Back East Backyard Big Year

Quite a bit has happened since the last time I wrote a blog post.  In the Fall of 2015 we made a huge move from L.A. to downstate New York (since moving here I’ve learned that the locals take their regional descriptions very seriously, and upstate NY does not start till up around Albany) and taken a job as Director of Conservation Science at the Mohonk Preserve.    I’ll write more about this amazing place later but for now I want to talk about my last post and how I’ve decided to put my metaphorical money where my mouth is.

It’s been about ten years since I’ve lived in the east, and during that decade trips to the right coast have been rather sporadic.  I also switched study species in that time, changing from birds to butterflies.  As a result, I’m much more familiar with the butterfly fauna of the western U.S. than I am that of the eastern U.S. despite spending 75% of my life in the east.  I’m delighted to be back in the land of green vegetation, spring wildflowers, and gentle rolling mountains, but I’m having to re-learn the local flora and fauna almost from scratch.  I decided that one way to do that, at least for butterflies, was to do a Big Year.

A quick refresher- a Big Year means trying to see as many species as possible in one calendar year.  Most people think of Big Years as being things that birders do, traveling around the country and spending lots of money, but there are other ways to go about it.  Not only is my Big Year focused on butterflies rather than birds, but I’m confining my Big Year to the species found on the lands of the Mohonk Preserve.  This does a few things:  it gets me familiar with the species in my new backyard/workplace, and it gives the Preserve a comprehensive list of what butterflies are found on the Preserve and where.  To keep things interesting, Zach is doing a Preserve Bird Big Year.

Rather predictably, Zach is waaaaaay ahead of me on species counts, but I’m finally starting to see some butterfly action.  While Zach has been in double digits almost since the first of the year and now hovers around 75 or, I’m delighted to be at 7*.  When it’s all said and done we’ll probably judge our ultimate successes as a percentage of possible species rather than just go based on raw totals, but really the competitive aspect is a distant second to the idea of getting out and seeing as much of the land as possible and learning to identify its inhabitants.

So what have I seen so far?  First up, unsurprisingly, were the Mourning Cloaks.  They started to show up in February due to our incredibly mild winter and their habit of overwintering as adults.  Compton’s Tortoiseshells came out at the same time, followed by Eastern Commas.  Cabbage Whites are now quite common and truthfully are driving me slightly nutty as I check each one to make sure it isn’t a Margined White. Eastern Tiger Swallowtails started to show themselves last weekend.  I’ve had a reliable report of Black Swallowtails but haven’t recorded one myself.  A few days ago I was thrilled to get my first member of the Melitaeini, a Pearl Crescent.

Blurry photo of an Azure, Celastrina sp., at Mohonk Preserve

The butterflyers amongst you may have noticed that I have not yet mentioned Azures, Celastrina spp.  That’s because the taxonomic status of this genus in our area is still a bit of a puzzle to me, and I need to do some careful reading and looking to see what’s possible and what’s out there.  For now I’m loosely calling everything “Spring Azure” but there’s a good chance there are two or more species of Celastrina flying right now.

*Pending a better understanding of Azures in the area I’m considering what I’ve seen so far one species.

Musings on Big Years, slowing down, and finding beauty in the ordinary.

Robert Michael Pyle’s “Handbook for Butterfly Watchers” is a must-have for anyone wishing to improve their butterflying skills

I just finished reading Robert Michael Pyle’s beautiful 2010 book, Mariposa Road: The First Butterfly Big Year. I’ve been a fan of Pyle’s writings for a while, and his Handbook for Butterfly Watchers is high on my recommendation list for people who want to expand their butterflying skill. Unfortunately I haven’t had much time for reading lately, so I’ve been sneaking little bites of Mariposa Road for months now- a trip to Texas here, a break in the Florida Keys there. I finally finished it, and now I’m pondering the idea of a Big Year.

A bit of background: The Big Year concept was first popularized by birders. A Big Year is an attempt by one person to count as many species as possible in one calendar year in a proscribed area, usually the U.S. (the specific “rules” have changed since the earliest days of Big Years). I first learned about the Big Year concept by reading Kenn Kauffman’s wonderful Kingbird Highway, and later followed it up with Mark Obmascik’s The Big Year: A Tale of Man, Nature, and Fowl Obsession. And yes, that last one was turned into a movie starring some folks you’ve probably heard of. Kauffman himself was famously inspired by Roger Tory Peterson and James Fisher’s 1955 Wild America.

Pyle’s “Mariposa Road” tells the story of the first-ever butterfly Big Year

Pyle’s book documents the first-ever verified butterfly Big Year, undertaken by him in 2008. Pyle’s Big Year was not some random butterfly watcher’s vain and selfish endeaver- Pyle has long been an important champion of butterfly conservation, and he used his Big Year as a fundraiser for the Xerces Society (which, by the way, he also founded). As always, his writing is lyrical, funny, and informative. One of the benefits of reading it in short chunks the way that I did is that each time I picked it up, I was inspired anew by his love of butterflies, and that pleasure was spread out over months.

One common criticism of Big Year attempts, similar to criticisms of speed records on the Appalachian Trail, is that there is little time to appreciate the ordinary, every day aspects of the endeavor, and barely time to revel in the joy of the exceptional. Pyle blasts that line of criticism to smithereens. He clearly states at the outset that familiarity most certainly will NOT breed contempt, and the reader doesn’t have to get very far into the book to enjoy Pyle’s own appreciation of the common species. My favorite bits, though, come from his delight in the inconspicuous or unassuming species. Take Erebia discoidalis, the Red-disked Alpine: “On this kind, the cinnamon scales smear all over the chocolate above. Below, the subtle but intricate mix brought to mind rust and cloud on peat and loam.” Most folks upon encountering this butterfly wouldn’t have noticed it; most who did would mistake it for a drab moth, wondering why it was out and about in the daytime if they even gave it a second thought. Pyle, though, manages to find beauty in it, and to make the reader share in that finding, as well.

Most people who encounter the Red-disked Alpine probably find it drab.

I’ve known birders who have done a Big Year and I can’t deny that they have some amazing stories and see some incredible things. The idea of doing a Big Year certainly has some appeal. But I could never quite imagine making the time commitment that a Big Year requires. It might sound like a wonderful way to see the country, but I’ve done field work. I know how time consuming it is. I know how easy it is to not really see the land around you when focused on a daunting task like this. And I know myself, and I wonder if I would really be able to drink it all in, the way Pyle manages to do in between sleep deprivation and road food. I don’t know if a Big Year is for me, but I’ve been thinking a lot lately about a modified Big Year. There are lots of way to reduce the scope of a Big Year, either geographically or temporally, in a way that still leaves time for work, family, and recreation.

How can you modify a Big Year? You can do a Big Month. Or even a Big Day. You could modify the geographic parameters- what about a County Big Year? For a birder in Los Angeles that’s something like 500 species of birds possible (feel free to correct me on that in the comments if my number is off. I was never a great west coast birder). For a butterflyer in Los Angeles, the number of possibilities is ~145. That’s still a pretty significant challenge! You can do your (modified) Big Year as part of a larger effort, contributing data to eButterfly, eBird, the annual NABA count or Christmas Bird Count; you can turn it into a fundraiser for your local Audubon group; or have the nerdiest competition ever with your friends.

But whatever you do, remember to take time to appreciate the common species, and to find beauty and wonder everywhere you look. And as Pyle says, “Then slow down, and let the butterflies lead. You’ll see just as many as you see; and much more besides.”

What I did on my summer vacation: Trip Report from the Mono Lake Bird Chautauqua

I just got back from one of my favorite events of the year, in one of my favorite places in California- the 14th annual Mono Lake Bird Chautuaqua in Lee Vining. 
The Chautauqua is a 3-day festival that celebrates not only birds, but the beauty and natural history of the Mono Basin, eastern Sierra Nevada, and the Great Basin. The long weekend is packed with field trips, presentations, and social events put on by people who are dedicated to protecting this important natural area and sharing its beauty with the over 400 participants who come to partake. I was looking forward to this trip for months, ever since the organizers got in touch and asked if I could lead a bug field trip. This would be my third Chautuaqua as a trip leader, and Zach’s fifth- sadly we had to miss last year’s event for crazy scheduling issues on our end. One of the wonderful things about the Chautauqua is getting to spend time with so many great people. It sounds cliched to say this, but I love getting to reconnect with old friends and make new ones- and every year it seems like we meet great new friends who I will look forward to catching up with the next year. This year was no exception.

If you’ve never been to Mono Lake, what are you waiting for? GO! NOW! I’ll wait…
The lake itself sits at the base of the eastern slope of the Sierras, just over the hill from Yosemite National Park and Tuolomne Meadows, at an elevation of almost 7000 feet. Highway 395 runs the length of the eastern Sierra, and while a few small towns dot the road, the whole area feels gloriously, luxuriously quiet and deserted after a year in Los Angeles. Mono Lake itself is formed from streams running out of the Sierras and draining into the Mono Basin. The lake has no outlet, so the water that collects has been subjected to eons of filling and evaporation cycles, concentrating salts and minerals in the water and driving the salinity levels higher than that of seawater. The lake supports an incredibly productive ecosystem, driven largely by brine shrimp and fly larvae that support migratory and breeding birds in spring, summer and autumn.

For a natural history enthusiast, Lee Vining offers spectacular scenery, clean air, and the promise of seeing lots of birds (or bugs, or whatever your pleasure) across a variety of different habitats. To the east, the sagebrush desert of the Great Basin stretches out as far as the eye can see, interrupted periodically by hills and mountains jutting up out of the landscape in dramatic fashion. To the west, the granite and metamorphic cliffs rise steeply upwards, quickly becoming snowcapped alpine peaks over 10,000 feet high- at least, in most years. California is in the 4th year of a well-publicized drought, and even after living here for a year, we were still shocked and saddened to see how dry the mountains are this year. The lack of snowpack in the Sierras is causing issues over a large part of the state as municipalities such as Los Angeles struggle to conserve what little water is available, and coming to Mono Lake is a stark reminder of just how severe this drought is. Much of Los Angeles’ water comes from the eastern Sierra, and the landscape around Lee Vining is dotted with signs warning would-be trespassers to stay off of the property, as it is now owned and controlled by the LA Water District. All Angelenos should come to Mono Lake and the Owens River Valley and witness for themselves just where their water is coming from, and what that water means to the wildlife that calls this area home.

My biggest regret of the weekend is that I forgot to get a group photo from my field trip.  The good folks who came along on my field trip Sunday morning were absolutely fantastic, and made my job as a presenter so easy.  I just wish the wind would have let up a bit so that we could have seen more butterflies, but I personally still had a great time.
I could easily spend a few thousand words extolling the virtues of Mono Lake, Lee Vining, the eastern Sierra, and of course, the Chautauqua. But I think instead I’ll put up some cellphone pictures of the long weekend, and leave you with an invitation to join the fun in 2016. Registration usually opens in the spring, and some of the programs fill up fast! Put it on your calendar!

We got in late Thursday and immediately set about procuring one of the necessities of any trip to Lee Vining- a milkshake from the Mono Cone. No lie, I spent weeks trying to decide what flavor of shake I should get each day (go with the old favorite every day, or change it up and risk disappointment- which is still relative, because even a non-favorite milkshake is still preferable to no milkshake. I digress.). The Mono Cone would be our primary lunch spot each day of our trip.

We camped next to Lower Lee Vining Creek. The water was coooooold.

No jargon, no confusion.

This trail runs along the lake in Lundy Canyon.

Can you spot the Bald Eagle? Lundy Canyon lake.

Drought or no, the snowmelt caused small streams along the trail.

Butterflies in the Sierras are living in a very different world than the ones in the Santa Monicas. This Azure rests on Aspen leaves.

The flowers in the Sierra are still beautiful, even if the drought means there are fewer of them.

This gorgeous Ruddy Copper was flitting about the Lundy Canyon trail. I couldn’t get a picture of its dorsal surface, but trust me that the shiny, copper penny upperside perfectly illustrates why coppers are so named.

Saddlebag Lake sits just east of the Yosemite National Park boundary and is normally a great place to find high elevation species of butterflies that are hard to get to. The water level is frighteningly low this year.

Looking east past Saddlebag Lake. No snow!

Friday evening we took one of the dirt roads toward Mono Lake to watch for Nighthawks flying.

While we waited for Nighthawks, this marmot tried to climb into the undercarriage of our car.

As soon as the sun set over the Sierras, we could see stars- a scarce sight in L. A.!

The pine pollen was covering everything! Walking through a meadow next to Lee Vining Creek even our feet turned yellow.

Everywhere we looked we found interesting nature stories. This aspen trunk is covered with the claw marks from a climbing black bear.

Aquatic insects are vital to many ecosystems, including mountain streams in the Sierras. The nymphs live in well-oxygenated streams before coming out of the water to shed their skins and becoming terrestrial adults. This is a shed exoskeleton (exuvia) of a member of the Plecoptera, or Stonefly, Order. Fly fishermen often use stonefly nymph lures in mountain streams to catch trout.

American Dippers are small birds that are adapted to a unique niche- they live in fast moving, rocky streams, often along waterfalls, in the American west. They hunt aquatic insects by diving into the water, drifting downstream, and catching their prey. They typically build their nests in crevices on the sides of rocks just a few inches above the water line. This spot in Lee Vining creek hosts a dipper nest every year and we always love to watch the adults provisioning the nest. This year, fledging came early and there were no young in sight. One of the adults was still around showing off its daredevil aquatic hunting skills.

We came across this female Sooty Grouse while out birding early one morning. It was such a thrill to get such a close look at this amazing bird.

On Saturday afternoon we went to the a set of freshwater ponds close to the edge of Mono Lake. The Deschambeau ponds are an incredible place for watching odonates (dragonflies and damselflies), and occasionally doing some catch-and-release for up close study. This 8-spotted skimmer consented to let us examine her up close for a few seconds before resuming her day’s activity.

The Deschambeau ponds are mainly fed by geothermal springs bubbling up out of the ground. Even on hot days one can sometimes see steam coming off of the water at the source. Shortly after draining into the ponds, though, the water cools sufficiently to support odonate nymphs and other aquatic fauna that support waterfowl.

Looking east over the Deschambeau Ponds toward the eastern Sierra. Everywhere one looks in the Mono Basin, stunning scenery abounds.

Saturday afternoon is the Presenters’ Reception, full of delicious food, good company, and drinks in wildlife-themed glasses. Each year a different glass (previous years’ glasses include etched hummingbirds, phalaropes, and brine shrimp (my favorite)), and this year captured one of the funniest scenes one might see on the lakeshore- gulls running along, open mouthed, scooping up flies. The Mono Lake Committee store sells a shirt with the same image and I happened to be wearing it! Of course, I had to pose with my wine glass next to the shirt.

Why Mimicry is the Coolest Thing Ever, Part 2: Mimicry Can be Mutually Beneficial

A while ago I wrote about the phenomenon of mimicry, and talked a bit about the earliest descriptions of mimicry.  In Batesian Mimicry, two species have converged on the same conspicuous “warning” phenotype, but only one is giving an honest signal.  In the case of butterflies this phenotype is usually warning coloration, or aposematism.  The honest signal indicates that the animal is toxic, and the animal who is giving this signal is called the model.  Predators that encounter the model have a bad reaction, associate it with the aposematic signal, and avoid prey with that phenotype in the future.  Mimicry comes in when another species, the mimic, is perfectly harmless but benefits from sharing a similar phenotype with the model.  Predators either can’t tell the difference between the two species, or aren’t willing to take a chance, and therefore avoid the harmless mimics.  Mimics get protection from predation by virtue of their false warning coloration, plus they don’t have to pay the metabolic cost of sequestering toxins in their bodies.  Henry Walter Bates first described this type of mimicry while studying butterflies in the Amazon.

Some of the many diverse mimetic Heliconius phenotypes

In 1878, Fritz Müller proposed another type of mimicry after studying some of the same butterflies in Brazil that Bates had investigated.  These specific cases had puzzled Bates, but Müller realized that mimicry doesn’t always involve a dishonest signal.  Like Batesian mimicry, this type of mimicry was eventually named after the naturalist who first described it.  In a Müllerian mimicry system, two or more species strongly resemble each other and are poisonous to common predators.  The burden of educating a predator to avoid a specific color pattern is shared between both species, and some biologists consider it a form of mutualism.

Monarch butterflies were originally believed to be Batesian models to Viceroy butterflies after a pioneering study performed by Jane Van Zandt Brower in 1958 indicated that naive Blue Jays would reject Viceroys after exposure to Monarchs.  The story wasn’t that simple, though, as David Ritland and Lincoln Brower showed later that Viceroy toxicity varies geographically (and, actually, so does Monarch toxicity).  In some areas, Viceroys are not poisonous, and if they coexist with Monarchs, they are Batesian mimics of Monarchs.  In other areas, though, Viceroys sequester toxins from their caterpillar host plants (often salicylic acids from willow trees) and function as Müllerian mimics.  Even more interesting, Viceroys also coexist with Queens in some places.  Queens and Monarchs are closely related, both sequester toxins from milkweed plants, and both are toxic.  This means there are many combinations of species pairs and mimicry types possible just within this one group: Monarch + Viceroy can be Batesian or Müllerian mimicry; Monarch + Queen is Müllerian mimicry; and Queen + Viceroy can be Batesian or Müllerian mimicry.

Queen butterflies ingest poisons from the milkweeds that they eat as caterpillars. The caterpillars and adults become toxic to predators.

Today some of the strongest research on Müllerian mimicry comes from researchers studying butterflies of the genus Heliconius.  Heliconians occur in the tropics of Central and South America, and there are about 39 recognized species within the genus.  They occur in many different species combinations and a variety of color pattern phenotypes.  They take in amino acids from feeding on pollens, and these compounds allow them to make cyanic compounds- cyanide.  Published studies on Heliconius mimicry have exploded in recent years, and have led to an understanding of the genetic mechanisms controlling color evolution, the physiological processes that protect the butterflies from the poisons they are carrying, the behavioral interactions that allow butterfly species to tell each other apart and find suitable mates, and many other things.

Heliconius

How do YOU wear down a field guide?

I was flipping through a field guide this weekend, and I couldn’t help but chuckle at the state of the thing. The cover is bent and coming loose in several places. Pages are stuck together, dogeared, ripped. Dirt splotches, bug guts, and sunscreen smears grace most of the pages. I have easily 20 different butterfly field guides, and at least 15 of those cover the area where I currently live, but I use this one almost exclusively. I’ve had it for about 10 years, and browsing through those pages tells a story of how I learned to ID butterflies, which species give me the most trouble, and which pages bring me the most joy.

Whenever I flip through any of my field guides I’m reminded of a quote from John Steinbeck’s East of Eden. In Chapter 22 Samuel goes to Adam’s house to help him choose names for his sons, and suggests that they take inspiration from the bible.
“…This one has been scraped and gnawed at,” he said. “I wonder what agonies have settled here. Give me a used Bible and I will, I think, be able to tell you about a man by the places that are edged with the dirt of seeking fingers. Liza wears a Bible down evenly. Here we are- this oldest story. If it troubles us it must be that we find the trouble in ourselves.”

I mentioned this to a friend who said she did the opposite- she quickly skipped over the parts of the bible that gave her trouble, because she didn’t like to think about those parts. But come to think of it, her herp field guide was really worn down in the tiny frog section…

I wish that 10 years ago I had bought 10 copies of this field guide, and used a different one each year. The first few years’ copies would certainly be worn down at the checkerspot section, as I learned to identify the species that formed the basis of my dissertation work. Three or four years in, the grass skippers’ pages would be ragged as I started a survey project in the Sutter Buttes, and couldn’t make heads or tails of the ‘sparrows of the butterfly world’. The years that we lived in Arizona would be worn down in lots of places- roadside skippers, metalmarks, the beautiful Lyside Sulfur, which I loved to just sit and gaze at- but this time the pages would hold less frustration, and more joy. By that time my identification skills had improved dramatically, and seeing a new species brought more pleasure than the vexation of those early years. I’m not sure what the wear pattern on this year’s field guide would look like- I suspect it would be much more even, like Liza’s Bible. This isn’t to say I have it all figured out now, but I’m familiar enough with most groups that my field guide perusals now mostly consist of a quick page-flip to double-check a host plant or confirm a range.

Someone I know very well wears down his field guide evenly by reading it cover to cover like a novel.  Now that I’ve gotten better at the process, I find myself doing something similar on occasion, although in my case I’m more likely to open at random and read for several minutes.  Or, now that I have a grasp of the things I’m likely to see, I have the luxury to look at and try to learn things that don’t typically live here, like the arctics and most of the wood-nymphs.

What about you? Do you wear down a field guide evenly, like Liza? Or does your field guide tell the story of your triumphs and confusion? Does it make a difference if the field guide is for your focal taxa vs. something you don’t study? I’d like to hear about it- leave a note in the comments. What does your field guide’s wear and tear say about you?

On second thought… the Coppers are getting worn down right now- I do wish some would turn up at my study sites…

Why Mimicry is the Coolest Thing Ever, and Why I Think Everyone Should Want to Study It

Recently I was lucky enough to record a podcast for Jason Goldman’s show The Wild Life.  One of the subjects that came up in our discussion was my love of mimicry, and my feeling that if the National Science Foundation proclaimed that from now on they planned to fund mimicry research and nothing else, that would make total sense to me.  You see, I love everything about mimicry.  I think it is probably the coolest evolutionary adaptation that has ever been described, and I just happen to be lucky enough to study the group of animals that are most closely associated with this amazing phenomenon.

There are lots of different kinds of mimicry, in lots of different taxa.  There are animals that mimic each other, animals that mimic inanimate things, plants that mimic animals, plants that mimic plants- you name it, someone, somewhere in the natural world, has mimicked it.  I could write dozens of posts about mimicry (and incidentally I can’t believe I haven’t already written at least one!) but for now I’ll start out with the first type of mimicry ever described, Batesian Mimicry.

This type of mimicry is forever associated with Henry Walter Bates, an English naturalist who spent 11 years in the Amazon studying and describing insects, plants, birds, and lots of other things that he saw there in the mid-19th Century.  Bates noticed that some of the butterflies around his camp were very colorful and conspicuous, but never seemed to take evasive flight patterns or hide from predators.  He also noticed that the birds and lizards who lived in the same areas as these butterflies ignored them, even though they would readily hunt down and eat other butterfly species.  After much careful observation Bates concluded that these butterflies were laying their eggs on toxic plants, and that the caterpillars that hatched from these plants ate these poisonous plants.  He surmised that because of this, the caterpillars themselves must be poisonous, and that predators either knew this innately, or learned it through trial and error.  Most importantly, the predators could associate this toxicity with the bright color patterns of these butterflies.  We now refer to this warning coloration as aposematism, and it’s found in lots of organisms that have some type of toxicity or other dangerous defense mechanism.

When Bates decided to collect some of these butterflies, he noticed something else:  he wasn’t seeing just one species of butterfly, he was seeing several that looked alike.  What’s more, some of these species were not laying eggs on toxic host plants, meaning that they and their caterpillars were perfectly edible!  Bates determined that these palatable butterflies were mimicking the unpalatable ones.  In mimicry terminology, we now refer to the toxic species as the model and the edible species as the mimic.  This particular brand of mimicry, comprised of a noxious model and a harmless mimic, is named after the man himself- Batesian mimicry.

For many years after Bates first published his findings on mimicry, scientists accepted his rationale without actually testing it.  Then, famously, in the 1950s a set of experiments were undertaken by Jane Van Zandt Brower and later by Van Zandt Brower and  Lincoln Brower, testing the effectiveness of several butterfly species that were assumed to be involved in mimicry.  Van Zandt Brower’s approach was simple:  feed the butterflies to their predators and wait to see how the predators respond.  Depending on the toxicity of the butterfly in question, and the learning abilities of the predator, predators sometimes ate the butterfly and responded  negatively (e.g. vomiting); tasted but didn’t eat the butterfly; or ignored it altogether.  Next, the birds (she usually used birds as predators) were given the presumed mimic and asked to respond- if the bird had learned to reject the poisonous model and, based on that experience, rejected the presumed mimic, Van Zandt Brower concluded that the latter species was indeed a mimic of the former.  Over the years many researchers (including me) have relied on this basic framework to test the efficacy of mimicry systems.  While some of Van Zandt Brower’s earliest results have stood the test of time, others have undergone more scrutiny and allowed us to refine the interpretations somewhat.  Regardless, though, this contribution has been essential to our understanding of how mimicry works.

What kind of Batesian Mimicry systems occur in your area?  I promise you they’re out there!

This Arizona Sister, Adelpha eulalia, is distasteful to predators due to toxins in the oak leaves that the caterpillars consume.  Its mimic, the Lorquin’s Admiral, Limenitis lorquini, is palatable.

It’s (still) Monarch season!

Monarchs basking in the sunlight

I’ve been meaning to write this post for a while but even so I’ve managed to get it done before Monarch season ends. Mainly because, at least in southern California, it’s always Monarch season!

Monarchs have been in the news a lot lately. Researchers have proposed the Monarch for consideration for formal protection as a Threatened or Endangered species. The US Fish and Wildlife Service will consider the proposal, listen to commentary from the public, and eventually make a decision, but that process will likely take a while. The argument for putting the Monarch on this list is mainly based on the fact that overwintering habitat has declined, fewer butterflies are showing up at these overwinter sites than in past years, and habitat along their migratory corridor is being lost to human development.

To understand all of this it’s important to understand how different Monarch biology is from that of most butterfly species. North American Monarchs can live as far north as southern Canada. In the fall they start to fly southward, most likely responding to temperature and daylight cues as well as cues sensed as their host plants, native species of milkweed, start to dry up and die back. Populations of Monarchs east of the Rocky Mountains generally fly south to spend the winter in Mexico, while those west of the Rockies usually make their way to the central and southern California coast.   When they get to their overwintering spot they congregate in huge numbers- millions at a time- and roost together in clusters along the trees. I’ve never been to the overwintering colonies in Mexico but I’ve heard that if you fly over in a plane, the trees below appear orange from all of the Monarchs hanging off of them.

A docent talks to the crowd about Monarch butterflies in Pacific Grove, California

In Pacific Grove on the central coast of California you can visit one of these overwintering sites between October and February. It’s hard to estimate how many butterflies spend the winter here, but it’s easily high into the tens of thousands. Last month we were lucky enough to visit this amazing place and see this awe-inspring natural history spectacle up close. The site itself is great- it’s easy to get to and a docent on duty will answer questions, make sure nobody harms the insects, and give talks about the butterflies’ biology to the public who come to view the phenomenon. You can buy butterfly-themed gifts and gadgets from a cart at the park, and all of the proceeds go to butterfly protection.

In Pacific Grove on the central California coast, thousands of Monarch butterflies cling together for protection on a winter day.

On the day we were there it was sunny and mild, and quite a few of the butterflies had warmed up enough to take short flights around the area. A few of them sauntered out looking for nectar plants, several were coupling despite the fact that successful matings are rare during overwintering, but the vast majority of them were hanging in clusters off of the trees. I had heard about and seen pictures of these clusters for years but seeing them in person was a completely different experience. It was incredible to see just how thick these groups were- layers and layers and layers of animals all clinging together for protection and warmth.

In another month or so these animals will start to disperse from their winter habitat and move northward. Generation by generation they’ll repopulate the US and southern Canada through the spring and summer, until the days grow short again next fall.

You can buy Monarch-themed clothes, toys, and other items, all for a good cause.

 

Enemies in the Garden

So you’ve created the perfect butterfly garden.  You’ve got nectar available spring through fall (or winter if you live in a warm climate!).  You’ve planted your garden with lots of native species that are attractive butterfly host plants, and included vertical, textured surfaces for the pupae you hope will soon populate your garden.  Sounds like butterfly paradise, right?

Not necessarily.  Butterflies have a lot of natural enemies, and they suffer a lot of mortality at every single life stage.  This makes sense- a female butterfly might lay between 20 and 100 eggs in her lifetime.  If they all survived to adulthood we’d be overrun  (this might not be that bad, actually…). Predators, diseases, and parasites are all part of a natural, healthy ecosystem.  It’s how nature keeps population size in check.  In the case of butterflies we typically think of the threat from predators like birds, spiders, or lizards.  But chances are good that mortality at other life stages actually plays a more significant role in the survival of most butterfly species.

Eggs are tiny, inconspicuous, and fragile.  They can easily be trampled by larger animals, eaten inadvertently by larger herbivores, or succumb to fungal infections.  Caterpillars can be eaten by predators, become infected by fungus or pathogens, drown, dry out, or become infected by parasitoids.  Pupae can be knocked loose from their hold, be crushed, or succumb to fungus, pathogens, or parasites.  Animals at all life stages can be destroyed by severe weather, including heat, cold, sun, rain, wind, or other abiotic forces like fires.

Out of all of these threats, the one I personally find the most fascinating is the threat posed by parasitoids.  Like a parasite, a parasitoid spends a significant portion of its life cycle living inside or attached to the body of another organism.  Parasitoids, however, typically consume and kill their host.  Charles Darwin found the existence of parasitoid wasps so troubling that he once wrote in a letter that “I cannot persuade myself that a beneficent and omnipotent God would have designedly created the Ichneumonidae with the express intention of their feeding within the living bodies of caterpillars.”  His concern was justified- many parasitoids are notorious for consuming their living host from the inside out, rendering the host organism little more than a zombie incubator for its parasitoid master. In many cases they start by consuming the non-essential organs so that the host lives as long as possible, only progressing to the essential organs when they are just about to emerge.   Once the parasitoid is finished growing it detaches (if it’s external) or burrows out (if it’s internal) from the host body and continues on its merry way, ready to mate and find a new host for its eggs.

Parasitoid species are many and varied, and they attack many other organisms besides butterflies.  Read about a cool parasitoid wasp that targets the Hemiptera, or true bugs here!