Comparative Foraging Ecology of Urban vs. Rural Birds Across Regions

Thesis Abstract

Urban environments alter resource distribution, predator exposure, and disturbance regimes, potentially reshaping foraging strategies, prey selection, and energetic efficiency in birds; while numerous studies document urban effects locally, there is a gap in cross-regional comparisons that controls for habitat structure, climate, and species assemblages. This study aims to quantify and compare foraging ecology of selected passerine and non-passerine bird species across urban and rural gradients in three biogeographically distinct regions, to identify consistent and region-specific drivers of foraging behavior. The specific objectives are (i) to characterize foraging time budgets, prey types, and patch use across urban and rural sites; (ii) to assess the influence of ambient noise, human activity, and habitat complexity on prey capture rate and handling time; (iii) to determine interregional variation in foraging plasticity and its relation to life-history traits; and (iv) to evaluate the applicability of optimal foraging theory and the niche-generalist framework in explaining observed patterns. The study employs a comparative, cross-regional design using a stratified random sampling of 60 sites per region (30 urban, 30 rural) across three regions with contrasting climates. Target species include 12 common bird taxa with overlapping ecological niches. Data collection combines focal animal sampling (n ? 720 hours of focal observations per region) and point-count based foraging surveys, supplemented by timed focal follows to record search time, handling time, movement between patches, and success rate. Foraging outcomes are quantified through prey encounter rates, caloric intake estimates derived from published metabolic rates and prey energy content, and time-activity budgets. Instruments include high-definition video cameras for foraging bouts, standardized ethograms, environmental sensors (sound level meters, light meters, temperature, and vegetation structure measures), and GPS/telemetry on a subset of individuals to assess spatial foraging patterns. Analytical methods integrate mixed-effects modeling to account for repeated measures and non-independence (bird identity and site as random effects) and include generalized linear models to test the effects of urbanization metrics (noise, human density, impervious surface) and habitat variables on foraging metrics. Regression analyses will test the relationship between prey diversity and foraging efficiency, while ANOVA and post-hoc comparisons examine regional differences. Time-budget analyses will employ survival-like methods for patch occupancy, and foraging theory will be applied through model comparison between optimal foraging theory predictions and empirical outcomes, incorporating risk-sensitive and revenue-maximizing variants. Multivariate analyses (principal components analysis) will synthesize habitat complexity, disturbance indicators, and resource availability into composite axes. Key expected findings include (i) urban birds exhibit reduced prey diversity but higher encounter rates for anthropogenic food sources, with shorter handling times in food-rich urban patches; (ii) rural birds display greater foraging sequence diversity and longer search times reflecting natural prey heterogeneity; (iii) interregional variation reveals that foraging plasticity is higher in regions with more heterogeneous urban-rural interfaces, whereas regions with homogeneous landscapes show more uniform strategies; (iv) ambient noise and human disturbance negatively affect vigilance and search efficiency, with compensatory shifts toward higher-probability prey items. The study contributes to knowledge by integrating cross-regional comparative data to evaluate the universality or context-dependence of urban-foraging patterns, informing theories of behavioral plasticity, niche generalism, and energy budgets under anthropogenic pressure. It will refine the applicability of optimal foraging theory in human-modified landscapes and provide cross-regional baselines for conservation planning, highlighting region-specific management strategies such as habitat augmentation in rural-urban mosaics, noise mitigation, and food resource governance to preserve native foraging behaviors. The main conclusion anticipated is that urbanization drives convergent foraging adjustments across regions for generalist species, yet lineage- and region-specific responses persist for specialist foragers, underscoring the need for region-tailored urban biodiversity interventions. Recommendations include deploying habitat restoration to increase natural prey availability in peri-urban areas, implementing quiet-hour policies in critical foraging periods, and incorporating cross-regional monitoring to detect shifting foraging dynamics under rapid urban expansion.