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

All species that we detected incidentally were
recorded using other methods except for the
Mexican spadefoot, canyon spotted whiptail,
ring-necked snake, western ground snake, and
Mojave rattlesnake.
Vouchers
We collected 10 specimen vouchers in 2001 and
2002 (Appendix E) and obtained voucher records
of 34 species collected by others (Appendix
F). We obtained 65 photographic vouchers of
44 species during 2001 and 2002 (Appendix E).
Photographic vouchers include five amphibian
and 39 reptile species from three orders and 17
families.
Inventory Completeness
We documented 7 species of amphibians and
39 species of reptiles during this inventory
(Appendix B). Based on the combined results
of our inventory and other recent research and
monitoring efforts for herpetofauna in the district,
we believe that 9 species of amphibians and
48 species of reptiles likely occur (Appendix
B). Therefore, our inventory effort found 81%
of the species present. Species accumulation
curves (Fig. 4.3) nearly reached an asymptote for
extensive and intensive surveys, suggesting that
additional surveys would have produced few new
species. In fact, many species that we found only
incidentally or have been documented few times
are so rare that encountering them is largely a
function of chance.
Species that we did not observe but that
we believe are present include seven species
confirmed by previous specimen vouchers
and/or confirmed by park staff during the past
decade and two other species believed to be
present based on nearby specimen vouchers and
unconfirmed observations. Species confirmed
by park staff during the time of this study are the
tiger salamander, American bullfrog, ornate box
turtle, and Mediterranean house gecko. Of these,
the non-native American bullfrog is certainly
incidental; this species has been observed at
the district in the past decade only during wet
summers, and then only as dispersing juveniles
that do not persist (Saguaro NP, unpubl. records).
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A population established in Wildhorse Canyon
in the 1970s (Kevin Black, pers. comm.) has
not been present for at least 15 years, possibly
because of the park’s effort to eliminate it. Tiger
salamanders are established in stock tanks in
Reddington Pass (north of the district) and
Danielle Foster observed one burrowed at the
base of an exotic grass that she was pulling out
near Rincon Creek in 2001. It is possible that
this species breeds in the district, but is difficult
to find because it spends little time above ground.
The ornate box turtle is likely established in the
district and staff found two individuals in 2005,
though some individuals may be periodically
released pets (P. Rosen, pers. comm.). The nonnative
Mediterranean house gecko occurs in
buildings in the Administration area only and
there is no evidence that it is established in other
areas.
Based on nearby voucher specimens and
unconfirmed observations, we believe that three
other species of reptiles and amphibians occur
in the district: long-nosed leopard lizard, glossy
snake, and saddled leaf-nosed snake. A glossy
snake was collected near the district entrance
in 1967 and this species may occur along the
district’s western boundaries. The long-nosed
leopard lizard has been observed by park staff
several times in areas such as the Javelina Picnic
Area (Robert Ellis, pers. comm., Black 1982). It
occurs on the Rocking K ranch adjacent to the
district (Murray 1996) and probably occurs in
the district as well. The checkered garter snake
(Thamnophis marcianus), a riparian species,
was reported for the district by Lowe and Holm
(1991), but we could not find any current or
historic records for this species.
Discussion
Biogeography
The Rincon Mountains contain elements of
several major biogeographic provinces, including
the Sonoran Desert to the south and west, the
Rocky Mountains to the north and east, and the
Chihuahuan Desert and Madrean “sky islands”
to the south and east (Shreve 1951, Brown 1994,
Bowers and McLaughlin 1987). The large