Peregrine Falcon Release Methods
Observers would carefully monitor the falcons' behavior during the early breeding season to determine when eggs were laid based on the adult peregrines' behavior. A climber would then rappel to the nest and collect the wild eggs, replacing them with porcelain replicas, which the adults would continue to incubate. It was not uncommon for some eggs to have already broken in the nest before we could collect them.
As soon as they were available, 14-17 day-old young peregrines hatched at our facility would be taken to the site and placed in the nest for the adults to raise to fledging. Despite that these young were orders of magnitude larger than a newly hatched peregrine, they were invariably accepted by the adults as their own. In this way we were able to bolster productivity in areas where most pairs were failing to hatch eggs on their own, helping maintain the population until the residual DDE problems subsided with time.