Presentation on theme: "Bats and ODOT Bridges ODOT Environmental Services November 15, 2000."— Presentation transcript:
Bats and ODOT Bridges ODOT Environmental Services November 15, 2000
ODOT bridges are used by bats for roosts n 13 species of bats use bridges for roosts; n Bridge roosts have replaced tree roosts that have been cut; n ODOT bridges are important to bat conservation.
Basics of Bat Behavior n Bats live year-round in Oregon; n Winter: some bats migrate; most hibernate (not in bridges) - some bats are active in western Oregon; n Summer: Day roosts (females in maternity colonies; males solitary or in bachelor colonies); Night roosts; n Emerge at dusk, drink, feed, rest at night roosts, feed again, go to day roost at dawn, sleep (in torpor) all day.
Night roosts and day roosts n Night roosts: Resting places to keep warm, digest food, engage in social behavior. n Day roosts: Hidden, dark places (crevices, caves, tree cavities) where the bats sleep through the day.
Bats select certain bridge types n Concrete bridges: u T-beam, Box beam, Sub-structure with vertical surfaces; Larger bridges; n Timber bridges: u Minor use if not treated with preservatives n Steel bridges not used
Bridge location is important n Sunny locations important n Shaded bridges in trees, canyons, or gorges get little use n Solar radiation = warmth at night n Larger bridges absorb more heat
Bridges are used as day roosts and night roosts n DAY ROOSTS: u Crevices u Inside box beams u Hollow spaces u Caverns n NIGHT ROOSTS: u Vertical surfaces u Ceilings u Abutments u Ends of the bridge
How to recognize bat use n You see bats. Look in crevices; n You hear bats. High-pitched chirps; n Bat sign: guano - dirty rice grains beneath vertical surfaces or crevices n Bat sign: urine stains - white and powdery on vertical surfaces; n Bat sign: body oil stains - dark, on vertical surfaces
Bat Guano n Contains insect parts, no vegetation; n Dark brown to black: insect skeletons; n Gray: moth wing scales; n Size: rice grain (small bats); n Size: puffed wheat (large bats)
Safety risks n Do not pick up bats; n Bats out in the open during the day are probably sick, and could be rabid; only rabid bats can transmit the disease; n Bats can get rabies but they do not carry the rabies virus; n If you need to move a bat, use a tool (shovel, broom);
Can bat presence affect your bridge work? n Yes, if the bridge has a maternity colony; the young cannot fly until late July; disturbance or demolition could kill the young bats. n Night roosting and day roosting by males is not a concern; they can find other roosts.
What to do if you find bats n Contact the Region Environmental Coordinator (Richard Beck, Molly Cary or Brian Bauman, Max Mizejewski; Shelly Schmidt, or Chuck Howe); n Determine if maternity colony (biologist) n Coordinate activities April 1 - September 1.
Big brown bat Photo by Merlin Tuttle
Big brown bats Photo by Merlin Tuttle
Pallid bat Photo by Merlin Tuttle
Pallid bat Photo by Merlin Tuttle
Silver-haired bat Photo by Merlin Tuttle
Hoary bat Photo by Merlin Tuttle
California myotis Photo by Roger Barbour
Little brown myotis Photos by Merlin Tuttle
Long-eared myotis Photo by B. Moose Peterson
Fringed myotis Photo by Roger Barbour
Long-legged myotis Photo by Roger Barbour
Yuma myotis Photo by Merlin Tuttle
Small-footed myotis Photo by Merlin Tuttle
Western pipistrelle Photo by Merlin Tuttle
Brazilian free-tailed bat Photo by Merlin Tuttle