A Completed Habitat and Water Management Project

While I worked at the Sacramento-San Joaquin Delta Conservancy (Delta Conservancy) I managed a grant funded by Proposition 1 that sent money for improvements to the water management system of the Yolo Bypass Wildlife Area. The organization managing the project was a nonprofit called Ducks Unlimited, and they worked with the wildlife area staff, several other funding agencies, and other nonprofit organizations to make these improvements happen.

Image showing a small drainage pipe that existed before this Ducks Unlimited project was undertaken. The pipe is small and easily choked with vegetation and debris. Photo courtesy of Ducks Unlimited.

The improvements that were needed all focused on allowing the wildlife area staff to be able to move water on and off the wildlife area when they needed to. To manage a site like the Yolo Bypass Wildlife Area, a lot of water needs to be brought onto and off of different sections of land at different times of year so that the different areas can be flooded to different depths for different amounts of time and in different seasons. All those differences mean that to move water around a lot of canals are needed that trace their way across the wildlife area, and a lot of pumps are needed that are scattered along those canals.

The particular issues that this project set out to fix were two points along some of the larger canals in the wildlife area were water flow was limited because of small pipes and shallow canals. These pipes were taken out and replaced by wider bridges and the canals dredged deeper. Further issues that this project addressed were the moving of one pump and the installation of a new one.

All this work took on the order of $5 million and about five years, but it is now complete! In early December of 2021, I joined a group of people including Ducks Unlimited staff, funders, other agency staff, elected officials, other nonprofit staff, etc. to take a tour around the wildlife area to see the improvements that were built! It was pretty great to see the completed project and think back on all the effort that went in to bringing the project to a successful close. To learn more about the project with really nice visuals that allow you to really get a sense of the work that was done, check out this YouTube video that Ducks Unlimited created.

Image showing a bridge that was built as part of this Ducks Unlimited project. The bridge is wide enough to allow for higher water flow to occur uninhibited by vegetation or debris. Photo courtesy of Ducks Unlimited.

This project is a great example of how changes to an area can sometimes be very important, yet not very exciting or dramatic to look at. These improvements are not as beautiful as planting oak trees along a stream, nor are they as interesting to look at as installing boulders in a river to create more habitat diversity, yet without improvements like this thousands of acres of land would not be providing the food, shelter, and other resources that are needed by thousands of birds, mammals, reptiles, amphibians, fish, insects, etc!

So, congratulations to Ducks Unlimited and all the other organizations and agencies that were involved in this project for getting a lot of hard and complex work done and allowing this wildlife area to continue to be the amazing resource for wildlife that it is!

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Bats Under the Bypass

If you are in the Davis or West Sacramento area in the late summer or early fall, and have an evening to spare, go and find a spot where you can sit beside the Yolo Bypass Causeway. This is where highway I-80 crosses over the Yolo Bypass.

Streams of Mexican Free-tailed Bats over the Yolo Bypass

Just as the sun begins to set, you will see an amazing sight. Columns of bat will flood out from under the bypass and stream across the sky in sinuous ribbons. About a quarter of a million Mexican Free-tailed Bats (Tadarida brasiliensis) live under the bypass this time of year, and every night they pour out and spread across the surrounding area to find small flying insects to eat.

These bats are incredible! They can fly about about 100 miles per hour, making them among the fastest mammals in the world! Remember that Cheetahs are the fastest land-mammal, but bats have them beat by a healthy margin. These bats can fly as high as a mile above the ground, and can forage out distances of several miles from their night roost before returning around dawn to sleep. Using their sonar they can detect and pinpoint the exact position of little insects flying through the air and then capture those insects on the wing, at speed!

My wife, daughter, and I joined some friends and went out for an evening visit to see the bats about a month ago. I was a spectacular evening in the Yolo Bypass Wildlife Area. We saw lots of Swainson’s Hawks; herons, egrets, and ibis galore; some of the biggest Western Saddlebags (which is a species of dragonfly) I have ever seen; and then we got to the causeway.

When we arrived, the sun was still a touch above the horizon, so we had some time to stand around the dirt road that runs parallel to I-80 and chat and watch the sunset. We got a very nice surprise when an adult Peregrine Falcon flew past and landed in the top of a tree a little ways to the west of us. I was so excited to see this bird that, in turning around for a better look, I clumsily stepped on my wife toes (sorry sweetheart)!

Mexican Free-tailed Bats as they leave from under the Yolo Causeway.

As the light began to fade, we started seeing little movements under the causeway. The first bats were starting to move. Interestingly, the bats do not wake up, take flight, and simply fly out from under the causeway wherever they happen to be. Instead, they wake up, take flight, and then fly directly under the causeway for a few hundred yards before turning a sharp left, and lifting up into the open sky. I have no idea why they decide to do this, but volunteers at the Wildlife Area know it is gong to happen so consistently, that they can tell you exactly which tree the bats will fly out near.

The numbers of bats moving under the causeway built and built until there were bats streaming along between the support pillars. Then they made that left, and out in to open they came! A snaking stream of bats began raising and twisting into the sky! Thousands and thousands of bats following one another out from where they had been sleeping to look for food. As we watched the seemingly endless flow of bats, we got a very cool surprise. That Peregrine Falcon that we had seen earlier came back. It started strafing through the flow of bats. It was hunting bats!

I have seen this behavior of raptors hunting bats as they leave their night roost on video before, and it is pretty spectacular to see on a screen. Seeing it in real life was thrilling! After a couple of passes, the Peregrine made a quick move to one side, and suddenly it had a bat in one talon! It flew off and out of sight carrying it’s dinnertime snack.

The rest of the bats were generally nonplussed by the Peregrine attack, and keep streaming and streaming into the coming night.

Finally, the last bat that was going to leave had departed, and the darkness was getting deep enough that we would not have been able to see the bats fl by even if they were there, so we piled back into our cars and headed for home.

All in all, a terrific way to spend and evening!

 

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