December 10, 2008 > Bat habitat
Submitted By Karla Tanner
Photos By Dustin Findley
An existing cement silo in Mayhew's Landing, once filled with grain, is now a home available for bats, birds, and some uninvited but always welcome lizards. The grain silo was turned into a "bat habitat" by the U.S. Fish and Wildlife Service in cooperation with Meadowsweet Dairy, a group of environmental artists dedicated to preserving wildlife.
According to the date stamped on the outside of the silo, it was built in
1917. It was constructed at the same time as dikes were created in surrounding tidal marshlands to create farmland. It was not used as a grain silo for long since farming in that area was short-lived. After decades of neglect, it was slated for demolition.
Meadowsweet Dairy first worked with the US Fish & Wildlife Service on
Farallon National Wildlife Refuge (NWR) to restore habitat. When the Farallon NWR project was completed, they volunteered to retrofit the grain silo on the Don Edwards San Francisco Bay NWR as a bat habitat, saving the old silo from demolition.
The Refuge acquired the Mayhew's Landing tract in 1995 because it provided important habitat for migratory birds and the endangered salt marsh harvest mouse. Since that time, Mayhew's Landing has been colonized by another endangered species, the California clapper rail, a species found only in San Francisco Bay marshlands. The Refuge manages the Mayhew's Landing tract as a sanctuary to enhance habitat for native wildlife and to encourage species diversity. The silo conversion project has helped diversify and enhance wildlife habitat in the area.
Several species of bats might make their home in the Mayhews Landing Silo including Mexican free-tailed bats, Yuma bats, big brown bats and possibly pallid bats and Townsend's big-eared bats. But it's not only for bats; the roof was designed to attract swallows and provide housing for white throated swifts.
Mexican free-tailed bats, a common species in California, are very social. They cluster in large colonies, often inside the expansion joints of bridges over watercourses. Mother bats can find their babies amongst a nursery of tens of thousands of crying bats by their unique voices and smells.
Bats can drop their internal temperature and go into torpor (like hibernation) if the weather changes and the food supply drops. However, disturbing a hibernating bat can cause the bat to raise its body temperature in preparation for escape, using 10 to 30 days of stored fat reserve. Because bats have very few energy reserves, they can die if disturbed too many times, especially during winter months. Babies are particularly vulnerable during cool periods in late spring and early summer.
Bat populations are under severe pressure due to habitat loss and pollution. Seven of the 45 species of bats living in the U.S. are in danger of becoming extinct. Bats are beneficial to humans for a number of reasons. They eat enormous numbers of insects, pollinate plants that provide food for humans, and reseed cut forests. Bats also provide material that is used to improve soaps, make gasohol, produce antibiotics, and make excellent fertilizer.
The silo is not open to the public because disturbing bats or other animals would put the animals at risk. Mayhew's Landing neighbors were invited to a ribbon-cutting ceremony celebrating completion of the bat silo conversion project during National Wildlife Refuge Week 2007. Many neighbors attended and were positive about the creation of the new wildlife habitat.
Don Edwards San Francisco Bay
National Wildlife Refuge
9500 Thornton Ave., Newark
1 Marshlands Road, Fremont