Beyond the wetland border: Estimating the impact of roads for two species of water snakes

We used models integrating road maps, traffic volume, and snake movements to examine the potential for roads to contribute to mortality in two species of water snakes that differ in their vagility, use of terrestrial habitats, and conservation status. Road networks and traffic volumes typical of three regions in Indiana, USA, may account for mortality of 14-21% of the population per year in the more vagile, terrestrial, and imperiled copperbelly water snake (Nerodia erythrogaster neglecta) but only 3-5% mortality in the more sedentary, aquatic, and common northern water snake (Nerodia sipedon). The majority (>91%) of road crossings and associated mortality are predicted to occur during overland migrations to other wetlands, suggesting roads bisecting travel routes between wetlands may function as mortality sinks. Our models highlight the proportionately greater risk of mortality for the more vagile and imperiled species, N. e. neglecta, and suggest current wetland conservation strategies that focus on the wetland alone are unlikely to adequately protect wetland biodiversity from certain types of anthropogenic habitat modification. What is needed is a landscape approach to wetland conservation that considers not only the quality of wetlands and nearby terrestrial habitats, but also ensures that terrestrial corridors between wetlands remain permeable and offer safe passage for wildlife.     

Heterogeneous wetland complexes, buffer zones, and travel corridors: Landscape management for freshwater reptiles

While the importance of nearby terrestrial habitats is gaining recognition in contemporary wetland management strategies, it is rarely recognized that different wetlands are often diverse in their functions of meeting the annual or life-cycle requirements of many species, and that migration between these wetlands is also critical. Using radio-telemetry, we examined terrestrial habitat use and movements of 53 eastern long-necked turtles (Chelodina longicollis) in an area of southeast Australia characterized by spatially diverse and temporally variable wetlands. Male and female C. longicollis exhibited a high degree of dependence on terrestrial habitat, the majority (95%) of individuals using sites within 375 m of the wetland. Turtles also associated with more than one wetland, using permanent lakes during droughts and moving en masse to nearby temporary wetlands after flooding. Turtles used 2.4 ± 0.1 (range = 1-5) wetlands separated by 427 ± 62 (range = 40-1470) m and moved between these wetlands 2.6 ± 0.3 (range = 0-12) times over the course of a year. A literature review revealed that several species of reptiles from diverse taxonomic groups move between wetlands separated by a mean minimum and maximum distance of 499-1518 m. A high proportion of studies attributed movements to seasonal migrations (55%) and periodic drought (37%). In such cases we argue that the different wetlands offer complimentary resources and that managing wetlands as isolated units, even with generous terrestrial buffer zones, would not likely conserve core habitats needed to maintain local abundance or persistence of populations over the long term. Core management units should instead reflect heterogeneous groups of wetlands together with terrestrial buffer zones and travel corridors between wetlands.     

Using habitat models to determine conservation priorities for pond-breeding amphibians in a privately-owned landscape of northern Idaho, USA

As rural landscapes experience increasing levels of residential development, the persistence of species that rely on them will depend on informed planning and management decisions. An understanding of habitat requirements is essential for setting priorities and developing landscape-level plans for the survival of these species. In many temperate rural landscapes, artificially created ponds may be the only wetlands available for aquatic reproduction by amphibians. The introduction of non-native fish into these ponds reduces survival and prohibits successful reproduction of many native pond-breeding amphibians. We surveyed 105 randomly selected wetlands in a primarily privately-owned, rural landscape in north Idaho, USA, for pond-breeding amphibian larvae in 2004 and 2005. We used an information theoretic multimodel inference and an algorithmic (random forests) approach to model habitat for each species based on local and landscape characteristics. We also used a mail survey to quantify how landowners value fish in their wetlands and their plans for future wetland development and fish stocking. Sixty-seven percent of pond owners reported that fishing in their pond was at least slightly important to them and 36% of owners indicated that they were at least 50% likely to add fish to their ponds in the next 5-10 years. Landscape change predictions for this area indicate that forests will become more open due to thinning; habitat models indicated that this is likely to be detrimental to long-toed salamanders and beneficial to Pacific treefrogs. Habitat models also indicate that Columbia spotted frog breeding sites consist of wetlands on flat ground with high solar insolation and that this species is sensitive to nearby development, indicating that as this landscape becomes further developed, this species may require habitat protection for persistence.     

Agricultural landscape modification increases the abundance of an important food resource: Mistletoes, birds and brigalow

Agricultural landuse alters landscape pattern, with important consequences for native species. Complex responses to changes in landscape pattern may be observed for species with strong inter-specific relationships. We investigate how the abundance of an ecologically important food resource, the grey mistletoe (Amyema quandang), is influenced by the interactive influences of human-modified landscape pattern, bird disperser abundance and host condition. Mistletoe abundance was estimated in brigalow (Acacia harpophylla) dominated remnants in three separate study areas with differing landscape patterns. Negative binomial generalised linear models of mistletoe abundance were tested with combinations of seven explanatory variables: study area, landscape connectivity and edge contrast, patch shape, bird disperser abundance, brigalow foliage cover and basal area of standing dead trees. Ranking of model averaged parameter estimates showed that study area, bird disperser abundance, patch shape, dead trees and connectivity had the strongest influence on A. quandang abundance. Mistletoe abundance apparently increased with landscape modification, particularly in narrow linear patches, but may be limited by the availability of seed dispersers and host condition. Given high landscape modification and ongoing degradation, management should be targeted towards maintaining brigalow remnant condition to ensure bird and mistletoe populations can be supported in the long-term.     

Amphibians in a human-dominated landscape: the community structure is related to habitat features and isolation

We studied amphibian populations in a human-dominated landscape, in Northern Italy, to evaluate the effects of patch quality and isolation on each species distribution and community structure. We used logistic and linear multiple regression to relate amphibian presence during the breeding season in 84 wetlands to wetland features and isolation. Jackknife procedure was used to evaluate predictive capability of the models. Again, we tested the response of each species to habitat features related to the richest communities. Amphibian presence depends strongly on habitat quality and isolation: the richest communities live in fish-free, sunny wetlands near to occupied wetlands. The negative effects of isolation do not seem to be biased by spatial autocorrelation of habitat features. The system shows strong nestedness: amphibian persistence depends on the contemporary effects of species adaptability and mobility. The commonest species, the pool frog (Rana synklepton esculenta) and the Italian tree frog (Hyla intermedia), are able to move through the matrix using canals and hedgerows, and can maintain metapopulations across the landscape; the rarest species (newts and toads) are more sensitive to habitat alteration, and they are strongly affected by isolation effects. If human exploitation of the landscape continues, only few species, mobile and opportunistic, will persist in this landscape.     

Protecting more than the wetland: The importance of biased sex ratios and habitat segregation for conservation of the Hine’s emerald dragonfly, Somatochlora hineana Williamson

Within species habitat use may depend on age, season or sex of an individual. The distribution of males and females may vary both temporally and spatially due to differences in the costs of reproduction and the distribution of critical resources. Conservation of a species requires knowledge of the habitat use of both sexes in order to predict the population size and protect all habitats that a species requires. Adult dragonfly populations often have highly male-biased sex ratios at the breeding habitat. This bias has been attributed to females using alternative habitats to avoid male harassment, or to high female mortality. We monitored adult Hine’s emerald dragonfly (Somatochlora hineana Williamson) populations, in breeding and non-breeding habitats in Door County, Wisconsin and found significant differences in habitat use between males and females. Males primarily used wetland habitats, while females primarily used dry meadows and marginal breeding habitats, only coming into wetlands to lay-eggs or find mates. We assessed food resources in the different habitats and found that high quality insect prey (primarily adult Diptera) were more available in the wetland habitat, indicating that these areas were likely a more productive foraging area for adult dragonflies. The fact that females appear to avoid the wetland habitat is consistent with the hypothesis that male harassment alters female distribution patterns. Consideration of the patterns of habitat use by S. hineana indicates the need to develop a broader understanding of the importance of non-wetland areas in the conservation of wetland species.     

Modelling the efficacy of proposed mitigation areas for shorebirds: a case study on the Seine estuary, France

A behaviour-based model was used to explore the effect of an extension of the port at Le Havre (Port 2000), and the effect of proposed mitigation measures, on the mortality and body condition of the three main shorebird species that overwinter in the estuary of the river Seine, France. In the model, a 20% reduction in the area of mudflats on the north side of the estuary had little effect on curlew Numenius arquata mortality and body condition but significantly increased mortality and decreased body condition in dunlin Calidris alpina and oystercatchers Haematopus ostralegus. Disturbance of feeding birds both day and night had a significant effect on the mortality and body condition of all three shorebird species, as did disturbance of roosting birds. Disturbance of feeding birds in the daytime only had a significant effect on dunlin mortality and body condition, but not that of curlew and oystercatchers. In the model, the creation of a buffer zone to reduce disturbance of feeding birds restored shorebird mortality and body condition to pre-disturbance levels. A new mudflat area was also effective in mitigating the effect of habitat loss on all three shorebirds and in mitigating the effect of roost disturbance on dunlin and curlew. However, a new mudflat area was not effective in mitigating the effect of roost disturbance on oystercatcher mortality and body condition. The effectiveness of the mitigating mudflat depended as much on its size as its quality. We believe that this is the first time that anyone has been able to forecast the efficacy of proposed mitigation measures.     

Beaver (Castor canadensis) mitigate the effects of climate on the area of open water in boreal wetlands in western Canada

Shallow open water wetlands provide critical habitat for numerous species, yet they have become increasingly vulnerable to drought and warming temperatures and are often reduced in size and depth or disappear during drought. We examined how temperature, precipitation and beaver (Castor canadensis) activity influenced the area of open water in wetlands over a 54-year period in the mixed-wood boreal region of east-central Alberta, Canada. This entire glacial landscape with intermittently connected drainage patterns and shallow wetland lakes with few streams lost all beaver in the 19th century, with beaver returning to the study area in 1954. We assessed the area of open water in wetlands using 12 aerial photo mosaics from 1948 to 2002, which covered wet and dry periods, when beaver were absent on the landscape to a time when they had become well established. The number of active beaver lodges explained over 80% of the variability in the area of open water during that period. Temperature, precipitation and climatic variables were much less important than beaver in maintaining open water areas. In addition, during wet and dry years, the presence of beaver was associated with a 9-fold increase in open water area when compared to a period when beaver were absent from those same sites. Thus, beaver have a dramatic influence on the creation and maintenance of wetlands even during extreme drought. Given the important role of beaver in wetland preservation and in light of a drying climate in this region, their removal should be considered a wetland disturbance that should be avoided.     

Core terrestrial habitat for conservation of local populations of salamanders and wood frogs in agricultural landscapes

Pond-breeding amphibians require aquatic and terrestrial habitats to complete their lifecycles, and preservation of both habitats is necessary for maintaining local populations. Current wetland regulations focus primarily on aquatic habitats, and criteria to define critical upland habitats and regulations to protect them are often ambiguous or lacking. We examined the association between the presence of seven pond-breeding amphibian species and the landscape composition surrounding 54 wetlands located within the Till Plains and the Glaciated Plateau ecoregions of Ohio, USA. We quantified landscape composition within 200 m of the wetland (“core terrestrial zone”) and the area extending from 200 m to 1 km from the wetland (“broader landscape context zone”). We constructed binary logistic regression models for each species, and evaluated them using Akaike Information Criterion. Presence of spotted salamanders (Ambystoma maculatum), Jefferson's salamander complex (A. jeffersonianum) and smallmouth salamanders (A. texanum) was positively associated with the amount of forest within the core zone. Presence of wood frogs (Rana sylvatica) was positively associated with the amount of forest within the core zone and the amount of forest within the broader landscape context zone. Presence of tiger salamanders (A. tigrinum tigrinum) was negatively associated with the cumulative length of paved roads within 1 km of the site, and presence of red-spotted newts (Notophthalmus v. viridescens) was negatively associated with the average linear distance to the five nearest wetlands. Overall salamander diversity was positively associated with the amount of forest within the core zone, and negatively associated with the presence of predatory fish and cumulative length of paved roads within 1 km of the site. Our results confirm the strong association between the structure of surrounding upland areas and amphibian diversity at breeding ponds, and stress the importance of preserving core terrestrial habitat around wetlands for maintaining amphibian diversity.     

Specialist response to proportion of arable land and pesticide input in agricultural landscapes

Increases in farming practice intensity and landscape simplification are two well-known threats for many farmland bird species. Nevertheless, the effects of these two factors may differ strongly among species. Here, we propose to use the specialist-generalist concept to assess which bird species are most affected by these two factors. Bird density and intensity of farming practices were assessed within a sample of 58 farms across the Seine-et-Marne region in France, using point counts and a standardised farmer survey. The local abundance of 41 farmland and non-farmland species was related to farming intensity (pesticide applications) and landscape simplification (proportion of arable land), which was quantified using generalised least square models to account for spatial autocorrelation. The more specialised the farmland and non-farmland birds were, the more negatively affected they were by the intensity of farming practices, relative to the generalist bird species. Local habitat simplification had a more positive effect on abundance of the most specialist farmland bird species. This latter relationship was not significant when tested at a landscape scale, which strongly suggests that the sensitivity of farmland specialists to landscape simplification is scale-dependent. Some non-farmland species’ abundance was also reduced by farming intensity and local landscape simplification suggesting that low-input agri-environmental measures could benefit both farmland and non-farmland specialists, regardless of local and landscape habitat context. However, if diversity-enhancing measures should benefit non-farmland populations, it is likely that they do not favour farmland specialist species which are more at risk. We suggest designing of priority areas for farmland specialist birds, and landscape managing accordingly.     

Comparative water snake ecology: conservation of mobile animals that use temporally dynamic resources

Obtaining information on movement and spatial patterns of animals and understanding the factors that shape their movements about the landscape are critical steps in designing conservation strategies. We conducted a comparative radiotelemetry study of two snake species, the northern water snake, Nerodia sipedon sipedon, and the imperiled copperbelly water snake, Nerodia erythrogaster neglecta, in northwest Ohio and southern Michigan to assess differences in movement patterns, spatial ecology, and resource use. N. e. neglecta moved distances (53.3 ± 7.1 m/day and 4809 ± 603 m/year) over twice as far as N. s. sipedon (25.6 ± 2.7 m/day and 2244 ± 228 m/year), and used areas nearly four times larger (15.8 ± 2.7 ha) than N. s. sipedon (4.0 ± 0.9 ha). When wetlands were widely dispersed in the landscape, N. e. neglecta moved longer distances and used larger areas, whereas spatial and movement patterns in N. s. sipedon were unaffected by wetland spatial distribution. N. e. neglecta’s long movements and large area use are likely related to its use of variable resources such as ephemeral wetlands and anuran prey. N. s. sipedon used more permanent wetlands and preyed more generally on fish and anurans. Habitat alterations that change the spatial distribution of wetlands in the landscape, such as the loss of small isolated wetlands, have likely increased energetic costs and mortality rates for N. e. neglecta. Conservation strategies for vagile wetland animals that use spatially and temporally variable resources over broad spatial scales should focus on protecting and restoring large areas with numerous, heterogeneous wetlands.     

Habitat requirements of passerines and reedbed management in southern France

Reedbeds have high conservation value in Europe. In southern France, they are the major breeding habitat of five passerine species. Yet, habitat management is done primarily by water control to serve socio-economic rather than conservation interests, because we lack information on the species' ecological requirements. Determinants of passerine abundance were assessed through a comparative analysis of water regime, plant structure, and arthropod (food) distribution at 12 sites consisting of at least 10 ha of marsh densely covered with common reed (Phragmites australis). Overall bird abundance estimated through standardised mist netting was positively correlated with food availability (sweep-netted arthropods weighted by their occurrence in birds' diet), which was in turn negatively correlated with duration of ground dryness between June and December. Abundance of four of the five bird species was associated with specific vegetation parameters (reed diameter, dry reed density, growing reed height, etc.), which could be associated with particular management practices, especially with regard to water levels and salinity. Potential impact of socio-economic activities through their water management is addressed, as well as possible ways to minimise these impacts.     

Landscape-moderated importance of hedges in conserving farmland bird diversity of organic vs. conventional croplands and grasslands

Hedges provide important nesting, feeding and sheltering sites for birds in agricultural areas, while organic farming also enhances farmland birds. However, it is little known how the interaction of these local variables (amount of hedges and organic management) with landscape scale variables affects birds. We selected paired conventional and organic winter wheat fields and meadows in each of 10 landscapes in Germany. Birds were surveyed in the fields and in the adjoining hedges. More bird species occurred in organic than in conventional fields regardless of land-use type (wheat fields and meadows). However, hedge length had a much stronger effect on bird richness than organic farmland management. We found an interaction of landscape complexity and hedge length in that hedge length enhanced bird richness only in case of simple landscapes (<17% semi-natural areas within a 500 m radius around the centre of bird survey plots). In more complex landscapes the local effect of hedge length levelled off because bird richness was high even without local hedges. Therefore, adding hedges or introducing organic farming practices should be primarily promoted in simple landscapes, where it really makes a difference for biodiversity.     

Estimating the potential effects of sudden oak death on oak-dependent birds

Sudden oak death (SOD), a disease induced by the fungus-like pathogen Phytophthora ramorum, threatens to seriously reduce or eliminate several oak species endemic to the west coast of North America. We investigated how the disappearance of one of these species, coast live oak (Quercus agrifolia), may affect populations of five resident oak-affiliated California birds - acorn woodpecker (Melanerpes formicivorus), Nuttall’s woodpecker (Picoides nuttallii), Hutton’s vireo (Vireo huttoni), western scrub-jay (Aphelocoma californica), and oak titmouse (Baeolophus inornatus) - using geocoded data from Audubon Christmas Bird Counts, North American Breeding Bird Surveys, and the California Gap Analysis. Capitalizing on observed relationships between the focal bird species and both oak species diversity and areal extent, we modeled relative bird abundance while assuming complete loss of Q. agrifolia and complete, partial, or no loss of oak habitat following a disease sweep. Post-SOD projections of bird populations occurring within the range of coast live oak were on average 25-68% smaller and 13-49% more variable relative to pre-SOD estimates. SOD effects were greatest for habitats with low initial oak species diversity. Climatic SOD models predicted that the disease stands to negatively impact populations of all five focal bird species throughout 20% of California’s coast live oak habitats. This study provides the first spatially explicit insights into the potential effects of SOD on avian distribution and abundance. Results may be used to help prioritize conservation plans aimed at minimizing overall community level disturbances resulting from the disease.     

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

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

Some alien birds have as severe an impact as the most effectual alien mammals in Europe

Invasive alien species cause considerable economic and environmental damage. Nevertheless which species should be targeted first and exact control strategies are controversial matters. As no categorization of the impact of alien bird species is available so far, we adopted an impact scoring system for mammals to birds and scored the impact of the alien birds established in Europe. We investigated 26 established alien birds in Europe and compiled all known impact data for these species. The species with highest environmental impact were the Canada goose (Branta canadensis), sacred ibis (Threskiornis aethiopicus) and ruddy duck (Oxyura jamaicensis). The most severe impact on economy was exerted again by the Canada goose. Also the ring-necked parakeet (Psittacula krameri) and monk parakeet (Myiopsitta monachus) had high impact in this category. Combining these potential impact data with the current distribution generates a list of alien birds with highest actual impact. These two values can be used to prioritise preventive and control measures. In comparison to birds, mammals in general have higher potential and actual impact in Europe, but some bird species reach impact values as high as some of the worst mammal species. Still, these bird species - in contrast to mammals with high impact - are hardly targeted by control programmes. This study shows that there is no scientific reason for this. With the here presented scoring system we offer a decision tool to practitioners which supports them in finding an appropriate reaction to invasive birds.     

Migration routes and important resting areas of Siberian cranes (Grus leucogeranus) between northeastern Siberia and China as revealed by satellite tracking

In 1995 and 1996 thirteen Siberian cranes (Grus leucogeranus) were fitted with satellite transmitters on the breeding grounds in northeastern Siberia. Eleven of these 13 birds were successfully satellite tracked, and five of these 11 provided complete migratory information from their breeding grounds in Yakutia, Siberia, to their wintering area at Poyang Lake, in China. Several stopover sites were identified, the most important being in Qiqihar-Baicheng (China), Shuangtaizi River delta (China), and Yellow River delta (China). Birds rested more frequently in Russia than in China, suggesting availability of suitable wetland habitat in Russia and absence of adequate, suitable wetland habitat in China. Wintering habitat in China also faces numerous threats. Habitats utilized by Siberian cranes are also important to other threatened wetland birds that have been satellite-tracked recently. If Siberian crane habitat needs fail to be addressed, this critically endangered species will be further endangered.     

Large-scale habitat associations of birds in lowland Iceland: Implications for conservation

Iceland is responsible for many internationally important populations of breeding bird species, yet very little is currently known about how these species use the habitats available to them. Lowland areas of Iceland, in particular, have undergone significant landscape changes over the last century, such as widespread drainage of wetlands and conversion to agriculture, changes in grazing pressure and recently, extensive afforestation. The impact of these changes on breeding bird species will depend on the relative importance of different habitats for each species, and the threats facing those habitats. Here we report the results of a large-scale survey of the factors influencing patterns of habitat selection of eight populations of Charadriiform bird species throughout lowland Iceland; oystercatcher Haematopus ostralegus, golden plover Pluvialis apricaria, dunlin Calidris alpina, snipe Gallinago gallinago, whimbrel Numenius phaeopus, black-tailed godwit Limosa limosa, redshank Tringa totanus and arctic skua Stercorarius parasiticus. Ordination analyses and multiple logistic regression models are constructed to explore the components of habitats that influence the distribution of these species. Five of the eight species analysed showed significant preferences for lowland wetland habitats and four significantly selected areas containing wet features such as pools and high water tables. These results allow us to identify future conflicts in land use that are likely to result from government-supported large-scale afforestation of lowland areas and hydro-electric developments.     

Habitat selection of the Eurasian woodcock in winter in relation to earthworms availability

The Eurasian woodcock (Scolopax rusticola) is a game species experiencing high hunting pressure, long-term modifications of its habitats, and with questions regarding its current conservation status. Winter is a season of highest concentration of birds and hunting pressure but woodcock precise habitat requirements are poorly known. It is crucial to assess threats and to develop sustainable management options for the conservation of woodcock populations. During three consecutive winters, we monitored 65 individual woodcocks fitted with radio-tags in Brittany, France. Habitat selection was analysed using GIS and compositional analysis, in relation to vegetation types, soil variables (humus types) and the abundance of their main prey (earthworms). Woodcocks used different habitats diurnally and nocturnally, generally preferring areas with high earthworm biomass. Diurnal habitat selection in forests was associated with humus type (preference for mulls, rich in earthworms) and dense shrub strata (better protection). Hedges with a high density of trees and shrub were also important habitat. At night, grazed meadows were the preferred habitat, containing five times higher biomass of earthworms compared to cultivated fields. Sustainable management of populations requires protection and management of habitats that incorporates food and cover. Forestry practices should preserve rich humus types and coppices by choosing tree species that ameliorate the soil and soil tilling. Changes in landscapes and intensive agricultural practices are current threats to woodcock populations: destruction of hedges, decrease of permanent grazed meadows, impoverishment of soils fauna biomasses from ploughing and chemical applications. However, woodcocks may benefit from the recent development of set-asides, grass field-borders and simplified farm practices (no-tillage and direct sowing).     

The value of bat-boxes in the conservation of Pipistrellus pygmaeus in wetland rice paddies

Wetlands with rice paddies are key habitats in the conservation of biodiversity in the Mediterranean Region and are potentially suitable habitats for foraging bats, since they provide food (insects) and drinking places; nevertheless, many wetlands lack natural roosting sites. A bat-box program designed to ascertain bat-box preferences was initiated in 1999 in the Ebro Delta (NE Spain), one of the most important wetlands in Europe. A total of 69 bat-boxes of two types (single and double compartment) were placed on three supports (trees, houses, and posts) facing east or west. Pipistrellus pygmaeus occupancy rates and the number of individuals per box were monitored on 16 occasions from July 2000 to February 2004. Bat-box preferences were only detected during the breeding season. Bat abundance was higher in east-facing boxes, in double-compartment boxes, and in boxes placed on posts and houses. Boxes on natural supports (trees) were avoided. Bat-box occupancy rates were higher during the breeding season (95.6%, spring-summer) due to the formation of maternity colonies. The number of individuals in bat-boxes during the breeding season increased as the study period progressed (from summer 2000 to summer 2003), suggesting a high degree of acceptance by maternity colonies of these alternative locations. Occupancy rates observed were the highest ever reported in bat-box scientific literature. This study highlights the role of bat-box programs as useful alternative management tools for the conservation of bat populations in highly productive wetland habitats where few natural roost sites are available.