Showing posts sorted by relevance for query monarch. Sort by date Show all posts
Showing posts sorted by relevance for query monarch. Sort by date Show all posts

Friday, September 04, 2020

A Monarch Butterfly Status Report

Around mid-summer, I begin wondering how the monarchs are doing. Last summer, in 2019, they were more numerous than usual in the Princeton area, and as I googled for news of their numbers in 2020, it was with the expectation that their population was on the upswing. Surprisingly, their overwintering numbers in the mountains west of Mexico City were down dramatically. The count comes out in March, just before they begin their journey north, and was down by half compared to the winter of 2018/19. 

The low count this past winter was due in part to less than favorable migration weather last fall. Warm weather in the north delayed migration southward, and a drought in Texas left little nectar for the monarchs as they funneled through Texas on their way to Mexico. From Princeton, that flight is about 2500 miles, powered by the liquid sunlight of nectar.


This summer, I saw one every few days. Here's a male visiting Joe Pye Weed in our backyard. 




You can tell it's a male by those two spots on the back wings. 

The monarch has a delicate look, but a powerful flight. A single beating of the wings sends it rocketing forward at unexpected speed. 

One of summer's finest moments can be spent watching a monarch navigate a garden. In our backyard, masses of variously sized wildflowers form a kind of mountain range with peaks and valleys that the monarch masterfully navigates just above. Turning on a dime, coasting, darting this way and that, the monarch's flight can seem like whimsy, or an incredibly efficient and complete survey of a garden. 

Sometimes a monarch visits every section of our garden without landing, then heads off. What was it looking for? A mate? A milkweed to lay eggs on? Clearly not nectar that other more predictable insects are busy feasting upon. Oftentimes, the monarch's motivations are an enigma.


One time this summer, I witnessed a monarch whose intent was very clear. In the "Veblen Circle" of wildflowers at the botanical garden we're creating next to the parking lot at Herrontown Woods, there's a mix of purple and common milkweeds in sufficient numbers to satisfy a monarch caterpillar's voracious appetite. Yet until this summer, I had never seen a female monarch land on one.

August 7, however, a monarch came along and perched on the side of a leaf, then bent its abdomen around and under to lay an egg on the underside. All I had was an iPhone to record the moment, and didn't dare get close enough for a good photo, lest the monarch be distracted from its mission.


Though we can witness, appreciate, and take small steps to support any monarchs that come along, our capacity to influence their destiny is limited. As Monarch Watch Director Chip Taylor explains on his highly detailed blog, "High numbers in the northeast do not translate to high overwintering numbers." In other words, we can support monarchs by planting milkweed and other wildflowers, but their fate is largely being determined by weather and land management playing out elsewhere.

A 2019 New Yorker article with a less than auspicious title, "The Vanishing Flights of the Monarch Butterfly," quotes Chip Taylor describing how a banner year in 2018 was largely due to the favorable weather the monarchs experienced at various stages in their migration. With humanity still on its climate-radicalizing fossil fuel treadmill, and massive misuse of herbicides killing milkweed in farm country, the cards are increasingly stacked against monarchs getting lucky with the weather. The "inland hurricane" that swept through Iowa in August seemed an example of the increasing extremes the monarchs face.

Still, there is the delicate, improbable power of their flight, and the promise of an egg. Nature is incredibly resilient if given a chance. There are raingardens to plant and milkweed to propagate. Common and purple milkweeds spread underground, making it easy to dig one up and start a new planting that will soon expand on its own. So much tears at the foundations of our world. Let the odds be what they may, to care and to act defines who we are. 

The best source I've found thus far for updates on monarch status, and potential for participating in a larger effort, is the Journey North website:


Sunday, October 06, 2013

Monitoring the Monarchs


This monarch visited our backyard October 1. Most of its fellow monarchs, what few there have been this year, have long since headed south towards the mountains northwest of Mexico City. A lot of people are worried about their low numbers this year, and are following its fall migration. For periodic updates, there's the monarch monitoring project in Cape May, through which many of New Jersey's monarchs are funneled.

Nationally, the best I have found thus far is the Monarch Butterfly Journey North website, which includes periodic updates and a "Where are the monarchs?" page that details their travails.

As with any complex entity, whether it be a car, the human body, the climate, or an ecosystem, one doesn't need to know how it works unless it starts breaking down. Thus, a lot of attention is being paid to how the monarch migration works, and what is causing it to diminish.

For anyone interested, longtime monarch advocate Chip Taylor offers an indepth look at how migration works, how weather and farming practices are affecting it, and what we can do to help the monarchs prosper. The video's is worth an hour of one's time.

Among my notes from his talk: 

Of the 73 species of milkweed growing in the U.S., common milkweed (Asclepias syriaca) supports 90% of the monarch population. It is not found in mature prairie, but rather is adapted to disturbed sites, such as roadsides and farm fields. In the distant past, when prairie covered much of America's heartland, the many species of milkweed that thrived there would have provided the monarch larvae food. But the conversion of nearly all of the original prairie to farms has made the monarchs dependent primarily on the common milkweed that can survive in the farm fields.

Beginning in the 1990s, however, the introduction of "Roundup Ready" GMO corn and soybeans brought about a dramatic transformation in farms across the Midwest. Using Roundup-proof crops allowed the intense spraying of herbicide, which led to the elimination of milkweed from more than 90% of its original farm habitat--about 160 million acres!

Additionally, as government began subsidizing ethanol projection in 2006 or so--an ill-conceived program that speaks more to the political power of sparsely populated cornbelt states and less to common sense--corn demand and prices leaped upwards. Farmers responded by expanding their fields, eliminating fencerows and plowing right up to the road, erasing even more habitat that formerly supported milkweed.

Fire ants, an invasive species introduced from Brazil that preys on butterflies, have also been expanding their range in the south. (For example, I witnessed their mounded nests appearing along right of ways in Durham, NC over the past ten years.)

Though weather has long been variable, global weirding, as it's sometimes called, is making these variations more extreme. A spring that's too warm, a summer that's too cool, a drought that's too deep--all of these can make for low monarch numbers in any given year. One interesting twist is that some drought can actually be a good thing for monarchs, if the dryness reduces the fire ant numbers while not affecting the deep-rooted milkweed.

Conditions in Texas are particularly critical as the monarchs move north from Mexico in the spring. Taylor calls it the "breadbasket" for monarchs, spawning the first new generation that then flies up our way. (Think of the migration as a multi-stage rocket fueled by milkweed, with each generation building on the boost in momentum provided by the previous one, until the season's fourth or fifth generation heads back south in the fall. No fuel, no momentum.) As an example of the impact of extreme weather, he described a phenomenal loss of trees--300 million--across Texas due to the 2011 drought.


Seeking to compensate in some small way for the human folly that's being perpetrated on a grand landscape scale, they have a WayStation program in which people all over the country register their monarch-oriented gardens. This one in the photo, along William Street, looks like a good candidate. It has two key plants for the monarch--for the larvae, the common milkweed with its light green pods in the background, and for the adults, the New England aster whose bloom is well timed with the monarch's fall migration. Princeton needs more family-oriented restaurants like this one.

Previous post on monarchs here.

Tuesday, December 17, 2013

Monarch Update, and the Empty Heartland

Other posts here on monarch butterflies have photos of the magical creature, but perhaps it's appropriate that this post does not. Having periodically searched this fall for updates on how many monarchs made it to their mountain sanctuary in Mexico for the winter, I finally found one. The news is not good. The monarchs didn't make their customary Nov. 1 arrival at their winter home, but instead began straggling in six days later, and now occupy only twelve trees. According to a NY Times article entitled "The year the monarch didn't appear", "Last year’s low of 60 million now seems great compared with the fewer than three million that have shown up so far this year."

Researching the monarch, I had heard that climate change might render their high altitude winter home too warm by the end of the century. Another expert, Chip Taylor, suggested the miracle of their migration might come to an end as soon as thirty years from now. An oped by a NY Times editor, entitled "Monarchs fight for their lives", stated, "One recent study suggests that the long-term survival of the species may be in doubt." But so pervasive has been the displacement and destruction of their critical habitat in the central U.S. by corn fields and pesticide use that their survival from one year to the next can no longer be taken for granted. That they arrived late this year at their winter roost could have to do with weather patterns, or it could be evidence that dwindling numbers deprives the monarchs of the mass momentum that each individual must feel in a mass migration.

What could help? A shift away from GMO corn and soybeans, a return to growing these crops for food rather than ethanol, and a return to giving the monarch's critical food source, milkweed, room to grow along roadsides, between fields and on land set aside for erosion control. But just when might that happen?

Whatever we thought we had learned from the loss of the passenger pigeon early in the last century, the lesson obviously was not learned well enough. The corn and soy fields of Iowa, Nebraska, Illinois and other central states have long been considered largely barren of other life. The Chicago Wilderness initiative to restore the rich intersection of northern, western and eastern flora in the Chicago area demonstrated how urban development can host accidental or intentional sanctuaries for biodiversity that would have long since been lost to plow and spray in agricultural zones.

What we learn in the story of the monarchs is that until recently those agricultural lands were still harboring populations of weeds sufficient to sustain butterflies. Only in the past fifteen years or so, as Roundup Ready corn and soybeans came to dominate, and the subsidized demand for ethanol motivated farmers to plant right up to the edge of roads and fences, did the extermination of weeds like milkweed approach complete. The impression created is of the genetic cleansing of some 150 million agricultural acres, with nothing left, after the gassing of the last remnant gypsy weed populations, but the master race of crops marching in rows.

Other factors compound the monarch's vulnerability. Though most large-scale cutting of trees in their Mexican sanctuary has been stopped, locals still sneak in to cut trees here and there. The thinning out of the forest increases the monarchs' exposure to occasional snow and ice storms. Extreme and freak weather events, becoming more frequent as the climate changes, are all the more dangerous when a species' numbers have dwindled.

By far the most detailed update and perspective comes from Linda Moulton Howe's Earthfiles website. Interestingly, she interviews Lincoln Brower, a Princeton alum ('53) who has devoted much of his life to studying the monarch. He recounts a talk he gave at his 60th reunion earlier this year:
"I gave a lecture to my 60th reunion class at Princeton University. At the end of my talk, I'd spilled my guts out over the whole monarch situation and my history of studying it for now 55 years. One man in the audience asked me, 'Well, what difference would it make if we lost the monarch butterfly anyway?' I took a deep breath and I looked straight into his eyes and said, 'What difference would it make if we lost the Mona Lisa?' The audience went very silent. 
That's what we're up against is this superficial How Do We Make Money approach to the world and people have got to realize that we are dependent upon the biota for our own survival.”
My brother and his wife traveled this past summer to Iowa, to search graveyards for ancestors and see the landscape where her recently deceased mother grew up. Her mother's name was Lucille. She had spent her youth on a farm not far from the Mississippi, where the bluffs along the river transition into the great flat expanse of the plains. Back then, farms were small, within shouting distance of one another, and well populated by farm animals and people.

What they found on this trip was an eerie silence, a void filled only by endless fields of corn and soybeans. No animals, no people. Land is largely owned by descendants who have long since moved away and lease their land to be farmed as part of large scale operations. There's a flurry of activity in May, when massive machines prepare and plant the fields. Then little activity can be seen beyond an occasional spraying until fall harvest. Anyone wishing to open a business in the small towns would have their pick of many a shuttered building. To appreciate a monarch's predicament in such a landscape, think of Cary Grant in the cropduster scene in Hitchcock's North by Northwest.

This is America's empty heartland, the product of economic forces magnified by misguided government policies that drove people and nature from the land. And what sort of heart has a nation that would allow a miracle like the monarch's migration to teeter on the brink?

Saturday, July 14, 2018

First Monarch Sighted at Herrontown Woods


A monarch graced our "Phoenix Garden" next to the Herrontown Woods parking lot with its presence on a bright, sunny morning yesterday, July 13. It took an interest in the purple coneflowers transplanted into the garden this spring, and offered evidence of the importance of the garden for sustaining pollinators in Princeton through the summer months when forests offer few flowers.

The sighting prompted an internet search for the latest on the monarch's status, with one longtime monarch tracker, Chip Taylor of Monarch Watch, predicting that weather conditions this year are thus far allowing monarchs to rebound somewhat from the historic lows of recent years.

If you google "monarch butterflies" and then click on "news", you'll find lots of articles, for instance about efforts to create better habitat for them in Iowa. There's research on the impact of higher CO2 levels in the atmosphere on monarch's health, and Chip Taylor's detailed blog posts at MonarchWatch describe how higher temperatures can impact migration.

We don't yet have milkweed growing at the garden, but there are patches of common and purple milkweed in clearings near the Veblen House that can provide food for monarch larvae. Places where sun reaches the ground, whether in people's yards or at the Phoenix Garden (so-called because it's planted in the opening made after storms blew down the white pine plantation at Herrontown Woods) are critical for sustaining the summer flowers and milkweed that monarchs need to reproduce.

Wednesday, July 19, 2023

Monarch Butterfly Update -- July, 2023

How many monarch butterflies are people seeing this year? I've seen a grand total of two thus far. Neither paused for a photograph, so this picture is from a past year. 

On July 11, I saw one flying crazily at the Barden. They are expert and often seemingly whimsical flyers, but this one's flight was unusually frenetic. At double the usual pace, it would approach flowers but not land on them, leading me to speculate that it was looking for a mate rather than nectar. A useful Q&A post at JourneyNorth.org suggests that these episodes of particularly erratic flight are induced either by a predator's attack or by a male chasing a female. But the frenetic flight made me instead imagine what it is like for monarchs when their numbers are few, and the search for a mate consumes more and more of their energy. Might a fruitless search at some point become frantic?

A few days later, I saw a monarch in a pasture near Herrontown Woods, flying at a more measured pace. 

There were a few common milkweeds growing in the pasture, but I was particularly happy to discover a couple specimens of green comet milkweed (Asclepias viridiflora), growing there as well. It's a species I've only seen twice in Princeton, the other incidence being a few individuals in the Tusculum grasslands. 

It's common to think that monarchs gain all their sustenance from milkweeds, but in fact the adult butterflies obtain nectar from a broad range of flowers. Otherwise, they would starve after the milkweeds have finished blooming. The caterpillars, however, are highly particular, and will only eat the foliage of milkweeds. The milkweed foliage is around all season long for the munching, though a lot has to happen for the foliage to actually be put to use. A female needs to lay eggs, and those eggs need to elude predation long enough to hatch. I have not seen an actual caterpillar in years, nor much evidence of milkweeds being consumed, but clearly a few are surviving somewhere.

To get a more in-depth report on the status of monarchs, my go-to is the savant Chip Taylor, who blogs at MonarchWatch. In a June 14 post, writing about whether monarchs will be listed as threatened or endangered, Chip Taylor wrote openly about the eventual end of the great monarch butterfly migration. It's believed that the monarch itself is not likely to go extinct, but that the migration--involving the portion of monarchs that participate in the fantastic journey north from the mountains of Mexico up into the U.S. and Canada, then back to Canada in the fall--is increasingly vulnerable. According to Taylor,
"As applied in this case, extinction refers to the loss of the monarch migration and not the species per se. Given the link between the increase in greenhouse gas emissions and increasing temperatures and the world’s slow response to these changes, yes, the monarch migration will eventually be lost."

It's important to note that those who raise alarms about the climate crisis are the optimists. It is optimistic to face up to a grave risk, and call for action to save what will otherwise be lost. Denial and dismissiveness are rooted in pessimism. They take a gloomy view of 1) our capacity to recognize dangers and 2) our capacity to act collectively to prevent catastrophe. Taylor's recognition of the high likelihood that we will lose the migration raises an obvious question, which he hastens to answer.

"If the monarch migration will be lost eventually, why make great efforts to sustain it? Faith. We have to have faith that the world will come to its senses and work collaboratively toward the reduction of greenhouse gases to save the natural systems that sustain us. There is hope. The rate of increase in CO2ppm has declined in recent years."

Another answer is that, the longer the migration can be maintained, the longer humanity has to "come to its senses." 

It is stunning, knowing the extraordinary power of carbon dioxide to influence the earth's climate, that society has left it unregulated. As individuals, cities, and businesses, we remain free to pour as much of it as we please into the atmosphere. Until that giant hole in our regulatory protections is patched, the vast majority of people will not change their behavior. 

Tuesday, July 20, 2021

Monarchs and a Mid-Summer Multitude of Wildflowers at the Barden

So, I was at the Barden today, that being the Botanical Art Garden in Herrontown Woods, and amidst all the positive energy of budding flowers I had a cynical thought. There are a couple spots around the Veblen Circle of wildflowers where milkweed has been spreading. Lots of leaves and none of them being eaten by monarch caterpillars--an all too common observation over the years. People say to plant milkweed to help the monarchs, but the monarchs aren't helping themselves to the milkweed. What gives? 

As if on cue, a monarch appeared an instant after I had that thought. Only the third I'd seen this summer, it was checking out the milkweed and other plants growing in the sunny openings of the Barden. There are many kinds of native flowers blooming right now, which I'll show photos of later in this post, but the monarch headed over to one in particular,

a buttonbush, whose tiny flowers form the shape of a golfball--a convenient surface upon which the pollinator can go from flower to flower, sipping nectar. For an insect it must be like an assemblage of Hold the Cone miniature ice cream cones, but no need for a freezer. 

Moments later, another monarch butterfly caught my eye, and this one was showing a more intense interest in the milkweeds. There are two types at the Barden--purple and common. Both kinds spread underground, creating clones with many stems--enough to support a whole gang of hungry caterpillars. The butterfly was landing on the edge of the purple milkweed leaves and dipping its abdomen under the leaf to lay an egg. 
After doing this a number of times, it headed elsewhere, allowing me to take a look. Not easy to see. There, in the lower left. 
Here's an egg a little closer up.

There's actually quite a bit going on underneath a milkweed leaf. Here was a whole cluster, which I'm guessing are the eggs of the milkweed tussock moth--another Lepidoptera that can stomach milkweed's cardiac glycosides. 

Of course, it's a hopeful sign to see a monarch laying those single eggs, but we saw this last year, and it didn't lead to any sightings of caterpillars later on. It's possible the eggs are getting eaten by ants and spiders. A complex food web can have its perils, and it's interesting to note that milkweed that once grew in farm fields (in the days before Roundup-Ready corn and soybeans) might have had better monarch survival due to there being less predators in that simplified landscape. 

Still, we can hope that this is the year when the Barden does its part to build monarch numbers in preparation for their perilous flight back to Mexico in the fall.

Another sweet sight today, again not captured in a photo, was the pair of hummingbirds that landed on a wire cage just five feet away. Hummingbirds, in my experience, actually spend a lot of time perching, which makes sense given how intense is their flight. Their presence was the answer to a question overheard at the checkout counter at the Whole Earth Center: "Has anyone seen any hummingbirds?" Like monarchs, they also have to negotiate a difficult migration every year.

Maybe they were attracted to the tubular flowers of wild bergamot, 

or beebalm, or jewelweed.

What follows here is a documentation of all the flowers seen blooming right now in the Barden, as the midsummer diversity kicks in. After all the work of weeding and planting, there's pleasure in simply walking the paths and appreciating all that is growing so enthusiastically. 


There's a lot to document. These signs, created by Inge Regan, offer four species to look for. When learning plants, it's good to focus on a few at a time. 

For those more familiar, we've brought together some 40 species that bloom in mid-summer, some of them shown below. Maybe you can walk the pathways and see how many you can find. We're trying to figure out how to pot up all the excess and make them available to visitors to take home.

To see some of the other species showing their stuff this time of year, click on "read more", below.

Monday, September 13, 2010

Growing Monarchs

How does a kid end up with a beautiful monarch butterfly on her finger?

It helps to have a wildflower garden in the backyard, or to have scoped out a patch of milkweed elsewhere in town. This backyard garden is planted with pickerelweed, Joe-Pye-Weed, boneset, and many other native wildflowers.

Most importantly for the monarchs, it has lots of swamp milkweed. Monarchs will only lay their eggs on milkweed plants. In Princeton, there are several kinds of native milkweed. Swamp milkweed grows in low, wet places. Butterflyweed, which has beautful orange flowers, grows in sunny meadows. Common milkweed is, not surprisingly, the most common. It's also the biggest, growing to five feet high or more, in fields and floodplains.
A glass fishbowl works well for housing monarch caterpillars. For documentary purposes, a camera, journal, and a cup of coffee for the grownup are handy. The bowl stayed on our kitchen window sill most of the time.

Monarch butterflies visit our garden every year, but in 2007 a female monarch came and left some eggs under the leaves of a swamp milkweed plant. The picture mostly shows a bunch of yellow aphids, which are tiny insects that drink the plant's juices. But at the top of the photo, you can see a tiny monarch caterpillar that has hatched from one of the eggs the monarch left.

My daughters brought this and other little caterpillars inside, and fed them a steady supply of milkweed leaves. The bedding--folded paper towels occasionally moistened--needed to be changed every couple days because of the mess the caterpillars make with all their frass. One time, the caterpillars ran out of food, and one of them crawled down the hall into the family room. It helps to cover the top of the bowl with netting so they don't wander.


When a caterpillar has grown to full size, it will climb one of the sticks, attach itself to the bottom side, and go into a "J" position.


It becomes very still, and overnight transforms itself into a beautiful green chrysalis with gold spots (on the right in the photo). It's really important that the caterpillar find a good spot to hang from, so that when the butterfly emerges, the wings can unfold and dry without bumping into anything.


After a week or so, if you've been keeping an eye on the green chrysalis, you will see it start to change color. Before long, it becomes completely clear, revealing the butterfly that has been developing inside.


There are two monarchs in this photo. The lower one is just starting to emerge from its chrysalis.
Continuing to crawl out of its shell,
the butterfly emerges, wings ready to unfurl.

The monarch continues to cling to the remains of the chrysalis while its wings unfold and dry. This is a very delicate process, and any disturbance at this point risks deforming the wings.
When the wings have unfolded and dried completely, the butterfly is ready to crawl up and out of the bowl,


and take wing. From this backyard, the butterflies will head south to a mountain in Mexico, where they'll spend the winter clinging to trees on little more than five acres in a special forest.

This miraculous journey is threatened. Logging is reducing the size of the forest where they overwinter. And as we continue to use fossil fuels, changes in climate leave the monarchs increasingly vulnerable to freak storms and other weather extremes.








Sunday, November 24, 2024

Whither the Migration of Monarch Butterflies?

Though the number of butterflies in general was radically down this summer, I still saw the occasional monarch. Some appeared frantic. Were they searching in vain for a mate? Other times they'd pause on a flower to take a long drink of nectar. Sometimes I'd just see a flash of orange out of the corner of my eye. No other butterfly can match a monarch's nimble power in flight. The number of sightings, maybe ten in all, wasn't much changed from previous years.

Their longterm prospects, though, are very much in question. Chip Taylor, who has tracked migrations as closely and for as long as anyone, says that monarchs as a species will survive, but their fabulous migration will not. Last year's overwintering numbers on Oyamel fir trees in the mountains of Mexico was the second lowest ever recorded. Resilient as the monarchs are, it's hard to imagine the delicate dynamic of migration surviving the rapidly increasing disruptions of climate change.

Yes, climate has changed in the past. It's said that, before humans started altering the atmosphere, the earth experienced a progression of ice ages every 100,000 years or so. During the last ice age, glaciers extended south almost to what is now NY City. What we have now is much faster change, as our machines pour a massive overdose of carbon dioxide into the atmosphere.

In a blog entry this past August, Taylor explained how extremes of weather can affect the monarchs' capacity to build numbers over the summer and migrate back to Mexico in the fall. Extended heavy rains in early summer can delay egg laying. Warmer temperatures in September and drought in October can impede a fall migration historically aided by cool winds out of the north. What we got this year was hot and dry, with three months of drought and warm weather extending into mid-November. That's a radical departure from anything I've ever witnessed.

Each year towards the end of October, I start looking for news about the migration south to Mexico. The first headline I found confirmed my suspicions: "This fall's monarch butterfly migration through Texas doesn't look promising." Then, finally, a report on-site at the roosting grounds in Mexico. Though a few had been straggling in over the past few weeks, the first largish group of 2000 monarchs wasn't reported until Nov. 21. In past years, monarchs would predictably arrive en masse in the first week of November. Then, after the monarchs had settled into their roosts, the Biosphere Reserve would be opened to tourists mid-month. This year that opening was cancelled, stranding those tourists who had traveled far to witness a unique example of nature's splendor. This is not the only destination being compromised in a world being heated in part by global tourism. There are different ways to show love for nature. Touristic love, which I was a part of in the past, becomes more ironic by the minute.

The radically dry, warm weather we've experience this fall has a lot to do with the increasing instability of the jet stream--high winds out of the west that normally feed us a steady stream of contrasting weather, but can get blocked and diverted north or south, causing weather systems to linger indefinitely. The jet stream is driven by the difference in temperature between the tropics and the arctic. As the arctic heats more quickly than lower latitudes, the temperature gradient is reduced and the jet stream becomes more malleable. 

Consider the extraordinary ambition and brilliance of the monarch butterfly's eastern migration. Huddled overwinter in the mountains of Mexico, its numbers head north in March, then each succeeding generation--usually four total--fans out from Texas to harvest the richness of flowers and milkweed foliage from the whole eastern half of the U.S. and even up into Canada, before somehow knowing how to navigate all of that embodied richness back to their little hideout in Mexico. Over the past million years, the distance flown would have contracted during ice ages, then expanded as the glaciers withdrew. I think of the monarch migration as akin to a rubber band, stretched northward by the supply of nectar and milkweed, then contracting back down to Mexico for the winter.

The vast territorial expansion each summer is surely dependent on numbers. Otherwise, how will the monarchs find each other to mate as they spread out across the continent? Though much different in behavior, the passenger pigeon was also dependent on big numbers. Its demise, more than a century ago, was due to radical habitat change and a wanton harvest and slaughter that Aldo Leopold described as "trigger-itch." Now, our itch is to take photos, and our intention is to preserve. And yet, we watch as the collateral damage of a machine-driven economy accumulates.

A post on the Monarch Watch Blog describes the Symbolic Monarch Migration that school kids in Mexico, the U.S., and Canada take part in. Kids in Mexico send paper monarchs to kids up north in the spring, and vice versa in the fall. Monarchs ignore country boundaries. They are telling anyone who takes time to listen that our interests don't stop at the border, what we do affects people and nature far away. 

One halcyon autumn day when I was a kid, walking across the broad lawns surrounding Yerkes Observatory in Wisconsin, I was astonished by the sight of countless thousands of monarchs flying above me. There was a thrilling collective energy to their flight, not dutifully unidirectional towards the south but instead more like a dance. They seemed to feed off of each other's proximity and energy--an uncanny mix of whimsy, skill, and determination. 

If the great migration were to be lost, monarchs would still persist in pockets further south. Here's a post on how the loss of migration's rigors would change them.

Thursday, August 14, 2014

Searching for Monarchs in Princeton


The monarch butterfly, as most people know, is in trouble, due in part to a radical decimation of milkweed on more than one hundred million acres of farmland in the U.S. in recent years. Thus far this summer, I had seen a grand total of two monarchs, one having visited the raingarden in my front yard on Harrison Street. Another raingarden on Harrison Street, at the Spruce Circle senior housing, had just been bulldozed while in full flower.

With that traumatic step backwards in mind, I set out yesterday on my bike to check out a few spots elsewhere in Princeton. If a monarch were to travel around town at about the speed of a bike, wings warmed by the sun after a recent rain, would it find any prospective mates?

First stop was the meadow at the corner of Mountain Ave and the Great Road. The Joe-Pye-Weed was blooming as it does every year, but no monarchs to be seen.


Then a ride up the Great Road to Farmview Fields, where I had hooked the town up with Partners for Fish and Wildlife--a federal agency--to plant a meadow of warm-season native grasses in a stormwater detention basin that had previously been mowed as turf. More habitat, less mowing. Everyone was happy. I had added some native wildflowers, and others had seeded in. When I checked last year it was doing great. Yesterday, however, I was surprised to find the grasses stunted and the wildflowers gone. It hadn't been bulldozed, but something's wrong with the mowing regime, which should be just once a year during the dormant season.

Again, there's a sign that should signal that this is a special area, requiring a different management.

The heavy equipment had left some patches of ground scarred and bare. Mowing crews are so used to mowing these detention basins elsewhere that they may have started regularly mowing this one, out of habit. I had a job mowing a golf course one summer. It's not the kind of work that encourages thinking outside the box.

An unmowed area nearby showed what the basin should have looked like, with the "turkey feet" of big bluestem rising to the sky.

There was a swallowtail butterfly sampling the basin's meagre offerings, but still no monarchs.

Back down the Great Road to the opening in the fence, near Pretty Brook Rd, to take the boardwalk across the bottom of Coventry Farm over to Mountain Lakes. Lots of common milkweed in the field, but no signs of their being munched on by monarch caterpillars.

Finally, along the boardwalk near a big wet meadow of ironweed (the hydrologic conditions a raingarden imitates), I saw a lone monarch, flying about but not landing. As the monarch numbers have dwindled since the 1990's, the question arises, how do they find each other? They start each year in a small enclave in the mountains of Mexico, then spread out across vast areas of the U.S. and Canada. This migration, with one generation succeeding another as they move northward, is predicated on having sufficient numbers for individuals to find each other and mate. The lone monarch and the uneaten milkweeds offered little reason for optimism.

At Mountain Lakes House, a popular place for weddings and other gatherings, and also home base for Friends of Princeton Open Space, the raingarden I designed was prospering.

Lots of color there,


and in another rain garden in the driveway, but no monarchs to be seen.

There was still one spot to look, though, in the fields of Tusculum, preserved by Friends of Princeton Open Space and others, and packed with milkweed. To get there meant maneuvering through the now tattered evergreen forest of Community Park North. High winds in recent years have knocked down most of the pines and spruce, which really aren't natural to this area but had provided a deep forest feel that was enjoyable to walk through. Now, fallen trees have opened up the canopy, energizing an understory of invasive stiltgrass and honeysuckle.

Some trails are lined by young ash trees that will likely be attacked by the emerald ash borer when it reaches Princeton. This strangest of woods was not feeding optimism either.

The fields of Tusculum also looked different than in past years, perhaps again due to a mowing regime that might not be the best for wildlife habitat. Mountain mint, once a common wildflower there, was nowhere to be seen. And no monarchs.

But then, near Cherry Hill Road, next to a purple patch of tick trefoil and Indian grass,

monarchs, a pair, mating!

They flew over into the meadow to continue. Part naturalist, part voyeur, I lingered, wishing to document how long such pivotal acts take. It became clear that this was no brief rendezvous, so I moved on,

to the next field over, where common milkweed sprawled over more than an acre.  And there, another monarch, showing off its brilliant, speedy flight, ducking in and out among the milkweeds, as if in a hurry yet undecided as to where to land. It did land a few times, briefly, perhaps to lay an egg? I checked the undersides of leaves, but it was hard to tell from a distance where it had landed.

I biked home more hopeful than two hours prior. Those monarchs were starting the last generation of the year, the one that will fly all the way back to Mexico. On the way back, I passed the Princeton High School's detention basin just north of the performing arts center on Walnut Street. Now wouldn't that be a fine gesture, an act of generosity and belief in the future, if the school were to turn that empty, unused basin into a monarch meadow.