#ISeeChange: What's up with the Monarch butterflies?
With our new project #ISeeChange, we're aiming to hear more about what you see changing in our environment. That could mean climate change, but it doesn't have to - and some of your most interesting observations, in a vacuum, are hard to attribute to any one cause. The story of Tim Dikdan's observations of monarch butterflies is a great illustration of the problems of attribution.
Dikdan is a science teacher at Port of Los Angeles High School. (A few months ago I talked to him for a story about observing king tides.)
When I asked him whether he noticed anything changing with his environment, he immediately thought of Monarch butterflies he sees in his backyard. This year he and his family saw something different with their habitat in his backyard, specifically a milkweed plant. "In the beginning of February, my sons noticed that there was a couple of caterpillars in a milkweed plant, and the milkweed hadn’t really regenerated from the last year. There was a few leaves on it but nothing of large quantity."
In previous years, he and his wife and children had noticed butterflies passing through, Dikdan said. This year, "We noticed that there was not just one or two caterpillars. But we ended up counting more than 50 different caterpillars, on this one milk weed."
What we don't know about the behaviors of Monarch butterflies is a lot. That makes chasing down the meaning behind Tim Dikdan's one observation kind of difficult.
Why the observation is interesting
Monarch butterflies lay their eggs on the leaves of milkweed plants, and those are hard to find sometimes. One reason is insecticides. In the Midwestern United States, chemicals applied for agricultural crops really don't like milkweed, and that's help shrinking the plant's range. So is drought and extreme weather, including in California.
In the last few years, scientists have learned a lot about Monarch migration. Monarchs that fly south go dormant at the foot of their journey, then return north, laying eggs on milkweed in the southern parts of the United States. The egg-laying and migrating is pretty well observed, so much so that earlier this year, citizen observers helped a team at the University of Georgia Athens establish that a lot of well-intentioned monarch supporters have planted the wrong type of milkweed - a tropical one more vulnerable to a destructive parasite.
What we don't know
We don't know whether Tim Dikdan saw a migrating Monarch or a non-migrating one, which we're figuring out is a genetically driven distinction. The migratory population lives longer (long enough to make the trip), is better adapted to cold, and has a strong desire to fly south.Scientists are interested in the health of that population because it appears to be in decline.
We don't know how drought is affecting milkweed in California (though we're welcoming observations about that). But so far we can't say much for certain about how milkweed has changed in the last few years in Tim Dikdan's neighborhood or even what kind of milkweed he's got.
And so we really don't know why caterpillars were crowded on this one plant.
#ISeeChange is a national effort to track how climate change is affecting our daily lives.
Notice any bugs in your backyard lately? Wondering why you're seeing coyotes where you don't expect? Seen changes in your favorite tide pool? Snap a picture and tag it @KPCC and #ISeeChange on Twitter or Instagram, let us know through our Public Insight Network, or post your questions on www.iSeeChange.org. Then see what others have found and observed in their environment.