Vascular Plant and Vertebrate Inventory of Saguaro ... - USGS

can impact other native plant and vertebrate
communities through alteration of vegetation
structure and ecosystem function. Also
associated with housing developments are
increases in the number of free-roaming feral
pets, which kill and harass native wildlife (Clarke
and Pacin 2002). Finally, with development
come roads, which act as barriers to movement
of wildlife because of direct mortality and
modification of behavior (e.g., Kline and Swann
1998, Trombulak and Frissell 2000, Clark et al.
2001, Cain et al. 2003).
Wildland fire has always played a major
role in shaping pine-oak woodlands and conifer
forests of western North America. At the Rincon
Mountain District, the forests have experienced
low- to moderate-intensity burns approximately
every decade since the 15 th century (Swetnam
and Baisan 1996). Recently (last 100 years)
active fire suppression has reduced the frequency
of these low- and moderate-intensity burns, and
increased the occurrence of high-intensity burns
(Allen 1996, Pyne 1996, Swetnam et al. 1999)
that radically alter forest structure (Swetnam and
Baisan 1996). Using data (in part) from surveys
in the district, Kirkpatrick and Conway (2006)
found a number of bird species to be positively
associated with the occurrence of fire in pine-oak
woodlands. In particular, they found the hairy
woodpecker, greater pewee, western wood pewee,
white-breasted nuthatch, Virginia’s warbler, house
wren, spotted towhee, and yellow-eyed junco to
be positively associated with moderate- to high-
intensity fires. These species were common in
the Conifer Forest community (Table 5.4) and
may reflect the recent fire history of these areas.
Short (2002) studied the effects of prescribed
fire on the high-elevation bird community of
the district. She found inconsistent results
with regard to population changes of the most
common species, but nest success of the groundnesting
yellow-eyed junco declined dramatically
the year following fires. Recent large standreplacing
fires in the nearby Santa Catalina
Mountains should reinforce to park managers the
vital role of an active prescribed-burning program
and a fire management program that allows for
some natural fires to burn their course. The park
has both of these programs and they should be
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commended for using fire to restore the district’s
high-elevation communities. We encourage
managers to include bird monitoring in these
programs (see below).
The district’s bird community has
undoubtedly undergone significant changes in the
recent past. In addition to a changed fire regime
in the high-elevation areas of the district, the
low-elevation and semi-desert grassland areas
have experienced an increase in shrubs and cacti.
Unfortunately, there are no baseline data to which
we can compare our results. There are a number
of species that probably occurred in the district
and that have undergone range-wide population
declines. Based on its distribution in the
nearby mountain ranges, the thick-billed parrot
(Rhynchopsitta pachyrhyncha) was probably
resident in the Rincon Mountains at the turn of
the 20 th century (Phillips et al. 1964). Similarly
the Aplomado falcon (Falco femoralis) was
considered common in the semi-desert grasslands
of southeastern Arizona in the late 19 th and early
20 th centuries, but no longer occurs in the region.
The district lies within the historical range for
this species (Keddy-Hector 1998), and based
on its habitat requirements, it would have been
likely to occur on the north side of the district
near Douglas Springs. The eastern bluebird
probably bred in the district; it bred in Happy
Valley (just east of the park boundary) and in the
nearby Santa Catalina Mountains in the 1970s
(Corman and Wise-Gervais 2005) but no longer
nests in these areas. There were a few incidental
records of the California condor (Gymnogyps
californianus) in the sky island region in the
1880s (Phillips et al. 1964).
Additional Research Needed
The bird community along Rincon Creek is
likely to change more than any other community
in the district if the drought and groundwater
pumping continue. The inclusion of birds in the
I&M program is encouraging and we suggest
that emphasis be put on important areas such as
Rincon Creek. Courtney Conway (University of
Arizona) is preparing to determine reproductive
success of riparian birds along Rincon Creek and
similar nearby areas to investigate the impacts of