Biology subjects

Marescot, L.

Publications and source records attributed to Marescot, L..

5 recordsLinked to original sources

bioRxiv2026

Using stochastic dynamic programming for making decisions about invasive species

1. Invasive species pose significant ecological, economic, and public health challenges. Their management requires repeated decisions under uncertainty about when, where and how intensively to intervene. Although structured decision-making and adaptive management provide conceptual frameworks for addressing these challenges, their practical implementation remains limited because optimization methods such as stochastic dynamic programming (SDP) are often perceived as mathematically complex, challenting to apply and difficult to interpret. 2. Here, we provide a practical guide to using SDP and its extensions for invasive species management. Using coypu (*Myocastor coypus*) management as a running case study, we introduce the framework through a minimal working example before progressively extending it to spatial dynamics, imperfect detection using partially observable Markov decision processes (POMDPs), adaptive management under model uncertainty, and value-of-information analyses that quantify the benefits of learning before acting. 3. All examples are accompanied by reproducible implementations in R, together with recommendations on model formulation, parameterization and interpretation. We also discuss the strengths and limitations of SDP. 4. By lowering the technical barrier to SDP, this guide aims to help ecologists and wildlife managers integrate decision theory into invasive species management, enabling transparent, reproducible and objective-driven management strategies under uncertainty. More broadly, the methods presented here are applicable to a wide range of ecological decision problems beyond invasive species, wherever management requires balancing immediate actions against uncertain future outcomes.

ecology↗

bioRxiv2023

Can snare removal safeguard protected areas caught in the Southeast Asian snaring crisis? Promises and perspectives

Unsustainable snaring is causing biodiversity declines across tropical protected areas, resulting in species extinctions and jeopardizing the health of forest ecosystems. Here, we used 11 years of ranger collected data to assess the impact of intensive snare removal on snaring levels in two protected areas in Viet Nam. Snare removal resulted in significant declines in snare occupancy (36.9, 95% BCI [4.6, 59.0] reduction in percent area occupied), but snaring levels nonetheless remained high (31.4, [23.6, 40.8] percent area occupied), and came with a substantial financial cost. Our results indicate that snare removal remains an important component of efforts to protect tropical protected areas, but by itself, is likely insufficient to address this threat. To stop snaring in protected areas, a multifaceted approach will be necessary that combines short-term reactive snare removal with long-term proactive programs that address the underlying drivers behind snaring.

ecology↗

bioRxiv2021

Population monitoring of snow leopards using camera trapping in Naryn State Reserve, Kyrgyzstan, between 2016 and 2019

Four field seasons of snow leopard (Panthera uncia) camera trapping inside Naryn State Reserve, performed thanks to citizen science expeditions, allowed detecting a minimal population of five adults, caught every year with an equilibrated sex ratio (1.5:1), and reproduction: five cubs or subadults have been identified from three litters of two different females. Crossings were observed one to three times a year, in front of most camera traps, and several times a month in front of one of them. Overlap of adults territories was observed in front of several camera traps regardless of their sex. Significant snow leopard presence was detected in the buffer area and at Ulan, situated at the reserve border. To avoid poaching on this umbrella species and its preys, extending the more stringent protection measures of the core zone to both the Southern buffer area and land adjacent to Ulan is necessary.

ecology↗

bioRxiv2020

Keeping the kids at home can limit the persistence of contagious pathogens in social animals

In social species where offspring are reared together in communal burrows or similar structures, young animals typically do not engage in between-group contact during their development - a behavioural trait we call offspring with restricted between-group contact (ORC). The impact of this trait on the persistence of contagious pathogens that generate lifelong immunity in their hosts is currently unclear. We hypothesize that in populations with ORC, the formation, in groups, of a protective barrier of only recovered adults, prevents the transmission of this type of pathogens to the new susceptible hosts (i.e. young animals), thereby increasing the probability of epidemic fade-out. We implement a spatially implicit individual-based Susceptible-Infected-Recovered (SIR) model for a large range of host and pathogen traits and show that the epidemic fade-out probability is consistently higher in populations with ORC, especially when disease spread is fast (high basic reproduction number R0). We also show that ORC can counteract the cost of group-living in terms of disease risk to a greater extent than variation in other traits. We discuss our findings in relation to herd immunity and outline how they could be used to implement efficient management measures such as vaccinations.

ecology↗

bioRxiv2019

Inferring wildlife poaching in Southeast Asia with multispecies dynamic site-occupancy models

Determining the space race between sympatric species is crucial to understand the effects of interspecific interactions on the extinction risk of species threatened by poachers, predators, pathogens, and invasive competitors. Dynamic two-species occupancy models provide a flexible framework to decompose complex species interaction patterns while accounting for imperfect detection. In particular, these models can describe poachers-wildlife interactions by considering the occupancy, the extinction and colonisation probabilities of wildlife conditional on the presence or absence of poachers and vice versa. We apply our model to a case study on wildlife poaching in the Eastern plains of Cambodia. We used co-occurrence data extracted from the database of the SMART partnership to study the distribution dynamics between poachers and six ungulate species regarded as main prey of tigers. We used 4 years of survey data reporting the locations of ranger patrols on the detection of snares with visual detections or presence signs of the ungulates. Our results showed that a substantial proportion of the sites occupied by ungulate species went extinct over the years of the study while the proportion of sites colonised by poachers increased. We also showed, for the first time, that spatio-temporal heterogeneity in the patrolling effort explains a great deal of the variation in the detection of poachers and ungulates. Our approach provides practitioners with a flexible and robust tool to assess conservation status of species and extinction risk of wildlife populations. It can assist managers in better evaluating, learning and adapting the patrolling strategies of rangers.

ecology↗