The Natural History of Tassel-Eared Squirrels
Publication Year: 2010
Published by: University of New Mexico Press
Title Page, Copyright Page
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I live in the middle of an almost two-million-acre ponderosa pine forest--the largest in the world. In moments I can leave my home and be in the habitat of the tassel-eared squirrel, which I have studied for more than twenty-five years. From my dining table I can watch these tassel-eared rascals climb along a branch of a ponderosa pine, clip...
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Tassel-eared squirrels were first described and collected near the San Francisco Peaks in northern Arizona by Dr. Samuel W. Woodhouse, a physician and naturalist with Captain Lorenzo Sitgreaves' expedition in 1851. "Ears large and broad, tufted with long black gray hairs" began Woodhouse's description of the squirrels he...
2. Physical Characteristics of Tassel-Eared Squirrels
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Ear tassels have been the identifying characteristic from the very first published account of these squirrels given by Dr. Samuel Woodhouse (ref. 1). Other researchers have either reported tassel measurements or noted their existence and colorations upon collecting the various subspecies...
3. Habitat, Home Range, and Distribution
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The natural habitat of the tassel-eared squirrels is characterized by ponderosa pines. The home range is the area that includes all the travels of an individual squirrel daily and throughout the year. The geographical distribution of these squirrels is that of specific stands of ponderosa pine forests found in...
4. Food and Feeding Activities
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Feeding almost exclusively on various parts of ponderosa pine trees, Abert's squirrels' diets include inner bark or phloem of terminal shoots, seeds of ovulate cones, pollen of staminate cones, and new apical buds (ref. 1). Two other items fed upon by squirrels, associated with ponderosa pines, are dwarf mistletoe and the fruiting...
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Abert's squirrels build nests either in the tops of ponderosa pines near the trunk or in the forks of trees. Nests most often face south and east, which increases the amount of solar warming of the nest and its occupant. Branches of the nest tree frequently overlap with branches of adjacent trees, providing alternate routes for leaving...
6. Behavior and Social Interactions
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Behavior of the tassel-eared squirrels has been a focus of many researchers, with one of the first observations made in 1894: "It had a loud 'barking' call and feeds on cones of Pinus ponderosa, and usually builds its nest of branches in some lightning-blasted trees" (ref. 1)....
7. Reproduction, Embryology, and Development
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This chapter is dedicated to Michael D. Rose (1972--2000). Michael earned an MS at Northern Arizona University with me. His thesis research was on the male tassel-eared squirrel reproductive cycle. Michael died in a boating accident off the coast of California in 2000....
8. Mortality and Parasites
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In 1947, Vernon Cahalane wrote in Mammals of North America that "[r]uthless hunting or the destruction of the yellow pine forest could wipe out the . . . Kaibab squirrels" (ref. 1). Although Cahalane was addressing only one of the six subspecies of tassel-eared squirrels, his...
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The earliest genetic study, which produced the first karyotype of tassel-eared squirrels, was conducted in 1967 (ref. 1). The term "genetic polymorphism" was used to explain coat color of tassel-eared squirrels in Colorado (ref. 2). Several genetic studies have examined T-cell receptor genes, phylogeny of mitochondrial DNA,...
10. The Kaibab Squirrel
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The Kaibab squirrel was named after the geographical area where it lives, the Kaibab Plateau. Kaibab, a Piute word, means "mountain lying down." In 1882 Clarence Dutton, with the U.S. Geological Survey, wrote, "The Kaibab is the loftiest of the four plateaus through which the Grand Canyon extends . . . We, who through successive summers...
11. Ecology [Includes Image Plates]
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The importance of the relationship between the tassel-eared squirrel and the ponderosa pine forest was first noted in 1925 when Taylor stated, "Its attractive presence could ill be spared from the woods" (ref. 1). Bailey wrote of a conversation he had regarding tassel-eared squirrels on the South Rim of the Grand Canyon: "[T]he gardener...
12. Census and Monitoring Methods and Techniques
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Every research project on the tassel-eared squirrel that involves observation, monitoring, or direct contact requires a method or technique that should be consistent and reproducible. This chapter discusses the many methods and techniques used in the history of tassel-eared squirrel studies, from the first census studies when...
13. Management and Conservation of Tassel-Eared Squirrels
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Ponderosa pine forests were deemed to be endangered ecosystems in a 1995 assessment of ecosystems conducted for the National Biological Survey (ref. 1). Almost twenty years earlier, Pederson and his colleagues in Utah recommended in a paper addressing habitat requirements of tassel-eared squirrels that "the forest should be managed solely for the...
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One late summer morning, while walking through my study plots in the ponderosa pine forest at Lowell Observatory conducting a weekly census of squirrel herbivory activities, I noticed a young squirrel on the ground about 10 meters away. I stopped and we stared at each other. After a long minute of staring, the squirrel began to advance...
Appendix 1. Taxonomy of Tassel-Eared Squirrels
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The Order Rodentia contains 2,277 of the 5,416 named species of mammals, representing 42% of the mammalian biodiversity on the Earth (ref. 1). Descriptively named from the Latin rodere--to gnaw--rodents have a constant need to gnaw on surfaces to file down their ever-growing incisor teeth....
Appendix 2. History of Tassel-Eared Squirrel Nomenclature
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APPENDIX THREE: THE NATURALISTS AND THE SIX RECOGNIZED SUBSPECIES OF TASSEL-EARED SQUIRRELS
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Samuel Washington Woodhouse (1821--1904) was an American physician and a knowledgeable naturalist who accompanied the Sitgreaves Expedition, serving in both capacities (ref. 1, 2). Woodhouse collected the first tassel-eared squirrel, in October 1851, from an area in the San Francisco Peaks, near present-day Flagstaff, Arizona, and named it Sciurus dorsalis (ref. 3). Woodhouse renamed this specimen...
Appendix 4. Faunal Remains, an Artifact, and Fossils of Tassel-Eared Squirrels
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Bones, teeth, claws, feathers, and pelts that are located upon excavation within archaeological sites are useful to scientists who reconstruct ecosystems from the past and discern cultural activities during those times. Faunal remains of tassel-eared squirrels have been reported in numerous locations in the southwestern United States....
Appendix 5. A Brief Evolutionary History of Tassel-Eared Squirrels
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Jefferson's squirrel, Douglassciurus jeffersoni, is recognized as the earliest fossil squirrel. This fossil is from the late Eocene, approximately thirty-six million years ago, and was found in Wyoming in 1975 (ref. 1). Evidence suggests that tree squirrels originated in the Northern Hemisphere (ref. 2) and expanded west into...
Appendix 6. Average Measurements of Tassel-Eared Squirrels (not segregated by sex)
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Appendix 7. Tassel-Eared Squirrel Embryo Measurements
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Appendix 8. Changes in Weights of Developing Young Abert's Squirrels
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Appendix 9. Standard Mammal Measurements at Birth and Six Weeks of Young Abert's Squirrels
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Page Count: 280
Illustrations: 9 halftones, 52 color photographs
Publication Year: 2010