The Importance of Supratidal Habitats for Wintering Shorebirds and the Potential Impacts of Shrimp Aquaculture

Intensive black tiger shrimp (Penaeus monodon) aquaculture ponds have replaced significant areas of coastal wetlands throughout tropical Asia. Few studies have assessed potential impacts on avian foraging habitats. At Khao Sam Roi Yod National Park, Thailand, seminatural wetlands have been converted to either shrimp ponds or to salinization ponds that provide saline water for shrimp aquaculture. Although shorebirds cannot feed in aquaculture ponds, hypersaline ponds can provide productive foraging areas. Thus, the overall impact of the shrimp industry on shorebirds depends partly on the relative quality of the salt ponds compared to seminatural wetlands. In this study, we examined wintering shorebird use of tidal (N = 5 sites) and supratidal areas (four wetland sites, four salt pond sites) and compared the shorebird community (14 species), prey availability, profitability, and disturbance rates between wetlands and salt ponds. Two shorebird species fed in higher densities in wetlands, whereas seven species were more abundant in salt ponds. Large juvenile fish and dragonfly larvae were more abundant in wetlands, whereas there were more small Chironomid midge and fly larvae in salt ponds. We conclude that salt ponds might provide higher-quality foraging habitats compared to wetlands for small shorebirds species because of the abundance of small larvae. However, the shrimp aquaculture industry reduces habitat availability for shorebirds feeding on larger prey. This study demonstrates a comprehensive, multispecies approach to assess the impacts of a large-scale change in coastal habitats for wintering shorebirds.     

Effects on fisheries and waterbirds of raising water levels at Kerkini Reservoir,a Ramsar site in northern greece

A new, higher dam was installed at Kerkini Reservoir in 1982, causing habitat and landscape disruption. A decrease in the area of grassland and shallow water areas, the rapid disappearance of reedbeds, the appearance of beds ofNymphaea, and the disappearance of half the forest area were all observed between 1982 and 1991. With the new hydrological regime, a lacustrine system was created, with an extensive, rather deep (4–8 m), pelagic zone favorable for the development of coarse fish species throughout the year. After 1982, an increase in fishing effort and a change in the relative abundance of fish species in the catch, including the disappearance of eels and wels, were observed. The impact of the rise in the water level of breeding aquatic birds led to a general decline in species typical of marshy habitats in favor of species preferring deeper open water habitats. A decrease was recorded in bird species that feed largely on invertebrates and to a lesser extent fish (e.g., glossy ibis) and that require extensive shallow feeding areas. There was a decline in geese, whose nests were regularly flooded, and a major increase in piscivorous birds, particularly diving birds (e.g., cormorants), which prefer deeper open water and benefitted directly from the large increase in coarse fish biomass. The disappearance of birds breeding in flooded meadows (e.g., black-winged stilts) and of those restricted to reedbeds (e.g., marsh harrier) occurred from 1983. Over the same period, the changes in populations of wintering birds at Kerkini were different from those occurring in other wetlands in northern Greece. The changes recorded in the populations of wintering birds at Kerkini did not therefore result from overall regional trends but from the major habitat modifications that occurred to this wetland. As for breeding birds, strictly piscivorous species increased greatly as a result of the increased availability of fish, but also due to the appearance of many suitable night roosting sites (flooded trees) and to the great increase in the area of open water greater than 2 m deep. Today, Kerkini has become the most important breeding site in Greece for a majority of colonial waterbirds. In contrast, wintering shorebirds practically disappeared. The many changes recorded in the status of breeding and wintering birds at Kerkini can mostly be explained by the changes that occurred in the functioning of the ecosystem and in the habitat structure following the inauguration of the new hydrological regime. These changes did not all occur at the same time: some were immediate and others required a delay before they could be detected.     

Issues and approaches in assessing cumulative impacts on waterbird habitat in wetlands

Wetlands are attractive to vertebrates because of their abundant nutrient resources and habitat diversity. Because they are conspicuous, vertebrates commonly are used as indicators of changes in wetlands produced by environmental impacts. Such impacts take place at the landscape level where extensive areas are lost; at the wetland complex level where some (usually small) units of a closely spaced group of wetlands are drained or modified; or at the level of the individual wetland through modification or fragmentation that impacts its habitat value. Vertebrates utilize habitats differently according to age, sex, geographic location, and season, and habitat evaluations based on isolated observations can be biased. Current wetland evaluation systems incorporate wildlife habitat as a major feature, and the habitat evaluation procedure focuses only on habitat. Several approaches for estimating bird habitat losses are derived from population curves based on natural and experimentally induced population fluctuations. Additional research needs and experimental approaches are identified for addressing cumulative impacts on wildlife habitat values.     

Using Earth Observation to update a Natura 2000 habitat map for a wetland in Greece

The European Habitats Directive 92/43/EEC has defined the need for the conservation of habitats and species with the adoption of appropriate measures. Within the Natura 2000 ecological network of special areas of conservation, natural habitats will be monitored to ensure the maintenance or restoration of their composition, structure and extent. The European Space Agency's GlobWetland project has provided remotely sensed products for several Ramsar wetlands worldwide, such as detailed land cover-land use, water cycle and inundated vegetation maps. This paper presents the development and testing of an operational methodology for updating a wetland's habitat map using the GlobWetland products, and the evaluation of the extent to which GlobWetland products have contributed to the habitat map updating. The developed methodology incorporated both automated and analyst-supervised techniques to photo-interpret, delineate, refine, and evaluate the updated habitat polygons. The developed methodology was proven successful in its application to the wetland complex of the Axios-Loudias-Aliakmon delta (Greece). The resulting habitat map met the European and Greek national requirements. Results revealed that GlobWetland products were a valuable contribution, but source data (enhanced satellite images) were necessary to discriminate spectrally similar habitats. Finally, the developed methodology can be modified for original habitat mapping.     

Mine-drainage treatment wetland as habitat for herptofaunal wildlife

Land reclamation techniques that incorporate habitat features for herptofaunal wildlife have received little attention. We assessed the suitability of a wetland, constructed for the treatment of mine-water drainage, for supporting herptofaunal wildlife from 1988 through 1990 using diurnal and nocturnal surveys. Natural wetlands within the surrounding watershed were also monitored for comparison. The treatment wetland supported the greatest abundance and species richness of herptofauna among the sites surveyed. Abundance was a function of the frog density, particularly green frogs (Rana clamitans) and pickerel frogs (R. palustris), while species richness was due to the number of snake species found. The rich mix of snake species present at the treatment wetland was believed due to a combination of an abundant frog prey base and an amply supply of den sites in rock debris left behind from earlier surface-mining activities. Nocturnal surveys of breeding male frogs demonstrated highest breeding activity at the treatment wetland, particularly for spring peepers (Hyla crucifer). Whole-body assays of green frog and bullfrog (R. catesbeiana) tissues showed no differences among sites in uptake of iron, aluminum, and zinc; managanese levels in samples from the treatment wetland were significantly lower than those from natural wetlands. These results suggest that wetlands established for water quality improvement can provide habitat for reptiles and amphibians, with the species composition dependent on the construction design, the proximity to source populations, and the degree of acidity and heavy-metal concentrations in drainage waters.     

Vegetative Ecological Characteristics of Restored Reed (Phragmites australis) Wetlands in the Yellow River Delta, China

In this study, we compared ecological characteristics of wetland vegetation in a series of restoration projects that were carried out in the wetlands of Yellow River Delta. The investigated characteristics include plant composition structure, species diversity and community similarity in three kinds of Phragmites australis wetlands, i.e. restored P. australis wetlands (R1, R2, R3 and R4: restored in 2002, 2005, 2007 and 2009, respectively), natural P. australis wetland (N) and degraded P. australis wetland (D) to assess the process of wetlands restoration. The coverage of the R1 was 99%, which was similar to natural wetland. Among all studied wetlands, the highest and lowest stem density was observed in R1 and R2, respectively, Plant height and stem diameter show the same trend as N > R2 > R1 > R3 > D > R4. Species diversity of restored P. australis wetlands became closed to natural wetland. Both species richness and Shannon–Wiener index had similar tendency: increased first and then decreased with restored time. The highest species richness and species diversity were observed in R2, while the lowest values of those parameters were found in natural P. australis wetland. Similarity indexes between restored wetlands and natural wetland increased with the restoration time, but they were still less than 50%. The results indicate that the vegetation of P. australis wetlands has experienced a great improvement after several years’ restoration, and it is feasible to restored degraded P. australis wetlands by pouring fresh water into those wetlands in the Yellow River Delta. However, it is notable that costal degraded P. australis wetland in this region may take years to decades to reach the status of natural wetland.     

Critique of present wetlands mitigation policies in the united states based on an analysis of past restoration projects in San Francisco Bay

A detailed evaluation of past wetland restoration projects in San Francisco Bay was undertaken to determine their present status and degree of success. Many of the projects never reached the level of success purported and others have been plagued by serious problems. On the basis of these findings, it is debatable whether any sites in San Francisco Bay can be described as completed, active, or successful restoration projects at present. In spite of these limited accomplishments, wetland creation and restoration have been adopted in the coastal permit process as mitigation to offset environmental damage or loss of habitat. However, because the technology is still largely experimental, there is no guarantee that man-made wetlands will persist as permanent substitutes for sacrificed natural habitats. Existing permit policies should be reanalyzed to insure that they actually succeed in safeguarding diminishing wetlands resources rather than bartering them away for questionable habitat substitutes. Coastal managers must be more specific about project requirements and goals before approval is granted. Continued research on a regional basis is needed to advance marsh establishment techniques into a proven technology. In the meantime, policies encouraging or allowing quid pro quo exchanges of natural wetlands with man-made replacements should proceed with caution. The technology and management policies used at present are many steps ahead of the needed supporting documentation.     

Integrated Management to Create New Breeding Habitat for Dalmatian Pelicans (Pelecanus crispus) in Greece

/ An integrated management plan to create favorable nesting habitat for the world-endangered Dalmatian pelicans, was tested at Kerkini irrigation reservoir, a Ramsar wetland. The lake is the major wintering site of Dalmatian pelicans in Europe, where the species lives year-round without breeding. The rise of water level at the reservoir during spring (exceeding 5 m) has an impact on the whole system, including several birds, which lose their nesting habitat. Although the integrity of the wetland demands ecological restoration with changes in its hydrologic regime, local socioeconomic conditions allow only habitat level interventions. During the planning phase of the management plan, both the ecological and social context of the interventions were considered. Monitoring of all pelican habitats and populations provided the scientific basis, while a socioecological survey on knowledge/attitudes of local fishermen toward wetland identified conflicts with specific resources and planned management. To gain public support, a broad information/education program was implemented. The education program for fishermen was based on the findings of the socioecological survey. The in situ management involved experimental construction of floating rafts, platforms over water, dredged-spoil islands, and platforms at various sites of the wetland. Monitoring of the managed habitats showed that most waterbirds used them for resting and roosting. Common terns nested on the rafts, cormorants on the platforms, and Dalmatian pelicans on the man-made island. Under the prevailing hydrologic and weather conditions, islands seem to be the most suitable habitat for pelican nesting. It is concluded that wildlife habitat management should integrate the ecological component, related to the needs of the species and ecosystem, with the social one, expressed by cooperation and involvement of the local community.KEY WORDS: Integrated management; Pelican; Nesting habitat; Habitat management; Reservoir-wetland; Public participation, Greece     

Can Human-made Saltpans Represent an Alternative Habitat for Shorebirds? Implications for a Predictable Loss of Estuarine Sediment Flats

Estuarine areas worldwide are under intense pressure due to human activities such as upstream dam building. Shorebirds strongly depend on estuarine intertidal flats during migration and wintering periods and so are particularly vulnerable to such impacts, whose magnitude will depend on the availability of alternative feeding habitats. In this study we analyze if man-made saltpans can represent an alternative habitat for wintering and migrating shorebirds in the Guadiana estuary, a wetland that is already experiencing environmental changes due to the building of the Alqueva reservoir, the largest in Western Europe. We compared the use of mudflats and saltpans as feeding areas by several shorebird species before the construction of the dam. A dataset with 26 years of counts data was also analyzed in order to detect any long-term trend in shorebirds abundance. We concluded that saltpans, in particular the fully mechanized, can be used as an alternative habitat by larger species during winter and southward migration, thus playing a major role in minimizing the possible effects of sediment loss due to dam building. In contrast, smaller species were particularly dependent on mudflats to feed. A significant change in population trends, from positive to negative, was detected for two species. Although we still have no evidence that this is directly linked to dam building, this result and documented changes that limit primary productivity justifies the implementation of a long-term monitoring scheme of shorebird populations in this estuary. We also reinforce the need to manage the saltpans as key habitats for shorebirds.     

Use of Aquaculture Ponds and Other Habitats by Autumn Migrating Shorebirds Along the Lower Mississippi River

Populations of many shorebird species are declining; habitat loss and degradation are among the leading causes for these declines. Shorebirds use a variety of habitats along interior migratory routes including managed moist soil units, natural wetlands, sandbars, and agricultural lands such as harvested rice fields. Less well known is shorebird use of freshwater aquaculture facilities, such as commercial cat- and crayfish ponds. We compared shorebird habitat use at drained aquaculture ponds, moist soil units, agricultural areas, sandbars and other natural habitat, and a sewage treatment facility in the in the lower Mississippi River Alluvial Valley (LMAV) during autumn 2009. Six species: Least Sandpiper (Calidris minutilla), Killdeer (Charadrius vociferous), Semipalmated Sandpiper (Calidris pusilla), Pectoral Sandpiper (C. melanotos), Black-necked Stilt (Himantopus himantopus), and Lesser Yellowlegs (Tringa flavipes), accounted for 92 % of the 31,165 individuals observed. Sewage settling lagoons (83.4, 95 % confidence interval [CI] 25.3–141.5 birds/ha), drained aquaculture ponds (33.5, 95 % CI 22.4–44.6 birds/ha), and managed moist soil units on public lands (15.7, CI 11.2–20.3 birds/ha) had the highest estimated densities of shorebirds. The estimated 1,100 ha of drained aquaculture ponds available during autumn 2009 provided over half of the estimated requirement of 2,000 ha by the LMAV Joint Venture working group. However, because of the decline in the aquaculture industry, autumn shorebird habitats in the LMAV may be limited in the near future. Recognition of the current aquaculture habitat trends will be important to the future management activities of federal and state agencies. Should these aquaculture habitat trends continue, there may be a need for wildlife biologists to investigate other habitats that can be managed to offset the current and expected loss of aquaculture acreages. This study illustrates the potential for freshwater aquaculture to provide habitat for a taxa at risk. With the rapid growth of aquaculture worldwide, the practices of this industry deserve attention to identify benefits as well as risks to wildlife.     

Impoundment Productivity in the Prudhoe Bay Oil Field, Alaska: Implications for Waterbirds

a ), and nutrient availability (phosphorus and nitrogen). High variability in these limnological characteristics, particularly among impoundments, obscured potential differences between impoundments and ponds. No significant differences were found in chlorophyll or nutrient concentrations, and in only two cases were there differences in invertebrate production: gastropods were significantly more abundant in impoundments than in ponds in June, and trichopterans were significantly more abundant in impoundments than in ponds in July. For comparisons within impoundments and ponds, there were significant differences in invertebrate abundance between habitats and between wetland types. For example, plecopterans, trichopterans, and gastropods (all taxa combined) were consistently more abundant in shallow–Arctophila impoundments and ponds than in shallow–Carex impoundments and ponds. Thus, ponds and impoundments may differ significantly in invertebrate production, but we lack information on the amount of different habitat types (i.e., center versus emergent vegetation, Carex versus Arctophila) used by these taxa within each water body type. It is a reasonable speculation, based on results of this study, that impoundments and ponds may have similar value as feeding habitat for invertebrate-eating waterbirds. Thus the presence of impoundments may be consistent with waterbird management goals on the Arctic Coastal Plain.     

Bird distributions relative to remotely sensed habitats in Great Britain: towards a framework for national modelling

This paper develops a comprehensive and objective picture of bird distributions relative to habitats across Britain. Bird species presence/absence data from an extensive field survey and habitat data from the remotely sensed UK Land Cover Map 2000 were analysed in 36,920 tetrads (2 kmx2 km) across Britain (a 65% sample of Britain's c. 240,000 km2). Cluster analysis linked birds to generalised landscapes based on distinctive habitat assemblages. Maps of the clusters showed strong regional patterns associated with the habitat assemblages. Cluster centroid coordinates for each bird species and each habitat were combined across clusters to derive individualised bird-habitat preference indices and examine the importance of individual habitats for each bird species. Even rare species and scarce habitats showed successful linkages. Results were assessed against published accounts of bird-habitat relations. Objective corroboration strongly supported the associations. Relatively scarce coastal and wetland habitats proved particularly important for many birds. However, extensive arable farmland and woodland habitats were also favoured by many species, despite reported declines in bird numbers in these habitats. The fact that habitat-specialists do not or cannot move habitat is perhaps a reason for declining numbers where habitats have become unsuitable. This study showed that there are unifying principles determining bird-habitat relations which apply and can be quantified at the national scale, and which corroborate and complement the cumulative knowledge of many and varied surveys and ecological studies. This 'generality' suggests that we may be able, reliably and objectively, to integrate and scale up such disparate studies to the national scale, using this generalised framework. It also suggests the potential for a landscape ecology approach to bird-habitat analyses. Such developments will be important steps in building models to develop and test the sustainable management of landscapes for birds.     

Wetland development trends in coastal North Carolina,USA, from 1970 to 1984

Coastal wetlands are a valuable resource to North Carolina, USA, representing important habitat for marine organisms and providing flood control areas and buffer zones from marine storms. An analysis of wetland development trends in coastal North Carolina from 1970 to 1984 was conducted using over 3000 files containing 15 years of permitting records. The total amount of coastal wetland area altered due to authorized development under the Coastal Area Management Act (CAMA), the Dredge and Fill Law, and Section 404 of the Federal Water Pollution Control Act is 1740 ha. This represents nearly 2% of the salt marsh wetlands along the coast of North Carolina. The number of permits issued steadily increased during the 1980s; however, the total amount of wetland loss decreased each year. A few large projects in the early 1970s accounted for nearly 70% of all wetland area developed during the 15-year period. Nearly two-thirds of all projects involving wetland destruction involved impacts on high marsh ecosystems. Bulkheads, canals, and filling activities made up 80% of the projects requiring permits; 62% of the permits were issued to private landowners, but this group accounted for only 16% of the losses of wetland area. Utility companies, which accounted for less than 1% of the permits issued, were responsible for 46% of the permitted wetland loss during the 15-year study period. Future studies should address agriculture and forestry practices which are exempt under CAMA laws and therefore their effects on wetland alteration have not been quantified.     

History Matters: Relating Land-Use Change to Butterfly Species Occurrence

Western European landscapes have drastically changed since the 1950s, with agricultural intensifications and the spread of urban settlements considered the most important drivers of this land-use/land-cover change. Losses of habitat for fauna and flora have been a direct consequence of this development. In the present study, we relate butterfly occurrence to land-use/land-cover changes over five decades between 1951 and 2000. The study area covers the entire Swiss territory. The 10 explanatory variables originate from agricultural statistics and censuses. Both state as well as rate was used as explanatory variables. Species distribution data were obtained from natural history collections. We selected eight butterfly species: four species occur on wetlands and four occur on dry grasslands. We used cluster analysis to track land-use/land-cover changes and to group communes based on similar trajectories of change. Generalized linear models were applied to identify factors that were significantly correlated with the persistence or disappearance of butterfly species. Results showed that decreasing agricultural areas and densities of farms with more than 10 ha of cultivated land are significantly related with wetland species decline, and increasing densities of livestock seem to have favored disappearance of dry grassland species. Moreover, we show that species declines are not only dependent on land-use/land-cover states but also on the rates of change; that is, the higher the transformation rate from small to large farms, the higher the loss of dry grassland species. We suggest that more attention should be paid to the rates of landscape change as feasible drivers of species change and derive some management suggestions.     

Differing Modes of Biotic Connectivity within Freshwater Ecosystem Mosaics

We describe a collection of aquatic and wetland habitats in an inland landscape, and their occurrence within a terrestrial matrix, as a “freshwater ecosystem mosaic” (FEM). Aquatic and wetland habitats in any FEM can vary widely, from permanently ponded lakes, to ephemerally ponded wetlands, to groundwater‐fed springs, to flowing rivers and streams. The terrestrial matrix can also vary, including in its influence on flows of energy, materials, and organisms among ecosystems. Biota occurring in a specific region are adapted to the unique opportunities and challenges presented by spatial and temporal patterns of habitat types inherent to each FEM. To persist in any given landscape, most species move to recolonize habitats and maintain mixtures of genetic materials. Species also connect habitats through time if they possess needed morphological, physiological, or behavioral traits to persist in a habitat through periods of unfavorable environmental conditions. By examining key spatial and temporal patterns underlying FEMs, and species‐specific adaptations to these patterns, a better understanding of the structural and functional connectivity of a landscape can be obtained. Fully including aquatic, wetland, and terrestrial habitats in FEMs facilitates adoption of the next generation of individual‐based models that integrate the principles of population, community, and ecosystem ecology.     

Comparison of Function of Created Wetlands of Two Age Classes in Central Pennsylvania

Hydrogeomorphic (HGM) functional assessment models were used to assess whether function in created wetlands of two ages (1 year old and >12 years old) was equivalent to that of natural (reference) mainstem floodplain wetlands. Reference wetlands scored higher than both created age classes for providing energy dissipation and short-term surface water storage. Reference wetlands scored higher in maintaining native plant community and structure than 1-year-old sites, and 12-year-old wetlands scored higher than reference sites for providing vertebrate habitat structure. Analysis of individual model variables showed that reference wetlands had greater vegetative biomass and higher soil organic matter content than both created wetland age classes. Created wetlands were farther from natural wetlands and had smaller mean forest patch sizes within a 1-km-radius circle around the site than did the reference sites, indicating less hydrologic connectivity. Created wetlands also had less microtopographic variation than reference wetlands. The 1-year-old created sites were placed in landscape settings with greater land use diversity and road density than reference sites. The 12-year-old sites had a higher gradient and a higher percentage of their surrounding area in urban land use. These results show that the created wetlands were significantly structurally different (if not functionally so) from reference wetlands even after 12 years. The most profound differences were in hydrology and the characteristics of the surrounding landscape. More attention needs to be focused on placing created wetlands in appropriate settings to encourage proper hydrodynamics, eliminate habitat fragmentation, and minimize the effects of stressors to the site.     

Understanding the Value of Local Ecological Knowledge and Practices for Habitat Restoration in Human-Altered Floodplain Systems: A Case from Bangladesh

Worldwide there is a declining trend in natural fish catch (FAO, The state of world fisheries and aquaculture. , 2002) and Bangladesh is no exception. The vast inland fisheries of Bangladesh have been declining over the years, largely a result of human alteration of the aquatic habitats arising from human interventions in the floodplain systems such as the establishment of water control structures which favor agricultural production but reduce fish habitats. It can be assumed that conventional management measures are not adequate to conserve natural fisheries and exploring alternative knowledge systems to complement existing management is warranted. This paper focuses on local ecological knowledge and several other local practices held by fishers engaging directly with floodplain ecosystems. These knowledge systems and practices may be valuable tools for understanding ecosystems processes and related changes and developing local level responses to avert negative consequences of such changes. This may help in devising alternatives to ecosystem management and the conservation of floodplain fish habitats of Bangladesh and elsewhere in the world. This study was conducted in a natural depression (locally called beel) and its surrounding floodplain system located in north central Bangladesh which has become highly degraded. The results of the study indicate that the fishers and local users of the floodplain ecosystems are rich in local ecological knowledge concerning the hydrology of the floodplains and small lakes, the habitat preferences of fish, the role of agricultural crops on fish habitats, and the impact of habitat human interventions in aquatic ecosystems. Given the apparent inadequacy of the present management regime, this article argues for an inclusion of local knowledge and practices into habitat management as a more holistic approach to floodplain habitat restoration and conservation that encourages multi-level cooperation and which builds on diversified knowledge systems.     

Simplified method for wetland habitat assessment

This article presents a wetland habitat assessment technique (HAT) using birds as indicators of habitat quality. The technique is quick, simple, inexpensive, and lends itself to screening large numbers of wetlands. HAT can provide input to more extensive evaluation techniques. Measures of species diversity and rarity are used to assess the quality of the wetland. By applying the notion of ecologically optimum size, the technique addresses the issue of economic efficiency. Results of field testing HAT on 11 tidally influenced wetlands are presented to illustrate HAT's utility. Application of HAT in a variety of situations is discussed.     

Safeguarding Wetlands and Their Connections within Wetlandscapes to Improve Conservation Outcomes for Threatened Amphibian Species

Wetlands should not be considered as independent objects but as dynamically connected objects, collectively known as wetlandscapes. We developed a framework that analyzes the influences of wetland suitability and connectivity on amphibian distributions. We defined two indices: a Wetland Suitability Index describing wetland quality and a Movement Permeability Index characterizing wetland connectivity for amphibian population dynamics. These indices were calculated from raster datasets and time‐varying inundation estimates. The indices were used to define a wetlandscape and an amphibian model was used to simulate population dynamics within the wetlandscape. The framework was applied to the Nose Creek watershed, a highly modified wetlandscape in Alberta, Canada. Two amphibian species were selected with different habitat preferences: the Northern Leopard Frog that prefers wet habitats and has high mobility over land, and the Great Plains Toad that prefers terrestrial habitats and has low mobility over land. We found each amphibian species had a “preferred” wetlandscape, reflecting their life cycle traits and migration strategies which in turn were dependent on the hydrological and ecological connections within the wetlandscape. This study highlights the importance of investigating both individual wetlands and the wetlandscape and considering both wetland habitat quality and connectivity as non‐substitutable properties that act jointly, but differently, on population dynamics.     

THE IMPORTANCE OF BEAVER TO WETLAND HABITATS AND WATERFOWL IN WYOMING1

ABSTRACT: Beaver (Castor canadensis) are habitat‐modifying keystone species, and their activities broadly influence many other plants and animals. Beaver are especially important to waterfowl in the western U.S. where riparian and wetland habitats comprise less than 2 percent of the landscape yet provide habitat for greater than 80 percent of wildlife species. Wyoming is currently ranked sixth of the 50 states in the size of its breeding waterfowl population, and beaver ponds may play a significant role in providing habitat for these birds. The objectives of this research were to: (1) identify streams in Wyoming where beaver are currently present, extirpated, or used to manage riparian habitat; (2) identify areas where beaver could be relocated to create wetlands and improve riparian habitat; (3) compare wetland surface areas between areas that have beaver with those that did not; and (4) compare waterfowl numbers in areas with and without beaver. Using a survey of 125 land managers in Wyoming, we found that beaver have been removed from 23 percent (6,497 kin) of the streams for which managers had direct knowledge (28,297 kin). The same managers estimated that there are over 3,500 km of streams where beaver could improve habitat conditions. The riparian width in streams with beaver ponds averaged 33.9 m (95 percent CI = 25.1–42.7 m) in contrast to 10.5 m (CI = 8.6–12.4 m) in streams without beaver. During waterfowl surveys we counted 7.5 ducks/km (CI = O.9–14.4 ducks/kin) of stream in areas with beaver ponds and only O.1 ducks/km (no CIs calculated) of stream in similar areas without beaver present. Beginning in 1994, we restored beaver to 14 streams throughout Wyoming in an effort to create wetlands and improve riparian habitat. Waterfowl have been quick to respond to these important habitats. We feel that beaver restoration and management can be used to improve habitat in drainages where conflicts with other land uses are minimal.