Inside Seven
Current Issue: April 2014
article
Feature
The new I-5/Santa Clara River Bridge bat habitat.

I-5 SANTA CLARA RIVER BRIDGE: EXTREME MAKEOVER, BAT CAVE EDITION
by  Judy Gish
Issue Date: 11/2006

Caltrans helps bats so they, in turn, can help the ecosystem.

Michael Klima didn’t start out being, well, batty for bats. The Associate Environmental Planner, Mountain Area Projects and Biological Services, began to appreciate, if not actually love, the animals after becoming lead biologist on the I-5/Santa Clara River Bridge Replacement Project.

The project, winner of a 2006 Excellence in Transportation award, involved creation of a new habitat for approximately 3,000-3,500 Mexican freetail bats (Tadarida brasiliensis) following demolition of their home in the old I-5 Santa Clara River Bridge.

When the colony of bats was discovered, in September 2002, bridge demolition was postponed approximately two and a half months until they could migrate south for the winter. While they were away, temporary bat houses were constructed on the nearby Old Road Bridge, which served as their home until the winter of 2004, when the new bridge and permanent habitat were finished.

If the words “bat habitat” conjure up images of a castle in the Carpathian Mountains, it is helpful to know that there are over 1,100 species of bats in the world, “more than any other mammal,” Klima said. The Mexican freetail bats are considerably smaller than those usually associated with Count Dracula et al.; their new habitat consists of a 20-inch deep, 75-foot long concrete crevice on both sides of the bridge, with 1-inch wide gaps for the bats.

The habitat, jointly created by the Division of Design and the Division of Environmental Planning, was designed not to interfere with routine bridge operations and maintenance, at the relatively low cost of $50,000. A survey conducted in early summer, 2005, found approximately 250 bats living in the habitat. Another survey soon after found roughly 750 bats. In August, 2006, around 1,000 bats were counted. “So the numbers are increasing,” Klima said, adding that “the goal is to re-establish the original population of 3,000 – 3,500 bats.” Two additional surveys are scheduled for next summer and two for the summer of 2008.

For those who might wonder why it is important to preserve bats in the first place, Klima noted that the flying mammals are instrumental in reducing the numbers of agricultural pests. “Without bats, we would be swimming in insects,” he said. “And bat guano is nitrogen-rich, making it an excellent fertilizer. They even sell it in gardening stores.”

Klima is quick to mention that the project is not his alone. “Paul Caron, Branch Chief for Mountain Area and Biological Projects, came up with the idea and supplied guidance and support through the entire design process,” he said. “And Barbara Marquez, Senior Environmental Planner, took the lead in applying for the Excellence in Transportation Award.”
He also credited Greg Farr, who took the lead in Design, Kami Sharifi and Jagdish Patel in Construction, Aziz Elattar, Office Chief, Division of Environmental Planning, and, of course, Ron Kosinski, Deputy District Director of Environmental Planning.

The Excellence in Transportation awards will be presented on November 6. 

Bat habitat project lead biologist Michael Klima. Mexican freetail bat in relation to the human hand. The new I-5 Santa Clara River Bridge, where the bat habitat is located. Another view of the new I-5 Santa Clara River Bridge.