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

with some pine trees, mostly pinyon and
ponderosa pine (Happy Valley Saddle).
• Conifer Forest. Two high-elevation
random transects (113 and 191) and one
non-random transect (Rincon Peak).
Forests of ponderosa pine, Douglas-fir,
and some Gambel oak.
Repeat-visit VCP Surveys
We recorded 143 species at all repeat-visit VCP
stations combined. We found the most species
in the Riparian community (n = 102 species) and
fewest species in the Conifer Forest community
(n = 51; Appendix G), though survey effort
among communities was unequal (Table 5.2).
The number of species found in the other three
communities was intermediate (Appendix G). As
expected, estimates of species richness (using the
1 st order jackknife procedure) followed the same
pattern: the Riparian community was the most
species rich (n = 119 species) and the Conifer
Forest was the least species rich (n = 69). The
Sonoran Desertscrub (n = 97 species), Pine-oak
Woodland (n = 93 species), and Oak Savannah (n
= 79) were intermediate.
We recorded twelve species in all five
communities and 39 species in only a single
community (Appendix G). The ash-throated
flycatcher was the most widespread species; we
recorded it on 93% (21 of 23) of repeat-visit
transects. We recorded four other species at
>75% of transects: rufous-crowned sparrow,
common raven, brown-headed cowbird, and
white-winged dove. We recorded an additional
22 species on >50% of transects and an equal
number of species on only a single transect.
The white-winged dove had the highest mean
frequency of detection (1.25 + 0.44) across strata
and it was the only species for which we recorded
54
an average of over one individual per station.
The mourning dove (0.98 + 0.42) and ashthroated
flycatcher (0.85 + 0.24) were the only
other species with relative frequency of detection
estimates > 0.75.
There were differences in mean relative
abundance estimates among transects (F 4, 263
= 4.2, P = 0.003, ANOVA on log-transformed
data). Specifically, the Conifer Forest community
was different from both the Riparian and Pineoak
Woodland communities (Table 5.3). Mean
species richness per visit also varied among
communities (Table 5.3; F 4, 111 = 6.7, P = < 0.001,
ANOVA). The Riparian community had the most
species per visit and was significantly different
from all communities except the Conifer Forest
community.
We calculated relative abundance for 120
species (Table 5.4). The most abundant species
(based on relative abundance estimates) for each
community type were:
• Riparian: verdin, Lucy’s warbler, and
mourning dove;
• Sonoran Desertscrub: black-throated
sparrow, cactus wren, and verdin;
• Oak Savannah: Bewick’s wren, rufouscrowned
sparrow, and ash-throated
flycatcher;
• Pine-oak Woodland: Bewick’s wren,
spotted towhee, and black-throated gray
warbler;
• Conifer Forest: yellow-eyed junco,
mountain chickadee, and spotted towhee
and cordilleran flycatcher.
Reconnaissance VCP Surveys
We recorded 75 species during reconnaissance
VCP surveys in 2002, including two species
that we did not record during repeat-visit VCP
Table 5.3. Bird measures by community type and compared using Tukey-Kramer multiple pairwise
procedure, Saguaro National Park, Rincon Mountain District, 2001 and 2002. Communities with different
superscripted letter(s) are significantly different (P < 0.05).
Riparian Sonoran Desertscrub Oak Savannah Pine-oak Woodland Conifer Forest
Bird measure Mean SE Mean SE Mean SE Mean SE Mean SE
Relative abundance (log transformed) -3.4 a 0.2 -3.1 a 0.2 -2.7 b 0.2 -3.2 a 0.2 -2.2 b 0.2
Species richness a 25.9 a 0.7 22.1 b 0.8 21.2 b 1.1 20.6 b 0.9 22.1 b 1.2
a From 1 st order jackknife procedure.