Mice eat monarch butterflies in Pismo Beach

Good morning and welcome to the Essential California newsletter. It’s Thursday, January 13th. I’m justin ray

Regular readers may recall our in-depth account of the mysterious happenings involving seashells on Pismo Beach. Well, I’m here to tell you about another strange thing that is going on in the area.

A recent study by biologists from the University of Utah found that mice there had no problem eating monarch butterflies.

The study of the eating habits of the harvested mice was carried out at the Pismo State Beach Monarch Butterfly Grove. The good news is that this diet didn’t add to the demise of the monarchs. Instead, biologists believe that this behavior indicates how little we know about the interactions in our ecosystem.

“One of the things that really makes this stand out is that there is a butterfly here, an insect that we are all so familiar with, that we all know. Almost every school kid in California knows their life cycle and toxins, and it is in every garden. And yet, here is an interaction that we had no idea existed, ”Sara Weinstein, the postdoctoral researcher who helped write the study, told the San Luis Obispo-Tribune.

How was the study conducted?

Interesting facts about butterflies: Monarch butterflies have a “chemical armor”, explain the researchers. As caterpillars, they eat plants that are filled with toxic compounds (so-called cardenolides). This makes them disgusting to most – but not all – predators.

To see if mice would eat the butterflies, the researchers caught the rodents in the grove in February 2020. They were eventually released, but their feces were saved and tested for Monarch DNA – which was found in a sample. They conducted the experiment in late winter, which wasn’t ideal as the insects went away so the mice didn’t have as many to eat.

The researchers intended to conduct the survey again the following fall, which would have been the peak season for monarchs. But the butterfly population had plummeted by then.

“In a place where 100,000 butterflies used to nest, in 2020 there were fewer than 200 monarchs. So we had to change tactics, “said Weinstein, according to the announcement. “We tested with captive-raised monarchs whether rodents would feed on the butterflies.”

They placed carcasses of monarchs under camera traps in the laboratory and watched as the wild harvest mice ate the insects. They seemed to like to eat on their “stomach or chest, high-calorie, less-toxic parts,” the press release said.

“Many species of rodents in monarchs are likely to have some resistance to cardenolides due to genetic changes where these toxins bind,” Weinstein said in the press release. “The Pismo Grove is one of hundreds of western monarch aggregation places, and it is likely that rodents throughout the western monarchy region have supplemented their winter diet with monarchs, at least in the past. If you can handle the cardenolides in a monarch, their bodies are full of fat and make a pretty good meal. “

The population of western monarch butterflies has been decimated over the past 40 years. There will be an impact on the ecosystem as many organisms depend on others for their survival.

And now this is happening across California:

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Patrisse Cullors at Crenshaw Dairy Mart, an art gallery.

(Jason Armond / Los Angeles Times)

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Anthony Sheriff, stage name Sheriff Drumman, plays the drums

Anthony Sheriff, stage name Sheriff Drumman, plays the drums.

(Jason Armond / Los Angeles Times)


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If you remember, I asked readers about music they listen to when they want some nostalgia in their life. Here is an answer from Kelly C. Richardson:

Everything from Kid Stuff Records & Tapes. An endless offer that never gets boring. When I was unable to save or uncover on flea markets in 2020, I was able to shop on Discogs and buy an album from Kid Stuff for less than the shipping cost! Saved my mind

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