Potential Negative Ecological Effects of Corridors

Despite many studies showing that landscape corridors increase dispersal and species richness for disparate taxa, concerns persist that corridors can have unintended negative effects. In particular, some of the same mechanisms that underlie positive effects of corridors on species of conservation interest may also increase the spread and impact of antagonistic species (e.g., predators and pathogens), foster negative effects of edges, increase invasion by exotic species, increase the spread of unwanted disturbances such as fire, or increase population synchrony and thus reduce persistence. We conducted a literature review and meta‐analysis to evaluate the prevalence of each of these negative effects. We found no evidence that corridors increase unwanted disturbance or non‐native species invasion; however, these have not been well‐studied concerns (1 and 6 studies, respectively). Other effects of corridors were more often studied and yielded inconsistent results; mean effect sizes were indistinguishable from zero. The effect of edges on abundances of target species was as likely to be positive as negative. Corridors were as likely to have no effect on antagonists or population synchrony as they were to increase those negative effects. We found 3 deficiencies in the literature. First, despite studies on how corridors affect predators, there are few studies of related consequences for prey population size and persistence. Second, properly designed studies of negative corridor effects are needed in natural corridors at scales larger than those achievable in experimental systems. Third, studies are needed to test more targeted hypotheses about when corridor‐mediated effects on invasive species or disturbance may be negative for species of management concern. Overall, we found no overarching support for concerns that construction and maintenance of habitat corridors may result in unintended negative consequences. Negative edge effects may be mitigated by widening corridors or softening edges between corridors and the matrix. Other negative effects are relatively small and manageable compared with the large positive effects of facilitating dispersal and increasing diversity of native species. Efectos Negativos Potenciales de los Corredores     

Management Decentralization and Montane Forest Conditions in Tanzania

Abstract: We examined how differences in local forest‐management institutions relate to disparate anthropogenic forest disturbance and forest conditions among three neighboring montane forests in Tanzania under centralized, comanaged, or communal management. Institutional differences have been shaped by decentralization reforms. We conducted semistructured interviews with members of forest management committees, local government, and village households and measured anthropogenic disturbance, tree structure, and species composition in forest plots. We assessed differences in governance system components of local institutions, including land tenure, decision‐making autonomy by forest users, and official and de facto processes of rule formation, monitoring, and enforcement among the three management strategies. We also assessed differences in frequencies of prohibited logging and subsistence pole cutting, and measures of forest condition. An adjacent research forest served as an ecological reference for comparison of forest conditions. Governance was similar for comanaged and centralized management, whereas communal managers had greater tenure security and decision‐making autonomy over the use and management of their forest. There was significantly less illegal logging in the communal forest, but subsistence pole cutting was common across all management strategies. The comanaged forest was most disturbed by recent logging and pole cutting, as were peripheral areas of the larger centralized forest. This manifested in more degraded indicators of forest conditions (lower mean tree size, basal area, density of trees ≥ 90 cm dbh, and aboveground biomass and higher overall stem density). Greater tenure security and institutional autonomy of the communal strategy contributed to more effective management, less illegal logging, and maintenance of good forest conditions, but generating livelihood benefits was a challenge for both decentralized strategies. Our results underscore the importance of well‐designed institutional arrangements in forest management and illustrate mechanisms for improved forest governance and conservation in the context of Tanzanian decentralization reforms.     

Graduate Student's Guide to Necessary Skills for Nonacademic Conservation Careers

Graduate education programs in conservation science generally focus on disciplinary training and discipline‐specific research skills. However, nonacademic conservation professionals often require an additional suite of skills. This discrepancy between academic training and professional needs can make it difficult for graduate students to identify the skills and experiences that will best prepare them for the conservation job market. We analyzed job advertisements for conservation‐science positions and interviewed conservation professionals with experience hiring early‐career conservation scientists to determine what skills employers of conservation professionals seek; whether the relative importance of skills varies by job sector (government, nonprofit, and private); and how graduate students interested in careers in conservation science might signal competency in key skills to potential employers. In job advertisements, disciplinary, interpersonal, and project‐management skills were in the top 5 skills mentioned across all job sectors. Employers’ needs for additional skills, like program leadership, conflict resolution and negotiation, and technical and information technology skills, varied across sectors. Our interview results demonstrated that some skills are best signaled to employers via experiences obtained outside thesis or dissertation work. Our findings suggest that graduate students who wish to be competitive in the conservation job market can benefit by gaining skills identified as important to the job sector in which they hope to work and should not necessarily expect to be competent in these skills simply by completing their chosen degree path. Guía para el Estudiante de Grado de las Habilidades Necesarias para Carreras de Conservación Académicas     

Estimating the Effect of Protected Lands on the Development and Conservation of Their Surroundings

Abstract:  The fate of private lands is widely seen as key to the fate of biodiversity in much of the world. Organizations that work to protect biodiversity on private lands often hope that conservation actions on one piece of land will leverage the actions of surrounding landowners. Few researchers have, however, examined whether protected lands do in fact encourage land conservation nearby or how protected lands affect development in the surrounding landscape. Using spatiotemporal data sets on land cover and land protection for three sites (western North Carolina, central Massachusetts, and central Arizona), we examined whether the existence of a protected area correlates with an increased rate of nearby land conservation or a decreased rate of nearby land development. At all sites, newly protected conservation areas tended to cluster close to preexisting protected areas. This may imply that the geography of contemporary conservation actions is influenced by past decisions on land protection, often made for reasons far removed from concerns about biodiversity. On the other hand, we found no evidence that proximity to protected areas correlates with a reduced rate of nearby land development. Indeed, on two of our three sites the development rate was significantly greater in regions with more protected land. This suggests that each conservation action should be justified and valued largely for what is protected on the targeted land, without much hope of broader conservation leverage effects.     

Conflicting and Complementary Ethics of Animal Welfare Considerations in Reintroductions

Despite differences in focus, goals, and strategies between conservation biology and animal welfare, both are inextricably linked in many ways, and greater consideration of animal welfare, although important in its own right, also has considerable potential to contribute to conservation success. Nevertheless, animal welfare and animal ethics are not always considered explicitly within conservation practice. We systematically reviewed the recent scientific peer‐reviewed and online gray literature on reintroductions of captive‐bred and wild‐caught animals (mammals, birds, amphibians, and reptiles) to quantify the occurrence of animal welfare issues. We considered monitoring that could be indicative of the animal's welfare status and supportive management actions that could improve animal welfare (regardless of whether the aim was explicitly animal‐welfare orientated). Potential welfare issues (of variable nature and extent) were recorded in 67% of 199 projects reviewed; the most common were mortality >50%, dispersal or loss of animals, disease, and human conflict. Most (>70%) projects monitored survival, 18% assessed body condition, and 2% monitored stress levels. Animal welfare, explicitly, was referred to in 6% of projects. Supportive actions, most commonly use of on‐site prerelease pens and provision of supplemental food or water, were implemented in 79% of projects, although the extent and duration of support varied. Practitioners can address animal‐welfare issues in reintroductions by considering the potential implications for individual animals at all stages of the release process using the decision tree presented. We urge practitioners to report potential animal‐welfare issues, describe mitigation actions, and evaluate their efficacy to facilitate transparent evaluation of common moral dilemmas and to advance communal strategies for dealing with them. Currently, comparative mortality rates, health risks, postrelease stress, effectiveness of supportive measures, and behavior of individuals warrant further research to improve animal welfare in reintroductions and to increase success of such projects. Ética Conflictiva y Complementaria al Considerar el Bienestar Animal en Reintroducciones     

Critical Assessment of Claims Regarding Management of Feral Cats by Trap–Neuter–Return

Abstract:  Many jurisdictions have adopted programs to manage feral cats by trap–neuter–return (TNR), in which cats are trapped and sterilized, then returned to the environment to be fed and cared for by volunteer caretakers. Most conservation biologists probably do not realize the extent and growth of this practice and that the goal of some leading TNR advocates is that cats ultimately be recognized and treated as "protected wildlife." We compared the arguments put forth in support of TNR by many feral cat advocates with the scientific literature. Advocates promoting TNR often claim that feral cats harm wildlife only on islands and not on continents; fill a natural or realized niche; do not contribute to the decline of native species; and are insignificant vectors or reservoirs of disease. Advocates also frequently make claims about the effectiveness of TNR, including claims that colonies of feral cats are eventually eliminated by TNR and that managed colonies resist invasion by other cats. The scientific literature contradicts each of these claims. TNR of feral cats is primarily viewed and regulated as an animal welfare issue, but it should be seen as an environmental issue, and decisions to implement it should receive formal environmental assessment. Conservation scientists have a role to play by conducting additional research on the effects of feral cats on wildlife and by communicating sound scientific information about this problem to policy makers.