2018 09-01 Yolo Causeway
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Brazilian (aka Mexican) free-tailed bats.
After a nice early supper in Davis we drove to a location on the western edge of the Yolo bypass wildlife area and arrived around 7 PM. Sunset was 737pm. I had gotten good advice that the bats, which spend the daytime resting under the Yolo Causeway, usually take flight 15 or 20 minutes before sunset. We were also told that the best viewing area was not inside the wildlife area, which closes and is locked at sunset, but to park outside the gate and walk across the top of the levee towards the freeway (causeway). This is next to a major exit point where bats leave their daytime habitat and disperse when it starts to get dark. The bats move over a couple of miles of estuary and farm land to feed on insects at night. Bats average 3¾ inches long, and have a 12 inch wingspan. They fly quickly, perhaps 50-60 mph.
Sure enough, around 720pm, things got under way. A veteran bat watcher on site told us we might expect three main flows of bats. The truth was that there was pretty much an endless flow of bats for 20 minutes or more. At certain times the flow was heavy and at other times it was not so heavy. The bats came out from under the I-80 Bridge, turned a little bit to their left and moved up through a small clump of trees. They exited the tops of the trees and continue to moving upward and headed south, flying above a much longer tree line that paralleled the levee.
It seemed to us that the bats “got themselves organized” as they moved across this tree line. They came in as a random mass but soon formed very tight and distinct rivers. The rivers somewhat resembled murmur rations of blackbirds or starlings. The rivers continued uninterrupted as I put my camera and long lens to heavy use.
The location, atop the levee, is a good one. It provides a great vantage point to start the viewing (and photographing) bats at eye level. Some of the groups meandered directly overhead for another interesting photo angle. The setting sun was behind our backs and definitely helped illuminate the animals. This would’ve been much better except tonight there was a low stratus layer mixed with smoke from wildfires in the distance, between us and the setting sun.
The bats are supposed to be here only during the summer so I suspect they will be migrating south to Mexico soon. Our plan is to study today’s photographs, devise any modifications needed in our strategy, and return fairly soon for additional photos. For one thing, I know Suellen wants to me to carry a smaller lens next time so that images of the bat rivers can be captured. I’d like to get some short video clips too.
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Read MoreBrazilian (aka Mexican) free-tailed bats.
After a nice early supper in Davis we drove to a location on the western edge of the Yolo bypass wildlife area and arrived around 7 PM. Sunset was 737pm. I had gotten good advice that the bats, which spend the daytime resting under the Yolo Causeway, usually take flight 15 or 20 minutes before sunset. We were also told that the best viewing area was not inside the wildlife area, which closes and is locked at sunset, but to park outside the gate and walk across the top of the levee towards the freeway (causeway). This is next to a major exit point where bats leave their daytime habitat and disperse when it starts to get dark. The bats move over a couple of miles of estuary and farm land to feed on insects at night. Bats average 3¾ inches long, and have a 12 inch wingspan. They fly quickly, perhaps 50-60 mph.
Sure enough, around 720pm, things got under way. A veteran bat watcher on site told us we might expect three main flows of bats. The truth was that there was pretty much an endless flow of bats for 20 minutes or more. At certain times the flow was heavy and at other times it was not so heavy. The bats came out from under the I-80 Bridge, turned a little bit to their left and moved up through a small clump of trees. They exited the tops of the trees and continue to moving upward and headed south, flying above a much longer tree line that paralleled the levee.
It seemed to us that the bats “got themselves organized” as they moved across this tree line. They came in as a random mass but soon formed very tight and distinct rivers. The rivers somewhat resembled murmur rations of blackbirds or starlings. The rivers continued uninterrupted as I put my camera and long lens to heavy use.
The location, atop the levee, is a good one. It provides a great vantage point to start the viewing (and photographing) bats at eye level. Some of the groups meandered directly overhead for another interesting photo angle. The setting sun was behind our backs and definitely helped illuminate the animals. This would’ve been much better except tonight there was a low stratus layer mixed with smoke from wildfires in the distance, between us and the setting sun.
The bats are supposed to be here only during the summer so I suspect they will be migrating south to Mexico soon. Our plan is to study today’s photographs, devise any modifications needed in our strategy, and return fairly soon for additional photos. For one thing, I know Suellen wants to me to carry a smaller lens next time so that images of the bat rivers can be captured. I’d like to get some short video clips too.
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