What are the 'objects' ?
Your falcons are used to carrying little transmitters. Make a package of an IR lLED and a NE555 to flash the led at the normal IR remote frequency of 38 kHz. Make a sensor to detect the modulated LED that has a narrow vertical slit to minimize the side view. The sensor will detect the bird when it is in view of the sensor. You can take the project from there.Paul
The linked sensor measures the distance at a singular point in front of it. If the falcons do not fly EXACTLY over it, you will miss the falcon completely.You'd probably do best with cameras at either end. You might also be interested in this: https://rfidtiming.com/project-details/running/
I want to avoid attaching any chip to the falcons for so many different reasons. still finding ways to detect the falcon through the laser scanner or ultrasonic sensors.