Three decades of research on Iberian wild Carnivora: trends, highlights, and future directions

1. Mammalian carnivores (Carnivora) are crucial components of landscapes, because of both their top-down effects on lower trophic level species and their sensitivity to bottom-up processes, such as limited food resources (e.g. due to climate instability). To understand their functional role in Iberian ecosystems more clearly, and to define effective plans for their management and conservation, it is crucial to sum up the available regional knowledge that can inform decision-making processes.
2. We review bio-ecological research on wild Iberian carnivores over 30 years (1990–2020) and identify key knowledge gaps and priority avenues for future research. Based on a systematic review of the scientific literature, we aimed to: 1) summarise current knowledge; 2) assess species and ecoregion representativeness; 3) identify key research topics addressed and those lacking investment and 4) suggest key future research priorities.
3. We examined 920 peer-reviewed articles involving wild Iberian mammalian carnivores, focusing on different bio-ecological issues. We found considerable heterogeneity in the topics and species investigated, as well as in the study areas (ecoregions) explored, with a mismatch between the research priorities identified by researchers and the knowledge gaps.
4. We suggest that future research should prioritise: 1) rear-edge populations that are at the southwestern limits of the species' Eurasian range, thus being particularly sensitive to the increasing fragmentation and aridity of Iberian ecosystems, and that were less studied (e.g. brown bear Ursus arctos, stoat Mustela erminea, European mink Mustela lutreola and pine marten Martes martes); 2) less-studied topics, such as morphometry and body condition, ecophysiology, and reproductive biology, all of which provide essential information for species' management and conservation and 3) specific ecoregions for which studies on species' adaptations to environmental and anthropic contexts are lacking (e.g. northern ecoregions of Iberia, Iberian conifer forests and Northwest Iberian montane forests). Our review provides the necessary background to support future research on carnivore populations in Iberia.