FIGURE 2.

Conceptual framework illustrating how urbanization and its associated factors can drive interactive changes in food resources, life‐history traits, and breeding fitness. This framework consists of four horizontal sections. The first section on top depicts four environmental factors. The second section with box around depicts potential mechanisms through which environmental factors can affect either food resources or species (i.e., fourth section). Food resources, as a mediator, is the third section, through which environmental factors and species are linked. Specifically, urbanization‐related land‐use changes such as conversion of natural land to built‐up areas can not only be linked to decreased habitat quality and productivity (Breeding Site Selection), and reduced insect abundance, but also elevated ambient temperature urban heat island (UHI). Increased temperatures may increase insect populations, but also result in phenological mismatches between the bird–insect–plant food chain and disrupt the timing of incubation (laying and mating behavior, and phenological response). Noise pollution may decrease insect abundance via interfering with courtship and reproduction processes and drive abnormal physiological responses of birds and their offspring (laying and mating behavior, physiological response, and foraging and communicating behavior). Artificial light at night may disrupt circadian rhythms by reducing sleeping time and negatively affecting breeding fitness and long‐term individual survival (physiological response), whereas extended light at nighttime would also enable breeding individuals to forage longer and attract common insect species, therefore, providing more food to their offspring (foraging behavior). Light gray icons represent potential food loss or breeding cost due to environmental factors, in comparison to the absence of these factors. The framework is conceptualized by authors, and icons adapted from NounProject.com (CC BY 3.0, Appendix S4: Table S1).