https://www.aba.org/birding_archive_files/v37n1p44.pdf

The early months of a captive bred chick’s life now more closely mimic nesting practices of wild condors, in which a newborn chick sits by itself in a cave or cavity and sees primarily adult condors. In using this new approach of raising chicks “singly in a social environment”, captive-bred birds are allowed to see an adult “mentor” condor to learn proper behaviors and are introduced to peers slowly over time.

Behavior training continues when birds are moved to five release-sites in central and southern California, in Arizona, and in Baja California. In a release-site flight pen, young condors spend several more months adapting to the area under further tutelage by a mentor condor. The flight pens are mesh-enclosed structures with 60-foot sides and a height of about 30 feet. They have built-in blinds containing one-way glass that allows biologists to monitor the birds unseen.

Intensive Field Management

Dangers abound for newly released young condors. Birds have been killed by collisions with power lines, electrocuted, shot, eaten by predators, and even poisoned by drinking antifreeze. To protect and monitor the birds, biologists equip each condor with numbered wing tags and lightweight radio transmitters. This allows researchers to track released birds and head off danger or provide support if a bird gets in trouble. The rugged terrain that condors favor,however, can block radio signals, and birds sometimes disappear for two or three days at a time. A few recently released birds sport a new GPS (Global Positioning System)monitoring system that provides biologists with improved tracking and a plethora of information on condor movement and behavior. Researchers make arduous journeys through chaparral-choked canyons and rappel down cliffs to remote nest sites to monitor the birds. Released condors are also recaptured to run health checks and replace radio transmitters. Recently, the recovery team recaptured released birds to vaccinate against the West Nile virus.