Data from: Terminal attack trajectories of peregrine falcons are described by the proportional navigation guidance law of missiles

The ability to intercept uncooperative targets is key to many diverse
flight behaviors, from courtship to predation. Previous research has
looked for simple geometric rules describing the attack trajectories of
animals, but the underlying feedback laws have remained obscure. Here, we
use GPS loggers and onboard video cameras to study peregrine falcons,
Falco peregrinus, attacking stationary targets, maneuvering targets, and
live prey. We show that the terminal attack trajectories of peregrines are
not described by any simple geometric rule as previously claimed, and
instead use system identification techniques to fit a phenomenological
model of the dynamical system generating the observed trajectories. We
find that these trajectories are best—and exceedingly well—modeled by the
proportional navigation (PN) guidance law used by most guided missiles.
Under this guidance law, turning is commanded at a rate proportional to
the angular rate of the line-of-sight between the attacker and its target,
with a constant of proportionality (i.e., feedback gain) called the
navigation constant (N). Whereas most guided missiles use navigation
constants falling on the interval 3 ≤ N ≤ 5, peregrine attack trajectories
are best fitted by lower navigation constants (median N < 3). This
lower feedback gain is appropriate at the lower flight speed of a
biological system, given its presumably higher error and longer delay.
This same guidance law could find use in small visually guided drones
designed to remove other drones from protected airspace.