SAN JOSE (CBS SF) — A biologist rappelled down the side of San Jose’s City Hall Tuesday morning to the spot where a falcon family has set up its nest to band and determine the sex of several new falcon chicks.

Glenn Stewart, a biologist with the University of California at Santa Cruz Predatory Bird Research Group, rappelled down from the top of the 18-story building into the falcons’ nest at approximately 7:15 a.m.

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His aim was to place bands around the chicks’ legs so scientists can track them and collect data, according to the mayor’s office.

Stewart has been banding falcons since the early 1980s and said it is exciting every time.

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“I don’t like to climb trees or mountains but it’s where the birds are,” Stewart said. “It never gets old … Every time you do it, you’re going to be really careful.”

The process usually takes about 20 minutes, he said.

Scientists are looking at the life spans of the birds because they believe it is an indicator of the overall health of the environment, he said.

Stewart said that because the falcons are high up on the food chain, if the animals they eat have contaminants, that will be reflected in their life span.

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