Predation Risk, Elk, and Aspen: Comment

With the exception of humans, gray wolves (Canis lupus) are perhaps the most significant predator of cervids in the northern hemisphere, mainly due to the group-hunting, year-round activity, and widespread geographic distribution (Peterson et al. 2003). Thus, interactions between wolves and large herbivore prey, such as elk (Cervus elaphus) and moose (Alces alces), have long been of interest to biologists (Peterson 1995, Jęodrzejewska et al. 2000, Mech and Boitani 2003). The potential ecological role this apex predator may have, via trophic cascades, has also received attention in recent years by researchers (e.g., Callan et al. 2013, Kuijper et al. 2013, 2014), wildlife management agencies (e.g., state wolf management plans), as well as the general public. Perhaps nowhere in the western United States has a heightened examination of this large predator been more focused than in Yellowstone National Park (YNP; Laundré et al. 2001, Smith et al. 2003, 2013, Fortin et al. 2005). Here, wolves were reintroduced in the mid-1990s, again completing the park\u27s large predator guild after approximately seven decades of absence, thus providing a long-term, landscape-scale, natural experiment (Diamond 1983). The Gallatin winter range is one of two that occur along the northern portion of YNP, the other is the northern ungulate winter range, or “northern range,” located some 25 km or more to the east. Of these, the Gallatin has been less studied. Nevertheless, the Gallatin winter range, like the northern range, experienced high levels of elk herbivory following the extirpation of wolves in the early 1900s. Over a period of approximately seven decades, intensive herbivory by elk led to the long-term decline in aspen (Populus tremuloides) and willow (Salix spp.) recruitment (i.e., growth of young plants above the browse level of elk) in the Gallatin winter range, leaving these plant communities in an impoverished condition (Lovaas 1967, Patten 1968, Kay 2001, Ripple and Beschta 2004, Halofsky and Ripple 2008). Accelerated soil and channel erosion also occurred (Lovaas 1967, Beschta and Ripple 2006). Thus, when wolves were reintroduced into Yellowstone in the mid-1990s, aspen recruitment within the Gallatin elk winter range, had been largely absent for several decades (Kay 2001, Halofsky and Ripple 2008). In 2010, Winnie (2012) sampled 65 aspen stands in the northwestern corner of YNP, within the Gallatin elk winter range, to determine if a behaviorally mediated trophic cascade (BMTC) was occurring. As background information Winnie (2012:2600) included only a single sentence about wolves in the Greater Yellowstone Ecosystem and the remainder of the paragraph briefly discussed elk numbers, with most of the emphasis on elk in YNP\u27s northern range where there has been a pronounced redistribution of elk since the reintroduction of wolves (White et al. 2012). A more complete summary regarding the status and dynamics of wolves and elk over the last 15 years (i.e., 1995–2010) in the Gallatin elk winter range, as well as in the Daly Creek sub-drainage where Winnie\u27s study occurred, would have helped readers better understand the context of his study. Furthermore, information regarding human harvest of elk in the Gallatin winter range since the return of wolves, or whether such hunting has been affecting elk numbers or distribution in recent years was not provided. As part of his 2010 field study, Winnie (2012) characterized the presence or absence of several hypothesized risk factors (independent variables) for each aspen stand, including escape impediments, visual impediments, distance to conifer forest edge, and presence of deadfall trees. For dependent variables, Winnie (2012) recorded the presence or absence of browsing on aspen suckers (ramets \u3c2 m in height) and the number of aspen juveniles (plants \u3e2 m in height but \u3c6 cm in diameter at breast height). A height of 2 m generally represents the upper browse level of elk, and young aspen exceeding this height are considered to have successfully recruited. Such recruitment would represent a major departure from the browsing suppression that occurred in his study area over recent decades (Kay 2001, Halofsky and Ripple 2008) and an indication that a tri-trophic cascade involving wolves, elk, and aspen may be underway. From the results of his analyses, Winnie (2012:2600) concluded that “aspen were not responding to hypothesized fine-scale risk factors in ways consistent with the current BMTC hypothesis.” We respectfully submit that the design and analysis used to support such a conclusion may be deficient for two reasons, the first based on conceptual concerns and the second on statistical concerns. (1) Unfortunately, some aspen stands Winnie (2012) sampled contained juveniles associated with “physical barriers,” barriers that could prevent elk from browsing young aspen. To be scientifically valid, a risk assessment using young aspen as the dependent variable must inherently assure that all evaluated plants were accessible to elk browsing. (2) The inclusion of 10 aspen stands containing some physically protected aspen likely confounded results from his predation risk analyses (i.e., Figs. 5, 6, and 7 in Winnie 2012). While the inclusion of stands with protected aspen may increase the variance associated with his dependent variables (i.e., browsing rate, number of juveniles), the fallacy of doing so is revealed by inspecting these variables for the 85% of his stands (n = 55 stands) that did not have physically protected aspen. Here, a browsing rate of ∼99% and an average of \u3c1 juvenile per stand occurred (back-transformed means from Fig. 8b and a, respectively [Winnie 2012:2609]), indicating a general lack of variance in the dependent variables associated with these stands and little likelihood of a statistically significant outcome. Thus, we suspect that the “statistically significant” results Winnie (2012) found in Figs. 5, 6, and 7, whether contrary to or in support of a BMTC hypothesis, are primarily influenced by the occurrence of risk factors associated with those stands where some of the young aspen were physically protected. A reanalysis by Winnie of browsing rate and number of juveniles vs. his risk factors, using just the 55 stands accessible to elk, could clarify this issue. Because of the above concerns, we would offer that results of Winnie\u27s (2012) analyses of “proportion of sprouts browsed” or “number of juveniles per stand” relative to his hypothesized risk factors may well be spurious. If so, any discussions and conclusions based on those results are in question. A 2004 field study of aspen stands in the Gallatin winter range found aspen recruitment had declined precipitously following the extirpation of wolves in the 1920s and remained essentially absent through the late 1990s (Halofsky and Ripple 2008). Thus, when Winnie (2012) undertook his field study in 2010, a wolf–elk–aspen trophic cascade had not yet been confirmed. While the occurrence of juvenile aspen would be important to the long-term survival of aspen stands, the data for elk-accessible stands continue to show exceptionally high browse rates and little or no recruitment (Winnie 2012). This situation contrasts with YNP\u27s northern range where decreased browsing and increased heights of young aspen in portions of that range have been observed some 6–10 years after the occurrence of increased willow growth, although this recruitment has been spatially patchy (e.g., Ripple and Beschta 2012, Painter 2013; also see northern range photos of aspen recruitment available online).5 It should be noted that decreased browsing and increased heights of willows in the Gallatin winter range (at the base of the Daly Creek watershed) following the return of wolves, and consistent with the occurrence of a trophic cascade, were documented as early as 1999–2000 (Ripple and Beschta 2004), with heights continuing to increase in more recent years (Beschta and Ripple 2010). Also consistent with a trophic cascade, various northern range studies have found increased willow growth/canopy cover, sometimes interacting with climatic fluctuations, following wolf reintroduction (e.g., Groshong 2004, Beschta and Ripple 2007, Beyer et al. 2007, Baril 2009, Tercek et al. 2010, Marshall 2012). The occurrence of 192 juvenile aspen within Winnie\u27s (2012) study area would seem to indicate the beginnings of a tri-trophic cascade, particularly when compared to the lack of juvenile production in the decades immediately before wolf reintroduction (Halofsky and Ripple 2008). However, most of the 192 juveniles were associated with aspen stands characterized as having some degree of physical protection from elk (Fig. 8a in Winnie 2012), making it difficult to confirm if they represent a wolf–elk–aspen trophic cascade involving density and/or behavioral mediation. A trophic cascade involving aspen can be complex and context dependent (e.g., linked to bottom-up factors such as fire [Eisenberg et al. 2013]). Furthermore, undertaking risk assessments associated with large mammalian predators and ungulates in mountainous terrain, where human hunting is also occurring across part of the landscape, can be especially challenging. While we commend Winnie (2012) for attempting such an assessment, without a reanalysis of only those young aspen accessible to elk it would appear that his evaluation may not have been sufficiently rigorous to evaluate the presence or absence of a potential BMTC in the Gallatin winter range

The impact of large terrestrial carnivores on Pleistocene ecosystems

Large mammalian terrestrial herbivores, such as elephants, have dramatic effects on the ecosystems they inhabit and at high population densities their environmental impacts can be devastating. Pleistocene terrestrial ecosystems included a much greater diversity of megaherbivores (e.g., mammoths, mastodons, giant ground sloths) and thus a greater potential for widespread habitat degradation if population sizes were not limited. Nevertheless, based on modern observations, it is generally believed that populations of megaherbivores (>800 kg) are largely immune to the effects of predation and this perception has been extended into the Pleistocene. However, as shown here, the species richness of big carnivores was greater in the Pleistocene and many of them were significantly larger than their modern counterparts. Fossil evidence suggests that interspecific competition among carnivores was relatively intense and reveals that some individuals specialized in consuming megaherbivores. To estimate the potential impact of Pleistocene large carnivores, we use both historic and modern data on predator–prey body mass relationships to predict size ranges of their typical and maximum prey when hunting as individuals and in groups. These prey size ranges are then compared with estimates of juvenile and subadult proboscidean body sizes derived from extant elephant growth data. Young proboscideans at their most vulnerable age fall within the predicted prey size ranges of many of the Pleistocene carnivores. Predation on juveniles can have a greater impact on megaherbivores because of their long interbirth intervals, and consequently, we argue that Pleistocene carnivores had the capacity to, and likely did, limit megaherbivore population sizes.National Science Foundation provided funding from EAR 1237928.http://www.pnas.orghb2016Centre for Wildlife Managemen

Vision, mission, and values: From concept to execution at Mayo Clinic

Mayo Clinic displays steadfast commitment to patient care, referral relations, and health care quality through institutional examples of unique, value-add endeavors that are under way with the Mayo Clinic Patient Experience Subcommittee and the Referring Physician Office. In this article, we share the Mayo Model of Care and patient stories that embody the 8 Mayo Clinic values of respect, compassion, integrity, healing, teamwork, excellence, innovation, and stewardship. The Mayo founders imparted to their staff the passion for patient care by encouraging a fair and just culture for its employees. This culture allows the creation, maintenance, and improvement of clinical care, research studies, and educational curricula, which in turn propagate the mission–“To inspire hope and contribute to health and well-being by providing the best care to every patient through integrated clinical practice, education, and research.

Relative efforts of countries to conserve world’s megafauna

Surprisingly little attention has been paid to variation among countries in contributions to conservation. As a first step, we developed a Megafauna Conservation Index (MCI) that assesses the spatial, ecological and financial contributions of 152 nations towards conservation of the world’s terrestrial megafauna. We chose megafauna because they are particularly valuable in economic, ecological and societal terms, and are challenging and expensive to conserve. We categorised these 152 countries as being above- or below-average performers based on whether their contribution to megafauna conservation was higher or lower than the global mean; ‘major’ performers or underperformers were those whose contribution exceeded 1 SD over or under the mean, respectively. Ninety percent of countries in North/Central America and 70% of countries in Africa were classified as major or above-average performers, while approximately one-quarter of countries in Asia (25%) and Europe (21%) were identified as major underperformers. We present our index to emphasize the need for measuring conservation performance, to help nations identify how best they could improve their efforts, and to present a starting point for the development of more robust and inclusive measures (noting how the IUCN Red List evolved over time). Our analysis points to three approaches that countries could adopt to improve their contribution to global megafauna conservation, depending on their circumstances: 1) upgrading or expanding their domestic protected area networks, with a particular emphasis on conserving large carnivore and herbivore habitat, 2) increase funding for conservation at home or abroad, or 3) ‘rewilding’ their landscapes. Once revised and perfected, we recommend publishing regular conservation rankings in the popular media to recognise major-performers, foster healthy pride and competition among nations, and identify ways for governments to improve their performance

Conserving the World’s Megafauna and Biodiversity: The Fierce Urgency of Now

First paragraph: In our recent perspective article, we noted that most (approximately 60 percent) terrestrial large carnivore and large herbivore species are now threatened with extinction, and we offered a 13-point declaration designed to promote and guide actions to save these iconic mammalian megafauna (Ripple et al. 2016). Some may worry that a focus on saving megafauna might undermine efforts to conserve biodiversity more broadly. We believe that all dimensions of biodiversity are important and that efforts to conserve megafauna are not in themselves sufficient to halt the dispiriting trends of species and population losses in recent decades. From 1970 to 2012, a recent global analysis showed a 58 percent overall decline in vertebrate population abundance (WWF 2016). Bold and varied approaches are necessary to conserve what remains of Earth’s biodiversity, and our declaration in no way disputes the value of specific conservation initiatives targeting other taxa. Indeed, the evidence is clear that without massively scaling up conservation efforts for all species, we will fail to achieve internationally agreed-upon targets for biodiversity (Tittensor et al. 2014).Additional co-authors: Holly T Dublin, James A Estes, Kristoffer T Everatt, Mauro Galetti, Varun R Goswami, Matt W Hayward, Simon Hedges, Michael Hoffmann, Luke TB Hunter, Graham IH Kerley, Mike Letnic, Taal Levi, John C Morrison, Michael Paul Nelson, Thomas M Newsome, Luke Painter, Robert M Pringle, Christopher J Sandom, John Terborgh, Adrian Treves, Blaire Van Valkenburgh, John A Vucetich, Aaron J Wirsing, Arian D Wallach, Christopher Wolf, Rosie Woodroffe, Hillary Young, And Li Zhan

Bushmeat hunting and extinction risk to the world's mammals

Terrestrial mammals are experiencing a massive collapse in their population sizes and geographical ranges around the world, but many of the drivers, patterns and consequences of this decline remain poorly understood. Here we provide an analysis showing that bushmeat hunting for mostly food and medicinal products is driving a global crisis whereby 301 terrestrial mammal species are threatened with extinction. Nearly all of these threatened species occur in developing countries where major coexisting threats include deforestation, agricultural expansion, human encroachment and competition with livestock. The unrelenting decline of mammals suggests many vital ecological and socio-economic services that these species provide will be lost, potentially changing ecosystems irrevocably. We discuss options and current obstacles to achieving effective conservation, alongside consequences of failure to stem such anthropogenic mammalian extirpation. We propose a multi-pronged conservation strategy to help save threatened mammals from immediate extinction and avoid a collapse of food security for hundreds of millions of people

The Rise of the Mesopredator

Apex predators have experienced catastrophic declines throughout the world as a result of human persecution and habitat loss. These collapses in top predator populations are commonly associated with dramatic increases in the abundance of smaller predators. Known as “mesopredator release,” this trophic interaction has been recorded across a range of communities and ecosystems. Mesopredator outbreaks often lead to declining prey populations, sometimes destabilizing communities and driving local extinctions.We present an overview of mesopredator release and illustrate how its underlying concepts can be used to improve predator management in an increasingly fragmented world. We also examine shifts in North American carnivore ranges during the past 200 years and show that 60% of mesopredator ranges have expanded, whereas all apex predator ranges have contracted. The need to understand how best to predict and manage mesopredator release is urgent—mesopredator outbreaks are causing high ecological, economic, and social costs around the world