Evaluating recovery strategies for an ocelot (Leopardus pardalis) population in the united states

The ocelot Leopardus pardalis population in the United States was listed as endangered in 1982, with only two known isolated breeding populations occurring in southern Texas. Conservation concerns for ocelots include loss of dense thornshrub habitat, mortality from ocelot-vehicle collisions, and genetic erosion. In this study, we used a population viability analysis (PVA) to evaluate four recovery strategies (i.e., supplementation of additional ocelots, reduced road mortality, habitat protection and restoration, and linkage of two breeding populations) for ocelot conservation management. We used the VORTEX (Version 9.42) program to conduct our PVA for an ocelot population located in Cameron County, Texas. Each scenario was simulated 500 times over 100 years. We compared the effectiveness of recovery strategies and combinations thereof with estimates of extinction probability and final population size. Model scenarios with no recovery strategies predicted an extinction probability of 0.65 for the Cameron population of ocelots over 100 years. The protection and restoration of thornshrub habitat was the most effective recovery strategy, followed by population linkage and reduced road mortality, with the supplementation of ocelots being the least effective strategy. Protection and restoration of ocelot habitat cannot be accomplished without the participation of private landowners. Using an adaptive management approach, future actions need to be taken to monitor ocelot populations and habitats and help to reduce the high probability of extinction predicted in our PVA for the ocelot population in Cameron County.     

Metapopulation dynamics and conservation of the marsh fritillary butterfly: Population viability analysis and management options for a critically endangered species in Western Europe

This study investigates the dynamics and viability of a marsh fritillary butterfly Euphydryas aurinia metapopulation in a Belgian successional landscape. Based on capture-mark-recapture and winter nest census data, we first estimated demography (survival and recruitment rates, population size, density dependence) and dispersal parameters (emigration rate, effect of patch connectivity on dispersal, mortality during dispersal). Then using RAMAS/GIS platform, we parameterised a population viability analysis (PVA) model with these parameters to simulate the future of this metapopulation under different scenarios.The metapopulation does not seem viable even if natural reforestation is controlled by adequate management. In its present state, the patch system is not able to sustain enough individuals: due to the large temporal fluctuations in demographic parameters, a carrying capacity far higher than currently would be necessary to limit extinction risk to 1%, suggesting the existence of an extinction debt for the species in Belgium. The situation of E. aurinia appears much worse compared to two other fritillary species threatened in Belgium, for which similar PVA are available. It is therefore urgent to increase the carrying capacity of the patch system. How and where it is achieved are of secondary importance for the gain in viability: improvement of habitat quality through restoration, or increase of habitat quantity via enlargement of existing patches and/or creation of new habitat in the matrix. A regime of management based on regular re-opening and maintenance of habitat patches may be the only guarantee of long-term persistence for this critically endangered species in Belgium.     

Using Penrose distance to identify potential risk of wildlife–vehicle collisions

Knowledge of the relationship between wildlife and roads is important for management of wildlife–vehicle collisions, which represent a serious threat to many wildlife populations and to human life and property. Effective reduction of these threats requires identification of variables influencing collision locations, and the use of these variables in spatially-explicit predictive models. We used Penrose distance modeling and 61 confirmed bobcat (Lynx rufus) road mortality locations in southern Illinois, USA, to demonstrate a rapid and accurate technique for the spatial mapping of wildlife–vehicle collision risk. We used the Penrose distance statistic to quantify the similarity between the mean multivariate habitat signature at bobcat-collision areas and road sections throughout the study area. Habitat variables assessed included road-related variables (e.g., traffic volume) and land cover characteristics (e.g., mean patch area of the landscape). Bobcat-collision areas were characterized by smaller, less-clustered habitat patches and more, large independent patches of grass cover than were study area roadway sections in general. As expected for a generalist carnivore in highly-suitable habitat, risk mapping indicated that large sections of the roaded landscape had high similarity to bobcat-collision areas. Unlike other modeling techniques used to identify risk of road mortality, our method requires little field data collection and relies on readily available digital spatial data. This technique can be used by wildlife managers and road planners, and may be particularly important in reduction of road mortality for species such as the Iberian lynx (Lynx pardinus), Florida panther (Puma concolor coryi), and Texas ocelot (Leopardis pardalus), which exist in small populations fragmented by development, and are limited by road mortalities.     

Removing erosion control projects increases bank swallow (Riparia riparia) population viability modeled along the Sacramento River, California, USA

Spatially-explicit population viability analysis (PVA) is a powerful method for modeling the extinction risk of populations that show variation over space and time. It is especially effective for comparing relative effect of different management scenarios on population dynamics. Here, I present a habitat patch-based PVA for a population of the California state-listed threatened bank swallow (Riparia riparia) nesting along the Sacramento River. This model incorporates the effects of habitat availability and location, density dependence, site fidelity, and stochasticity in survival and fecundity. River bank habitat patches suitable for this species were delineated using a geographic information systems (GIS) model of river bank height and were used in a PVA scenario analysis to assess the effects of habitat restoration—that could occur by removing bank erosion control projects (bank revetment)—on population viability. Sensitivity analysis showed that the model estimated probability of quasi-extinction (dropping below 2000 breeding pairs) ranged from 0 to 0.8 depending on the input parameters, with juvenile survival causing the greatest variability. However, comparing changes to the probability of quasi-extinction between the restored habitat scenario and current conditions showed a consistent 40-60% decrease in probability of quasi-extinction across all parameter combinations. The results of this research reaffirm the need for continued protection of the bank swallow as a listed species indicate that the removal of bank erosion control projects would increase viability of this population.     

Use of monitoring data and population viability analysis to inform reintroduction decisions: Peregrine falcons in the Midwestern United States

The peregrine falcon (Falco peregrinus anatum) has not yet recolonized natural cliff sites in Illinois and much of the lower Midwestern US, and remains restricted to urban areas. We constructed a landscape-linked population viability analysis using RAMAS/GIS software to compare possible reintroduction strategies for the species. Habitat-specific (i.e. cliff and urban) demographic parameters such as survival, fecundity, and dispersal rates were derived from the Midwest Peregrine Society Database for peregrines in the central Mississippi River region during 1982-2006. We simulated a base scenario of no reintroduction and 18 models of reintroduction with varying cohort sizes, supplementation schedules, and number of reintroduction sites, and used the Lake Superior population to test our model. Our analysis indicated that even without reintroductions in Illinois, the peregrine population in the lower Midwestern region is slowly increasing and is not likely to go extinct. Recolonization of cliff sites in southern Illinois likely will occur via dispersal from urban populations, however further research on dispersal rates between urban areas and cliffs is needed. Analysis indicated that the most cost-effective reintroduction strategy would be priced at approximately $280,000 and would result in only two additional breeding pairs compared to the no-action scenario. Thus, funds would be more effectively used in other management efforts such as habitat preservation. This study provides an example of how post-release monitoring can be used to inform future reintroduction plans.     

Probable consequences of high female mortality for speckled warblers living in habitat remnants

The effects of habitat fragmentation on the Australian avifauna have been widespread with species richness and abundance declining with reduced remnant size and habitat quality and increased habitat isolation. The speckled warbler, Chthonicola sagittata is one species from the highly fragmented temperate woodlands of eastern Australia that has declined across its range and populations that remain appear to be patchily distributed in habitat remnants. Specific causes of decline are unknown but several aspects of its biology make the species particularly vulnerable to decline in fragmented landscapes. Here, we analyse survey data (presence/absence) of speckled warblers in a large sample of habitat remnants from three regions to identify patterns of occupancy. We explore the effects of patch size on extinction risk using population viability analyses (PVA) and detailed demographic data from a behavioural study of individuals in the Australian Capital Territory, south-eastern Australia. Patch size was a strong predictor of the persistence of speckled warblers in habitat remnants. High density populations had higher probabilities of persisting, and inclusion of an Allee effect during drought decreased the probability of persistence. In the absence of an Allee effect, only high density populations in patches greater than 300 ha and low density populations in patches greater than700 ha had more than an 80% probability of persisting over 100 years. The accelerating decrease in population persistence below approximately 200-400 ha suggests that small populations were particularly vulnerable to stochastic demographic and environmental events. Adult female mortality was the single most important factor in driving population extinction. Our PVA model predictions matched the survey data for the Australian Capital Territory region remarkably well, but failed to predict occupancy rates in remnants in other regions. Differences in occupancy patterns between regions may, however, have resulted from inbreeding depression. This study demonstrates both the strengths and limitations of PVA analysis. PVA can predict occupancy patterns with reasonable accuracy, given good demographic data, but data for one region cannot be used universally for all regions. We highlight the need for studies of demography in different regions to interpret regional patterns of occupancy and to identify mechanisms of decline in remnant habitat.     

The relative importance of patch habitat quality and landscape attributes on a declining steppe-bird metapopulation

Metapopulation theory is one of the most popular approaches to identify the factors affecting the spatial and temporal dynamics of populations in fragmented habitat networks. Habitat quality, patch area and isolation are mainly focused on when analyzing distribution patterns in fragmented landscapes. The effects of landscape heterogeneity in the non-occupied matrix, however, have been largely neglected. Here, we determined the relative importance of patch quality and landscape attributes on the occurrence, density and extinction of the Dupont’s lark (Chersophilus duponti), an endangered steppe passerine whose habitat has been extremely reduced to highly isolated and fragmented patches embedded in a mainly unsuitable landscape matrix. Habitat patch quality, measured in terms of vegetation structure, grazing pressure, arthropod availability, predator abundance, and inter-specific competition, did not affect occurrence, density or extinction. At the landscape scale, however, the species’ occurrence was principally determined by the interactions among patch size, geographic isolation and landscape matrix. Isolation had the main independent contribution to explaining the probability of occurrence, followed by landscape matrix composition and patch size. The species’ density was negatively correlated to patch size, suggesting crowding effects in small fragments, while extinction events were exclusively related to isolation. Our findings suggest that landscape rather than local population characteristics are crucial in determining the patterns of distribution and abundance of non-equilibrium populations in highly fragmented habitat networks. Consequently, conservation measures for these species should simultaneously involve patch size, isolation and landscape matrix and apply to the entire metapopulation rather than to particular patches.     

Landscape evaluation of female black bear habitat effectiveness and capability in the North Cascades, Washington

We used logistic regression to derive scaled resource selection functions (RSFs) for female black bears at two study areas in the North Cascades Mountains. We tested the hypothesis that the influence of roads would result in potential habitat effectiveness (RSFs without the influence of roads) being greater than realized habitat effectiveness (RSFs with roads). Roads consistently had a negative influence on black bear RSFs across seasons and study areas. Roads reduced habitat effectiveness during all seasons at both study areas and changes in the potential habitat values ranged from 1.7% to 16.9%. The greatest reduction in habitat values occurred during the early-season on the west-side study area due to high open road densities. These results support the hypothesis that roads reduce habitat effectiveness for black bears. The influence of roads could be reduced through road closures to reduce open road densities and limit traffic volumes. We then used the scaled RSFs in a habitat-based population model to assess the influences of timber harvest and roads on potential black bear population sizes. On the west-side study area the potential black bear population size was most influenced by moderate use roads and timber harvest during the early-season (41% reduction). On the east-side study area, low use roads had the greatest effect on potential black bear population during the early-season (10% reduction). During the late-season, in both study areas, roads had less influence on the potential population sizes as bears were able to access habitats away from roads. The habitat-population model provided reasonable estimates of bear densities compared to other study areas with similar habitats and could be extrapolated to estimate potential black bear populations in other areas with similar habitats. This approach may provide a useful link between the landscape ecology and population biology of black bears, and could eventually be useful in the development of habitat-based population viability analyses.     

Plant species extinction debt in a temperate biodiversity hotspot: Community, species and functional traits approaches

Destruction and fragmentation of (semi-) natural habitats are considered the main causes of biodiversity loss worldwide. Plant species may exhibit a slow response to fragmentation, resulting in the development of an extinction debt in fragmented plant communities. The detection of extinction debt is of primary importance in habitat conservation strategies. We applied two different approaches proposed in the literature to identify extinction debt in South-East Belgium calcareous grasslands. The first method compared species richness between stable and fragmented habitat patches. The second explored correlations between current species richness and current and past landscape configurations using multiple regression analyses. We subsequently examined results generated by both methods. In addition, we proposed techniques to identify species that are more likely to support extinction debt and associated functional traits. We estimated a respective extinction debt of approximately 28% and 35% of the total and specialist species richness. Similar results were obtained from both methods. We identified 15 threatened specialist species under the current landscape configuration. It is likely the landscape configuration no longer supports the species habitat requirements. We demonstrated that non-clonal species are most threatened, as well as taxa that cannot persist in degraded habitats and form only sparsely distributed populations. We discussed our results in light of other studies in similar habitats, and the overall implications for habitat conservation.     

Thresholds in landscape parameters: occurrence of the white-browed treecreeper Climacteris affinis in Victoria, Australia

The concept of critical thresholds of habitat loss has recently received considerable attention in conservation biology and landscape ecology, yet empirical examples of thresholds are scarce. Threatened species management could benefit from recognition of thresholds because conditions under which populations are at risk can be specified. In this study, 56 woodland patches in north-west Victoria were surveyed for the white-browed treecreeper Climacteris affinis, a threatened insectivorous bird of the semi-arid zone of southern Australia. Comparisons with historic records indicate the species’ range is contracting in Victoria. Using logistic regression and hierarchical partitioning, two models of patch occupancy were developed. Tree species composition was an important factor in both models, confirming the treecreepers’ affinity for belah Casuarina pauper and slender cypress-pine Callitris gracilis-buloke Allocasuarina luehmannii woodlands in north-west Victoria. The first model emphasized the importance of demographic isolation: probability of patch occupancy decreased with distance to the nearest occupied patch. A threshold response in demographic isolation was apparent. In agricultural landscapes, most suitable woodland patches within 3 km of an occupied patch were occupied, whereas patches beyond the threshold were vacant. The threshold distance increased to a minimum of 8 km in a matrix of native vegetation, suggesting landscape context affects the response of white-browed treecreepers to habitat fragmentation. Demographic isolation is a quasi-dependent variable and therefore a second model was developed using surrogate variables for demographic isolation. A positive relationship with the proportion of woodland cover in the landscape (100 km²) emerged as the pre-eminent explanatory factor. Depending on woodland quality, a threshold of patch occupancy was apparent at levels of woodland cover between 15 and 25%. However, belah and slender cypress-pine-buloke woodlands now cover only 10% of their original extent in the region. These results highlight the inter-dependence of patch isolation with the amount and quality of habitat in the landscape and the implications this has for maintaining functional connectivity. The retention (or restoration) of suitable habitat is the critical issue for conservation of the white-browed treecreeper, but in landscapes below the threshold of habitat cover, viability of local populations may be influenced by the configuration and quality of remaining habitat.     

Predicting potential habitat and population size for reintroduction of the Far Eastern leopards in the Russian Far East

The Far Eastern Leopard (Panthera pardus orientalis; Schlegel, 1857) is perhaps the world’s most endangered large felid subspecies occurring in a single population of ?30 adults, and faces immediate risk of extinction unless additional populations can be established within its historical range in the Russian Far East. We used locations of leopard tracks (and their ungulate prey) collected from snow track surveys from 1997 to 2007 to develop resource selection functions (RSF) to identify potential habitat for reintroduction. We compared models that include prey versus those based on landscape covariates, and also included covariates related to human-induced mortality. To estimate potential population size, we used a habitat-based population estimate based on the ratio of population size and RSF value of occupied range. Far Eastern leopards selected for areas with high ungulate density, lower-elevation Korean pine forests on southwest facing slopes, and in areas far from human activity. Using this RSF model, we identified a total of 10,648 km² in eight patches >500 km² of potential Far Eastern leopard habitat that could harbor a potential population of 105.3 (57.9–147.2) adults. In combination with the existing population, successful reintroductions could result in a total of 139.2 (76.5–194.6) adult leopards, a 3–4-fold increase in population size. Our habitat models assist the reintroduction planning process by identifying factors that predict presence and potential suitable habitat. Identifying the highest quality, most connected patches, in combination with appropriate selection and training of released animals, is recommended for successfully reintroducing Far Eastern leopards, and potentially other endangered carnivores into the wild.     

Does habitat restoration cause species extinction?

Habitat destruction is a major cause for species extinction. Does habitat restoration on species evolution with stable state cause species extinction? To address the problem, a multi-species coexistence dynamical model under habitat restoration is set up to simulate the evolutionary trait of different species in different communities. Relevant researches show that habitat restoration has great impacts on landscape changes and species combination. The results find two kinds of latent mechanism of species extinction: the first latent extinction mechanism and the quasi-second latent extinction mechanism. The former refers to the extinction of several vulnerable species while the latter is the extinction of some relatively strongest (not the best) populations. Those survivors experience three phases of transitory increase, adjustment and stability. The dominant species persist and grow fast in different communities, while other several sub-dominant species face the fate of latent crisis of extinction. Two mechanism of n-species community as habitat restorations are found via a number of numerical simulations. One is the mechanism of alternation between oddness and evenness, and the other is the mechanism of coordinate evolution and coordinate degeneration. Two field investigation examples have been given to clarify the evolutionary mechanisms.The results may be helpful for biological conservation and provide theoretical guidance to construct nature reserves.     

Anthropogenic determinants of primate and carnivore local extinctions in a fragmented forest landscape of southern Amazonia

Habitat fragmentation has been shown to influence the abundance, movements and persistence of many species. Here, we examine the effects of forest patch and landscape metrics, and levels of forest disturbance on the patterns of local extinction of five primate and 14 carnivore species within 129 forest patches in a highly fragmented forest landscape of southern Brazilian Amazonia. Classic habitat area effects were the strongest predictors of species persistence, explaining between 42% and 55% of the overall variation in primate and carnivore species richness. Logistic regression models showed that anthropogenic disturbance, including surface wildfires, timber extraction and hunting pressure, had detrimental effects on the persistence of some species over and above those of fragment size. Different species ranged in their responses from highly sensitive to highly tolerant to forest fragmentation. Patterns of local extinction documented here were by no means chance events, and the nestedness of the overall species-by-site matrix was highly nonrandom in terms of the sets of species extirpated from the most to the least species-rich forest patches.     

Small patches can be valuable for biodiversity conservation: two case studies on birds in southeastern Australia

Presence/absence datasets on birds from two landscapes in southeastern Australia were analysed as a case study to examine the conservation value of small habitat patches. In the Tumut landscape, patch sizes ranged between 0.5 and 97.6 ha; 30 species of birds (37%) were observed in patches of up to 1 ha, and 74 species (91%) were found in patches of up to 10 ha. In the Nanangroe landscape, patch sizes ranged from 0.4 to 15.6 ha, and 74 species of birds (75%) were found in patches smaller than 1 ha. In both landscapes, small patches contributed strongly to species accumulation curves. While large patches are needed by many species to maintain viable populations, it is important to recognise the complementary value of small remnants. In many landscapes, the conservation and restoration of small patches will often be the only feasible management option.     

Patch dynamics and the timing of colonization-abandonment events by male Kirtland’s Warblers in an early succession habitat

Habitat colonization and abandonment affects the distribution of a species in space and time, ultimately influencing the duration of time habitat is used and the total area of habitat occupied in any given year. Both aspects have important implications to long-term conservation planning. The importance of patch isolation and area to colonization-extinction events is well studied, but little information exists on how changing regional landscape structure and population dynamics influences the variability in the timing of patch colonization and abandonment events. We used 26 years of Kirtland’s Warbler (Dendroica kirtlandii) population data taken during a habitat restoration program (1979-2004) across its historical breeding range to examine the influence of patch attributes and temporal large-scale processes, specifically the rate of habitat turnover and fraction of occupied patches, on the year-to-year timing of patch colonization and abandonment since patch origin. We found the timing of patch colonization and abandonment was influenced by patch and large-scale regional factors. In this system, larger patches were typically colonized earlier (i.e., at a younger age) and abandoned later than smaller patches. Isolated patches (i.e., patches farther from another occupied patch) were generally colonized later and abandoned earlier. Patch habitat type affected colonization and abandonment; colonization occurred at similar patch ages between plantation and wildfire areas (9 and 8.5 years, respectively), but plantations were abandoned at earlier ages (13.9 years) than wildfire areas (16.4 years) resulting in shorter use. As the fraction of occupied patches increased, patches were colonized and abandoned at earlier ages. Patches were abandoned at older ages when the influx of new habitat patches was at low and high rates. Our results provide empirical support for the temporal influence of patch dynamics (i.e., patch destruction, creation, and succession) on local colonization and extinction processes that help explain large-scale patterns of habitat occupancy. Results highlight the need for practitioners to consider the timing of habitat restoration as well as total amount and spatial arrangement of habitat to sustain populations.     

Small mammals, habitat patches and PVA models: a field test of model predictive ability

The results are described of comparisons between actual values for patch occupancy for two species of Australian small mammals (Bush Rat Rattus fuscipes and Agile Antechinus Antechinus agilis) determined from field sampling and predictions of patch occupancy made using VORTEX, a generic simulation model for Population Viability Analysis (PVA). The work focussed on a fragmented forest in south-eastern Australia comprised of a network of 39 patches of native eucalypt forest surrounded by extensive stands of exotic softwood Radiata Pine (Pinus radiata) plantation. A range of modelling scenarios were completed in which four broad factors were varied: (1) inter-patch variation in habitat quality; (2) the pattern of inter-patch dispersal; (3) the rate of inter-patch dispersal; and (4) the population sink effects of the Radiata Pine matrix that surrounded the eucalypt patches. Model predictions were made for the total number of animals, the distribution of animal density among patches, the total number of occupied patches, and the probability of patch occupancy. Predictions were then compared with observed values for these same measures based on extensive field surveys of small mammals in the patch system. For most models for the Bush Rat, the predicted relative density of animals per patch correlated well with the values estimated from field surveys. Predictions of patch occupancy were not significantly different from the actual value for the number of occupied patches in half the models tested. The better models explained 10-16% of the log-likelihood of the probability of patch occupancy. While some of the models gave reasonable forecasts of the number of occupied patches, even in these cases, they had only moderate ability to predict which patches were occupied. Field surveys revealed there was no relationship between patch area and population density for the Agile Antechinus—an outcome correctly predicted by only a few models. Five of the 18 scenarios completed for the Agile Antechinus gave predicted numbers of occupied patches not significantly different from the observed number. In each of these five cases, large standard deviations around the mean predicted value meant uncertainty generated by the simulation model limited the predictive power of the PVA. Some of the models gave reasonable predictions for the number of occupied patches, but those models were unable to predict which ones were actually occupied. The results of our study suggest that key processes influencing which specific patches would be occupied were not modelled appropriately. High levels of variability and fecundity drive the population dynamics of the Bush Rat and Agile Antechinus, making the patch system unpredictable and difficult to model accurately. Despite the fact that both the Bush Rat and the Agile Antechinus are two of the most studied mammals in Australia, there are attributes of their biology that are presently poorly understood (which were not included in the VORTEX model), but which could strongly influence patch occupancy. For example, local landscape features may be important determinants of inter-patch movement and habitat utilisation in the patch system. Further empirical studies are needed to explore this aspect of small mammal biology.     

Viability of mountain caribou in British Columbia, Canada: Effects of habitat change and population density

Population viability analyses (PVA) are frequently employed to develop recovery plans and inform management of endangered species. Translating results from PVA into meaningful management recommendations often depends on an understanding of how population parameters change with environmental conditions as well as population density. The decline of mountain caribou (Rangifer tarandus caribou) in British Columbia, Canada, is believed to be caused by apparent competition with alternative prey species following changes to the forest age structure from timber harvest and wildfire. In addition, populations have been shown to decline at faster rates at low population density. To evaluate the potential effects of habitat change and population density on population persistence, we used stochastic projection models for 10 distinct populations varying in initial size from <10 to approximately 150 females. In an initial model, we used estimates of vital rates based on information sampled from >350 radiocollared caribou between 1984 and 2004. We then compared the results of the initial model to a set of models that evaluated the effects of habitat conditions and population density via their expected relationships to female adult survival. Assuming that vital rates remain constant over a 200-year time frame, only three populations have high probabilities (>0.95) of extinction. When models incorporate the declines in adult female survival know to occur with increasing proportions of young forest and declining population densities, all 10 populations are predicted to decline to extinction within <200 years. Based on our results, we suggest that PVA models that fail to incorporate the effects of changes in vital rates with habitat and population density may lead to overly optimistic assessments of the probability of population persistence in endangered species.     

Density and activity patterns of ocelots (Leopardus pardalis) in northern Peru and the impact of oil exploration activities

The western Amazon is experiencing unprecedented levels of oil and gas exploration, a trend of particular concern given the high levels of biodiversity found in this relatively pristine and unstudied region. Despite the widespread use of seismic reflection technology for exploration, no studies have investigated the response of wildlife populations to this disturbance in the tropics. We conducted a trail camera survey inside a large oil concession (Block 39) in the Peruvian Amazon near the Ecuador border with ongoing 2D seismic explorations to investigate its effects on ocelot (Leopardus pardalis) activity and abundance. The estimated size of the ocelot population within our 22 km² study area was the same before (control period: 34 ± 6.9 ocelots) and during exploration operations (disturbance period; 34 ± 4.6 ocelots) and we detected no change in activity patterns between the two periods. Ocelot capture rate was unaffected by the presence of seismic crews, and distance to the nearest seismic line was not correlated with capture rate at individual stations. Our density estimates (ocelots/100 km²) from the control (75.2) and disturbance period (94.7) include the highest reported for the species, and represent the first ocelot density estimates from the northwest Amazon forest. These high values conform to recent research showing a positive association between ocelot density, annual rainfall, and proximity to the equator (this study: >2500 mm annual rainfall; <200 km from equator). We discuss the potential short- and long-term environmental impacts of seismic operations, particularly as they relate to large mammal populations.     

The age and amount of regrowth forest in fragmented brigalow landscapes are both important for woodland dependent birds

In highly-modified agricultural landscapes, regrowth (secondary) forest on abandoned farmland offers the potential for passive landscape restoration for biodiversity conservation. While numerous studies have investigated the ecological values of regrowth for fauna recovery at the local-level (1-10 ha), there is a dearth of studies quantifying the contribution of regrowth forest at the landscape-level (100-1000s ha). To address this critical knowledge gap we question how the age and amount of regrowth forest in the landscape influence species richness and abundance of mature forest dependent species? Using woodland dependent birds in fragmented sub-tropical brigalow landscapes in southern Queensland, Australia, we applied model averaging and hierarchical partitioning analyses to test and rank the relative importance of the amount of regrowth forest in the landscape in three age classes (<15, 15-30, and >30 years) compared to local (grazing disturbance, abundance of aggressive miners, mistletoe abundance and patch age) and landscape measures of habitat (amount of mature forest and number of mature forest patches). Response variables included the species richness of woodland dependent birds and sub-groupings of foraging guilds, and the abundance of selected individual species. The importance of explanatory variables differed considerably among response groups. Local attributes, such as patch age and the abundance of mistletoe plants, had the strongest influences on woodland dependent birds. However, we found that the amount of regrowth forest, particularly >30 years, also had a strong influence on both species richness and abundance. This study confirms that regrowth, especially older regrowth, can make an important contribution to landscape restoration in highly-modified agricultural landscapes.     

Testing the importance of spatial configuration of winter habitat for woodland caribou: An application of graph theory

Conservation of remaining woodland caribou (Rangifer tarandus caribou) populations requires land management strategies that not only maintain caribou habitat, but also favour habitat connectivity. This study presents and field tests graph theory-based measures of landscape connectivity, and demonstrate an association between the distribution of woodland caribou and well-connected winter habitat. Cost values for the intervening land cover types were determined based on the probability of selection relative to high-quality winter habitat. Habitat connectivity was then represented by linking high-quality habitat patches along least-cost paths through this parameterized cost surface. A randomization procedure was used to assess the animal’s association with habitat connected at increasing distance thresholds to identify appropriate scales of response. A strong relationship was obtained between large clusters of high-quality winter habitat patches and winter GPS telemetry location points (November 1-March 15) from two woodland caribou herds in Manitoba, Canada. This relationship was stronger when only late winter location points (January 1-March 15) were used. Our results highlight the importance of accounting for the spatial configuration of habitat on the landscape and the intervening land cover types when assessing range quality for woodland caribou. They also provide support for the use of graph theory to assist in identifying core activity areas for woodland caribou and key linkages between these areas and other parts of the landscape.