Avian Demography in Tropical Ecosystems

Avian demography in tropical ecosystems examines the vital rates—survival, reproduction and dispersal—that determine population dynamics across complex and highly biodiverse regions. Tropical forests, savannahs and island systems together host more than half of the world’s bird species, yet demographic data remain scant compared with temperate zones. Research has shown that patterns of mortality and breeding success often vary with local rainfall regimes, forest cover and resource pulses, creating spatially heterogeneous population trends. In recent years, advances in remote sensing, long-term monitoring and analytical models have improved estimates of survival and productivity, revealing both exceptional longevity in many tropical landbirds and pronounced sensitivity to habitat disturbance. Understanding these demographic processes is critical for identifying climate refugia, guiding protected-area planning and forecasting the resilience of tropical avifauna under rapid environmental change.

Research from Nature Portfolio

A detailed study of a single-island endemic has provided new insights into how rainfall and population density drive annual survival in tropical passerines. Using a 14-year capture–resighting dataset, researchers found that adult survival in a Critically Endangered lark remained exceptionally high (above 0.80) but fluctuated markedly between wet and dry years. Survival declined when population density was high during droughts, and a modest linear decline with age was identified, emphasising the role of environmental stochasticity and intraspecific competition in shaping demography on small islands.

Avian Demography in Tropical Ecosystems publication trend

The graph below shows the total number of articles in avian demography in tropical ecosystems across all publications each year (not limited to Nature Index journals).

Technical terms

Apparent survival: The proportion of individuals alive and present in a population at one time that are still alive and detectable at a later time, as estimated by capture–mark–recapture models.

Capture–mark–recapture: A method for estimating demographic parameters in wildlife by capturing individuals, marking them uniquely, and then recording subsequent recaptures or resightings over time.

Climate refugia: Areas where local conditions buffer species from regional climate change, allowing populations to persist despite broader environmental shifts.

Demography: The study of population processes and vital rates—birth, death and movement—that drive changes in population size and structure.

Seasonality: Regular, cyclical changes in environmental conditions such as rainfall or temperature that influence timing of breeding and survival in bird populations.

References

1. Survival of a long-lived single island endemic, the Raso lark Alauda razae, in relation to age, fluctuating population and rainfall. Scientific Reports (2019).
2. Prospects for Neotropical Forest Birds and Their Habitats Under Contrasting Emissions Scenarios. Global Change Biology (2024).
3. Long‐term monitoring reveals the long lifespans of Neotropical forest landbirds. Ecology (2024).
4. Effects of Deforestation on Foraging Behavior, Ectoparasites, and Adult Survival in the Vulnerable La Selle Thrush, Turdus swalesi, in Haiti. Sustainability (2023).