Yellowstone Cougars: Ecology before and during Wolf Restoration
335
Yellowstone Cougars: Ecology before and during Wolf Restoration
335eBook
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Overview
Of practical importance, Yellowstone Cougars addresses the management and conservation of multiple carnivores in increasingly human-dominated landscapes. The authors move beyond a single-species approach to cougar management and conservation to one that considers multiple species, which was impossible to untangle before wolf reestablishment in the Yellowstone area provided biologists with this research opportunity.
Yellowstone Cougars provides objective scientific data at the forefront of understanding cougars and large carnivore community structure and management issues in the Greater Yellowstone Ecosystem, as well as in other areas where wolves and cougars are reestablishing. Intended for an audience of scientists, wildlife managers, conservationists, and academics, the book also sets a theoretical precedent for writing about competition between carnivorous mammals.
Product Details
| ISBN-13: | 9781607328292 |
|---|---|
| Publisher: | University Press of Colorado |
| Publication date: | 09/23/2019 |
| Sold by: | Barnes & Noble |
| Format: | eBook |
| Pages: | 335 |
| File size: | 11 MB |
| Note: | This product may take a few minutes to download. |
About the Author
Polly C. Buotte is currently a research ecologist at Oregon State University, working to improve ecosystem models to assess the influence of climate change on the carbon cycle. She previously worked with the Selway Institute, Hornocker Wildlife Institute, and Wildlife Conservation Society, studying cougars in Yellowstone.
Maurice G. Hornocker is a wildlife biologist and founder of the Hornocker Wildlife Institute in 1985 and the Selway Institute in 2005. Throughout his 50-plus-year career he has studied big mammalian carnivores, beginning with his experience with the Craighead brothers and grizzlies in Yellowstone. He has since initiated and directed original research on the big cats on several continents, authored and coauthored more than 100 scientific publications, and received numerous awards for his work, including the Wildlife Society’s 2010 Book of the Year award for Cougar: Ecology and Conservation.
Read an Excerpt
CHAPTER 1
Introduction and Background
What carnivores eat, their hunting behavior and habitat use, and how they survive is not only a function of their predatory nature but also hinges on the pivotal role other large carnivores play in the lives of less dominant ones — by competing with them for food, by preying on them, or both (Creel 1998; Ballard et al. 2003; Caro and Stoner 2003). In some instances, competition for resources determines whether one predator is even allowed to live where another predator exists, which can have important implications for carnivore management and conservation (Donadio and Buskirk 2006; Murphy and Ruth 2010). For instance, rare African wild dogs do not fare well where African lion and spotted hyena densities are high (Creel and Creel 1996, 2002). Competition with coyotes (Canis latrans) reduces survival of endangered San Joaquin kit foxes (Vulpes macrotis multica), although kit foxes reduce some of this predation mortality by avoiding coyote-dominated shrub habitats (Cypher and Spencer 1998; Nelson et al. 2007). Hence, along with predation, competition between carnivores for resources has important implications for the structure and function, as well as conservation, of ecological communities (Schoener 1982; Palomares and Caro 1999; Linnell and Strand 2000; Creel et al. 2001; Caro and Stoner 2003).
At the time of European settlement of North America, cougars (Puma concolor), wolves (Canis lupus), black bears (Ursus americanus), and brown bears (U. arctos) were widely distributed, occupying diverse habitats (Wilson and Ruff 1999; Laliberte and Ripple 2004). Such extensive distribution meant that many carnivores were regionally sympatric, and during their co-evolution, interspecific interactions and competition may have been one of several evolutionary forces contributing to the structure of assemblages of carnivores in the various environments (Schaller 1972; Mills 1990; Caro 1994; Durant 1998). As human settlement increased, particularly in the 1800s and early 1900s, people altered habitats and drastically changed carnivore distribution and abundance. In most of the United States, the complex system of interactions between these species was altered or eliminated. Large carnivores now occupy remnants of their former distribution — grizzly bears persist in roughly 45 percent of their historical range and cougars and wolves in about 60 percent of theirs (Laliberte and Ripple 2004: 126).
Although scientific research has advanced our understanding of carnivores substantially since the early 1970s, we are still learning how to live with cougars and wolves and how best to understand their management and conservation needs in the various states where they remain or are becoming restored (Mech and Boitani 2003a; Hornocker and Negri 2009; Jenks 2011). During the time we were writing this book, wolves in Idaho and Montana reached numbers that met federal goals for recovery from endangered status; they were frequently in the news, and their status was haggled over in and out of the courts. Wolves were delisted from endangered status in 2008, quickly relisted after litigation, and delisted again in 2009. They were hunted in Idaho and Montana in the winter of 2009–10, relisted as endangered in August 2010, and then fully delisted, with hunting resumed in both states in late 2011 (Idaho Department of Fish and Game 2012). Later, on September 30, 2012, Wyoming assumed management authority for wolves (Wyoming Game and Fish Department 2013). Meanwhile, cougars were in the news as they worked their way eastward, showing up on remote cameras, shot in farmers' fields, or killed along highways in Nebraska, Missouri, Michigan, Wisconsin, and other midwestern states (Cougar Network 2012).
Questions concerning how species within the large carnivore guild interact, how they partition resources, and what enables or hampers their coexistence are pertinent to management and conservation of these large species as they are restored in our human-dominated landscape. However, in most ecosystems in North America, little information has accumulated regarding such interspecific interactions. This is the case for several reasons. Sustaining long-term ecological studies of large carnivore populations is challenging and expensive because they necessitate working at large spatial scales (Hobbs 1996; Garrott and White 2009). In addition, the rarity of multi-species carnivore assemblages has made investigation of communities of carnivores less common than the single-species approaches that have thus predominated in conservation efforts for these large species. Hence it is not surprising that much of what we have learned about cougars has occurred in the absence of wolves, their main natural competitors.
Given limited funding and logistical support, many studies on cougars have lasted only two to four years — far short of the cougar's natural life span of twelve to fourteen years for females in the wild. However, more recently, a number of studies have provided continual investigation over eight years or more (Beier 1996; Logan and Sweanor 2001; Maehr et al. 2002; Beier et al. 2003; Laundré and Clark 2003; Laundré et al. 2007). In comparison, much greater numbers of short- and long-term research studies have amassed critical information on wolves and bears, both in and beyond Yellowstone National Park. But again, most of these studies, including the famous studies of wolves in Alaska and Michigan (see Mech 1970; Carbyn et al. 1995; Mech and Boitani 2003a), have occurred in the absence of cougars.
Today only a few relatively intact ecosystems remain where we can further our understanding of interactions among multiple large carnivores. With the restoration of wolves in 1995 and 1996, the Greater Yellowstone Ecosystem became one of these.
This book is about cougar ecology and how cougars responded to the restoration of their main competitors, wolves, on the Greater Yellowstone Northern Range. At its core, our research was directed toward understanding whether cougars and wolves would compete for certain resources directly and indirectly, how they might sort out the landscape as a result of competition and avoidance, and whether wolves negatively affected cougar population performance, including survival and reproduction. These questions encompass topics that have been of interest to the general public, hunters, agencies charged with management of these controversial top carnivores, and conservationists seeking to incorporate ecological and community information into long-term wildlife conservation.
The book is arranged in five parts consisting of eighteen chapters. This first part covers background on development of the project and includes the evolutionary history and taxonomy of cougars and wolves, describes the study area, highlights how we went about quantifying competition and coexistence, and describes our methods of studying cougars before and during wolf restoration. Prey selection, kill rates, and interactions at kills are the focus of part 2. Part 3 addresses whether the movement behavior and spatial-habitat use patterns of cougars changed after wolf restoration. In part 4 we assess whether reproduction, survival, and numbers of cougars have been negatively influenced by the presence of wolves. Finally, in part 5 we synthesize our findings and present our ideas for the management and conservation of cougars in the Greater Yellowstone Ecosystem and in states where cougars and wolves are now naturally being restored.
Co-Evolution and Taxonomy of Cougars and Wolves
Up until the time they were eradicated by humans from much of their range, cougars and wolves shared a long evolutionary history across North, Central, and South America. At one time cougars had the broadest geographic distribution of any terrestrial mammal in the Western Hemisphere (Logan and Sweanor 2001; Cougar Management Guidelines Working Group 2005; Culver 2010).
Cougars, wolves, and other extinct and extant carnivores originated from a common ancestor between 65 million and 55 million years ago during the Miocene — from a tree-dwelling shrew-like predator called a miacid that scurried after insects (Ewer 1973; Macdonald 1992). At the base of the carnivores' story were two types of miacids, one that probably looked much like modern martens — vulpavines — and the other resembling modern genets — viverravines. These early arboreal carnivores gave rise to two main branches of the order Carnivora: the Canoidea arose from the vulpavines of the New World, and the Feloidea arose from the Old World viverravines (Ewer 1973; Kleiman and Eisenberg 1973; Macdonald 1992).
The teeth of the Canoidea and Feloidea exemplify the differences in skeletal structure that separate these two major divisions. In the canids, one of the lower carnassials retains a broad shelf (talonid) that provides a dual function — cutting at the front and crushing behind — which enables mastication of food; hence, digestion can begin in the mouth (Tedford 1994). As a result, dogs and their close relatives can process a variety of foods — meat, bone, sinew, invertebrates, plants — which provides great survival value because the wider range of food enables the canids to adapt to shifting resources as local conditions dictate. The dog branch diversified and gave rise to four caniform families: dogs (Canidae), bears (Ursidae), weasels (Mustelidae), and raccoons (Procyonidae). Members of the cat group, in contrast, lack the talonid shelf, and their molars are all specialized to cut meat and deliver the chunks whole to the stomach for digestion (Tedford 1994). Four feliform families sprouted from the cat branch: cats (Felidae), civets (Viverridae), hyenas (Hyaenidae), and mongooses (Herpestidae).
Tracing the diversification of modern felids and canids is not easy (Ewer 1973; O'Brien and Johnson 2007). Fortunately, advances in DNA sequencing have allowed mapping of the genomes of various species, which made it possible to construct the first resolved family tree for cats (Culver 1999; O'Brien and Johnson 2007) and an improved tree for the dog family (Wayne and Vilà 2003).
Evolutionary History of Cougars and Wolves
Before modern carnivore families appeared, the dog and cat branches evolved separately in the New World and the Old World. When the Bering land bridge opened up between America and Eurasia roughly 30 million years ago, representatives of each branch made the crossing, and dogs and cats came face to face (Macdonald 1992).
The cougar belongs to the extremely old puma lineage, members of which originated from a common North American ancestor roughly 7 million to 8 million years ago (Culver 2010). The puma lineage also includes the cheetah (Acinonyx jubatus) and jaguarondi (Puma yaguarondi), with the cheetah first to diverge from the common felid ancestor about 5 million to 8 million years ago, making it the second closest relative of the cougar (Johnson and O'Brien 1997; Turner and Antón 1997; Culver 2010). Later, the jaguarondi and cougar diverged around 4 million to 5 million years ago, making them the closest relatives in the puma lineage (Janczewski et al. 1995; Johnson and O'Brien 1997; Johnson et al. 2006; Culver 2010).
Fossil evidence in North America suggests that cougars or an ancestor may have evolved in North America and migrated to southern continents approximately 2 million to 4 million years ago (Patterson and Pascual 1968; Webb 1976; Logan and Sweanor 2001; Culver 2010). But more recent research using genetic tools finds disagreement between the fossil record and the molecular data. Specifically, molecular analyses indicate that the oldest cougar population inhabits Brazil and Paraguay, the North American population is the most recently founded, and cougars as a species are ~0.39 million years old (Culver et al. 2000). Around 10,000–17,000 years ago, during the late Pleistocene, the North American cougar population experienced a demographic contraction event, or "bottleneck," persisting as a small population while many other large mammals went extinct (Driscoll et al. 2002). Descending from a "founder event" involving this small number of individuals, modern North American cougars then expanded from the south, where populations remained stable, to the north, where populations had been extirpated (Culver et al. 2000; Culver 2010). This relatively young age for cougars in North America is directly related to the lack of genetic diversity and differentiation observed in extant North American cougars (Culver 2010: 33). Providing further evidence to support expansion from south to north, molecular genetic data show higher levels of genetic variation among cougars in California and Arizona–New Mexico than among cougars residing farther north (Ernest et al. 2003; McRae et al. 2005).
Wolves arose at about the same time cougars did. By the Pliocene, Canis had diversified and become widespread in both the Old World and North America, with wolf-like canids diverging from a common ancestor approximately 2 million to 3 million years ago (Nowak 1979; Wayne et al. 1995). A related branch of small canids entered South America and began an entirely separate evolutionary lineage (Nowak 1979; Kurtén and Anderson 1980; Tedford et al. 1995). It is likely that wolves arose from some population of those small early canids and that the ancestral line also led to coyotes (Nowak 2003). Wolf and coyote lineages diverged between 2.5 million and 1.8 million years ago, not long after divergence of the cougar and jaguarondi lineages (Kurtén 1974; Nowak 1979).
The emergence of modern wolves occurred sometime between 300,000 and 130,000 years ago (Nowak 1979; Wayne et al. 1995). An ancestor to today's wolves probably arose in North America and crossed via the Bering land bridge into Eurasia, where it evolved in the direction of C. lupus, the gray wolf (Nowak 2003). The gray wolf is thought to have developed fully in the Old World and then reinvaded the New World in the Pleistocene by once again crossing the Bering land bridge (Nowak 1979; Kurten and Anderson 1980; Brewster and Fritts 1995). Wolf populations of the Old and New World show varying degrees of genetic subdivision, and this, in combination with the extremely high mobility of wolves, suggests the effect of multiple invasions following the numerous glacial advances and retreats of the Pleistocene (Wayne et al. 1992; Forbes and Boyd 1996, 1997; Vilà et al. 1999a).
Regardless of their exact point of origin, cougars and wolves fared well after the late Pleistocene extinctions when the demise of mega-herbivores led to the demise of many of the larger carnivores (Macdonald 1992). Five species of carnivorous mammals disappeared from North America at the end of the Pleistocene: giant short-faced bear, American lion, American cheetah, sabertooth, and dire wolf (Pielou 1991). As many of the larger carnivores went extinct, interspecific competition would have declined somewhat, and the midsized cougar was well adapted to subsist on the smaller, soft-skinned grazers as well as on a wide range of other prey in various habitats (Logan and Sweanor 2001). After the extinction of their dominant competitor, the dire wolf (C. dirus), about 8,000 years ago, gray wolf populations grew and remained abundant until they were all but exterminated by modern hunters (Pielou 1991). Along with cougars and wolves, several other midsized to large North American carnivores survived the extinctions: grizzly and black bears, wolverines, coyotes, badgers, red and gray foxes, lynxes and bobcats, and polar bears (Pielou 1991). Thus, in addition to wolves, cougars still had to contend with a few formidable competitors.
Taxonomy
From the mid-1700s to the mid-900s — using morphological characteristics, habitat, and general geographic distribution — biologists described thirty-two distinct subspecies of the cougar, distributed throughout North and South America (Young and Goldman 1946). The cougar was originally named Felis concolor by Linneaus in 1771 (Wozencraft 1993; Culver 2010) and later renamed Felis (Puma) concolor when Jardine (1834) recognized Puma as a subgenus of Felis. Although Puma was recognized as a separate genus as recently as 1973 (Ewer 1973), Felis remained the more commonly referenced genus until the mid-1990s. By then, taxonomy could draw upon molecular genetics to examine the accuracy of generic and subspecific divisions. When cougar DNA was analyzed from blood and tissue samples collected throughout the Americas, Culver and colleagues (2000) determined that there were six groups of cougars, not thirty-two, across their range. One cougar subdivision occurred from Nicaragua northward and five subdivisions existed south of Nicaragua. Apparently, cougars had been breeding with each other, wandering great distances to do so and even swimming substantial bodies of water, over much larger areas than originally thought. In South America a high level of genetic diversity was found in cougars, whereas Central and North American cougars, north of Nicaragua, had only moderate levels (microsatellite DNA) to no variation (mitochondrial DNA). Culver and co-workers (2000, 2011) eventually proposed taxonomic revisions to include the six subspecies: in North America Puma concolor cougar, Central America P. c. costaricensis, northern South America P. c. concolor, eastern South America P. c. capricornensis, central South America P. c. cabrerae, and southern South America P. c. puma.
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Copyright © 2019 Toni K. Ruth, Polly C. Buotte, and Maurice G. Hornocker.
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