How do bats change their echolocation calls while chasing an insect?

When chasing an insect, bats systematically alter their echolocation calls through three distinct phases of pulse output: search, approach, and terminal.1

• Search Phase: The bat emits pulses at a relatively low rate, typically about 10 pulses per second, while scanning for prey.1
• Approach Phase: Once a target is detected, the bat increases its pulse rate to approximately 25 to 50 pulses per second. During this phase, the bat also shortens the duration of its pulses as the distance to the insect decreases and often modifies the frequency pattern.1
• Terminal Phase: As the bat nears the final interception, it enters a rapid terminal phase lasting about 100 milliseconds. In this stage, the bat emits extremely short pulses at a high repetition rate, reaching 200 or more pulses per second. This rapid-fire signaling allows the bat to perform precise final maneuvers to capture the target.12

Once the bat intercepts or passes the insect, the terminal phase ceases, and the bat typically returns to a search phase.1