Discussion

With 23 species and 918 specimens, Porcupine Cave contains the richest Irvingtonian carnivore assemblage known. Today in South Park, 11 species of carnivores inhabit the area; 3 others (Canis lupus, Ursus arctos, and Mustela nigripes) have been extirpated within historic times. Remains of Spilogale putorius and Vulpes velox are common in the cave, but these species have not been reported from South Park or Park County. The 12 areas in the cave where carnivores have been found were not all open nor did they close at the same time, so the 23 species were not all faunal associates. The most productive areas in the cave for carnivores are the Badger Room, Mark's Sink, the Velvet Room, Generator Dome, and the Pit. Table 13.3 lists the most abundant species in each of these areas. The Badger Room and Generator Dome are close to the surface and had natural openings in the past; badgers, coyotes, skunks, and weasels probably denned there. The abundance of carnivores and their prey (rodents, lagomorphs) in Mark's Sink suggests a carnivore trap into which animals fell and then could not get out. If so, the cries and struggles of trapped animals would have attracted carnivores, which also would have fallen in and become entrapped; thus, over time, a talus cone would have been built below the natural opening. Carnivores in the Pit and Velvet Room tend to be small, and their remains may have been brought in by wood rats (Neotoma spp.) and in raptor pellets.

Remains of Taxidea taxus, Canis latrans, and Spilogale puto-rius outnumber all other carnivores. T. taxus (badgers) and

C. latrans (coyotes) are common in the area today. Other species—for example, Lutra canadensis, Mephitis mephitis, Urocyon cinereoargenteus, Ursus americanus, and Lynx rufUs— are represented by only a few specimens. Whether this is an artifact of preservation or collecting, or indicative of actual rarity in the fauna, is unknown. Extinct species include Martes diluviana, Martes species A, Gulo schlosseri, Mustela species A, Brachyprotoma obtusata, Canis edwardii, Canis sp., and Miraci-nonyx inexpectatus.

The diverse habitats around Porcupine Cave today include wet meadows, high and dry steppe, montane shrub, and montane forest. In the Irvingtonian, grasslands and alpine tundra as well as the other habitats supported a heterogeneous fauna; the presence of mink, otter, and muskrat indicates nearby permanent streams and ponds. At least 35 species of rodents and lagomorphs and 12 species of equids and ar-tiodactyls provided an ample prey base for the carnivores. Eurychores like the coyote, red fox, long-tailed weasel, and bobcat lived and hunted in all these communities (Armstrong, 1972). Other species are restricted to one or two of them, for example, mink and river otter in riparian areas, black-footed ferret and kit fox in grasslands, and marten and ermine in montane forests. Many species of rodents are even more habitat specific. Correlating presence and abundance with known habitat preferences and requirements of the different species helps in interpreting the paleoecology and climatic conditions during the Irvingtonian in south-central Colorado.

Work is continuing at Porcupine Cave—excavating new areas, interpreting the geology, mapping the cave and its environs, studying the extant flora and fauna—and at the museums—picking matrix, identifying specimens, describing new species, drawing and photographing specimens (including scanning electron microscope work), interpreting what has been found, and comparing the data with that for other Irvingtonian faunas. Porcupine Cave is just starting to reveal its secrets.

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