Treesearch

We intensively sampled the riparian herpetofauna at three sites in southeastern Arizona, a canyon site, Leslie Canyon, and two lowland sites, San Bernardino NWR and Empire-Ci¨¦nega Creek at Las Ci¨¦negas National Conservation Area. We also compiled a list of herpetofaunal records for the original lowland riparian area at Tucson using museum records. The herpetofaunas of the three lowland sites are more similar to one another than they were to the Leslie Canyon assemblage, and, collectively, the lowland riparian system may support the richest herpetofauna in the Southwest, at least when...

Population genetic analysis of Yarrow’s spiny lizard, Sceloporus jarrovii, suggests a metapopulational distribution pattern with potential divergence of genetically based traits. Comparing male pushup displays revealed populations east and west of the San Pedro River valley to be more similar among themselves than to those on the other side. Intensive studies of a single population revealed high site fidelity and movement constrained by the availability of crevices suitable for over-wintering and habitat with suitable thermal and humidity ranges. Observations suggest a species that does...

Previous work has shown that southeastern Arizona has a characteristic, high diversity lowland riparian herpetofauna with 62-68 or more species along major stream corridors, and 46-54 species in shorter reaches within single biomes, based on intensive fieldwork and museum record surveys. The San Pedro River supports this characteristic herpetofauna, at least some of which still occurs in the lower basin within the Sonoran Desert. It has about 64 species (55 vouchered to date), with 48-53 species within each of three somewhat ecologically homogeneous portions of the basin. This assemblage...

The western and southern edges of the Madrean Sky Island region are poorly defined and have received little study. After exploring mountains in these areas, we documented range extensions and additional records for several species of interest. Although many of these disjunct mountains have not been considered Sky Islands, their flora and fauna are similar to other areas within the region. Therefore, we suggest their biota indicate they require inclusion as part of the Madrean Sky Island region. Distribution and abundance of organisms within our study areas should be carefully inventoried...

The evolution of the western range involves millions of years of coexistence of herbaceous plants with a great many kinds of large herbivores, most of the latter suddenly removed around 13,000 years ago. The fossil record indicates more diversity of large herbivores before this time, not less, and with more taxa of large herbivores consuming more forage than livestock eat at present. With extinction of megafauna coinciding with Clovis colonization around 13,000 years ago, large herbivores and their herbivory decreased. Most of our large native herbivores vanished when these prehistoric...

The Borderlands region of the Madrean Sky Island Archipelago provides an excellent opportunity to compare a variety of landholding systems. During the past four centuries, landholding has been regulated by diverse systems that vary from the customary land distribution practices of native peoples to formalized written land laws imposed by the nation states that currently regulate land ownership and use. The following very informal review of landholding systems is intended to provide historical context for current scientific studies. Hopefully it will initiate a discussion of the relationship...

Denali National Park and Preserve, at over 6 million acres (2.5 million ha) contains the highest point in North America. Mount McKinley, at more than 20,000 feet (more than 6,000 m) above sea level, watches over thousands of caribou, moose, packs of wolves, grizzly bears, and Dall sheep, as well as many other mountains and a vast amount of rare plant life. Research was conducted at Denali in 2004 as a way to understand the experiences people have when they either fly into the park to climb Mt. McKinley or the surrounding peaks, or just to see the glaciers and mountains within the park....

Actinorhizal plants are nodulated by the symbiotic, nitrogen-fixing actinomycete Frankia. The genus Alnus in the family Betulaceae is one of the 24 genera in 8 families of angiospermous plants that are actinorhizal. Arizona alder (Alnus oblongifolia Torr.) occurs in isolated populations associated with the watersheds of Madrean Sky Islands in the Southwestern United States between 1,370 and 2,285 m in elevation. We have found root nodules on alder trees from Oak Creek Canyon in central Coconino County, Arizona, and from the Santa Catalina Mountains in southeastern and central Pima County,...

While the unique geographic location of the Sky Islands is well recognized as a primary factor for the elevated biodiversity of the region, its unique tectonic history is often overlooked. The mixing of tectonic environments is an important supplement to the mixing of flora and faunal regimes in contributing to the biodiversity of the Madrean Archipelago. The Sky Islands region is located near the actively deforming plate margin of the Western United States that has seen active and diverse tectonics spanning more than 300 million years, many aspects of which are preserved in the present-day...

We estimated the potential geographic distribution of jaguars in the southwestern United States and northwestern Mexico by modeling the jaguar ecological niche from occurrence records. We modeled separately the distributions of males and females, assuming records of females probably represented established home ranges while male records likely included dispersal movements. The predicted distribution for males was larger than that for females. Eastern Sonora appeared capable of supporting male and female jaguars with potential range expansion into southeastern Arizona. New Mexico and...