Why red kites gather at night—and why age changes everything

A new study by the Swiss Ornithological Institute has uncovered why red kites gather in large groups at night. Researchers tracked nearly 34,000 overnight stays using GPS data from 216 birds over six years. The findings reveal clear differences in behaviour based on age and breeding status.

The study focused on red kites fitted with GPS transmitters between 2015 and 2021. Data showed that breeding adults rarely use communal roosts, preferring to stay close to their own territories. Younger birds, especially males, were far more likely to join these nighttime gatherings.

During winter, red kites often form groups of dozens at shared roosting sites. Researchers suggest these locations may serve multiple purposes. For non-breeding birds, roosts could act as a 'partner exchange', helping them find mates or vacant nesting areas. They might also allow young kites to share information about reliable food sources.

As red kites grow older, their roosting habits change. The study found that older birds visit communal roosts less frequently. This shift in behaviour appears gradual, with maturity reducing their dependence on group gatherings.

The research forms part of a long-term project examining red kite ecology. While the study provides insights into Swiss populations, most existing data on communal roosts comes from German regions like Neckar-Alb and Brandenburg. The findings help explain how these birds balance social behaviour with territorial needs across different life stages.