Predicting Predatory Outcomes in the Context of Carryover Effects: Interactions between Juvenile Frogs and Spider Predators

As representatives of organisms with complex life histories, frogs provide an ideal system to study predator‐induced carryover effects: how the risk of predation in one life stage can impact predator–prey interactions in a later stage. Invertebrate predation on frogs has been widely reported, although studies of the behavioral mechanisms underlying their interactions in the terrestrial stage have been lacking. We made detailed observations of interactions between a wolf spider (Tigrosa helluo) and Blanchard's cricket frog (Acris blanchardi) to determine factors that predict capture success and to evaluate potential carryover effects from aquatic predation risk. Juvenile frogs, reared with or without dragonfly predator cues, were placed in an arena with or without spider cues and allowed to interact with a spider. Spiders captured frogs, and an interaction between frog size and activity predicted frog survival. We found no evidence that either aquatic or terrestrial cues altered frog behavior or survival. By preying upon a demographically important life stage, spiders may contribute to population dynamics in frogs.     

Management of modern agricultural landscapes increases nest predation rates in Black‐tailed Godwits Limosa limosa

Effective conservation of endangered species requires a solid understanding of the demographic causes of population change. Bird populations breeding on agricultural grasslands have declined because their preferred habitat of herb‐rich meadows has been replaced by grassland monocultures. The timing of agricultural activities in these monocultural grasslands is critical, as they often coincide with the nesting phase of breeding birds. Here, we aim to identify the effect of habitat management and targeted nest protection on nest survival of Black‐tailed Godwits Limosa limosa in the Netherlands, a population that has shown a 70% reduction in breeding population size since the 1970s. To protect nests in monocultures from destruction, farmers are paid to either delay mowing or leave a patch of unmown grass around the nest, a patch which in practice varied in size. In herb‐rich meadows, which are typically managed for bird conservation purposes, mowing occurs after hatching. Nest survival declined as the season advanced, more steeply on monocultures than on meadows. Targeted nest protection was only partially successful, as nest predation was considerably higher on mown grassland monocultures with small unmown patches around the nest than in mown monocultures with large unmown patches and in unmown fields. Increased predator densities over the years have been suggested as an important cause of the trend towards lower nest survival, but here we show that nest survival was higher on herb‐rich meadows than on monocultures, and similar to the 1980s. It thus seems that increased predator densities are an increased threat during the egg stage only if habitat quality is low. High‐quality habitat in the form of herb‐rich meadows therefore provides a degree of protection against predators.     

Obligate crayfish burrow use and core habitat requirements of crawfish frogs

Crawfish frogs (Lithobates areolatus) have experienced declines across large portions of their former range. These declines are out of proportion to syntopic wetland-breeding amphibian species, suggesting losses are resulting from unfavorable aspects of non-breeding upland habitat. Crawfish frogs get their common name from their affinity for crayfish burrows, although the strength of this relationship has never been formally assessed. We used radiotelemetry to address 4 questions related to upland burrow dwelling in crawfish frogs: 1) what burrow types are used and how do they function to affect crawfish frog survivorship; 2) what are the physical characteristics and habitat associations of crawfish frog burrows; 3) what are the home range sizes of crawfish frogs when burrow dwelling; and 4) where are crawfish frog burrows situated with respect to breeding wetlands? We tracked crawfish frogs to 34 burrows, discovered another 7 occupied burrows, and therefore report on 41 burrows. Crawfish frogs exclusively occupied crayfish burrows as primary burrows, which they inhabited for an average of 10.5 months of the year. With one exception, crawfish frogs also used crayfish burrows as secondary burrows—temporary retreats occupied while exhibiting breeding migrations or ranging forays. Burrows were exclusively located in grassland habitats, although crawfish frogs migrated through narrow woodlands and across gravel roads to reach distant grassland primary burrow sites. Home range estimates while inhabiting burrows were 0.05 m² (the area of the burrow entrance plus the associated feeding platform) or 0.01 m³ (the estimated volume of their burrow). Crawfish frog burrows were located at distances up to 1,020 m from their breeding wetlands. To protect crawfish frog populations, we recommend a buffer (core habitat plus terrestrial buffer) of at least 1.2 km around each breeding wetland. Within this buffer, at least 3 critical habitat elements must be present: 1) extensive grasslands maintained by prescribed burning and/or logging, 2) an adequate number of upland crayfish burrows, and 3) no soil disturbance of the sort that would destroy crayfish burrow integrity. © 2012 The Wildlife Society.     

Canopy Closure and Emigration by Juvenile Gopher Frogs

ABSTRACT Although studies have addressed effects of abrupt transitions in habitat type (e.g., forest-clear-cut or forest-field edges) on amphibian movements, little is known about effects of more subtle habitat transitions on patterns of migration and habitat use in amphibians. We used radiotelemetry to study movement patterns of juvenile gopher frogs (Rana capito) emigrating from ponds that were surrounded by longleaf pine (Pinus palustris) forest that varied in structure as a result of fire suppression. Our primary purpose was to determine if frogs emigrate directionally from their natal ponds and select habitat at random during their first month following metamorphosis. We found that frogs emigrated in nonrandom directions from ponds that were surrounded by heterogeneous habitat and selected fire-maintained habitat that was associated with an open canopy, few hardwood trees, small amounts of leaf litter, and large amounts of wiregrass (Aristida beyrichiana). Fire-maintained habitat contained higher densities of burrows excavated by gopher tortoises (Gopherus polyphemus) and small mammals, which are the priamry refuge sites for both juvenile and adult gopher frogs. Frogs moved up to 691 m from their natal ponds, frequently crossed dirt roads, and even seemed to use these roads as migration corridors. To maintain suitable terrestrial habitat for gopher frogs, including habitat used by migrating individuals, it is important to apply frequent prescribed fire to uplands surrounding breeding ponds that lead all the way to the edges of breeding ponds, as well as through ponds during periodic droughts.     

Salamander Dispersal Across a Forested Landscape Fragmented by a Golf Course

Abstract: We assessed dispersal behavior of 78 radiotagged adult spotted salamanders (Ambystoma maculatum) at a 36-hole golf course in southeastern Connecticut, USA. Lake of Isles Golf Course is atypical of most golf courses in North America because it is much larger (461 ha) than average 18-hole golf courses (54 ha) and deciduous forests accounted for 70% landscape composition on the course. We tracked individuals an average of 164 days as they emigrated from 3 seasonal pools surrounded by golf course fairways and one pool located in contiguous forest (control pool) from March through December 2004. Males and females dispersed similar distances at the control pool, averaging 71 ± 10 m. However, females migrating across the golf course dispersed twice as far (214 ± 25 m) as males on the golf course (102 ± 15 m) and both genders at the control pool. Over 40% the salamanders at the golf course crossed fairways; thus, fairways were not a dispersal barrier to adult spotted salamanders. Previous researchers have suggested establishing a 164-m life zone around breeding ponds to protect pond-breeding amphibian populations. Our results suggest that strategies that protect core upland habitat within 164 m of wetland boundaries would include 82% of adult males and only 50% of adult females. Empirical estimates based on our telemetry study suggest that core terrestrial habitat would have to extend 370 m to protect 95% of adult females, which is much farther than previous estimates.     

Competing tadpoles: Australian native frogs affect invasive cane toads (Rhinella marina) in natural waterbodies

The cane toad (Rhinella marina) is one of the most successful invasive species worldwide, and has caused significant negative impacts on Australian fauna. Experimental work in the laboratory and in mesocosms has shown that tadpoles of native frogs can affect survival, size at metamorphosis and duration of larval period of cane toad tadpoles. To test if these effects occur in nature, we conducted a field experiment using two temporary ponds where we set up enclosures with tadpoles of native green tree frogs (Litoria caerulea) and cane toads in treatments with a range of densities and combinations. The presence of green tree frog tadpoles significantly decreased the growth rate of toad tadpoles and increased the duration of their larval period in both ponds; in one pond, frog tadpoles also significantly reduced the body length and mass of metamorph toads. Toad tadpoles did not have any significant negative effects on green tree frog tadpoles, but there was strong intraspecific competition within the latter species: increased frog tadpole density resulted in increased larval period and reduced survival, growth rate and size at metamorphosis for frogs at one or both ponds. Our results are encouraging for the possibility of using native frogs as one component of an integrated approach to the biological control of cane toads.     

Habitat-mediated impact of alien mink predation on common frog densities in the outer archipelago of the Baltic Sea

Alien predators have been recognised as one possible cause for amphibian declines around the world, but little is known of habitat-mediated predation impacts especially on adult amphibians. We studied common frog Rana temporaria under American mink Mustela vison predation in the outer archipelago of the Baltic Sea, south-western Finland. Using egg batches as an index of breeding frog female numbers we compared frog numbers and densities between a large, long-term mink-removal area and a comparable control area. Frog numbers in the removal area were at least 2.7-fold higher than those in the control area. In the presence of mink, frog densities increased with the amount of vegetation cover on the islands, indicating that mink predation affected frog densities especially on less-vegetated islands. An opposite trend appeared to be true for frogs in the mink-removal area, where other predators like snakes could induce a decline of frog densities on more vegetated islands. Shrub or grass vegetation seems to provide frogs shelter against alien mink predation. Our result highlights the importance of landscape-level habitat management as a conservation tool for amphibian populations.     

Intermediate Pond Sizes Contain the Highest Density,Richness, and Diversity of Pond-Breeding Amphibians

We present data on amphibian density, species richness, and diversity from a 7140-ha area consisting of 200 ponds in the Midwestern U.S. that represents most of the possible lentic aquatic breeding habitats common in this region. Our study includes all possible breeding sites with natural and anthropogenic disturbance processes that can be missing from studies where sampling intensity is low, sample area is small, or partial disturbance gradients are sampled. We tested whether pond area was a significant predictor of density, species richness, and diversity of amphibians and if values peaked at intermediate pond areas. We found that in all cases a quadratic model fit our data significantly better than a linear model. Because small ponds have a high probability of pond drying and large ponds have a high probability of fish colonization and accumulation of invertebrate predators, drying and predation may be two mechanisms driving the peak of density and diversity towards intermediate values of pond size. We also found that not all intermediate sized ponds produced many larvae; in fact, some had low amphibian density, richness, and diversity. Further analyses of the subset of ponds represented in the peak of the area distribution showed that fish, hydroperiod, invertebrate density, and canopy are additional factors that drive density, richness and diversity of ponds up or down, when extremely small or large ponds are eliminated. Our results indicate that fishless ponds at intermediate sizes are more diverse, produce more larvae, and have greater potential to recruit juveniles into adult populations of most species sampled. Further, hylid and chorus frogs are found predictably more often in ephemeral ponds whereas bullfrogs, green frogs, and cricket frogs are found most often in permanent ponds with fish. Our data increase understanding of what factors structure and maintain amphibian diversity across large landscapes.     

Canopy Closure,Competition, and the Endangered Dusky Gopher Frog

Abstract: A major challenge facing wildlife biologists is understanding why some species go extinct while others persist in the same habitat. To address this question, we investigated whether tree canopy closure over ponds affects growth and survival of rare and common tadpoles within ponds and mediates competitive interactions among species. We conducted 2 experiments to test whether canopy closure and competition may have contributed to the decline of the endangered dusky gopher frog (Rana sevosa), but allowed the persistence of the southern leopard frog (R. sphenocephala). We explored the response of both species to canopy closure in single-species and mixed- (1:1) species treatments of identical total tadpole density. An experiment using aquatic enclosures in temporary ponds showed that canopy closure reduced tadpole growth approximately 20% for both species. Survival of dusky gopher frog tadpoles was higher in mixed-species enclosures than in single-species enclosures. In a complementary experiment using artificial ponds, dusky gopher frogs had lower survival to metamorphosis, reduced size at metamorphosis, and produced a lower total biomass of metamorphosed juveniles in shaded ponds. Southern leopard frogs exhibited reduced body size at metamorphosis only when shaded. These studies suggest that pond canopy closure, not larval competition, may be contributing to the decline of the dusky gopher frog. The different responses to canopy closure suggest a potential mechanism for the loss of dusky gopher frogs and the persistence of southern leopard frogs. Removal of trees from historically open-canopy ponds may help facilitate the recovery of dusky gopher frogs and benefit similar species.     

The role of golf courses in maintaining genetic connectivity between common frog (Rana temporaria) populations in an urban setting

We studied population size, genetic diversity and differentiation of common frog (Rana temporaria) populations at urban golf courses and reference natural ponds in the greater Helsinki region, southern Finland. A total of 248 tadpoles from 12 locations (six golf courses, six reference sites) were genotyped with 13 polymorphic microsatellite markers. The most urban populations, situated in northern Helsinki, were the largest breeding sites having >120 (golf courses) and >200 (reference sites) spawn clumps at the time of sampling. On average, there was no difference in the number of spawns between the anthropogenic ponds at golf courses and the natural water bodies. Genetic variation within populations was substantial (H _O = 0.68) while genetic differentiation between populations was low (F _ST = 0.016; average distance = 17.6 km). The golf course populations did not differ from natural populations in terms of genetic variability or differentiation. Hence, our results suggest that golf courses contribute positively to urban amphibian populations by providing suitable water bodies for reproduction and green corridors for dispersal, thus preventing isolation and loss of genetic variability within populations.     

Changing grass height alters foraging site selection by wintering farmland birds

Grassland is a valuable habitat for many farmland bird species, some of which have declined in Europe. Successful management of this habitat is important to benefit these species. Recent studies have suggested little correlation between food abundance and bird use in grassland; instead providing access to food may be crucial. We tested the importance of manipulating sward height (via mowing) on the distribution of wintering birds in agriculturally managed grass fields using two within-field experimental designs. In experiment 1, we investigated the effect of two treatments (mown once and control). In experiment 2, we investigated the effects of four treatments (mown once early, mown once late, mown early and late, and control).Mown plots supported higher abundances of foraging kestrels, thrushes and starlings. In contrast meadow pipits and grey herons preferred unmown plots with longer grass. These differences are probably explained by differing anti-predation strategies, increased food abundance for species that prefer above-ground invertebrates (e.g. more food for meadow pipits on longer swards) and increased food accessibility on short grass swards (e.g. for starling, thrush spp.). There were limited effects of multiple mowing events on plot use suggesting one early winter mowing treatment may suffice to create favourable conditions for species that prefer shorter swards.Providing grassland heterogeneity should benefit a range of wintering farmland birds. Although we use mowing to change grass sward height, our findings may also apply at other times of year when livestock grazing may be a more practical solution.     

An expert-based landscape permeability model for assessing the impact of agricultural management on amphibian migration

The persistence of pond-breeding amphibian populations is influenced on different spatial scales ranging from the individual breeding pond to surrounding habitat patches to landscape clusters of breeding pond populations. The connectivity among breeding ponds as well as the availability of suitable terrestrial habitats surrounding the ponds plays a major role in long-term viability of amphibian species. Besides road traffic and urban structures agricultural land activity can disrupt landscape connectivity through the use of pesticides, fertilizers and physical activity such as tillage. We developed an expert-based model to assess the impact of agricultural management measures on the migration area and terrestrial habitat availability for seven amphibian species. The model is based on a Habitat Suitability Index to identify suitable terrestrial habitats and includes a landscape permeability approach. Size of migration areas, connectivity of breeding ponds and number of reachable terrestrial habitats were modeled considering species-specific migration ranges and habitat preferences. We consider how pesticides application might lead to fragmentation and isolation of amphibian breeding pond populations. Therefore the potential disrupting impact of pesticides was simulated by inflating landscape resistance to medium and high migration cost. One amphibian species showed a decrease of migration area by 48.3% and a decrease of reachable terrestrial habitats by 41.5% at high migration costs. Three additional species showed a decrease of their migration areas between 31.5 and 35.7%. At increased migration cost, some of the investigated populations were isolated at breeding pond level or restricted to pond clusters. Our model could be used to prioritize conservation efforts for pond-breeding amphibians with adequate consideration of agricultural land use and its impact on amphibian migration.     

Habitat fragmentation causes bottlenecks and inbreeding in the European tree frog (Hyla arborea)

A genetic study of the European tree frog, Hyla arborea, in Denmark was undertaken to examine the population structure on mainland Jutland and the island of Lolland after a period of reduction in suitable habitat and population sizes. The two regions have experienced the same rate of habitat loss but fragmentation has been more severe on Lolland. Genetic variation based on 12 polymorphic DNA microsatellites was analysed in 494 tree frogs sampled from two ponds in Jutland and 10 ponds on Lolland. A significant overall deviation from Hardy-Weinberg expectations could be attributed to three ponds, all on Lolland. This was most probably caused by an inbreeding effect reducing fitness, which was supported by the observed significant negative correlation between larva survival and mean F(IS) value and mean individual inbreeding coefficient. A significant reduction in genetic variation (bottleneck) was detected in most of the ponds on Lolland. Population-structure analysis suggested the existence of at least 11 genetically different populations, corresponding to most of the sampled population units. The results indicated that the populations were unique genetic units and could be used to illustrate the migration pattern between newly established ponds arisen either by natural colonization of tree frogs or by artificial introduction. A high degree of pond fidelity in the tree frogs was suggested. A severe fragmentation process reducing population size and fitness within some of the populations probably caused the significant reduction in genetic variation of tree frog populations on Lolland.     

Modeling spatial distribution of amphibian populations: a GIS approach based on habitat matrix permeability

Predictions of occurrence of two amphibian species, the common toad and the alpine newt, were made using information on land use surrounding breeding ponds. A geographical information system (GIS) was used to compile a landuse map, from which permeability estimates (friction) were derived. Potential migration zones based on friction and maximum migration distance were then modeled. Contacts between several migration zones suggest the potential for migration between ponds by adult individuals. The ability of the migration zones to enhance predictions of species occurrence was tested using generalized additive models (GAMs), and several landscape variables were selected as determinants of amphibian presence. The area of a migration zone and the number of ponds within that zone were positively related to both toad and newt presence, suggesting the importance of buffer habitats around each pond in amphibian conservation. Toad presence declined with cultivated field area and newt presence declined with vineyard area, suggesting the negative effect of agricultural activity on amphibians. The friction-based modeling approach improved the prediction of toad presence when compared to a more classical analysis of habitat composition within a circular zone centered on the focal pond. Prediction of newt presence was, however, less accurate than prediction of toad presence. Despite its exploratory nature and the subjectivity of permeability estimates, this study shows the usefulness of GIS in the functional analysis of a landscape, with potential applications in biological conservation. It also highlights the need for improving our knowledge of habitat use by animals.     

Behaviour of male and female parasitoids in the field: influence of patch size,host density,and habitat complexity

1. Two field experiments were carried out to examine the role of patch size, host density, and complexity of the surrounding habitat, on the foraging behaviour of the parasitoid wasp Cotesia glomerata in the field. 2. First, released parasitoids were recaptured on patches of one or four Brassica nigra plants, each containing 10 hosts that were placed in a mown grassland area. Recaptures of females were higher than males, and males and females aggregated at patches with four plants. 3. In experiment 2, plants containing 0, 5 or 10 hosts were placed in unmown grassland plots that differed in plant species composition, on bare soil, and on mown grassland. Very low numbers of parasitoids were recaptured in the vegetated plots, while high numbers of parasitoids were recaptured on plants placed on bare soil or in mown grassland. Recaptures were higher on plants on bare soil than on mown grassland, and highest on plants containing 10 hosts. The host density effect was significantly more apparent in mown grassland than on bare soil. 4. Cotesia glomerata responds in an aggregative way to host density in the field. However, host location success is determined mostly by habitat characteristics, and stronger host or host‐plant cues are required when habitat complexity increases.     

Finding a place to live: conspecific attraction affects habitat selection in juvenile green and golden bell frogs

Conspecific attraction plays an important role in habitat selection of several taxa and can affect and determine distribution patterns of populations. The behaviour is largely studied and widespread among birds, but in amphibians, its occurrence seems limited to breeding habitats of adults and gregarious tadpoles. The Australian green and golden bell frogs (Litoria aurea) have suffered considerable shrinking of their original distribution in south-eastern Australia since the 1970s. Currently, with only about 40 populations remaining, the species is considered nationally threatened. In natural conditions, these frogs are aggregated in the landscape and do not seem to occupy all suitable ponds within the occurrence area. To date, studies focusing on the frogs’ habitat have failed in finding a general habitat feature that explains current or past occupancy. This led us to the hypothesis that social cues may play a key role in habitat selection in this species. Using two choice experiments, we tested the preference of juvenile green and golden bell frogs for habitats containing cues of conspecifics of similar size versus habitats without conspecific cues. Tested frogs did not show a preference for habitats containing only scent from conspecifics but did prefer habitats where conspecifics were present. Our results show that conspecific attraction is a determining factor in juvenile green and golden bell frog habitat selection. To our knowledge, this is the first time the behaviour is shown to occur in juvenile frogs in the habitat selection context. From a conservation management point of view, the behaviour may help to explain the failure of reintroductions to areas where the frogs have been extinct, and the non-occupation of suitable created habitats in areas where they still inhabit and develop appropriated management strategies.     

Defining core habitat of local populations of the gray treefrog (Hyla versicolor) based on choice of oviposition site

Concern over amphibian population declines and loss of terrestrial and aquatic habitat have emphasized the need to define habitat requirements for each stage in a species' life history. The realization that pond-breeding amphibians spend most of their lives in the terrestrial environment suggests the need to protect terrestrial as well as aquatic habitat. Many studies on amphibian populations have focused on emigration from breeding sites to define habitat use; however these studies do not typically elucidate terrestrial activities of adults within the breeding season. We measured colonization rates of artificial pools by gray treefrogs (Hyla versicolor) at multiple distances from natural breeding ponds. We found a non-random distribution of egg deposition among distances, with 95% of eggs deposited within 15 m of the breeding pond. Additionally, we found that the time to first colonization of artificial pools increased with respect to distance. Our results indicate that adult gray treefrogs may travel up to 200 m within a breeding season, and that multiple breeding ponds may be considered part of a single population. We suggest that a minimum core terrestrial habitat of 60 m surrounding breeding sites is appropriate for protection of local populations of gray treefrogs.     

Local and Landscape Factors Driving the Structure of Tropical Anuran Communities: Do Ephemeral Ponds have a Nested Pattern?

The sets of species in animal and plant communities often comprise nested subsets of the species in broader communities. Although most mechanisms causing nested patterns are known and have been demonstrated for different environments and taxa, how amphibian communities are structured in ephemeral ponds in tropical disturbed landscapes remains unknown. We investigated if pond size, duration, presence of trees (local factors), and the proportion of forest cover surrounding ponds (landscape factor) affect anuran species richness and composition, and if pond assemblages showed a nested pattern. We sampled 11 ephemeral ponds in a pasture matrix near a large Atlantic Forest remnant in Brazil and measured local and landscape variables inside two buffer zones around each pond (100 and 500 m). We marked 1514 individuals from 23 anuran species, and found that richness in ponds ranged from 3–14 species. Both local and landscape factors explained frog species richness in the sampled ponds, and seemed to affect community composition. Frog communities occurred in a non‐nested pattern, contrary to our expectations: species found in poor subsets were not found in larger, more complex ponds. Local and landscape characteristics create a variety of environments in ephemeral ponds, even in impoverished ones; these characteristics restrict pond occupancy for some species, and result in a non‐nested pattern.     

Green Frogs Show Reduced Foraging Success in Habitats Invaded by Japanese knotweed

Habitat loss is causing amphibian population declines worldwide, so there is increased attention to forces that degrade remaining habitats. Terrestrial habitats surrounding wetlands are critical foraging areas for temperate anurans. We investigated plant community changes in two old fields invaded by Japanese knotweed (Fallopia japonica) and the foraging success of Green frogs (Rana clamitans) in invaded and non-invaded portions of those fields. Within each field, vegetation data were recorded in quadrats located along two transects bisecting the invasion fronts. We placed frogs in ‘foraging buckets’ along transects and measured their change in mass over a 38 h period. There were significant changes in vegetation structure and composition associated with Japanese knotweed invasion. Diverse assemblages of native plants that covered non-invaded plots were absent from areas invaded by Japanese knotweed. There was also a significant change in vegetation architecture between invaded and non-invaded habitats. Change in frog mass declined significantly along transects, with most frogs in non-invaded plots gaining mass and no frogs in invaded plots gaining mass. Most frogs from non-invaded plots but only two from invaded plots defecated shortly after removal from foraging buckets (verification of recent feeding). We hypothesize that Japanese knotweed invasions degrade terrestrial habitat quality for frogs by indirectly reducing arthropod abundance. Nonnative plant invasions may be another factor contributing to amphibian population declines.     

Amphibian decline,pond loss and reduced population connectivity under agricultural intensification over a 38 year period

Habitat loss, together with less obvious land-use changes such as intensified farming practice, can have significant adverse impacts on biodiversity. An important factor in determining the ability of species to cope with such changes is their potential to sustain a populations network by dispersal across the landscape. Habitat quality and structure are particularly important for surface-dwelling species with low dispersal abilities, such as amphibians. To assess this ecological function, ponds in a coastal and typically rural area of northern France were surveyed for amphibians in 1974, 1992 and 2011. These repeated surveys yielded different outcomes for different species groups. Three rare species persisted in more or less specialized habitat types. Two moderately common species declined, but kept strongholds in coastal dunes and associated marshes. Five common species with broad ecological niches remained equally widespread. The Northern crested newt declined markedly and the Midwife toad declined dramatically, as did their breeding habitats in vegetated ponds and cattle drinking troughs. One species, the Moor frog, may have gone locally extinct. A model of relative resistance to amphibian dispersal was created for different landscape types, on a scale from 0 (low resistance) to 1 (high resistance). This generated values of 0.23 for pasture, 0.72 for arable and 0.98 for urban and transport. As pasture declined in the study area, while arable and urban/transport infrastructure increased, amphibian dispersal became more difficult. However, dispersal paths proved difficult to evaluate in a patchy landscape like the one surveyed, due to a paucity of spatial signal. Pond loss is a more tractable reason for the observed amphibian species decline than is the quality of intervening terrestrial habitat matrix. In 2011, 22 newly created ponds had species richness in line with pre-existing ponds and this will have counteracted a dwindling metapopulation structure, indicating that habitat creation/restoration can play a valuable role in conservation. The colonization of new ponds may also prove more informative for gauging the potential for amphibian dispersal in the landscape than the preceding decline.