Modeling landscape use (i.e., estimating the probability or relative probability of use, occurrence, or selection in a given area and time) by ungulates is an increasingly common and important practice in research and management. Models of occupancy, distribution, movement, habitat use, and resource selection are formal approaches by which landscape use has been characterized and results published for a myriad of ungulate species. Understanding landscape use has benefited from a growing volume of data on animal locations and model covariates, and the ease of modeling with automated software. These models are particularly noteworthy in their potential to estimate use at multiple scales, characterize individual and population distributions, and predict spatiotemporal responses to environmental change. Despite these advantages, ecological processes can be secondary or forgotten. Models without a strong ecological foundation may perform well in case studies but fail to advance our understanding of a species’ habitat requirements and response to habitat change across a broad inference space. In response, we describe criteria, synthesized from the ecological literature, of direct relevance to modeling landscape use for advancing the ecological understanding and effective management of ungulates. Criteria include (1) a knowledge coproduction framework for scientist-manager collaborations; (2) an explicit inference space with supporting replication for broad inference; (3) process covariates and their ecological scaling to address habitat requirements; (4) ecologically plausible sets of competing models; (5) model evaluation to address objectives and hypotheses of ecological importance; (6) assessment of relationships with animal and population performance; and (7) reliable interpretations for ecological understanding and management uses. Contemporary modeling of landscape use has been challenged by large, disparate data sources and an emphasis on statistical methods. However, advances in knowledge and conservation of ungulates based on tenets of ecology, management, and inference are achievable with careful consideration of these criteria.
Elk are an iconic species in the Pacific Northwest. The animals are valued as a cultural resource by American Indian tribes, and elk viewing and hunting bring economic and social benefits to many rural communities. Elk forage on grasses, shrubs, and other early-seral vegetation. As timber harvests have declined on federal land in the region over the past 30 years, so has the availability of quality elk forage. At the same time, recreation and other public uses of federal land have increased. As a result, elk are turning to private lands for forage and refuge from human disturbance. This leads to conflicts and reduced hunting opportunities.
Consequently, state and federal agencies, tribes, and hunting organizations are working to increase elk habitat on public and tribal lands where elk are a priority. In 2007, Mary Rowland and Michael Wisdom, research wildlife biologists with the USDA Forest Service, Pacific Northwest Research Station, were charged with developing new elk habitat and nutrition models for western Oregon and Washington. They enlisted the expertise of numerous scientists, and American Indian tribes provided telemetry data.
These summer range regional models of elk nutrition and habitat use incorporate the latest research on elk nutrition, elk response to disturbance, and other spatial landscape data to predict elk use of landscapes. National forests and tribes are using these models to identify areas where active management can improve elk habitat and the quality of their diets.
Conceptual and methodological tools from behavioral ecology can inform studies of habitat quality, and their potential for evaluating habitat restoration in conservation efforts is explored here. Such approaches provide mechanistic detail in understanding the relationship between organisms and their habitats and are thus more informative than correlations between density and habitat characteristics. Several Pacific salmon species have been the target of habitat restoration efforts for the past 2–3 decades, but most post-restoration effectiveness studies have been limited to correlative data described above. In mark–recapture assays from four different study years, the affinity of sub-yearling Chinook salmon (Oncorhynchus tschawytscha) and steelhead (O. mykiss) for stream pools restored with or created by engineered log structures was greater than that for pools without restoration, though with high interannual variability. From corresponding distribution and density data, it was clear that habitat affinity data are not always concordant with single observations of density. The same was true of the correlation between either affinity or density and physical characteristics of pools, although depth and current velocity had some explanatory power for both responses in Chinook. Movement into pools by Chinook during the assays indicated that restored pools can support more immigrants at a given density than can unrestored pools; however, no such pattern emerged for steelhead. Variation among individuals in body condition has implications for population-wide fitness, and such low variation was correlated with stronger affinity for pools in Chinook regardless of restoration status. This suggests that pools may mediate habitat-related trade-offs and that restoring them might have a positive effect on fitness. Thus affinity, immigration, and condition data give much-needed mechanistic indication of habitat selection for restored habitat via an apparent capacity increase and those potential fitness benefits. This is stronger support for restoration effectiveness than density differences alone because density data (1) may simply indicate redistribution of fish from poor to good habitats and (2) are not adequate to show correlations between restoration and positive change in traits correlated with fitness.
Conserving forests to provide ecosystem services and biodiversity will be a key environmental challenge as society strives to adapt to climate change. The ecosystem services and biodiversity that forests provide will be influenced by the behaviors of numerous individual private landowners as they alter their use of forests in response to climate change and any future carbon pricing policies that emerge. We evaluated the impact of forest landowners’ likely adaptation behaviors on potential habitat for 35 terrestrial, forest-dependent vertebrates across three U.S. Pacific states. In particular, we couple a previously estimated empirical-economic model of forest management with spatially explicit species’ range and habitat associations to quantify the effects of adaptation to climate change and carbon pricing on potential habitat for our focal species (amphibians, birds and mammals) drawn from state agency lists of species of conservation concern. We show that both climate change and carbon pricing policies would likely encourage adaptation away from currently prevalent coniferous forest types, such as Douglas-fir, largely through harvest and planting decisions. This would reduce potential habitat for a majority of the focal species we studied across all three vertebrate taxa. The total anticipated habitat loss for amphibians, birds and mammals considered species of state concern would exceed total habitat gained, and the net loss in habitat per decade would accelerate over time. Carbon payments to forest landowners likely would lead to unintended localized habitat losses especially in Douglas-fir dominant forest types, and encourage more hardwoods on private forest lands. Our study highlights potential tradeoffs that could arise from pricing one ecosystem service (e.g., carbon) while leaving others (e.g., wildlife habitat) unpriced. Our study demonstrates the importance of anticipating potential changes in ecosystem services and biodiversity resulting from forest landowners’ climate adaptation behavior and accounting for a broader set of environmental benefits and costs when designing policies to address climate change.