Explaining and predicting animal movement in heterogeneous landscapes remains challenging. This is in part because movement paths often include a series of short, localized displacements separated by longer‐distance forays. This multiphasic movement behavior reflects the complex response of an animal to present environmental conditions and to its internal behavioral state. This state is an autocorrelated process influenced by preceding behaviors and habitats visited. Movement patterns depending on the behavioral state of an animal represent the broad‐scale response of that animal to the environment. Quantifying how animals respond both to local conditions and to their internal state reveals how animals respond to spatial heterogeneity at different spatial scales. We used a state–space statistical approach to model the internal behavioral state and the proximate movement response of elk (Cervus elaphus) to available forage biomass, landscape composition, topography, and wolf (Canis lupus) density during summer in Yellowstone National Park, USA. We analyzed movement paths of 16 female elk fitted with global positioning system (GPS) radio collars that recorded locations at 5‐h intervals. Habitat variables were quantified within 175 m radii (one‐half of the median 5‐h displacement) centered on the beginning location of each interval. Stepwise model selection identified models that best explained the movement distances of each animal. The behavioral state changed very slowly for most animals (median autocorrelation r = 0.93), and all animals responded strongly to time of day (with more movement in the crepuscular hours). However, the spatial variables included in the best‐fitting models varied substantially among individual elk. These results suggest that strong patterns of habitat selection observed in other studies may result from frequent visits to preferred areas rather than a reduction of movement in those areas.

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Surveying and declaring disease freedom in wildlife is difficult because information on population size and spatial distribution is often inadequate. We describe and demonstrate a novel spatial model of wildlife disease-surveillance data for predicting the probability of freedom of bovine tuberculosis (caused by Mycobacterium bovis) in New Zealand, in which the introduced brushtail possum (Trichosurus vulpecula) is the primary wildlife reservoir. Using parameters governing home-range size, probability of capture, probability of infection and spatial relative risks of infection we employed survey data on reservoir hosts and spillover sentinels to make inference on the probability of eradication. Our analysis revealed high sensitivity of model predictions to parameter values, which demonstrated important differences in the information contained in survey data of host-reservoir and spillover-sentinel species. The modelling can increase cost efficiency by reducing the likelihood of prematurely declaring success due to insufficient control, and avoiding unnecessary costs due to excessive control and monitoring.

Identifying how habitat use is influenced by environmental heterogeneity at different scales is central to understanding ungulate population dynamics on complex landscapes. We used resource selection functions (RSF) to study summer habitat use in a reintroduced and expanding elk (Cervus elaphus nelsoni) population in the Chequamegon National Forest, Wisconsin, USA. Factors were examined that influenced where elk established home ranges and that influenced habitat use within established home ranges. We also determined grain sizes over which elk responded to environmental heterogeneity and the number of categories of habitat selection from low to high that the elk distinguished. At a large spatial extent, elk home-range establishment was largely explained by the spatial distribution of wolf (Canis lupus) territories. Forage abundance was also influential but was relatively more important at a small spatial extent when elk moved within established home ranges. Areas near roads were avoided when establishing a home-range, but areas near roads were selected for use within the established home range. Elk distinguished among 4 different categories of habitat selection when establishing and moving within home ranges. Spatial and temporal cross validation demonstrated that to improve the predictive strength of habitat models in areas of low inter-annual variability in the environment, it is better to follow more individuals across diverse environmental conditions than to follow the same individuals over a longer time period. Last, our results show that the effects of environmental variables on habitat use were scale-dependent and reemphasize the necessity of analyzing habitat use at multiple scales that are fit to address specific research questions. JOURNAL OF WILDLIFE MANAGEMENT 69(1):298-310; 2005

Entrained phenology patterns of tropical trees are expected to be sensitive to short‐term fluctuations in typical rainfall and temperature. We examined 47 mo of data on the flowering, fruiting, and new leaf phenology for 797 trees from 38 species in the Taï National Park, Côte d'Ivoire. We determined the timing of the phenology cycles in relation to seasonal rainfall, temperature, and solar radiation. Regression analysis was used to examine how variations in rainfall and temperature influenced deviations in the peaks and troughs of phenology cycles. We also investigated whether populations that fruit during periods of community‐wide fruit scarcity were those populations with relatively long‐ or short‐fruiting duration. Flower, fruit, and leaf‐flushing phenophases all exhibited 12‐mo cycles. The broad peak in flowering began with the northward zenithal passing in April and ended with the southward zenithal passing in September. Fruiting peaks occurred in the long dry season, and leaf flushing peaked in the long dry season but continued into the wet season. Deviations from phenology cycles were largely attributable to short‐term fluctuations in rainfall and/or temperature. Fruiting durations of species were related to the mean diameter at breast height. Species with long‐ and short‐fruiting durations contributed equally to fruit abundance during periods of community‐wide fruit scarcity.

Biotic invasions and habitat modification are two drivers of global change predicted to have detrimental impacts on the persistence of indigenous biota worldwide. Few studies have investigated how they operate synergistically to alter trophic interactions among indigenous and nonindigenous species in invaded ecosystems. We experimentally manipulated a suite of interacting invasive mammals, including top predators (cat Felis catus, ferret Mustela furo, stoat M. erminea), herbivores (rabbit Oryctolagus cuniculus, hare Lepus europaeus), and an insectivore (hedgehog Erinaceus europaeus occidentalis), and measured their effects on indigenous lizards and invertebrates and on an invasive mesopredator (house mouse Mus musculus). The work was carried out in a grassland/shrubland ecosystem that had been subjected to two types of habitat modification (widespread introduction of high-seed-producing pasture species, and areas of land use intensification by fertilization and livestock grazing). We also quantified food productivity for indigenous and invasive fauna by measuring pasture biomass, as well as seed and fruit production by grasses and shrubs. Indigenous fauna did not always increase following top-predator suppression: lizards increased on one of two sites; invertebrates did not increase on either site. Mesopredator release of mice was evident at the site where lizards did not increase, suggesting negative effects of mice on lizard populations. High mouse abundance occurred only on the predator-suppression site with regular production of pasture seed, indicating that this food resource was the main driver of mouse populations. Removal of herbivores increased pasture and seed production, which further enhanced ecological release of mice, particularly where pasture swards were overtopped by shrubs. An effect of landscape supplementation was also evident where nearby fertilized pastures boosted rabbit numbers and the associated top predators. Other studies have shown that both suppression of invasive predators and retiring land from grazing can benefit indigenous species, but our results suggest that the ensuing vegetation changes and complex interactions among invasive species can block recovery of indigenous fauna vulnerable to mesopredators. Top-down and bottom-up ecological release of mesopredators and landscape supplementation of top predators are key processes to consider when managing invaded communities in complex landscapes.

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