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

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gradient (Stein 2002), and is undoubtedly related to the physiology of these taxa. The far greater number of diurnal lizards detected on both intensive and extensive surveys compared to snakes and amphibians reflects the diurnal abundance of lizards. Snakes can be both diurnal and nocturnal, but are nearly always observed less frequently than lizards during species inventories in the southwestern United States (e.g., Turner et al. 2003, Swann et al. 2000, Swann and Schwalbe 2001, Powell et al. 2005). Excluding diurnal frogs in riparian areas, most amphibians we observed were toads, which are active almost exclusively at night during the summer rainy season – clearly evidenced by the large increase in the number of toads we detected with rising humidity. In contrast, lizard activity declines with increasing humidity and cloud cover, which is consistent with our observations. Study Design Our major goals for this inventory were to apply a repeatable study design that (in some cases) allowed inference to the whole district and also to detect the maximum number of species per unit time of field effort. In general we achieved these goals, but clearly some methods were more effective than others. Intensive surveys were not highly successful at the district, in part because of its large size and environmental heterogeneity. Intensive surveys had relatively low observation rates and poor species detections. For consistency with other inventories, we stratified our study plots based only on elevation, but species richness, abundance, and distribution of reptiles and amphibians are clearly based on key habitat features such as slope, aspect, geology, and presence of water. In recognition of this, we revised our strategy in 2002, increased the number of extensive surveys at lower elevations, and were more successful in detecting rare species. If intensive surveys are included in future species richness monitoring at the district, we would recommend a stratification approach that includes wet riparian areas. Extensive surveys detected many species (n = 39), in part because more time was spent 42 using this method and areas were surveyed in both day and night. However, this method did not detect as many species as incidental observations (n = 43). As in many previous herpetological inventories (see Swann 1999a), these results indicate how difficult it is to detect many reptile and amphibian species, which tend to be rare, extremely cryptic, subterranean in their habits, or a combination of these factors. Our study confirms that, at least until better technology is available for detecting rare species, a combination of methods, including incidental sightings and collection of roadkilled animals, is essential to achieve a complete list of species. Management Issues We did not observe any federally threatened or endangered species. The Sonoran Desert population of the desert tortoise is a species of conservation concern (Appendix B) and has been petitioned for federal listing. This species is abundant in and around the district (Swann et al. 2002), and the park has both a past inventory (Wirt and Robichaux 2000) and current monitoring plans for this species. Exotic diseases in tortoises, particularly upper respiratory tract disease (Jones et al. 2005), is a concern and monitoring the health of this species should occur periodically. The canyon spotted whiptail is another species of conservation concern (Appendix B). The only known population in the district occurs at Madrona ranger station (Bonine and Schwalbe 2003). The lowland leopard frog is probably the most threatened species of herpetofauna in the district, as the park has long recognized (Swann 1997). Lowland leopard frogs seem to have declined in southern Arizona and are extirpated in parts of their former range although populations in central Arizona seemed to be stable when last reported (Clarkson and Rorabaugh 1989, Sredl et al. 1997). In addition to habitat loss, a major threat to this species is the fungal disease chytridiomycosis, an introduced, potentially pandemic disease that occurs in the district (D. Swann, unpubl. data). The district has several small populations of lowland leopard frogs, yet at least one major population was extirpated
in recent years due to sedimentation of pools following major wildland fires (Swann et al. 2003). Most other populations seem to be stable, yet their small size and isolation may be factors that, when combined with stochastic events, may threaten their long-term persistence. We suspect that the district has a relatively stable herpetofauna community. There is little evidence that non-native species (reptiles, amphibians, mammals, or birds) are having an impact on reptile and amphibian populations. For example, if Mediterranean geckos were capable of establishing themselves in the district, they probably would have already done so. The greatest threat to herpetofauna from exotic species is probably from crayfish and American bullfrogs. Crayfish could have a dramatic negative impact on populations of lowland leopard frogs, canyon treefrogs, Sonoran mud turtles, and black-necked garter snakes if they were illegally introduced into the Rincon Creek watershed. Park personnel should be vigilant to prevent establishment. Reptile poaching may occur in the park, but is probably confined to areas along the western edge of the district. We suspect that individual Sonoran desert toads (Bufo alvarius), 43 a species that is traded and used because it possesses hallucinogenic qualities, are sometimes collected in the district. Roadkill has been welldocumented at the park; park staff estimate that literally thousands of reptiles and amphibians are killed by cars each year (Kline and Swann 1998). Species most impacted by roadkill tend to be long-lived species such as the desert tortoise and Sonoran Desert toad. However, the problem is likely more severe in the Tucson Mountain District, which is more bisected by roads. Finally, habitat loss and fragmentation outside the district are major threats to all wildlife at Saguaro National Park, although likely a greater threat for mammals than for herpetofauna (see Chapter 6). The major species impacted by habitat loss are desert species with limited habitat in the park. These include the lowland leopard frog, Mexican spadefoot toad (Spea multiplicada), Great Plains toad, canyon whiptail, long-nosed leopard lizard, glossy snake, and Pima (saddled) leaf-nosed snake. If any herpetological species is extirpated from the district in the next few decades, we predict it will be a species with more specialized habitat requirements, such as the canyon spotted whiptail or lowland leopard frog.
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Powell, Halvorson, Schmidt Vascular
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U.S. Department of the Interior DIR
Page 7 and 8:
Table of Contents Report Dedication
Page 9 and 10: Table 5.8. Number of breeding behav
Page 11 and 12: Figure 6.5. Locations of non-random
Page 13 and 14: Report Dedication Eric Wells Albrec
Page 15 and 16: Acknowledgements Thanks to Saguaro
Page 17 and 18: Executive Summary This report summa
Page 19 and 20: Chapter 1: Introduction to the Inve
Page 21 and 22: them out. This information, in conj
Page 23 and 24: communities and is especially usefu
Page 25 and 26: Chapter 2: Park Overview Brian F. P
Page 27 and 28: Figure 2.2. Aerial photograph showi
Page 29 and 30: Figure 2.4. Diagram of the major ve
Page 31: Non-native Species and Changes to V
Page 34 and 35: General Botanizing Methods We colle
Page 36 and 37: Figure 3.3. Locations of modified-W
Page 38 and 39: Focal-points: General Patterns We f
Page 40 and 41: Percent 120 100 80 60 40 20 0 Plant
Page 42 and 43: well (Swantek et al. 1999). The mos
Page 45 and 46: Chapter 4: Amphibian and Reptile In
Page 47 and 48: Figure 4.2. Locations of intensive
Page 49 and 50: features. We based extensive survey
Page 51 and 52: B). Reptilian species included two
Page 53 and 54: Table 4.6. Relative abundance (mean
Page 57 and 58: Cumulative number of species 50 40
Page 59: elevation range of the district all
Page 64 and 65: Spatial Sampling Designs We establi
Page 66 and 67: Figure 5.2. Location of section bre
Page 68 and 69: the relative abundance by repeat-vi
Page 70 and 71: Analysis We report relative abundan
Page 72 and 73: with some pine trees, mostly pinyon
Page 74 and 75: Riparian Sonoran Desertscrub Oak Pi
Page 76 and 77: Table 5.5. Mean relative abundance
Page 80 and 81: Nest Adults carrying objects Other
Page 82 and 83: Cumulative number of species Cumula
Page 84 and 85: can impact other native plant and v
Page 87 and 88: Chapter 6: Mammal Inventory Don E.
Page 89 and 90: Figure 6.3. Locations of random (fo
Page 91 and 92: calculated relative abundance by pl
Page 93 and 94: Figure 6.5. Locations of non-random
Page 95 and 96: (2) Receiver triggers camera to tak
Page 97 and 98: Excluding the results for the white
Page 99 and 100: Table 6.5. Number of photographs of
Page 101 and 102: Cumulative number of species Cumula
Page 103 and 104: point out that the pond at Manning
Page 105 and 106: There is some suggestion that popul
Page 107 and 108: Chapter 7: Literature Cited Albrech
Page 109 and 110: Davis, R., and C. Dunford. 1987. An
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Kirkpatrick, C., C. J. Conway, and
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Rice, J., B. W. Anderson, and R. D.
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orderlands. Pp. 15-16. In effects o
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100 Family Scientific name Common n
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130 Order Voucher Specimen (S), Fam
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132 UA survey type Survey or specie
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138 Survey type Documentation type
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Voucher Collection type Taxon Speci
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Appendix F. List of existing vouche
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Taxon Common name Collectiona Colle
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Appendix G. Mean frequency of detec
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Species Total transects observed Lo
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Oak Savannah Pine-oak Woodland Coni
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Appendix I. Details of small-mammal
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Random or Camera Number of Number o
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