Saiga Herd Vigilance & Flight Initiation Distance (2D)

Herd

Herd size 24

Predator Encounter

Flight initiation distance (base) 14 m

Alarm ripple speed 9 m/s

Flee speed 1.2×

Live Readout

Herd state

grazing

Detection radius

—

Time since alarm

—

Distance fled

0.00 km

🌾 Saiga (Saiga tatarica) is Critically Endangered — poaching and disease crashed the population over 90% in the 1990s–2000s. Kazakhstan's protected reserves have since driven a strong recovery, but mass predator/disturbance events still matter for herd survival.

How it works

Flight initiation distance (FID) is the measured distance at which a prey animal breaks off feeding and flees an approaching predator — a real behavioral-ecology metric (Ydenberg & Dill, 1986). Two real effects drive this model:

effectiveFID = FIDbase × (1 + 0.18·log2(herdSize/10 + 1))   "many-eyes" vigilance dilution
alertDelay(i) = dist(predator, i) / rippleSpeed + (direct ? 0 : 0.6s)   alarm propagation

Many-eyes effect — in a larger herd more eyes are scanning at any moment (Pulliam, 1973), so the group as a whole notices a predator farther away even though each individual spends less time vigilant.
Direct detectors — animals within the effective FID see the predator themselves and react almost immediately.
Social-contagion ripple — animals outside that radius flee only once the alarm (a neighbor bolting) reaches them, at the ripple-speed you set, with an added reaction-lag penalty since they are reacting to conspecifics, not the predator directly.
After fleeing together (cohesion keeps the herd from scattering), the group settles, re-grazes, and is ready for the next encounter.

Click the steppe to place a predator

Grazing Alert / vigilant Fleeing Settling