Aerial disturbance metrics 

by Jim Parker, Hamilton

Established wildlife biology literature provides clear, quantitative metrics projecting how high-frequency aerial and motorized disturbances during calving season devastate calf survival rates.

“Quantitative Impacts of Calving-Ground Disturbance

While an isolated helicopter flight may only cause temporary flight behavior, a high frequency of overflights—such as a portion of the 2,200 flights planned by USCM over a single season—creates chronic, additive stress:

 The “8-Disturbance” Threshold: Controlled studies tracking human and motorized disruptions on elk calving grounds indicate that an average of just over 8 disturbances per cow elk results in nearly 40% fewer surviving calves.

Cumulative Mortality Risk: Within these studies, each repeated high-level disturbance event carried an average of a 5% probability of calf death due to tracking exhaustion, abandonment, or separation.

Zero-Growth Ceiling: When cumulative human-induced disturbances reach an average of 10 events per cow above ambient baseline levels, monitored elk herds demonstrate no net population growth.

 Predation Vulnerability: Forcing nursing cows to abandon heavy timber security cover for open slopes leaves neonates highly exposed to apex predators.