page_title: Pack rat
section_title: Climate change indicators
hierarchical_section_title: Pack rat / Midden / Climate change indicators
caption_attribution_description: English: woodrat on midden
context_page_description: A pack rat or packrat, also called a woodrat, can be any of the species in the rodent genus Neotoma. Pack rats have a rat-like appearance with long tails, large ears and large black eyes. Pack rats are noticeably larger than deer mice, harvest mice and grasshopper mice, and are usually somewhat larger than cotton rats.
context_section_description: Zoologists examine the remains of animals in middens to get a sense of the fauna in the neighborhood of the midden, while paleobotanists can reconstruct the vegetation that grew nearby. Middens are considered reliable "time capsules" of natural life, centuries and millennia after they occurred. Woodrat middens are composed of many things, including plants macrofossils and fecal pellets.
   Paleo-ecologists have used a variety of techniques to analyze the plant and animal material in pack rat middens describe paleo-communities and infer paleo-climate. For example, the plant species present in middens, and the carbon isotope ratios on material in middens have been widely studied. The analysis of middens was key in understanding the biota around Pueblo Bonito, thus helping to explain its history.
  One form of midden analysis examined the size of fecal pellets in pack rat middens. The size of woodrat pellet is proportional to the size of the woodrat. By measuring the pellets, the approximate size of the woodrat was determined based on data from a study of field-trapped woodrats. From Bergmann’s rule, differences in climate then can be determined. According to Bergmann’s rule, the body size of vertebrates is closely related to the average ambient air temperature in the region in which the vertebrate lives, so organisms in warmer regions are typically smaller than members of the same species in colder regions.
caption: Bushy-tailed woodrat on midden
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