Intensive agriculture as the main limiting factor of the otter's return in southwest France

Couturier, Thibaut; Steinmetz, Julien; Rau, Pierre Defos du; Marc, Daniel; Trichet, Emma; Gomes, Régis; Besnard, Aurélien

doi:10.1016/j.biocon.2023.109927

Cited by 2 publications

(6 citation statements)

References 43 publications

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“…Marcelli et al (2012) analyzed the re-expansion of Eurasian otter in Czech Republic using a dynamic occupancy model and found that colonization was more likely to occur in areas where the reduction in intensive agriculture was larger. Couturier et al (2023) analyzed expanding otter populations in France and showed that agriculture had a negative impact on occupancy and colonization for areas that lack habitat connectivity. A preliminary exploration of our data did not reveal any indication of interaction between agriculture and habitat connectivity.…”

Section: Discussionmentioning

confidence: 99%

“…This species is a semiaquatic mesocarnivore inhabiting rivers and feeding on fish and anurans (Clavero et al, 2003), listed by the IUCN as Near Threatened (Loy et al, 2022) due to a widespread decline occurred across Europe from 1950s to 1980s. In recent times, otters have colonized parts of their former distribution ranges in Europe, primarily as a consequence of reduced anthropogenic pressures on streams (Clavero et al, 2010; Couturier et al, 2023; Marcelli et al, 2012; Marcelli & Fusillo, 2009a). In Italy, the geographic range of Eurasian otters collapsed from 1970s to 1980s.…”

Section: Introductionmentioning

confidence: 99%

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Stream size‐dependent effect of urban land use on occupancy of an apex freshwater carnivore recolonizing past ranges

Marcelli,

Luzzi,

Fusillo

2024

Ecosphere

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Accurate assessment of population trends and factors that limit distributions of threatened species is key to conserving biodiversity. A reduction in impacts of human land use on species habitats may be one of the factors involved in the recolonization of former ranges by native species. The signature of this process could be detected as a temporal reduction of land use effects on species distributions, or as a spatial reduction, with effects persisting only in habitats more sensitive to anthropogenic stressors. We explored these hypotheses in a recolonizing semiaquatic carnivore. Our species of interest was the Eurasian river otter (Lutra lutra) in Italy, a nationally vulnerable species with a restricted but expanding range. Human land use is likely to strongly affect riparian and stream communities through habitat degradation. We used three independent survey datasets collected in 2003, 2009, and 2019 at the southern range periphery, and unpaired‐site occupancy models to account for imperfect detection in otter surveys. To assess how land use affects recolonization by otters, we tested three main model predictions: (1) occupancy increased over years, (2) effects of agricultural and urban land cover on occupancy decreased over years, (3) effects of agricultural and urban land cover were constant across years and changed with stream size and elevation. We found evidence that otter occupancy increased over years, with predicted mean occupancy of 0.27 in 2003 and 0.65 in 2019. An interaction effect of urban land cover with stream size was the strongest predictor of otter occupancy. Interestingly, a higher percentage of urban land cover around streams was predicted to reduce the probability of occupancy at smaller streams, but did not influence occupancy at larger streams. Despite a large increase in occupancy, otters at the southern periphery of the Italian range are still unable to colonize small rivers in urbanized areas. This pattern supports our hypothesis that human land use can affect recolonizing species at sensitive habitats, considering the intrinsic vulnerability of small stream ecosystems to anthropogenic stressors. Restoring small streams impacted by urban areas can be a valuable conservation action to increase habitat connectivity and favor recolonization of otters.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Stream size‐dependent effect of urban land use on occupancy of an apex freshwater carnivore recolonizing past ranges

Marcelli,

Luzzi,

Fusillo

2024

Ecosphere

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“…We focus on the Eurasian otter population distributed in the Massif Central in France (Figures 1 a,b). We used detection/non-detection data from 158 sites in the Massif Central that were previously analysed by Couturier et al (2023). The sites are 300m transects along rivers where the centre is placed at potential marking locations (e.g.…”

Section: Methodsmentioning

confidence: 99%

“…We model initial occupancy probability as a function of elevation (BD ALTI ® Version 2.0, 01/2023) because otters are assumed to colonize from mountains (Appendix S1: Figure S1 a). Detection probability is assumed to be season-specific (Couturier et al 2023). Because otters mainly use rivers to colonise new habitats, we compute the distance to the closest river (BD TOPO ® Version 3.3, 12/2022) to create the resistance surface with a resolution of 0.04km 2 .…”

Section: Methodsmentioning

confidence: 99%

“…We run three chains each of length 10,000 and we discard the first 1,000 iterations as burn in. We use non-informative priors for all parameters except for the resistance parameter (Appendix S2) for which we use a uniform distribution between 1 and 5, because otters are semi-aquatic and do not go far away from rivers, and therefore the larger distances to rivers is assumed to strongly impede their movements (Couturier et al 2023). Given that the landscape covariate is reduced and that the resistance scale is exponential, we set the upper bound to 5 to ensure that the commute distance between all sites is not too small.…”

Section: Methodsmentioning

confidence: 99%

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Bringing circuit theory into spatial occupancy models to assess landscape connectivity

Kervellec,

Couturier,

Bauduin

et al. 2023

Preprint

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Connectivity shapes species distribution across fragmented landscapes. Assessing landscape resistance to dispersal is challenging because dispersal events are rare and difficult to detect especially for elusive species. To address these issues, spatial occupancy models have been developed to integrate the resistance surface concept of landscape ecology and model patch occupancy dynamics through colonization and extinction while accounting for imperfect species detection. However, the most recent approach is based on least-cost path distances which assume that individuals disperse along the optimal route. Here, we develop a new spatial occupancy model that incorporates commute distances derived from circuit theory to model dispersal across sites. Our approach allows for explicit estimation of landscape connectivity and direct measure of uncertainty from detection/non-detection data. To illustrate our approach, we study the recolonisation of two carnivores in France, and quantify the degree to which rivers facilitate Eurasian otter (Lutra lutra) dispersal and highways impede Eurasian lynx (Lynx lynx) recolonisation. Overall, spatial occupancy models provide a flexible framework to acccommodate any distance metric designed to align with species dispersal ecology.Open Research StatementData and code used in this research are available on Zenodo athttps://zenodo.org/record/8376577

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Intensive agriculture as the main limiting factor of the otter's return in southwest France

Cited by 2 publications

References 43 publications

Stream size‐dependent effect of urban land use on occupancy of an apex freshwater carnivore recolonizing past ranges

Stream size‐dependent effect of urban land use on occupancy of an apex freshwater carnivore recolonizing past ranges

Bringing circuit theory into spatial occupancy models to assess landscape connectivity

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