# Evaluating Management Scenarios for the European Hamster (Cricetus cricetus) Using Quantitative Models

## TL;DR

This study uses a model to test management strategies for the endangered European hamster, finding that population recovery requires significant improvements in reproduction and survival in agricultural areas.

## Contribution

The paper introduces an individual-based model using the GMSE framework to evaluate conservation scenarios for the European hamster.

## Key findings

- Current conditions predict a steady population decline for the European hamster in western Europe.
- Population growth requires improvements in multiple reproductive and survival parameters, not just increased litters per female.
- Hamster-friendly agricultural landscapes are essential for recovery, but ambitious interventions are needed.

## Abstract

The European hamster (
Cricetus cricetus
) is critically endangered across its range, with modern intensive agriculture and habitat fragmentation mainly driving population declines. Conservation efforts have been largely ineffective in reversing these trends, emphasising the need for innovative approaches, such as quantitative modelling, to evaluate and guide management actions. We used the Generalised Management Strategy Evaluation (GMSE) framework to develop an individual‐based model for the European hamster. We simulated population dynamics for a population in the western part of the species' range under various hypothetical management scenarios. Twelve scenarios were tested to evaluate the impact of different life history parameters on population dynamics over 5 years. Simulations based on current conditions, including low reproduction and survival rates under intensive agriculture, predicted a steady population decline. Scenarios incorporating increased reproduction and survival within hamster‐friendly agricultural fields demonstrated varying degrees of population stabilisation and growth, with only the most optimistic projection achieving the target population size. Our simulations suggest that, under current conditions and without substantial improvement in population parameter values, potentially achievable through targeted management interventions, the European hamster is unlikely to recover in the western part of its range. Increasing the average number of litters per female per year alone is insufficient; population growth was only observed in scenarios combining improvements in multiple reproductive parameters and survival rates, which may be difficult to achieve in practice. While our model is not intended to produce exact predictions or prescriptive guidance, it offers a valuable tool for exploring hypothetical scenarios and investigating the consequences of model assumptions. As such, it can inform the design of more adaptive and ambitious conservation strategies, in line with the IPBES Scenarios and Models Assessment, which highlights the role of modelling for policy development and integrating biodiversity conservation with ecosystem services.

We used an individual‐based model to evaluate hypothetical management scenarios for the critically endangered European hamster in Western Europe. Simulations indicate continued population decline in the absence of hamster‐friendly management, with recovery possible only through ambitious improvements in reproduction in hamster‐friendly agricultural landscapes.