Brad Griffith

Translocation as a Species Conservation Tool: Status and Strategy

Surveys of recent (1973 to 1986) intentional releases of native birds and mammals to the wild in Australia, Canada, Hawaii, New Zealand, and the United States were conducted to document current activities, identify factors associated with success, and suggest guidelines for enhancing future work. Nearly 700 translocations were conducted each year. Native game species constituted 90 percent of translocations and were more successful (86 percent) than were translocations of threatened, endangered, or sensitive species (46 percent). Knowledge of habitat quality, location of release area within the species range, number of animals released, program length, and reproductive traits allowed correct classification of 81 percent of observed translocations as successful or not.

Response of reindeer and caribou to human activities

Petroleum and mineral exploration and extraction, hydroelectric development, atmospheric transport of contaminants, timber harvesting and tourism are increasing worldwide, especially in the Arctic. This development may adversely affect populations of reindeer/caribou (Rangifer tarandus) which are the basis of subsistence economies for northern indigenous peoples. Our purpose is to present a survey of the literature that has investigated the response of reindeer/caribou to human activities. Individuals and groups of reindeer/caribou: 1) move away from point sources of disturbance; 2) increase activity and energy expenditure near disturbance; 3) delay crossing or fail to cross linear structures; 4) shift away from areas of extensive and intensive development; and 5) are killed by collisions with vehicles and by hunting along roads. Cows and calves during the calving season are the most easily disturbed group. Bulls in general and all reindeer/caribou during insect harassment are least likely to avoid development areas. Estimation of the proportion of a population that is exposed to disturbance and the implications of this exposure to annual energy budgets, survival and productivity of reindeer/caribou has received little attention. Future advances in understanding the implications of human disturbance to reindeer/caribou will require cumulative effects assessment at annual, population and regional scales. Although some level of cumulative effect is likely, clear separation of cumulative effects of development from natural variation in caribou habitat use and demography will be difficult.

A Bayesian Random Effects Discrete-Choice Model for Resource Selection: Population-Level Selection Inference

Abstract Modeling the probability of use of land units characterized by discrete and continuous measures, we present a Bayesian random-effects model to assess resource selection. This model provides simultaneous estimation of both individual- and population-level selection. Deviance information criterion (DIC), a Bayesian alternative to AIC that is sample-size specific, is used for model selection. Aerial radiolocation data from 76 adult female caribou (Rangifer tarandus) and calf pairs during 1 year on an Arctic coastal plain calving ground were used to illustrate models and assess population-level selection of landscape attributes, as well as individual heterogeneity of selection. Landscape attributes included elevation, NDVI (a measure of forage greenness), and land cover-type classification. Results from the first of a 2-stage model-selection procedure indicated that there is substantial heterogeneity among cow–calf pairs with respect to selection of the landscape attributes. In the second stage, selection of models with heterogeneity included indicated that at the population-level, NDVI and land cover class were significant attributes for selection of different landscapes by pairs on the calving ground. Population-level selection coefficients indicate that the pairs generally select landscapes with higher levels of NDVI, but the relationship is quadratic. The highest rate of selection occurs at values of NDVI less than the maximum observed. Results for land cover-class selections coefficients indicate that wet sedge, moist sedge, herbaceous tussock tundra, and shrub tussock tundra are selected at approximately the same rate, while alpine and sparsely vegetated landscapes are selected at a lower rate. Furthermore, the variability in selection by individual caribou for moist sedge and sparsely vegetated landscapes is large relative to the variability in selection of other land cover types. The example analysis illustrates that, while sometimes computationally intense, a Bayesian hierarchical discrete-choice model for resource selection can provide managers with 2 components of population-level inference: average population selection and variability of selection. Both components are necessary to make sound management decisions based on animal selection.

Modeling sustainability of Arctic communities: an interdisciplinary collaboration of researchers and local knowledge holders.

How will climate change affect the sustainability of Arctic villages over the next 40 years? This question motivated a collaboration of 23 researchers and four Arctic communities (Old Crow, Yukon Territory, Canada; Aklavik, Northwest Territories, Canada; Fort McPherson, Northwest Territories, Canada; and Arctic Village, Alaska, USA) in or near the range of the Porcupine Caribou Herd. We drew on existing research and local knowledge to examine potential effects of climate change, petroleum development, tourism, and government spending cutbacks on the sustainability of four Arctic villages. We used data across eight disciplines to develop an Arctic Community Synthesis Model and a Web-based, interactive Possible Futures Model. Results suggested that climate warming will increase vegetation biomass within the herd’s summer range. However, despite forage increasing, the herd was projected as likely to decline with a warming climate because of increased insect harassment in the summer and potentially greater winter snow depths. There was a strong negative correlation between hypothetical, development-induced displacement of cows and calves from utilized calving grounds and calf survival during June. The results suggested that climate warming coupled with petroleum development would cause a decline in caribou harvest by local communities. Because the Synthesis Model inherits uncertainties associated with each component model, sensitivity analysis is required. Scientists and stakeholders agreed that (1) although simulation models are incomplete abstractions of the real world, they helped bring scientific and community knowledge together, and (2) relationships established across disciplines and between scientists and communities were a valuable outcome of the study. Additional project materials, including the Web-based Possible Futures Model, are available at http://www.taiga.net/sustain.

The influence of valuational and organizational considerations on the success of rare species translocations

Abstract Translocations of rare and endangered species face significant valuational and organizational challenges; however, these dimensions are rarely discussed in the translocation literature. We employed a 98 question sample mail survey to assess these variables and received 131 responses from 110 individuals in 10 nations. In contrast to the literature which suggests that most translocations fail, a large proportion of the programs surveyed were perceived as being successful and most respondents identified relatively few valuational or organizational problems or difficulties in their translocation programs. While perceived local support was correlated with perceived translocation success, the presence of public relations/education programs was not. Therefore, simply having a public relations/education program is no guarantee that public support will increase or that a translocation will be more successful. Organizationally, translocations which established special groups or teams were perceived as increasing innovation, but not in improving program organization, nor decreasing conflict. Further, the presence of special groups or teams was not correlated with translocation success. Finally, translocations with the objective of augmenting populations were perceived to suffer from more problems, including greater local opposition, poorer public understanding, less money, and poorer leadership, than were translocations aimed at establishing or re-establishing populations. The results illustrated the difficulty of analyzing valuational and organizational aspects of conservation programs using questionnaires.

Evaluating growth of the Porcupine Caribou Herd using a stochastic model

Estimates of the relative effects of demographic parameters on population rates of change, and of the level of natural variation in these parameters, are necessary to address potential effects of perturbations on populations. We used a stochastic model, based on survival and reproduction estimates of the Porcupine Caribou (Rangifer tarandus granti) Herd (PCH), during 1983-89 and 1989-92 to obtain distributions potential population rates of change (r). The distribution of r produced by 1,000 trajectories of our simulation model (1983-89, r = 0.013; 1989-92, r = 0.003) encompassed the rate of increase calculated from an independent series of photo-survey data over the same years (1983-89, r = 0.048; 1989-92, r = −0.035). Changes in adult female survival had the largest effect on r, followed by changes in calf survival. We hypothesized that petroleum development on calving grounds, or changes in calving and post-calving habitats due to global climate change, would affect model input parameters. A decline in annual adult female survival from 0.871 to 0.847, or a decline in annual calf survival from 0.518 to 0.472, would be sufficient to cause a declining population, if all other input estimates remained the same. We then used these lower survival rates, in conjunction with our estimated amount of among-year variation, to determine a range of resulting population trajectories. Stochastic models can be used to better understand dynamics of populations, optimize sampling investment, and evaluate potential effects of various factors on population growth

Climate Change Adaptation for the US National Wildlife Refuge System

Since its establishment in 1903, the National Wildlife Refuge System (NWRS) has grown to 635 units and 37 Wetland Management Districts in the United States and its territories. These units provide the seasonal habitats necessary for migratory waterfowl and other species to complete their annual life cycles. Habitat conversion and fragmentation, invasive species, pollution, and competition for water have stressed refuges for decades, but the interaction of climate change with these stressors presents the most recent, pervasive, and complex conservation challenge to the NWRS. Geographic isolation and small unit size compound the challenges of climate change, but a combined emphasis on species that refuges were established to conserve and on maintaining biological integrity, diversity, and environmental health provides the NWRS with substantial latitude to respond. Individual symptoms of climate change can be addressed at the refuge level, but the strategic response requires system-wide planning. A dynamic vision of the NWRS in a changing climate, an explicit national strategic plan to implement that vision, and an assessment of representation, redundancy, size, and total number of units in relation to conservation targets are the first steps toward adaptation. This adaptation must begin immediately and be built on more closely integrated research and management. Rigorous projections of possible futures are required to facilitate adaptation to change. Furthermore, the effective conservation footprint of the NWRS must be increased through land acquisition, creative partnerships, and educational programs in order for the NWRS to meet its legal mandate to maintain the biological integrity, diversity, and environmental health of the system and the species and ecosystems that it supports.

Population-level resource selection by sympatric brown and American black bears in Alaska

Distribution theory predicts that for two species living in sympatry, the subordinate species would be constrained from using the most suitable resources (e.g., habitat), resulting in its use of less suitable habitat and spatial segregation between species. We used negative binomial generalized linear mixed models with fixed effects to estimate seasonal population-level resource selection at two spatial resolutions for female brown bears (Ursus arctos) and female American black bears (U. americanus) in southcentral Alaska during May–September 2000. Black bears selected areas occupied by brown bears during spring which may be related to spatially restricted (i.e., restricted to low elevations) but dispersed or patchy availability of food. In contrast, black bears avoided areas occupied by brown bears during summer. Brown bears selected areas near salmon streams during summer, presumably to access spawning salmon. Use of areas with high berry production by black bears during summer appeared in response to avoidance of areas containing brown bears. Berries likely provided black bears a less nutritious, but adequate food source. We suggest that during summer, black bears were displaced by brown bears, which supports distribution theory in that black bears appeared to be partially constrained from areas containing salmon, resulting in their use of areas containing less nutritious forage. Spatial segregation of brown and American black bears apparently occurs when high-quality resources are spatially restricted and alternate resources are available to the subordinate species. This and previous work suggest that individual interactions between species can result in seasonal population-level responses.

Variations in plant forage quality in the range of the Porcupine caribou herd

Understanding potential impacts of vegetation change on caribou energetics requires information on variations in forage quality among different plant types and over time. We synthesized data on forage quality (nitrogen, neutral detergent fiber and dry matter digestibility) for 10 plant growth forms from existing scientific literature and from field research in the Arctic National Wildlife Refuge, Alaska. These data describe forage quality of plant species in habitats found within the summer and winter range of the Porcupine caribou herd in northwestern Canada and northern Alaska, U.S.A. We compared mean levels of summer forage quality among growth forms and, where possible, estimated seasonal changes in forage quality. Preferred forage groups (deciduous shrubs, forbs, and cottongrass flowers) had higher nitrogen and digestibility, and lower fiber content, than other growth forms. Nitrogen concentration in green biomass peaked at the onset of the growing season in forbs and deciduous shrubs, whereas graminoids reached peak nitrogen concentrations approximately 15-30 days after growth initiation. In vitro dry matter digestibility (IVDMD) and concentration of neutral detergent fiber (NDF) of green biomass differed among growth forms, but did not show strong seasonal changes. IVDMD and NDF concentrations were correlated with nitrogen concentrations in studies that had paired sampling.

Winter Foraging Ecology of Moose on Glyphosate-Treated Clearcuts in Maine

The herbicide glyphosate is widely used in northern coniferous forests of the United States and Canada to promote conifer dominance on clearcut sites by suppressing regeneration of deciduous species. We determined effects of glyphosate treatment of regenerating clearcuts on (1) browse availability (total biomass, by species, and proportion with high digestible energy [DE] content), (2) browse use, and (3) diet quality of moose (Alces alces) in winter in Maine during 2 periods: 1-2 and 7-11 years posttreatment. We measured browse availability and use and collected browse samples for nutritional analyses on 12 clearcuts in January-March 1991 before aerial treatment with glyphosate of 6 of these clearcuts in August 1991. We conducted posttreatment sampling of treated and untreated clearcuts during January-March 1992 and 1993. We also sampled 14 clearcuts that had been treated with glyphosate 7-11 years earlier and 5 untreated clearcuts of similar age in January-March 1992 or 1993. Available biomass (kg/ha) of deciduous browse decreased (P = 0.001) 70% on treated clearcuts relative to untreated clearcuts from pretreatment to year 2, but was not affected (P = 0.29) at 7-11 years posttreatment. Available browse from red maple (Acer rubrum) and paper birch (Betula papyrifera) appeared to decrease less than pin cherry (Prunus pensylvanica) in years 1-2 suggesting that species composition on sites may influence the magnitude of effects on total browse availability. The proportion of deciduous browse biomass with a relatively high DE content (1.8 kcal/g) was not affected (P = 0.37) by treatment at 1-2 years, but was greater (P = 0.047) on treated than untreated clearcuts at 7-11 years posttreatment. Biomass and percent of available deciduous browse eaten by moose were not affected (P > 0.1) by glyphosate in years 1-2, but were 4-5 times greater (P 0.1) by treatment in either time period. Initial reductions in browse availability may decrease the suitability of clearcuts for foraging by moose, but this effect would decrease over the next 5-9 years because browse availability decreases naturally on untreated sites. We concluded that glyphosate did not have important effects on diet quality. Heavy browsing in older treated clearcuts suggests that moose may be attracted to these sites, but this behavior was not directly related to browse availability or nutrition. We discuss management options for minimizing effects of glyphosate treatment on moose habitat.