September 5, 2017
There is no magic line where nature stops and city begins. Nature can be found anywhere, even in heavily urbanized and modified landscapes. Don’t believe us? Well then check out the diversity of nature observed on a joint Natural History Museum of Los Angeles County - Heal the Bay bioblitz and creek cleanup along Compton Creek.
Heal the Bay is an active environmental nonprofit dedicated to cleaning up Southern California coastal waters and watersheds. They have been studying the water quality in Compton Creek for over a decade, so we were excited to collaborate with them this summer as we co-hosted our first joint effort, a bioblitz and cleanup effort in a special section of Compton Creek.
Compton is known as the “hub city” because it is located in the center of Los Angeles County, just a short distance south of downtown Los Angeles. It is one of the oldest cities in the L.A. area, meaning that people have been altering the landscape there for a long time, so if you can find incredible nature there, you can find it anywhere. Compton Creek is the last tributary to join the L.A. River before it drains into San Pedro Bay. Like its parent river, much of Compton Creek has been channelized, with a concrete bottom and concrete sides. Only a tiny fraction of the diversity of plants and animals that once inhabited these waterways can still be found in these channelized sections. In case channelization wasn’t insult enough, Compton Creek then flows underneath the massive parking lot of Gateway Towne Center. But after that parking lot, something magical happens—the concrete ends and the channel becomes soft-bottomed for the next 2.7 miles before joining the L.A. River. Water flows out from beneath acres of asphalt and the miles of storm drain, becoming a creek again. Here in this soft-bottomed stretch, native willow trees tower over a dense mix of native and nonnative vegetation, and nature abounds. On the morning of Saturday August 26, over 60 participants and staff showed up to observe nature in Compton and leave the creek channel cleaner than when we arrived. While there was a lot of trash to be picked up, there were also many nature discoveries to be made.
Our Top Five Discoveries
1. Two Cooper’s hawks call this section of Compton Creek home. Leaving their perches in the large willows, they fly out over parking lots and past nonnative palm trees in search of their favorite meal: smaller birds. On this particular morning, one of the hawks was successful in its hunt and returned to the safety of the tree canopy with a small songbird in its talons. This was one of many predator-prey interactions observed.
2. For many of the biologists on the trip, the absolute highlight was the hundreds of native harvester ants seen along the upper banks of the creek. Across much of the urbanized parts of the L.A. Basin, there is only a single ant, the hugely invasive Argentine ant. This nonnative species kicks out our native ants, so it was a big surprise to find hundreds of native harvester ants wandering about, doing harvester ant things, like collecting seeds and bringing them back to the nest.
Harvester ants don’t only harvest seeds; they also hunt down small animals to keep their colony-mates well fed. We found some ants killing and eating a caterpillar.
In case the life and death struggle of predator and prey wasn’t enough to convince you of the incredible nature even in the “hub city,” the center of L.A. County, we also observed some exciting scavenging behavior, with ants scavenging a house mouse carcass.
3. The predator-prey dynamics did not end there. Further downstream, ladybugs were amassing in high densities to feast upon a recent aphid outbreak.
4. How do we put this next one delicately? Let’s just say humans modify the landscape in many ways, with various goals in mind. Here, this nonnative plant (we’ll let you figure out what it is) was found growing in the creek bed and was being used by several species of insects. The little mud mound at the base of the leaf cluster is from a potter wasp. That really is its name, no pun intended. Oh, this is just too hard; we can’t help ourselves—clearly this should be called a POT-ter wasp!
Actually, the nature story doesn’t end with the wasp. See the little notch out of one of the leaflets? That was made by a leafcutter bee who will line her nest cavity with the plant material.
5. If you are still not convinced that nature is all around us at all times, consider this: In about 80 minutes, one dedicated participant, CSU Dominguez Hills Professor John Thomlinson, documented 12 species of butterflies and 3 species of dragonflies.
What an incredible morning of nature discovery. The active bioblitz and creek cleanup lasted about 80 minutes, and in that time, participants and staff submitted 323 observations to iNaturalist of 104 species! Of course, discovering nature was only one of our goals. Our other goal was to remove trash from the creek, and we had great success at this as well, removing 471 lbs of trash! Quite the successful morning in Compton.
Many thanks to the wonderful citizen scientists and volunteers who came to Compton Creek to help clean up and record the natural diversity of this remarkable urban waterway.