Of Droughts, Data, and Butterflies

August 21, 2015


Photo: Variable Checkerspot, Euphydryas chalcedona, nectaring along the Castro Crest Ridge, Santa Monica Mountains, May 2015 (Elizabeth Long).

Californians are all painfully aware that we are suffering through year 4 of a significant drought. It's easy to predict that animals that rely on streams, ponds, or lakes are going to suffer from the scarcity of water. Animals that live in water, reproduce in water, or simply need these water sources for drinking are all under an increased risk. But what about things like land-dwelling insects? One of the questions I've been asked often in the past few months is "How are the butterflies responding to the drought?" One might think that would be an easy question to answer, but the reality is more complex.

Butterfly watchers have some common wisdom that they share with each other when it comes to drought: One species isn't affected by a one-year drought, while this other species declines, and yet another species seems to thrive. Maybe a short drought triggers some sort of "now or never" mating response that results in lots of offspring being produced. You can hear the same sorts of generalities being discussed for the second year of a drought. But three years of drought? Four? That's when old butterfly watchers shrug their shoulders and say "this is uncharted territory." And finding data collected in a rigorous enough way to really answer the question of "how do butterflies respond to drought" is challenging. Because, in order to detect a change due to drought, we need to understand what "normal" populations really look like. And unless we can survey one area regularly, methodically, for a long time, we don't have the power to know if the numbers of butterflies we see today represent a decline or are just the status quo or even an increase.

This is where the power of long-term studies can help us understand animals' response to drought. Unfortunately, though, very few research studies are designed with this type of methodology, and most don't carry on long enough to really answer these questions about drought. One of the best long-term studies that I know of is conducted by Dr. Art Shapiro at UC Davis [in the interest of full disclosure, Art was my PhD advisor, and he and I continue to collaborate on research projects]. Art began surveying areas along the I-80 corridor in the 1970s. Today, Art has 10 field sites stretching from the San Francisco Bay Delta up to Donner Lake in the Sierra Nevada Range. He travels to each site every two weeks, walks a regular route, and records the butterflies he sees there. In recent years he and his collaborators have used this dataset to examine how butterflies respond to climate change. Now, Art's data is well-poised to let us ask questions about the response of butterfly populations to drought.

I can't tell you conclusively what Art's data say about butterflies and the drought (he's still figuring that out). But I can tell you what he has noticed in a general sense (and what other observers have confirmed anecdotally): at a given location, the number and composition of butterfly species doesn't seem to have changed much, but the overall abundance of butterflies is way down. And, interestingly, a lot of species seem to be carrying out their life cycles much earlier in the year than normal. This can pose a problem when, for example, abnormal weather events arise, like the monsoonal rain storms that dumped rain and snow on parts of California in mid-summer. Summer snow storms in the Sierras seems to have disrupted several butterfly species' life cycles—they were absent during the annual Yosemite Butterfly Count this July.

Despite the value of these types of long-term studies, it can be difficult to support and carry out such a labor of love. Finances add up, and funding is difficult to obtain when the potential pay-off is some vague day years, decades, or even centuries away. Personnel come and go, while personal lives and health issues can complicate our ability to spend this much time in one place collecting data. Fashions in scientific research can trend away from natural history observational research. But as most scientists will tell you, the more we learn, the more we realize how much there is to know, and nowhere is this as true as for complex ecological systems. How these biological communities respond in the face of extreme environmental conditions can only be answered by careful study, and in this case, many years of hard work.

 


(Posted by: Elizabeth Long)


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The Flight of Monarch Butterfly 64365

May 20, 2015

Somewhere in L.A. a monarch egg hatched and out popped a tiny girl caterpillar. That caterpillar ate, and ate, and ate. She ate milkweed, the only plant she could, until she molted her skin. All told, she molted four times until she was a big, fat, stripy caterpillar with black tentacles. She made one last molt and formed a bright green chrysalis with shining golden spots. Two weeks later she emerged from that chrysalis as an adult, and then she flew. On November 17, 2014 she was spotted in the Museum’s Nature Gardens. She was caught in a net, and gently removed by skilled hands. A small, circular, paper sticker was affixed to her hind wing with the numbers 64365 printed on it. She was released and flew off into the distance. We knew there was a good chance that we’d never see her again.

Monarch caterpillar by Courtney Celley/USFWS.

If you’ve roamed our Nature Gardens over the past few months you may have noticed tags on our monarch butterflies (Danaus plexippus). No, these aren’t fashion accessories like dog outfits—they’re actually a citizen science tool for tracking monarch movements. The small paper stickers are like a butterfly license plate and allow us to find out where the monarch butterflies in our garden are going. Very little is known about monarch populations of Los Angeles and urban areas in general.

It is pretty well known that some monarch butterfly populations migrate—we’ve all heard of the monarchs east of the Rockies that fly thousands of miles down to central Mexico to overwinter. Monarch populations west of the Rockies overwinter along the California coast between Sonoma and Baja. But, our L.A. monarchs are a bit of a mystery, it is not clear which migration path our monarchs follow, or if they migrate at all. Our tagging efforts in the Nature Gardens are part of the Southwest Monarch Study, a group dedicated to identifying and describing the migration and breeding patterns of monarch butterflies in the Western United States, and promoting monarch butterfly conservation.

We began tagging last fall in October, during one of our citizen science programs. Forty-four intrepid citizen scientists were trained how to safely capture, handle, and tag monarchs. That day we managed to tag 16 butterflies, and participants took extra tags home to continue the effort in their own neighborhoods. But, we still had a lot of tags left, and didn’t want to send them back.

We came up with an idea that would bring citizen science to our visitors! During our afternoon nature walks in the gardens, visitors learned how to tag monarchs with our staff. We showed them how to catch the butterflies, how to affix the tiny sticker, and how to record the data. Between October 2014 and March 2015 our visitors tagged over a 100 monarch butterflies.  

Of the 102 butterflies tagged, 33 were recaptured in the gardens including one that was caught two months and 24 days later. Then, on December 27, Donna N., a local Angeleno, found a butterfly on her car in Boyle Heights. She noticed the small sticker and called the phone number on it. She reported the finding and became LA’s newest citizen scientist. Turns out this butterfly was our female, monarch 64365! Although, her seven mile trip isn’t as harrowing as that of P-22, the famous Griffith Park mountain lion that crossed the 405 and 101 freeways, our little monarch had to fly over the 110 freeway. We’ll never know her exact route, or where she went in those intervening 30 days. But, we can hope she found some milkweeds and laid some eggs along the way.

The need to put monarchs on everyone’s radar is especially relevant now as they are currently under review by the U.S. Fish and Wildlife Service to be listed as “Threatened” under the Endangered Species Act. Although the season for tagging monarchs is over for the year, our effort to better understand and protect them is not. Our Monarch Waystation (next to the Butterfly Pavilion) recently opened for the year, our garden volunteers are continuing to care for the over 500 nectar and milkweed plants that monarchs rely on in our gardens, and we'll be tagging monarchs again in the fall. Ultimately all these efforts help to ensure that the children, grandchildren, and great-grandchildren of monarch 64365 have a place to thrive in Los Angeles.

**If you want to help us protect our L.A. monarchs send an e-mail to nature@nhm.org. We’ll send you details on the monarch citizen science/volunteer opportunities and programs you can sign up for.

Co-authored by Lila Higgins, and Miguel Ordeñana

 


(Posted by: Lila Higgins)


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Rotting Fruit and Puddle Parties: Check out the Butterfly Pavilion!

April 6, 2012

It is that time of year again! Sunday is the opening of our Butterfly Pavilion, and although we still have hundreds of free-flying butterflies there's a lot that has changed out there. We have replanted the entire space, adding many more nectar and host plants for adults and caterpillars. We have also added new food sources for some of the adult butterflies that aren't quite so partial to sipping nectar!The Mourning Cloak butterfly, Nymphalis antiopa, is one of the California native butterflies we put in our pavilion. Although these butterflies are not common to our area, they can be found in areas where their host plants thrive. Caterpillars of this species feed on various willow (Salix species), cottonwood (Populus species), and ornamental elms (Ulnus species). Unlike many of the other species of butterflies in our pavilion, the Mourning Cloak butterfly prefers to feed on rotting fruit  rather than plant nectar. In an effort to appeal to the tastes of this epicurean butterfly, we've put out platters of rotting banana, mango, and plum.

Mourning Cloak butterfly sucking up liquefied rotten fruittasty!

Shawna Joplin and Lydia Gotcher working in the Butterfly PavilionWe've also installed two mud puddles in the pavilion. These puddles will hopefully be places for butterflies to get the other nutrients they need beside sugarnutrients like salt, amino acids, and nitrogen. In nature, male butterflies are often seen gathering on the edges of puddles. Sometimes large numbers of males gather at the same puddle, which entomologists have termed, puddle parties! Males more often exhibit this behavior because they need salts and other nutrients for their spermatophores. Spermatophores are small capsules containing sperm and nutrients that are passed from the male to the female during mating.

Puddle party pads! Look very closely in the yellow circle and you can see a Buckeye, Junonia coenia, feeding.One of the questions I get asked most frequently is how we get all the butterflies for our pavilion. The short answer is, we buy 'em. This makes the process sound easy and non-time consuming, it is anything but! Months ago, Shawna Joplin, the Museum's Coordinator of Animal Care and Education, started placing orders for butterfly pupae. She works with vendors all over the United States, to ensure that we will have the numbers and diversity we need to achieve a magical butterfly experience. Last week we received our first pupae shipment. Each vendor sends us about one shipment a week, and each shipment can contain anywhere from 25 to 250 pupae! Every time we get a shipment, the Live Animal Program staff have to inspect each individual pupa and then prepare it for emergence. Some pupae get pinned and hung in our emergence case, whereas others can rest on the bottom of case. Twice a day this case is inspected and all healthy adult butterflies are removed and then released in the pavilion.

Emergence case with emerging sulphurs and monarchs

Pipevine Swallowtail, Battus philenor, pupa. Look at those colors!Come by and check out the Butterfly Pavilion! For ticketing information visit our website.


(Posted by: Lila Higgins)

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