In her article Spencer-Glasson takes a detailed look at the new “Bat Boxes” that are being installed in the new Ina Road Bridge over the Santa Cruz River. Her article looks at the importance of bats to the environment, and the specifics of the Ina Road Bridge project, including some of the challenges and strategies used to re-house the bats.
The rest of the issue has stories on the Year of the Bird, the Southeast Arizona Bird Calendar, Field Trip options, and more.
Bats Using Ina Road Bridge (an excerpt)
The Ina Road Bridge is one of many bridges in Tucson that provide significant roosts for bats. This bridge is home to about 15,000 thousand bats, mainly Mexican free-tailed bats (Tadarida brasiliensis) and some Cave myotis (Myotis velifer) during the summer. Approximately 5,000 Mexican free-tailed bats remain in the bridge in the winter. A large culvert adjacent to the Ina Road Bridge also provides rooting habitat for bats.
Because Tucson can get very hot during the summer and cold during the winter, it was important to design bat roosting habitat that is well-insulated in order to mimic, as closely as possible, the temperature moderation provided by the thermal mass of the bridge.
A thickened bridge deck was designed with cut-outs so that Modern Bat BoxesTM could be incorporated into the bridge deck mass to moderate temperatures for the bats. Modern Bat Boxes are designed and constructed in New Mexico, from a light-weight concrete material. Each bat box is 4 ft x 4 ft x 4ft, with a crevice varying from ¾ inch to 1 ½ inches in width.