Identification Of Critical Habitat Research Articles

Determining fine‐scale migratory connectivity and habitat selection for a migratory songbird by using new GPS technology

Migratory aerial insectivores are among the fastest declining avian groups, but our understanding of these trends has been limited by poor knowledge of migratory connectivity and the identification of critical habitat across the vast distances they travel annually. Using new, archival GPS loggers, we tracked individual purple martins Progne subis from breeding colonies across North America to determine precise (< > 10 m) locations of migratory and overwintering roost locations in South America and to test hypotheses for fine‐scale migratory connectivity and habitat use. We discovered weak migratory connectivity at the roost scale, and extensive, fine‐scale mixing of birds in the Amazon from distant (> 2000 km) breeding sites, with some individuals sharing the same roosting trees. Despite vast tracts of contiguous forest in this region, birds occupied a much more limited habitat, with most (56%) roosts occurring on small habitat islands that were strongly associated with water. Only 17% of these roosts were in current protected areas. These data reflect a critical advance in our ability to remotely determine precise migratory connectivity and habitat selection across vast spatial scales, enhancing our understanding of population dynamics and enabling more effective conservation of species at risk.

Using telemetry data to develop conceptual models of movement to support the management of riverine fishes

As human demands for freshwater resources increase, there is growing concern for the long-term viability of native fish populations globally. Understanding the movements of fish, and how these are influenced by or respond to environmental changes, is a critical knowledge requirement for effective management; however, limited information on the ecological requirements of many fish species currently hinders our ability to sustainably manage fish populations. In this paper, we use four native Australian fish species with contrasting life histories as case studies to demonstrate how data derived from acoustic and radiotelemetry studies can be synthesised into conceptual diagrams to help scientists and managers develop targeted and effective conservation management strategies. Commonalities in the observed movement patterns were observed among the species despite their contrasting life histories, but there were also important differences that need to be recognised in the development of species-specific conservation management strategies. We conclude by discussing how such information has been or could be incorporated into conservation management actions, including the implementation of environmental flow releases and the identification of critical habitats.

Key winter habitat of the ivory gull Pagophila eburnea in the Canadian Arctic

The ivory gull Pagophila eburnea is a rare Arctic seabird that breeds in remote loca- tions; little is known of its winter distribution and behaviour. It is listed under Canadian legislation as 'endangered', and as 'near threatened' by the International Union for the Conservation of Nature. A >70% population decline in the past 3 decades in Canada prompted research on ivory gulls to better understand their year-round movements and habitat requirements. Additionally, the identification of critical habitat is a research priority in the Recovery Strategy for the ivory gull in Canada. We used data from gulls tracked by satellite telemetry from the Canadian Arctic and Svalbard, Norway, as well as data from ship observations collected between 1969 and 2010. We determined that the area of highest use by these gulls in the winter was in Davis Strait, where 90% of their time was spent over sea ice. Agreement of findings among datasets through time and from different breeding regions suggests that the edge of the pack ice in Davis Strait is an annual, key habitat for ivory gulls in winter. Given the proximity of the core wintering area to known hooded seal Crystophora cristata whelping patches, we speculate that remains from seal breed- ing, as well as polar bear Ursus maritimus kills and pagophilic (ice-loving) fish accessed in the vicinity of pack ice have provided spatially and temporally predictable, and valuable, food resources for ivory gulls in the winter.

Change in the Beaufort Sea ecosystem: Diverging trends in body condition and/or production in five marine vertebrate species

Studies of the body condition of five marine vertebrate predators in the Beaufort Sea, conducted independently during the past 2–4 decades, suggest each has been affected by biophysical changes in the marine ecosystem. We summarize a temporal trend of increasing body condition in two species (bowhead whale subadults, Arctic char), in both cases influenced by the extent and persistence of annual sea ice. Three other species (ringed seal, beluga, black guillemot chicks), consumers with a dietary preference for Arctic cod, experienced declines in condition, growth and/or production during the same time period. The proximate causes of these observed changes remain unknown, but may reflect an upward trend in secondary productivity, and a concurrent downward trend in the availability of forage fishes, such as the preferred Arctic cod. To further our understanding of these apparent ecosystem shifts, we urge the use of multiple marine vertebrate species in the design of biophysical sampling studies to identify causes of these changes. Continued long-term, standardized monitoring of vertebrate body condition should be paired with concurrent direct (stomach contents) or indirect (isotopes, fatty acids) monitoring of diet, detailed study of movements and seasonal ranges to establish and refine baselines, and identification of critical habitats of the marine vertebrates being monitored. This would be coordinated with biophysical and oceanographic sampling, at spatial and temporal scales, and geographic locations, that are relevant to the home range, critical habitats and prey of the vertebrate indicator species showing changes in condition and related parameters.

Incorporating within- and between-patch resource selection in identification of critical habitat for brood-rearing greater sage-grouse

Abstract Introduction Incorporating information on animal behavior in resource-based predictive modeling (e.g., occurrence mapping) can elucidate the relationship between process and spatial pattern and depict habitat in terms of its structure as well as its function. In this paper, we assigned location data on brood-rearing greater sage-grouse (Centrocercus urophasianus) to either within-patch (encamped) or between-patch (traveling) behavioral modes by estimating a movement-based relative displacement index. Objectives were to estimate and validate spatially explicit models of within- versus between-patch resource selection for application in habitat management and compare these models to a non-behaviorally adjusted model. Results A single model, the vegetation and water resources model, was most plausible for both the encamped and traveling modes, including the non-behaviorally adjusted model. When encamped, sage-grouse selected for taller shrubs, avoided bare ground, and were closer to mesic areas. Traveling sage-grouse selected for greater litter cover and herbaceous vegetation. Preference for proximity to mesic areas was common to both encamped and traveling modes and to the non-behaviorally adjusted model. The non-behaviorally adjusted map was similar to the encamped model and validated well. However, we observed different selection patterns during traveling that could have been masked had behavioral state not been accounted for. Conclusions Characterizing habitat that structured between-patch movement broadens our understanding of the habitat needs of brood-rearing sage-grouse, and the combined raster surface offers a reliable habitat management tool that is readily amenable to application by GIS users in efforts to focus sustainable landscape management.

Current practices in the identification of critical habitat for threatened species.

The term critical habitat is used to describe the subset of habitat that is essential to the survival and recovery of species. Some countries legally require that critical habitat of listed threatened and endangered species be identified and protected. However, there is little evidence to suggest that the identification of critical habitat has had much impact on species recovery. We hypothesized that this may be due at least partly to a mismatch between the intent of critical habitat identification, which is to protect sufficient habitat for species persistence and recovery, and its practice. We used content analysis to systematically review critical habitat documents from the United States, Canada, and Australia. In particular, we identified the major trends in type of information used to identify critical habitat and in occupancy of habitat identified as critical. Information about population viability was used to identify critical habitat for only 1% of the species reviewed, and for most species, designated critical habitat did not include unoccupied habitat. Without reference to population viability, it is difficult to determine how much of a species' occupied and unoccupied habitat will be required for persistence. We therefore conclude that the identification of critical habitat remains inconsistent with the goal of protecting sufficient habitat to support persistence and recovery of the species. Ensuring that critical habitat identification aligns more closely with its intent will improve the accuracy of the designations and may therefore help improve the benefits to species recovery when combined with adequate implementation and enforcement of legal protections.

Post-Breeding Migration of Dutch-Breeding Black-Tailed Godwits: Timing, Routes, Use of Stopovers, and Nonbreeding Destinations

Conservation of long-distance migratory shorebirds is complex because these species use habitats spread across continents and hemispheres, making identification of critical habitats and potential bottlenecks in the annual cycle especially difficult. The population of Black-tailed Godwits that breeds in Western Europe, Limosa limosa limosa, has declined precipitously over the past few decades. Despite significant efforts to identify the root causes of this decline, much remains unclear. To better understand the migratory timing, use of stopover and nonbreeding sites, and the potential impact of breeding success on these parameters, we attached 15 Argos satellite transmitters and 10 geolocation tracking devices to adult godwits nearing completion of incubation at breeding sites in southwest Friesland, The Netherlands during the spring of 2009. We successfully tracked 16 adult godwits for their entire southward migration and two others for part of it. Three migration patterns and four regions of use were apparent. Most godwits left their breeding sites and proceeded south directly to stopover sites in the Mediterranean — e.g. Spain, Portugal, and Morocco — before flying on to non-breeding sites in West Africa. Other individuals spent the entire nonbreeding season in the Mediterranean. A third pattern included a few individuals that flew nonstop from their Dutch breeding sites to nonbreeding sites in West Africa. Tracking data from this study will be immediately useful for conservation efforts focused on preserving the dispersed network of sites used by godwits during their southward migration.

Predicting species distributions for conservation decisions.

Species distribution models (SDMs) are increasingly proposed to support conservation decision making. However, evidence of SDMs supporting solutions for on-ground conservation problems is still scarce in the scientific literature. Here, we show that successful examples exist but are still largely hidden in the grey literature, and thus less accessible for analysis and learning. Furthermore, the decision framework within which SDMs are used is rarely made explicit. Using case studies from biological invasions, identification of critical habitats, reserve selection and translocation of endangered species, we propose that SDMs may be tailored to suit a range of decision-making contexts when used within a structured and transparent decision-making process. To construct appropriate SDMs to more effectively guide conservation actions, modellers need to better understand the decision process, and decision makers need to provide feedback to modellers regarding the actual use of SDMs to support conservation decisions. This could be facilitated by individuals or institutions playing the role of ‘translators’ between modellers and decision makers. We encourage species distribution modellers to get involved in real decision-making processes that will benefit from their technical input; this strategy has the potential to better bridge theory and practice, and contribute to improve both scientific knowledge and conservation outcomes.

Corrigendum: The effects of lead agency, nongovernmental organizations, and recovery team membership on the identification of critical habitat for species at risk: insights from the Canadian experience

Corrigendum: The effects of lead agency, nongovernmental organizations, and recovery team membership on the identification of critical habitat for species at risk: insights from the Canadian experience

The effects of lead agency, nongovernmental organizations, and recovery team membership on the identification of critical habitat for species at risk: insights from the Canadian experience

Evaluation of legislation and procedures in place to help recover species at risk of extinction is an important component of conservation efforts. Despite its biological importance and key role in species protection and recovery legislation, identification of critical habitat is inconsistently applied. We analyzed data from 126 recovery strategies implemented under Canada’s nascent (2002) Species at Risk Act (SARA) to determine how lead agency, Federal Court rulings, and the proportion of independent team members influenced identification of critical habitat. Only 17% of strategies led by the Department of Fisheries and Oceans included critical habitat, compared with 63% of strategies led by Environment Canada, indicating that aquatic species at risk are much less likely to have critical habitat identified. A 50% increase in recovery strategies that identified critical habitat following precedent-setting court judgments suggests that legal action by nongovernmental organizations played a key role in the evolution of recovery policy for species at risk in Canada. The proportion of independent scientists on a recovery team was statistically unrelated to identification of critical habitat at a national scale, but case studies indicate that independent team members may play an important role in ensuring compliance and transparency during recovery planning.

Using species distribution and occupancy modeling to guide survey efforts and assess species status

Habitat loss and fragmentation continue to be major issues affecting the persistence and conservation of species, but identification of critical habitat remains a challenge. Species distribution modeling and occupancy modeling are both approaches that have been used to predict species distributions and can identify critical habitat characteristics associated with species occurrence. Additionally, occupancy sampling can provide measures of detectability, increasing the confidence that a species is truly absent when not detected. While increasingly popular, these methods are infrequently used in synergy, and rarely at fine spatial scales. We provide a case study of using distribution and occupancy modeling in unison to direct survey efforts, provide estimates of species presence/absence, and to identify local and landscape features important for species occurrence. The focal species for our study was Ambystoma jeffersonianum, a threatened salamander in the state of Illinois, U.S.A. We found that fine-scale distribution models accurately discriminated occupied from unoccupied breeding ponds (78–91% accuracy), and surveys could be effectively guided using a well-fit model. We achieved a high detection rate (0.774) through occupancy sampling, and determined that A. jeffersonianum never used ponds inhabited by fish, and the probability of a pond being used for breeding increased as canopy cover increased. When faced with limited resources, combining fine-scale distribution modeling with a robust occupancy sampling design can expedite survey efforts, confidently designate species occupancy status, prioritise habitat for future surveys and/or restoration, and identify critical habitat features. This approach is broadly applicable to other taxa that have specific habitat requirements.

Canada’s international and national commitments to sustain marine biodiversity1This manuscript is a companion paper to Hutchings et al. (doi:10.1139/a2012-011) and Hutchings et al. (doi:10.1139/er-2012-0049) also appearing in this issue. These three papers comprise an edited version of a February 2012 Royal Society of Canada Expert Panel Report.

Canada has made numerous international and national commitments to sustain marine biodiversity. International commitments include the implementation of ecosystem-based management, the establishment a network of marine protected areas, and the restoration of commercially exploited fish stocks. However, the international commitments tend to be quite general in nature with the precise governance implications of key principles, such as precaution and the ecosystem approach, being open to interpretation, thus leaving considerable room for discretion in implementation. Consequently, a plethora of soft law documents has emerged to provide more specific guidance to decision-makers and progressively develop international law and policy. Nationally, Canada has embraced a long list of commitments that are supportive of sustaining marine biodiversity through legislation and numerous policy-related documents. Nonetheless, Canada has left many of these commitments unfulfilled or inadequately fulfilled, such as (i) the development of integrated management plans for coastal and marine waters, (ii) the implementation of the precautionary approach for Canada’s fisheries, and (iii) the establishment of recovery strategies and identification of critical habitat for species at risk. Although the goal of effective protection of marine biodiversity in Canada appears to be guided by international and national commitments, there remains a clear need to fully implement, operationalize, and strengthen these commitments as articulated in the Oceans Act, fisheries management-related policies, the Species at Risk Act, and others.

Transcending scale dependence in identifying habitat with resource selection functions

Multi-scale resource selection modeling is used to identify factors that limit species distributions across scales of space and time. This multi-scale nature of habitat suitability complicates the translation of inferences to single, spatial depictions of habitat required for conservation of species. We estimated resource selection functions (RSFs) across three scales for a threatened ungulate, woodland caribou (Rangifer tarandus caribou), with two objectives: (1) to infer the relative effects of two forms of anthropogenic disturbance (forestry and linear features) on woodland caribou distributions at multiple scales and (2) to estimate scale-integrated resource selection functions (SRSFs) that synthesize results across scales for management-oriented habitat suitability mapping. We found a previously undocumented scale-specific switch in woodland caribou response to two forms of anthropogenic disturbance. Caribou avoided forestry cut-blocks at broad scales according to first- and second-order RSFs and avoided linear features at fine scales according to third-order RSFs, corroborating predictions developed according to predator-mediated effects of each disturbance type. Additionally, a single SRSF validated as well as each of three single-scale RSFs when estimating habitat suitability across three different spatial scales of prediction. We demonstrate that a single SRSF can be applied to predict relative habitat suitability at both local and landscape scales in support of critical habitat identification and species recovery.

An ecological model of the habitat mosaic in estuarine nursery areas: Part I—Interaction of dispersal theory and habitat variability in describing juvenile fish distributions

Identification of critical habitat in estuarine nursery areas is an important conservation and management objective. Habitat can be viewed as a mosaic of both temporally variable environmental features and spatially variable structural features that combine to define optimal habitat. Effective models of juvenile distributions should account for individual movement, as well as the full suite of habitat variability including both spatial and temporal components. We have extended a terrestrial model of small-scale movement patterns to describe habitat choices of an index juvenile fish in an estuarine nursery system. Movement of small juvenile fishes was found to be influenced by both spatial and temporal patterns in habitat quality, and it was a balanced mix of both that resulted in an optimal distribution. Fishes that perceive habitat on a scale much smaller than the scale of spatial heterogeneity may respond to temporal change as a movement cue allowing for more deterministic outcomes at larger scales despite perceptual limitations. These model outcomes suggest a hierarchical approach is best for describing habitat choice in juvenile fishes and this approach will be used in the future to explore individual and population responses to predictable habitat change.

Do riparian zones qualify as critical habitat for endangered freshwater fishes?

Identification of critical habitat is a key step in conservation and recovery of endangered and threatened freshwater fish. Critical habitat under Canadian and US legislation may include habitat that is not directly used by listed fish, provided it is necessary for species conservation or recovery. Riparian habitat meets biological criteria for critical habitat because riparian zones are integral to aquatic ecosystem functions of importance to many fish species and other organisms. These functions include provision of shade for temperature-sensitive species, control of channel complexity and sediment inputs through bank stabilization, input of large wood and allochthonous energy sources, and filtering of nutrients and toxins from adjacent land. In response to decades of stream-riparian research, widespread implementation of regulations to protect riparian zones in most developed countries represent a de facto consensus that riparian buffers are essential for aquatic ecosystem health and the maintenance of populations of fish and other species. Consistent with widespread riparian regulations deemed necessary to protect not-at-risk species, riparian habitat adjacent to a body of water containing a listed freshwater species should be considered biologically critical unless the habitat requirements of individual taxa are demonstrated to be insensitive to the ecological functions associated with riparian habitat.

Estimating Carrying Capacity for Sea Otters in British Columbia

ABSTRACT We estimated carrying capacity for sea otters (Enhydra lutris) in the coastal waters of British Columbia, Canada, by characterizing habitat according to the complexity of nearshore intertidal and sub‐tidal contours. We modeled the total area of complex habitat on the west coast of Vancouver Island by first calculating the complexity of the Checleset Bay‐Kyuquot Sound (CB‐KS) region, where sea otters have been at equilibrium since the mid‐1990s. We then identified similarly complex areas on the west coast of Vancouver Island (WCVI model), and adapted the model to identify areas of similar complexity along the entire British Columbia coast (BC model). Using survey data from the CB‐KS region, we calculated otter densities for the habitat predicted by the 2 models. The density estimates for CB‐KS were 3.93 otters/km2 and 2.53 otters/km2 for the WCVI and BC models, respectively, and the resulting 2 estimates of west coast of Vancouver Island complex habitat carrying capacity were not significantly different (WCVI model: 5,123, 95% CI = 3,337–7,104; BC model: 4,883, 95% CI = 3,223–6,832). The BC model identified the region presently occupied by otters on the central British Columbia coast, but the amount of coast‐wide habitat it predicted (5,862 km2) was relatively small, and the associated carrying capacity estimate (14,831, 95% CI = 9,790–20,751) was low compared to historical accounts. We suggest that our model captured a type of high‐quality or optimum habitat prevalent on the west coast of Vancouver Island, typified by the CB‐KS region, and that suitable sea otter habitat elsewhere on the coast must include other habitat characteristics. We therefore calculated a linear, coast‐wide carrying capacity of 52,459 sea otters (95% CI = 34,264–73,489)—a more realistic upper limit to sea otters in British Columbia. Our carrying capacity estimates are helping set population recovery targets for sea otters in Canada, and our habitat predictions represent a first step in Critical Habitat identification. This habitat‐based approach to estimating carrying capacity is likely suitable for other nonmigratory, density‐dependent species.

In search of a critical habitat concept for woodland caribou, boreal population

A hierarchical approach to critical habitat identification has been proposed in the draft National Recovery Strategy for the Woodland Caribou (Rangifer tarandus caribou), Boreal Population. This approach proposes that critical habitat for boreal caribou be identified as equivalent with caribou ranges and their composite range components, and that it be consistent with the biological needs of a wild, self-sustaining local population of woodland caribou. These components include seasonal ranges, high use areas and calving sites, each of which provide for important ecological functions and are subject to specific risks from human development activities. Protection of critical habitat is accomplished through management of the amount and type of human developments and potential natural disturbances, not by prohibiting all activity. This approach to critical habitat sets the stage for management and monitoring of habitat at spatial and temporal scales appropriate for conservation of a wide ranging species such as woodland caribou.

Records of Indo-Pacific Humpback Dolphins, <I>Sousa chinensis</I> (Osbeck, 1765), from the Waters of Western Taiwan

Indo-Pacific humpback dolphins (Sousa chinensis) occur in the coastal northern waters of Australia from approximately the Queensland – New South Wales border (31°27primeS, 152°55primeE) to Ningaloo Reef (22°17primeS, 113°48primeE) in Western Australia. Due to their coastal, estuarine distribution, Indo-Pacific humpback dolphins are particularly vulnerable to several human activities in and adjacent to coastal areas. At present, it is not possible to assess the population status of humpback dolphins in Australian waters because information on their biology and ecology is limited. The sparse data available for selected areas indicate that humpback dolphins occur in discrete, geographically localized populations and are susceptible to anthropogenic threats (e.g., incidental captures in gill nets). The conservation of humpback dolphins in Australia's northern coastline will depend on the maintenance of high-quality habitat in areas that are already under some protection, the identification of critical habitats, the inclusion of these habitats in the rezoning initiatives of protected areas, and the reduction of conservation threats. Precautionary measures should be adopted while further work on abundance estimates, population structure, and levels of human-caused mortality are carried out on a wider scale in Australian waters.