Natural take-off flight performance is repeatable and scalable in mixed flock tit species

Area of Science:

• * Ornithology
• * Biomechanics
• * Animal Behaviour

Background:

• * Traditional flight models struggle with small birds (<20 g) due to their non-steady-state flights.
• * Field measurements are hindered by the mass of high-resolution GPS loggers and low-resolution geolocators.
• * Spontaneous take-off flights in wild tit species present unique modeling challenges.

Purpose of the Study:

• * To measure and model spontaneous, non-steady-state take-off flights in wild tit species.
• * To develop a predictive model for in-flight acceleration based on initial velocity and wing loading.
• * To assess the repeatability of flight metrics as individual behavioral traits.

Main Methods:

• * Recorded 1434 spontaneous flights from 49 individuals of great tits, blue tits, and marsh tits using automated infrared tunnels.
• * Developed a power margin model to predict in-flight acceleration, scaled by species-specific wing loading.
• * Tested the repeatability of flight metrics (initial velocity, in-flight acceleration).

Main Results:

• * Significant differences in initial velocity and in-flight acceleration were observed between tit species.
• * The power margin model accurately predicted observed differences in in-flight acceleration.
• * Both initial velocity and in-flight acceleration demonstrated significant individual repeatability.

Conclusions:

• * Small bird flight performance can be reliably measured in field conditions.
• * Flight modeling can extend beyond steady-state assumptions for small birds.
• * Flight characteristics can be interpreted as consistent individual behavioral traits in small birds.