Conservation efforts fail to halt the decline of the regionally endangered Natterjack toad (Epidalea calamita) in Ireland

Reyne, Marina; Aubry, Aurélie; Emmerson, Mark; Marnell, Ferdia; Reid, Neil

doi:10.1016/j.biocon.2021.109228

Cited by 5 publications

(7 citation statements)

References 45 publications

(40 reference statements)

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“…Other demographic parameters such as low local breeding success may also contribute to lower recruitment and dispersal. Certainly, Natterjack toadsat Killeen and Roscullen have exhibited substantial census size declines over the past 15 years (Reyne et al 2019(Reyne et al , 2021b. We propose including Killeen and Roscullen in the Natterjack toad NPWS 'Head-start and Reintroduction Programme' with occupied breeding sites used as a source population, with assisted migration and translocation to adjacent artificial ponds.…”

Section: Discussionmentioning

confidence: 98%

“…The main habitats in this area are sand dunes and grasslands both identified in the present study as facilitating dispersal and gene flow. Cox et al (2017) demonstrated that dispersal of the Natterjack toad is facilitated by sand dunes and beaches, and the largest Natterjack toad population in Ireland is in the Magharees sand dune system, but breeding depends on the formation of ephemeral breeding pools in sand dune slacks (Reyne et al 2019(Reyne et al , 2021b. Access to permanent ponds at the nearby Castlegregory Golf Course (CGC) and suitable sites along the lakeshore of Lough Gill provide a valuable alternative in dry years, thus maintaining connectivity between the breeding sites is essential.…”

Section: Discussionmentioning

confidence: 99%

“…Grasslands and proximity to the coast facilitated Natterjack toad dispersal and gene flow with the species known to inhabit and forage even on intensively managed agricultural lands most notably during summer (Miaud et al 2000;Miaud and Sanuy 2005;Schweizer 2014). A further 20 artificial ponds that have been created in proximity (within 4 km) to Killeen and Roscullen have not yet been colonised naturally up to 10 years after their creation (Reyne et al 2019(Reyne et al , 2021b. Most adult toads have high breeding-site fidelity with dispersal usually by juveniles (Stevens et al 2004).…”

Section: Discussionmentioning

confidence: 99%

“…The species is highly range-restricted in Ireland, found only in Co Kerry. Ireland has lost most of its freshwater ponds (Reid et al 2012), with the loss of suitable breeding sites identified as the single most important driver of Natterjack toad population declines (Reyne et al 2021b). The Natterjack toad is Red-listed as Endangered with a 23% decline in fecundity (number of eggs strings deposited annually) in Ireland over a 14-year period.…”

Section: Introductionmentioning

confidence: 99%

“…However, at some breeding sites (Roscullen and Dooks Golf Course DGC) egg string production declined by over 90% since 2004. Fecundity has increased only at three breeding sites in the North of the species distribution (Magharees, Castlegregory Golf Course CGC and Lough Gill), but this is insufficient to offset the overall species decline in Ireland (Reyne et al 2021b). To halt the Natterjack toad decline, the National Parks and Wildlife Service (NPWS) initiated a 'Pond Creation Scheme' in 2008 installing over 100 artificial ponds on agricultural grasslands throughout the Natterjack toad range.…”

Section: Introductionmentioning

confidence: 99%

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Landscape genetics identifies barriers to Natterjack toad metapopulation dispersal

et al. 2023

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Habitat fragmentation and loss reduce population size and connectivity, which imperils populations. Functional connectivity is key for species persistence in human-modified landscapes. To inform species conservation management, we investigated spatial genetic structure, gene flow and inferred dispersal between twelve breeding sites of the Natterjack toad (Bufo calamita); regionally Red-Listed as Endangered in Ireland. Spatial genetic structure was determined using both Bayesian and non-Bayesian clustering analysis of 13 polymorphic microsatellite loci genotyping 247 individuals. We tested the influence of geographic distance, climate, habitat, geographical features, and anthropogenic pressure on pairwise genetic distances between breeding sites using Isolation-by-distance and Isolation-by-resistance based on least-cost path and circuit theory models of functional connectivity. There was clear spatial structuring with genetic distances increasing with geographic distance. Gene flow was best explained by Isolation-by-resistance models with coniferous forestry plantations, bog, marsh, moor and heath, scrub, anthropogenic presence (Human Influence Index) and rivers (riparian density) identified as habitats with high resistance to gene flow while metapopulation connectivity was enhanced by coastal habitats (beaches, sand dunes and salt marshes) and coastal grassland. Despite substantial declines in census numbers over the past 15 years and its regional status as Endangered, the Natterjack toad population in Ireland retains high genetic diversity. If declines continue, maintaining habitat connectivity to prevent genetic erosion by management of coastal grasslands, pond construction and assisted migration through translocation will be increasingly important.

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Landscape genetics identifies barriers to Natterjack toad metapopulation dispersal

et al. 2023

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Population genetic structure of the Natterjack toad (Epidalea calamita) in Ireland: implications for conservation management

et al. 2021

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Molecular methods can play a crucial role in species management and conservation. Despite the usefulness of genetic approaches, they are often not explicitly included as part of species recovery plans and conservation practises. The Natterjack toad (Epidalea calamita) is regionally Red-Listed as Endangered in Ireland. The species is declining and is now present at just seven sites within a highly restricted range. This study used 13 highly polymorphic microsatellite markers to analyse the population genetic diversity and structure. Genetic diversity was high with expected heterozygosity between 0.55 and 0.61 and allelic richness between 4.77 and 5.92. Effective population sizes were small (Ne < 100 individuals), but not abnormal for pond breeding amphibians. However, there was no evidence of historical or contemporary genetic bottlenecks or high levels of inbreeding. We identified a positive relationship between Ne and breeding pond surface area, suggesting that environmental factors are a key determinant of population size. Significant genetic structuring was detected throughout the species’ range, and we identified four genetic entities that should be considered in the species’ conservation strategies. Management should focus on preventing further population declines and future loss of genetic diversity overall and within genetic entities while maintaining adequate local effective population size through site-specific protection, human-mediated translocations and head-start programs. The apparent high levels of genetic variation give hope for the conservation of Ireland’s rarest amphibian if appropriately protected and managed.

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Invasive Australian swamp stonecrop (Crassula helmsii) negatively affects spawning but accelerates larval growth of the endangered natterjack toad (Epidalea calamita)

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et al. 2023

Hydrobiologia

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The invasive Crassula helmsii is rapidly expanding in Europe. Several ecological effects are described, most of which focus on ecosystem functioning and native vegetation but rarely on fauna. In North-western Europe, C. helmsii often invades the breeding habitat of endangered amphibians, such as Epidalea calamita. The spawning rate, egg survival and the speed of larval growth of this toad species in relation to the presence of C. helmsii were studied. In order to unravel causal mechanisms, effects on natterjack toads were related to the effects of C. helmsii presence/absence on temperature and chemical properties of the water. Spawning and egg survival were significantly lower under C. helmsii dominance compared to bare soil conditions, and negatively affected the population size of E. calamita. However, larval growth rate was significantly higher in C. helmsii dominated treatments, which could be beneficial. Differences in water temperature and chemistry were a possible explanation for these effects. It remains unclear whether the population viability of E. calamita is negatively affected when C. helmsii is present. In many areas, however, this plant species completely overgrows and causes desiccation of waterbodies. Therefore, appropriate management measures will be required to protect this toad against this invader.

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Conservation efforts fail to halt the decline of the regionally endangered Natterjack toad (Epidalea calamita) in Ireland

Cited by 5 publications

References 45 publications

Landscape genetics identifies barriers to Natterjack toad metapopulation dispersal

Landscape genetics identifies barriers to Natterjack toad metapopulation dispersal

Population genetic structure of the Natterjack toad (Epidalea calamita) in Ireland: implications for conservation management

Invasive Australian swamp stonecrop (Crassula helmsii) negatively affects spawning but accelerates larval growth of the endangered natterjack toad (Epidalea calamita)

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