographic
variables: distances to nearest road, man-made
structure, available water, and desert wash.
In addition to these variables, the cavity
aspect, internal dimensions, height from the
ground and diameter will be measured.
Research results will also provide useful information about the distribution
of pygmy-owls in southern Arizona. Identifying the habitat requirements
of pygmy-owls will better enable wildlife managers and urban planners to
develop management prescriptions that can ensure future viability of pygmy-owls
For more information
Michael Ingraldi, Arizona Game and Fish Department, 5000 W. Carefree Highway Phoenix, AZ 85086-5000
Phone: (928) 523-5625 E-mail: firstname.lastname@example.org
Shawn Lowery, Arizona Game and Fish Department, 5000 W. Carefree Highway Phoenix, AZ 85086-5000
Phone: (520) 742-1911 E-mail: email@example.com