In the dense, layered world of forest canopies, where sunlight filters softly and the air is thick with the scent of pine and decaying leaves, an intricate dance of coexistence is playing out. Recent research from the University of Göttingen sheds new light on how two elusive species—the red squirrel (Sciurus vulgaris) and various dormice species—navigate their arboreal habitats, revealing that mixed broadleaf-conifer forests provide a unique ecological niche favoring their peaceful coexistence. This study, published in the European Journal of Wildlife Research, offers a groundbreaking perspective on forest biodiversity and has potent implications for sustainable forestry management.
The central question addressed by this research was how red squirrels and dormice, both grammatically arboreal rodents with somewhat overlapping resource needs, manage to inhabit the same treetop space without long-term displacement or competition driving one species out. Conventional wisdom held that such species might exhibit spatial avoidance or competition-driven segregation, particularly given the varying food preferences and nesting habits of these animals. However, the Göttingen team’s detailed observations over a seven-month period reveal a subtler, more complex symbiosis fostered by mixed forest types.
To investigate this, the team deployed 80 motion- and heat-triggered cameras across 20 distinct forests in northern Germany, a region typified by its diverse stand structures. These cameras were installed at heights ranging from two to thirty meters, ensuring comprehensive coverage of the complex vertical stratification within the forest canopy. Scaled by professional climbers, each camera was carefully positioned to capture the activity of arboreal mammals in their preferred microhabitats.
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During the extensive observational period, the team recorded an impressive 468 sightings of red squirrels alongside 446 observations of dormice, which were further categorized into 249 edible dormice (Glis glis) and 197 hazel dormice (Muscardinus avellanarius). This robust dataset allowed for an unprecedented statistical analysis correlating species occurrence with forest composition, specifically the relative abundance of coniferous and deciduous tree species within each locale.
The analysis uncovered a clear preference in habitat use: red squirrels exhibited a marked affinity for coniferous forests dominated by species such as Douglas fir and spruce, capitalizing on the abundant seed resources and structural complexity provided by these evergreens. In contrast, dormice were more frequently encountered in forest stands rich in European beech (Fagus sylvatica), a deciduous tree whose nut and fruit production aligns with the dormice’s dietary needs. Remarkably, in mixed stands that combined both coniferous and broadleaf species, both red squirrels and dormice were observed cohabiting with minimal apparent interference or direct competition.
This finding challenges the classical ecological assumption that sympatric species competing for similar resources must partition habitats strictly or temporally avoid one another to minimize niche overlap. Instead, the study suggests that heterogeneous forest environments provide diversified niches and an abundance of microhabitats enabling these species to coexist by resource partitioning at the landscape scale. This nuanced coexistence likely reduces direct interspecific competition and promotes biodiversity maintenance within forest ecosystems.
Lead author Pedro Mittelman highlights that their research dispels the misconception that arboreal mammals with overlapping ecological traits are necessarily competitors that exclude one another. Their data demonstrated no significant avoidance behavior between dormice and red squirrels and underscored how mixed-species forests can create conditions conducive to multifaceted wildlife assemblages. This insight is vital for forestry management, advocating for the cultivation of diverse tree species mixtures rather than monocultures, particularly in areas managed for timber production.
The study’s methodology also stands out, given the technical challenge of installing remote monitoring equipment high in the tree canopy. The team’s collaboration with professional climbers ensured safe and accurate placement of cameras, a task that requires not only skill but an understanding of tree anatomy and an awareness of animal behavioral patterns to maximize data collection. This integrative approach, combining field expertise with cutting-edge technology, sets a standard for future wildlife monitoring research.
Beyond immediate ecological implications, the findings have broader consequences for conservation biology and ecosystem management. By affirming that structurally and compositionally diverse forests better support wildlife richness and ecological interactions, this research reinforces global calls for biodiversity-friendly forestry practices. These practices encourage natural regeneration cycles and mixed-species afforestation, aligning ecological sustainability with economic forestry goals.
Furthermore, the study contributes to functional trait ecology by illustrating how the interplay of species-specific resource preferences shapes community assembly and ecosystem functionality. The coexistence of red squirrels and dormice in mixed forests exemplifies how functional diversity at species and habitat levels promotes resilience and stability in forest systems, particularly in the face of anthropogenic pressures such as habitat fragmentation and climate change.
In summary, the University of Göttingen team’s research elegantly demonstrates that mixed broadleaf-conifer forests serve as critical habitats promoting the coexistence of red squirrels and dormice through habitat heterogeneity and niche differentiation. These insights emphasize the importance of adopting forestry management strategies that preserve or restore mixed forest stands to sustain diverse wildlife communities. As global forest landscapes continue to evolve under human influence, such scientifically grounded knowledge will be paramount in informing policies that balance economic use with ecological preservation.
This study not only enriches our understanding of small mammal ecology but also shines a spotlight on the canopy—the often-overlooked frontier of forest ecosystems—where vibrant and complex biological interactions unfold. By employing innovative remote camera technologies and meticulous field efforts, the researchers have opened a new window into the lives of elusive treetop dwellers, providing valuable data that bridges field ecology, forest management, and conservation science.
Given the urgency of conserving biodiversity in temperate forests worldwide, these findings arrive at a crucial moment, offering actionable knowledge to forest managers, conservationists, and policymakers striving to design landscapes that support both wildlife diversity and sustainable resource extraction. As Mittelman and colleagues have demonstrated, fostering heterogeneous forest landscapes may be a fundamental key to reconciling human use with nature’s intricate webs of life.
Subject of Research: Not applicable
Article Title: Mixed broadleaf-conifer forests promote coexistence of red squirrels and doormice
News Publication Date: 7-Jun-2025
Web References: http://dx.doi.org/10.1007/s10344-025-01947-y
References: Mittelman P, Pineda M, Balkenhol N (2025): Mixed broadleaf-conifer forests promote coexistence of red squirrels and doormice. European Journal of Wildlife Research, 71:67.
Image Credits: Pedro Mittelman
Keywords: Forest diversity, Mammals, Rodents, Forests, Animals, Wildlife management, Wild populations, Wildlife, Environmental management, Agriculture, Agroforestry, Silviculture, Forest resources, Forestry, Ecological diversity, Habitat diversity, Species diversity, Conservation biology, Ecological communities, Species, Species competition, Biodiversity
Tags: arboreal habitat coexistenceconservation of small mammalsecological niche of rodentsecological research methodsEuropean wildlife studiesforest biodiversity researchimpact of habitat diversitymixed broadleaf-conifer forestsred squirrels and dormice coexistenceresource sharing among mammalsspecies interactions in forestssustainable forestry management
