Upland–wetland linkages: relationship of upland and wetland characteristics with watersnake abundance

Land-use practices surrounding a wetland may be as important for maintaining wildlife populations as the wetland itself. Although imperiled species may appear to be more impacted than ubiquitous species from changes in the landscape surrounding wetlands, studies of common wetland species are useful for conservation because they provide insight into why some species persist despite landscape changes. We therefore investigated the relationship between connectivity, measured as the wetland distance to other wetlands; connectivity quality, implied by wetland distance to roads and forest area within 30, 125, 250, 500 and 1000 m buffer zones around the wetland; and patch size as indicated by wetland size with northern watersnake Nerodia sipedon sipedon abundance. Our results suggest that both upland and wetland characteristics influence the abundance of N. s. sipedon , as wetland size and wetland connectivity to other wetlands were significantly associated with abundance. Abundance was positively correlated with increasing wetland size and wetland connectivity. We were not able to find a significant relationship between abundance and connectivity quality, and wetland distance to road or forest area within 30, 125, 250, 500 and 1000 m buffer zones. We conclude that wetland conservation should focus on wetland complexes as well as individual wetlands. In addition, common wetland species such as the northern watersnake do not appear to be negatively impacted by modifications to nearby terrestrial habitats, such as deforestation and roads, and may benefit from the creation of larger, permanent wetlands.     

When corridors collide: Road-related disturbance in commuting bats

As an increasingly dominant feature in the landscape, transportation corridors are becoming a major concern for bats. Although wildlife–vehicle collisions are considered to be a major source of mortality, other negative implications of roads on bat populations are just now being realized. Recent studies have revealed that bats, like many other wildlife species, will avoid roads rather than cross them. The consequence is that roads act as barriers or filters to movement, restricting bats from accessing critical resources. Our objective was to assess specific features along the commuting route, road, or surrounding landscape (alone or in combination) that exacerbated or alleviated the likelihood of a commuting bat exhibiting an avoidance behavior in response to an approaching vehicle. At 5 frequently used commuting routes bisected by roads, we collected data on vehicles travelling along the roads (such as visibility and audibility), commuting bats (such as height), and composition of the commuting route. We revealed that commuting route structure dictated the frequency at which bats turned back along their commuting routes and avoided the road. We found that gaps (>2 m) in commuting routes, such as the road itself, caused bats to turn away just before they reached the road. Furthermore, we found that turning frequencies of bats increased with vehicle noise levels and the locations at which bats responded to vehicles corresponded with areas where noise levels were greatest, including gaps <2 m. This suggested that bats had a disturbance threshold, and only reacted to vehicles when associated noise reached a certain level. We found that threshold levels for our study species were approximately 88 dB, but this value was likely to vary among species. Thus, our findings indicate that restoring (e.g., replanting native trees and shrubs in gaps) and establishing commuting routes (such as planting tree-lines and wooded hedgerows), as well as creating road-crossing opportunities (such as interlinking canopies) will improve the permeability of a road-dominated landscape to bats. Furthermore, our study highlights the influence of the soundscape. We recommend that effective management and mitigation strategies should take into account the ecological design of the acoustic environment. © 2012 The Wildlife Society.     

Landscape genetics reveal broad and fine‐scale population structure due to landscape features and climate history in the northern leopard frog (Rana pipiens) in North Dakota

Prehistoric climate and landscape features play large roles structuring wildlife populations. The amphibians of the northern Great Plains of North America present an opportunity to investigate how these factors affect colonization, migration, and current population genetic structure. This study used 11 microsatellite loci to genotype 1,230 northern leopard frogs (Rana pipiens) from 41 wetlands (30 samples/wetland) across North Dakota. Genetic structure of the sampled frogs was evaluated using Bayesian and multivariate clustering methods. All analyses produced concordant results, identifying a major east–west split between two R. pipiens population clusters separated by the Missouri River. Substructuring within the two major identified population clusters was also found. Spatial principal component analysis (sPCA) and variance partitioning analysis identified distance, river basins, and the Missouri River as the most important landscape factors differentiating R. pipiens populations across the state. Bayesian reconstruction of coalescence times suggested the major east–west split occurred ~13–18 kya during a period of glacial retreat in the northern Great Plains and substructuring largely occurred ~5–11 kya during a period of extreme drought cycles. A range‐wide species distribution model (SDM) for R. pipiens was developed and applied to prehistoric climate conditions during the Last Glacial Maximum (21 kya) and the mid‐Holocene (6 kya) from the CCSM4 climate model to identify potential refugia. The SDM indicated potential refugia existed in South Dakota or further south in Nebraska. The ancestral populations of R. pipiens in North Dakota may have inhabited these refugia, but more sampling outside the state is needed to reconstruct the route of colonization. Using microsatellite genotype data, this study determined that colonization from glacial refugia, drought dynamics in the northern Great Plains, and major rivers acting as barriers to gene flow were the defining forces shaping the regional population structure of R. pipiens in North Dakota.     

Uneven Rates of Landscape Change as a Source of Bias in Roadside Wildlife Surveys

ABSTRACT Roadside survey data have been used frequently to assess species occurrence and population trends and to establish conservation priorities. However, most studies using such data assume that samples are representative of either the amount of habitat or its rate of change at larger spatial scales. We tested both of these assumptions for the Breeding Bird Survey (BBS) from 1974 to 2001 in New Brunswick, Canada. Our study focused on mature forest—a cover type that we predicted would be characterized by rapid change due to human activities and that is of high ecological importance. We also sought to determine whether land cover changes adjacent to BBS routes were related to bird population trends detected in BBS data. Within all 3 time periods examined (1970s, 1980s, and 1990s), the amount of mature forest adjacent to BBS routes was significantly lower than in surrounding 1° blocks of latitude and longitude. This could be problematic for studies that use roadside data to compare the relative abundance of species. On average, mature forest declined at a rate of-1.5% per year over the 28-year study period. We detected no significant difference in the rate of change between degree blocks and BBS routes over this time span. However, in the 1970s and 1980s, mature forest declined more rapidly in degree blocks (-2.7%/yr) than adjacent to BBS routes (-0.5/yr). We also found that the BBS trend for a mature forest-associated species, blackburnian warbler (Dendroica fusca), was correlated with the trend in mature forest along BBS routes. This, combined with slower rates of mature forest change along routes in the 1970s and 1980s, suggests that BBS data may have underestimated population declines during this period. It is important that research be conducted to test for potential biases in roadside surveys caused by uneven rates of landscape change, particularly in regions characterized by rapid habitat alteration.     

Changes in the diversity structure of avian assemblages in North America

Aim To determine the major patterns of change in avian diversity structure over space and time at a local resolution and continental extent in non‐urban areas in North America. Location The contiguous United States and southern Canada. Methods We used 1673 North American Breeding Bird Survey (BBS) routes containing 547 terrestrial and aquatic species to estimate four diversity components: species richness, individual abundance, taxonomic distinctness and species evenness. We implemented three levels of analysis to examine changes in diversity structure on a yearly basis from 1968 to 2003: (1) a canonical analysis of discriminance, (2) a univariate analysis across BBS routes, and (3) a univariate analysis at individual BBS routes. We estimated changes in similarity in species composition over time between 470,730 BBS route pairs. We also estimated the level of human activity at BBS routes using three spatial anthropogenic databases. Results BBS routes were located in non‐urban areas in association with low nighttime light activity and moderately low human population densities. The analysis of diversity structure indicated the presence of two independent patterns: (1) a temporally consistent pattern defined by increasing species richness (12% increase from 1968 to 2003) associated with limited gains in taxonomic distinctness, and (2) an association between species abundance and evenness related to variability in abundance associated with the most abundant species. The similarity analysis indicated that BBS routes located closer to the Atlantic and the Pacific coasts of the United States experienced the strongest patterns of homogenization of species composition. Main conclusions Our results suggest that avian diversity structure has changed at the local scale in non‐urban areas in North America. However, there was no evidence for a consistent continent‐wide pattern. Instead, the evidence pointed to the presence of regional factors influencing diversity patterns. This study provides a foundation for more detailed investigations of the spatiotemporal and taxonomic details of these general patterns.     

Wetland complexes and upland–wetland linkages: landscape effects on the distribution of rare and common wetland reptiles

We used landscape ecology concepts to test the importance of upland–wetland linkages on the distribution of two common wetland species, the northern watersnake Nerodia sipedon sipedon and midland painted turtle Chrysemys picta marginata , and two rare wetland species, the copper-bellied watersnake Nerodia erythrogaster neglecta and Blanding's turtle Emydoidea blandingii . We tested if connectivity (proximity to other wetlands), connectivity quality (wetland distance to roads and forest area within 30, 125, 250, 500 and 1000 m of the wetland), and patch size (wetland size and shoreline length) affected the distribution of these four species. Our results show that both common species were more likely to occur in larger, less isolated wetlands, but their distribution were not influenced by proximity to roads or the amount of adjacent forest area surrounding the wetland. Both rare species were more likely to occur in wetlands that were farther away from roads and that had more surrounding forest. Proximity to other wetlands was not a significant predictor of either rare species' distribution. Our results suggest that management practices should focus on protecting wetland complexes and maintaining upland–wetland linkages by improving landscape connectivity, increasing forest area surrounding wetlands and reducing road effects.     

Compositional changes over space and time along an occurrence–abundance continuum: anthropogenic homogenization of the North American avifauna

Aim Changes in community attributes due to the influence of anthropogenic activities have been examined primarily using occurrence data with little consideration of associated changes in abundance. To determine how this influences our perception of biotic homogenization, we examined compositional patterns for avian assemblages over space and time along an occurrence–abundance continuum. Location The contiguous United States and southern Canada. Methods We examined avian assemblages at 951 Breeding Bird Survey (BBS) routes from 1970 to 2005 that contained a total of 443 species. We used five dissimilarity indices to estimate compositional patterns along an occurrence–abundance continuum of assemblage structure (from species occurrence to transformed abundance to raw abundance) for 396,925 unique combinations of BBS route pairs. We examined annual plots of dissimilarity by distance between BBS routes pairs to estimate spatial and temporal patterns for each index. Results Dissimilarity declined with increasing distance between route pairs for occurrence and transformed abundance, reaching an asymptote at approximately 2500 km. For raw abundance, dissimilarity peaked at intermediate distances (1000–2500 km) with no evidence of an asymptote. Avian assemblages became more similar over time at all points along the continuum. Occurrence and transformed abundance presented the weakest temporal trends, which were uniform or poorly delineated as a function of distance between routes. Raw abundance presented the strongest temporal trends, which declined in strength with increasing distance between routes. Main conclusions With the addition of abundance, there was a substantial and consistent pattern of degradation of β‐diversity for North American avifauna that differed considerably from that observed from occurrence data alone. The geographical expansion of a few species, which recently benefited from the direct and indirect consequences of anthropogenic activities, probably played a prominent role in these patterns. When broad‐scale expansions in occupancy are evident, minor gains in similarity based on species occurrence can mask more substantial gains in similarity based on local abundance. When abundance information is unavailable, its role can be estimated by how occupancy has responded geographically to anthropogenic activities and the expectations of the abundance–occupancy relationship. Our findings support previous work indicating that widespread and locally abundant species will tend to benefit more from anthropogenic activities, creating a possible synergism that enhances biotic homogenization.     

Sub-sampling data from the North American Breeding Bird Survey for application to the Bird Community Index,an indicator of ecological condition

We examined the use of data from the North American Breeding Bird Survey (BBS) for assessments of ecological condition using an avian community-based indicator, the Bird Community Index (BCI). In previous research, the BCI was developed and applied to a random sample of sites in the Mid-Atlantic Highlands. The goal of providing national scale assessments with bird community indicators hinges on a demonstration that existing monitoring programs, like the BBS, can be tapped as source data for the indicators. Our goal was to compare a BBS-based assessment of the Mid-Atlantic Highlands to our original assessment based on random sampling locations. We subsampled three iterations of BBS route data from the study area to account for spatial and temporal scale differences between 40 km BBS routes and the original 1 km transects sampled to develop the BCI. All three iterations of BBS subsamples provided lower overall assessments of ecological condition for the Mid-Atlantic Highlands relative to our original research. Land cover analysis, however, revealed that BBS routes sampled land cover types in proportion to their actual prevalence in the region. Thus, we conclude that BBS data are appropriate as source data for broad scale ecological assessments with indicators such as the BCI. For numerous analytical and logistical reasons, we recommend 10-stop subsamples of BBS data as the preferred scale at which to apply bird community indicators of ecological condition.     

Reassessing perennial cover as a driver of duck nest survival in the Prairie Pothole Region

Conservation plans designed to sustain North American duck populations prominently feature a key hypothesis stating that the amount of the landscape in perennial cover surrounding upland duck nests positively influences nest survival rates. Recent conflicting research testing this hypothesis creates ambiguity regarding which management actions to pursue and where to prioritize conservation delivery. We compared existing models and new formulations of existing models explaining spatiotemporal variation in nest survival using independent data documenting the fate of >20,000 duck nests within the Drift Prairie, Missouri Coteau, and Prairie Coteau physiographic regions of the United States Prairie Pothole Region during 2002–2018. Our results suggest an inconsistent relationship between perennial cover and survival of upland duck nests, which depended upon physiographic region and current and time-lagged landscape and environmental conditions. The magnitude and direction of how perennial cover correlated with daily nest survival depended on its dominance as a landcover type. A positive relationship existed when perennial cover was a minor component of landcover in all physiographic regions (<30% of a 10.4-km² area) and, in the Drift Prairie and Prairie Coteau, when perennial cover was the dominant landcover type (>60%). A constant or negative relationship was predicted at locations of about 30–60% perennial cover. Additionally, environmental conditions (i.e., density of wetlands and estimated gross primary productivity in the previous year) moderated or enhanced the effect of perennial cover on nest survival, depending on physiographic region. Our finding of inconsistency in the relationship between perennial cover and nest survival contradicts the conservation premise that nest survival universally increases linearly when uplands are converted to perennial cover. Promoting policies and management actions designed to increase perennial cover can be expected to be situationally but not consistently associated with higher survival of upland duck nests.     

The role of the landscape in structuring immature mosquito assemblages in wetlands

The distribution of mosquito populations is spatially heterogeneous and influenced by factors acting at a wide range of scales. The aim of this study was to assess the role of environmental heterogeneity at the landscape level in shaping the composition of immature mosquito communities inhabiting surface water habitats. The Paraná Lower Delta (Argentina) is a temperate wetland that extends along a 1º north–south gradient and presents high landscape heterogeneity, due to the combined action of geomorphology, hydrology and human intervention. Immature mosquitoes were collected every 2 weeks (Nov 2011–April 2012) from surface water habitats within 11 peridomestic areas interspersed along a 75 km north–south transect. The environment was quantified by 24 variables regarding the geomorphology, geography, economic use, climate, landcover and topography of each site and its surroundings at three radii. The association between the mosquito assemblage and the environment was tested by two multivariate approaches, the community-based outlying mean index and by-species generalized linear models. The former explained 93.6 % of the marginality of all taxa as a function of the type and diversity of landcover, precipitation, presence of cattle and altitude. The niche of six species, most of which were floodwater mosquitoes of the genera Ochlerotatus and Psorophora, deviated significantly from uniformity. The by-species approach rendered significant models for four species as a function of landcover type and precipitation. Both methodologies were broadly consistent in pointing that landscape elements affect the distribution of immature mosquitoes, thereby shaping the composition of the mosquito assemblage in peridomestic environments within wetlands.     

Landscape complexity influences route-memory formation in navigating pigeons

Observations of the flight paths of pigeons navigating from familiar locations have shown that these birds are able to learn and subsequently follow habitual routes home. It has been suggested that navigation along these routes is based on the recognition of memorized visual landmarks. Previous research has identified the effect of landmarks on flight path structure, and thus the locations of potentially salient sites. Pigeons have also been observed to be particularly attracted to strong linear features in the landscape, such as roads and rivers. However, a more general understanding of the specific characteristics of the landscape that facilitate route learning has remained out of reach. In this study, we identify landscape complexity as a key predictor of the fidelity to the habitual route, and thus conclude that pigeons form route memories most strongly in regions where the landscape complexity is neither too great nor too low. Our results imply that pigeons process their visual environment on a characteristic spatial scale while navigating and can explain the different degrees of success in reproducing route learning in different geographical locations.     

Comparing areas of suitable habitats along travelled and possible shortest routes in migration of White-naped Cranes Grus vipio in East Asia

Many migratory species take detours when migrating from their breeding to wintering grounds rather than following the shortest route available. To test whether the distribution of potentially suitable habitats might be a factor causing the use of less direct detours during migration, we analysed the migratory routes of five White-naped Cranes Grus vipio satellite-tracked from central–east Russia, and compared the total area of wetlands and grasslands along the migratory routes travelled by the Cranes with that along the shortest possible routes to the Cranes' wintering grounds. All five Cranes made an easterly detour, and the distance ratio of the routes used by Cranes to the shortest possible route was 1.13 ± 0.03 sd. Based on National Oceanic and Atmospheric Administration satellite images, we demonstrate that the area of wetlands and grasslands along the migration routes travelled by Cranes was greater than along the shortest possible routes.     

Role of infrastructure and other environmental factors affecting the distribution of alien plants in the Tatra Mts

Alien plants, although usually rare in mountain habitats, can significantly impact native species diversity. The aim of this study was to analyse patterns of alien plant distribution in the Tatra Mts (Slovakia), focusing primarily on comparison of various transportation routes as a conduit for the spread of alien plants. We collected data on transects along: (i) railways, (ii) paved roads with unlimited access, (iii) tourist routes in mountain valleys (paved and unpaved roads, footpaths) with limited access and (iv) plots in areas surrounding mountain chalets. The majority of alien plants were found in locations at lower elevations and with intensive human activity. Patterns of distribution along the main corridors in the Tatras reflect the intensity and manner of use of each transportation route. Paved roads with unlimited access and railways are used most frequently and host the greatest number of alien species. Our observations show that the mode of access of these routes is more important than the road surface. Roads with limited vehicular access, be it unpaved and paved, are very similar in their alien species richness, while paved roads with limited and unlimited access significantly differ. Footpaths that cannot be accessed by vehicles are almost free of alien plants, even though they are found in the widest elevation range and often parallel to roads in the same valley. Other factors significantly negatively affiliated with alien species richness were elevation, cover of the tree and moss layer and moisture, and positively affiliated with the amount of nutrients.     

长白山典型林区森林资源景观格局变化分析

利用研究区1985年及1999年遥感影像作为数据源,在GIS支持下并结合地面资料对森林资源景观格局及其变化进行研究．从两期地物斑块面积标准偏差来看,成熟针叶林(1985年为279．3,1999年为98．64)、成熟阔叶林(1985年为162．94,1999年为68．54)、中龄阔叶林(1985年为113．14)、中龄针叶林(1999年为160．71)斑块面积分布均匀程度均较同期其它地物类型小,这也说明这些地物组成中景观类型多样性及物种多样性．从景观相似性指数分析来看,中龄阔叶林(1985年为0．118,1999年为0．116)、中龄针叶林(1985年为0．07,1999年为0．336)、成熟阔叶林(1985年为0．312,1999年为0．228)、成熟针叶林(1985年为0．237,1999年为0．174)4类植被在15年间较同期其它地物类型稳定,是研究区景观的主要组成部分．湿地在两期的孔隙度都较大,湿地的均质化程度很小,形成了更多的斑块镶嵌体,湿地破碎化程度较高．     

Land cover differentially affects abundance of common and rare birds

While rare species are vulnerable to global change, large declines in common species (i.e., those with large population sizes, large geographic distributions, and/or that are habitat generalists) also are of conservation concern. Understanding if and how commonness mediates species' responses to global change, including land cover change, can help guide conservation strategies. We explored avian population responses to land cover change along a gradient from common to rare species using avian data from the North American Breeding Bird Survey (BBS) and land cover data from the National Land Cover Database for the conterminous United States. Specifically, we used generalized linear mixed effects models to ask if species' commonness affected the relationship between land cover and counts, using the initial amount of and change in land cover surrounding each North American BBS route from 2001 to 2016. We quantified species' commonness as a continuous metric at the national scale using the logarithm (base 10) of each species' total count across all routes in the conterminous United States in 2001. For our focal 15-year period, we found that higher proportions of initial natural land cover favored (i.e., were correlated with higher) counts of rare but not common species. We also found that commonness mediated how change in human land cover, but not natural land cover, was associated with species' counts at the end of the study period. Increases in developed lands did not favor counts of any species. Increases in agriculture and declines in pasture favored counts of common but not rare species. Our findings show a signal of commonness in how species respond to a major dimension of global change. Evaluating how and why commonness mediates species' responses to land cover change can help managers design conservation portfolios that sustain the spectrum of common to rare species.     

Plant species diversity and composition of wetlands within an upland forest

Though often overlooked, small wetlands in an upland matrix can support diverse plant communities that increase both local and regional species richness. Here we characterize the full range of wetland vegetation within an upland forest landscape and compare the diversity and composition of different wetland plant communities. In an old-growth forest reserve in southern Quebec, Canada, we sampled wet habitats including lakeshores, permanent and seasonal ponds, swamps, glades, and streamsides. We used clustering, indicator species analysis, and nonmetric multidimensional scaling ordination to identify and compare vegetation types. The wetlands contained 280 species of vascular plants, 45% of the reserve's flora, in only 1.1% of its area. Local diversity averaged 24 ± 0.7 species per 7 m(2), much higher than in the surrounding upland forests. Plant communities sorted into five types, whose strongest indicator species were Osmunda regalis, Glyceria striata, O. cinnamomea, Deparia acrostichoides, and Matteuccia struthiopteris, respectively. Both local species richness and compositional variation among sites differed among the vegetation types. By combining species representative of the region's major wetlands with species from the upland forest matrix, the plant assemblages of these wetlands make disproportionately important contributions to landscape-level diversity.     

Response of breeding duck pairs to predator reduction in North Dakota

Predator management regularly improves waterfowl nesting success, often beyond levels believed necessary for population maintenance. If recruitment, survival of breeding females, and/or breeding site fidelity is increased on predator-reduced sites, then local breeding populations may increase in subsequent years. During 2005–2008, we annually conducted breeding pair surveys on >600 wetlands at 6 township-sized (93.2 km²) trapped sites and 4 non-trapped sites for the 5 most common upland nesting ducks in eastern North Dakota, USA. For each species, we developed a series of competing regression models that related breeding pair abundance to wetland size, predator management, and upland habitats adjacent to sampled wetlands. In contrast to previous studies, we found limited and equivocal evidence that breeding populations increased following predator management. We discuss multiple potential explanations for this lack of effect and suggest that managers should not assume that increased production as a product of elevated nest success will be compounded over years. © The Wildlife Society, 2013     

Landscape Genetics for the Empirical Assessment of Resistance Surfaces: The European Pine Marten (Martes martes) as a Target-Species of a Regional Ecological Network

Coherent ecological networks (EN) composed of core areas linked by ecological corridors are being developed worldwide with the goal of promoting landscape connectivity and biodiversity conservation. However, empirical assessment of the performance of EN designs is critical to evaluate the utility of these networks to mitigate effects of habitat loss and fragmentation. Landscape genetics provides a particularly valuable framework to address the question of functional connectivity by providing a direct means to investigate the effects of landscape structure on gene flow. The goals of this study are (1) to evaluate the landscape features that drive gene flow of an EN target species (European pine marten), and (2) evaluate the optimality of a regional EN design in providing connectivity for this species within the Basque Country (North Spain). Using partial Mantel tests in a reciprocal causal modeling framework we competed 59 alternative models, including isolation by distance and the regional EN. Our analysis indicated that the regional EN was among the most supported resistance models for the pine marten, but was not the best supported model. Gene flow of pine marten in northern Spain is facilitated by natural vegetation, and is resisted by anthropogenic landcover types and roads. Our results suggest that the regional EN design being implemented in the Basque Country will effectively facilitate gene flow of forest dwelling species at regional scale.     

Tracking palustrine water seasonal and annual variability in agricultural wetland landscapes using Landsat from 1997 to 2005

Wetlands densely populate the ecoregion transecting the center of the Prairie Pothole Region (PPR) known as the Missouri Coteau and epicenter to the most productive waterfowl‐breeding habitat in North America. These palustrine, depressional basin waters vacillate with regional drought and deluge, so surface water fluctuations over time modulate wetland productivity, habitat, and water quality functions. Models predict formidable effects of climate change on glacial basin surface waters, yet large‐scale, long‐term observation data are lacking to compare against predicted changes. Current, optical‐based water detection models do not delineate marsh vegetation from shallow, turbid, high‐chlorophyll waters common to the region. We developed a palustrine wetland spectral model for tracking open surface waters using Landsat imagery, which we evaluated for a 2500 km² landscape that estimates seasonal and annual open water variability for thousands of individual wetlands in the Missouri Coteau ecoregion. Detection accuracy of 96% was achieved for water bodies greater than a half‐pixel in size. We identified shifts in the distribution of water permanence classes within and between years for waters emerging in spring, mid‐summer, and late summer from 1997 to 2005 and identified a maximum of 19 047 basins with open water (12% of the landscape) populating 2500 km². For the 2005 growing season, we observed only 8757 basins with open water (6% of the landscape) for the same area. Declines were greatest for water bodies detected only in spring, suggesting a loss of those wetlands functioning to recharge groundwater stores early in the season and a high sensitivity to observed reductions in snowfall. If landscape factors driving open water coverage and wetland density are similar for the entire Missouri Coteau, we estimate the number of basins containing at least a pixel of water for this region declined from 577 600 to 266 000 between 1997 and 2005.     

Feeding Ecology of Arctic-Nesting Sandpipers During Spring Migration Through the Prairie Pothole Region

ABSTRACT We evaluated food habits of 4 species of spring-migrant calidrid sandpipers in the Prairie Pothole Region (PPR) of North Dakota. Sandpipers foraged in several wetland classes and fed primarily on aquatic dipterans, mostly larvae, and the midge family Chironomidae was the primary food eaten. Larger sandpiper species foraged in deeper water and took larger larvae than did smaller sandpipers. The diverse wetland habitats that migrant shorebirds use in the PPR suggest a landscape-level approach be applied to wetland conservation efforts. We recommend that managers use livestock grazing and other tools, where applicable, to keep shallow, freshwater wetlands from becoming choked with emergent vegetation limiting chironomid production and preventing shorebird use.