Animals across multiple taxa form groups for various benefits. These groups can be formed with members of the same species or different species. When members of different species of birds forage and move together, they are called mixed species bird flocks (hereafter, MSFs). MSFs provide enhanced benefits such as reduced predation risk and increased foraging efficiency but also impose costs. This cost–benefit trade-off affects flock composition as species join when benefits outweigh the potential cost of associating. Benefits gained by joining a flock will vary among species, which is likely to be context-dependent. Therefore, my thesis aims to understand MSF compositions across different contexts such as (a) elevational gradients, (b) biogeographic regions and (c) phenotypic traits.

Microclimates (temperature and humidity) along with prey abundance and diversity are expected to change with increasing elevation, making conditions harsher, which influence MSF interactions. Therefore, in Chapter 1, I plan to investigate variation in MSF composition and networks along with microclimates and prey availability across an elevational gradient (1500 m to 3200 m ASL) in Kedarnath Wildlife Sanctuary, Uttarakhand, in the Western Himalaya.

      MSFs represent a subset of the avifauna in most forested regions. Studies on composition of MSFs across biogeography hold potential to better understand species roles and community organization. Therefore, in Chapter 2, I plan to compare the species composition of flock types across forest strata in three biogeographic regions (Eastern Himalayas, Western Himalayas and Western Ghats) and examine species roles based on taxonomy, body size and behaviour.

      Species traits play a major role in flock composition to minimise costs and maximise benefits (by being similar in certain traits and dissimilar in others). Therefore, in Chapter 3, I plan to conduct a global analysis to answer the question. “Do birds of a colour flock together?”. I will use null models to compare observed flocks at 24 sites globally with random flocks to investigate whether birds in MSFs are more similar in colour than expected by chance.

Overall, my thesis will explore the factors that drive species participation and association in MSFs.