A groundbreaking study spearheaded by the University of East Anglia (UEA) has unveiled compelling insights into the adaptive strategies of mountain birds amid shifting climatic conditions. This research penetrates the long-standing scientific puzzle concerning why species diversity alters predictably with increasing elevation on mountains, a phenomenon observed but not fully explained until now.
Traditionally, ecologists posited two predominant hypotheses to decipher elevational biodiversity patterns. The first theory hinges on long-term evolutionary processes, suggesting that species’ climatic niches are fine-tuned over millennia to particular temperature ranges and habitats found at specific altitudes. Conversely, the ‘energy efficiency’ hypothesis argues that contemporary ecological dynamics—how species optimize energy consumption and manage resource competition across fluctuating environments—play a decisive role. UEA’s research rigorously tested these ideas by analyzing seasonal altitudinal movements of nearly 11,000 avian populations distributed across 34 mountainous regions worldwide.
Published in the esteemed journal Science Advances, the study employed elaborate computational models to simulate avian energy expenditure throughout seasonal cycles. Contrary to expectations derived from the evolutionary climate niche hypothesis, many bird species did not simply track fixed temperature ranges as seasons changed. Instead, their migratory behaviors and elevational shifts aligned closely with predictions from energy optimization models, signaling a sophisticated behavioral mechanism aimed at maximizing energy efficiency in the face of variable resource landscapes and interspecies competition.
Dr. Marius Somveille, the lead scientist of the study from UEA’s School of Environmental Sciences, elucidated that altitudinal migration—the movement of birds vertically along mountain slopes following seasonal patterns—is a globally widespread, yet understudied phenomenon. By comparing elevational gradients to latitudinal gradients, the research revealed parallels between altitudinal migration in mountains and long-distance latitudinal migrations, such as those seen in species relocating toward tropical regions during winter. Both types of migrations serve the ecological purpose of energy conservation and survival amidst climatic variability.
This revelation challenges the simplistic view that birds are rigidly bound to habitats defined solely by thermal tolerances. Instead, altitudinal migration emerges as a dynamic, energy-driven strategy allowing birds to navigate seasonal changes and resource competition effectively. The researchers argue that mountains constitute natural laboratories where such adaptive behaviors can be studied extensively given the replicated environmental gradients and distinct seasonality evident across latitudes.
A critical facet highlighted by the study is the uneven distribution of altitudinal migrants dependent on latitude. In equatorial tropical mountain regions, like the Southern Ghats of India, approximately 20 percent of bird species undertake vertical seasonal migrations despite minimal temperature variations. In contrast, colder temperate zones such as the Swiss Alps exhibit nearly 57 percent altitude-migrating species, underscoring seasonality’s role as a fundamental evolutionary driver in shaping behavioral adaptations. Eastern Taiwan, positioned within subtropical mid-latitudes, represents an intermediate case with about 43 percent of avian species engaging in altitudinal migration, illustrating the nuanced gradient of energy-based migration correlating with latitude.
Furthermore, the study reveals that only a minority of populations make drastic seasonal shifts exceeding 1,000 meters in elevation, mirroring patterns seen in latitudinal migratory distances where most species prefer shorter-range movements. This finding emphasizes that energy efficiency, rather than extreme displacement, is the selective pressure molding migration behaviors on mountains. The majority of species optimize energy budgets with relatively modest altitudinal excursions to exploit fluctuating resource hotspots and avoid intense competition during lean seasons.
Advanced modeling efforts incorporated real-world data from nearly 11,000 bird populations across 2,684 species, leveraging publicly available citizen science databases. This substantial dataset allowed for a robust, quantitative understanding of altitudinal migration and seasonal distribution dynamics on a global scale. The integrative approach combined ecological theory, energetic cost-benefit analysis, and spatial modeling to deepen comprehension of how ecological and climatic forces interact with animal behavior.
Beyond academic curiosity, such insights bear consequential implications for conservation biology and biodiversity resilience under climate change. Human activities disproportionately degrade lower elevation habitats due to urbanization, agriculture, and other land-use pressures, while the inaccessibility of higher altitudes affords them relative protection. As the spatial distribution of resources and energy availability shifts with ongoing environmental change, understanding how birds modulate their seasonal elevational ranges becomes critical in predicting population viability and ecosystem stability.
Dr. Somveille highlighted that this energy-centric perspective informs future projections about mountain bird responses to global warming and habitat alteration. Changes in energy landscapes caused by habitat fragmentation and climate-induced phenological shifts could disrupt finely balanced migratory strategies. Anticipating which populations are most vulnerable requires integrating behavioral ecology with climate models and human impact assessments.
Collaborating with colleagues from institutions including Georgia Institute of Technology, Yale University, and Academia Sinica, the research team synthesized interdisciplinary expertise to unravel the complex interplay of climate, ecological dynamics, and bird behavior. Manifesting the power of global data sharing, participatory science initiatives enabled this unprecedented evaluation of seasonal altitudinal distribution patterns, providing a template for future ecological investigations across taxa and biomes.
This pioneering investigation redefines altitudinal migration as a crucial ecological adaptation shaped by real-time energy economics rather than solely by historical evolutionary constraints. It bridges the conceptual gap between evolutionary niche conservatism and ecological plasticity, situating energy efficiency at the forefront of understanding species’ spatial dynamics in mountainous landscapes. As climate variability intensifies, elucidating how animals like mountain birds deploy energy-optimizing strategies will be indispensable for mitigating biodiversity loss and preserving ecosystem functions.
Subject of Research: Animals
Article Title: Climate, ecological dynamics, and the seasonal distribution of birds in mountains
News Publication Date: 6-Feb-2026
Web References: DOI 10.1126/sciadv.adz5547
References: Somveille, M., Freeman, B.G., La Sorte, F.A., & Tuanmu, M.-N. (2026). Climate, ecological dynamics, and the seasonal distribution of birds in mountains. Science Advances.
Keywords: Altitudinal migration, energy efficiency, seasonal distribution, bird ecology, mountain biodiversity, climate adaptation, ecological modeling, elevational gradients, species diversity, global change adaptation
