Butterflies will blow your mind: A new Giant Screen Theatre film gives viewers new respect for migrating Monarchs

If you — like me — have long thought of butterflies as delicate, simple creatures, you have been sorely mistaken.

A new Giant Screen Theatre film, Flight of the Butterflies, opens tomorrow and frames familiar Monarch butterflies in a new light as masters of migration. The film follows the life’s work of Dr. Fred Urquhart and his wife in stunning 3D as they tag and track the migratory patterns of Monarch butterflies. After 40 years of tracking and thanks to the  help of thousands of citizen scientists, the Urquharts were finally able to unlock the mystery of Monarch migration and identify their winter gathering place in remote mountaintops of Mexico.

Flight of the ButterfliesAnd it’s not just the visual spectacle that’s stunning. Did you know that a super-butterfly is born every third generation that lives longer and flies farther than its predecessors? Or that this Super Generation that makes the extended trek from Canada all the way to Mexico can fly as much as mile up in the air, catching rides on the wind? It challenges your perception of butterflies as erratic, delicate things, that’s for sure. They’re marksmen; weathering one of the longest migrations on earth to target an isolated mountaintop they’ve never even seen with incredible accuracy. Even our great state of Texas is featured, in all its bluebonnet-blanketed glory.

Make it a butterfly-filled weekend with the Semi-Annual Plant Sale and you can even establish a garden to help these guys along! For a schedule of showings, click here.

Tagging Monarchs at HMNS

Today Soni (CBC horticulturist) came down to my office and said “You should see all the monarchs in the outdoor butterfly garden. They must be part of the fall migration. Why don’t we tag them?”’

Surely by now most people are aware of the amazing migration undertaken each year by the fall generation of monarch butterflies. As the temperatures cool and the days shorten, monarchs emerging from their chrysalids are cued to head south. Somehow they “know” that their survival depends on it. Before winter sets in, millions of individuals – basically the entire eastern population – start to fly southwest, towards the remote mountain sites in central Mexico where they will spend the winter hanging on the branches of fir and pine trees.

Soni and net
Soni netting butterflies

The spring and summer generations behave very differently. After emerging from its chrysalis, one of the first things a new butterfly typically does is look for a mate (“nature abhors a virgin” as my friend Phil DeVries would say). Mated females search for milkweed plants on which to deposit their eggs; males look for more females! These fair-weather generations probably live for a month or so as adults. The autumn generation, however, does not mate, but saves its energy for the long journey ahead. As fall approaches, butterflies stock up on nectar, packing on fat for the flight and for several months of hibernation.

At the northern edge of the population (southern Ontario/northern Great Lakes area), the migration starts in late August, with butterflies flying on average about 50 miles a day and picking up more migrants as they travel south. By early to mid October, monarchs are streaming through Texas. Virtually the entire eastern population passes through our state – but most of the migrating butterflies pass to the west of us, through Dallas and Austin and San Antonio, then over to Del Rio and into Mexico. Since fewer butterflies typically pass this way, the coastal migration route is not as well known. All the more reason for us to get out there and tag!

monarch tag
How to tag a monarch

Monarch researchers began tagging monarchs back in the early 70s, even before anyone knew where the migrating monarchs were ending up (the roost locations were discovered in 1975). Tagging data collected over the years has enabled us to map the distribution of the population, and to understand that a single generation makes the long trip south and then heads north again after spending the winter, largely dormant, in Mexico. This is hard for some people to understand, especially given that most butterflies only live for a few weeks. The migrating/hibernating monarchs may live as long as eight or nine months.

tag instructions
Tagging instructions from Monarch Watch

The monarchs’ arrival at the overwintering grounds typically coincides with Dia de los Muertos (November 1, Day of the Dead), an important fall festival in Mexico. Some locals apparently see the orange and black visitors as the spirits of their dear departed relatives, returning to celebrate the day. This is not as far-fetched as it may seem; throughout history humans have used butterflies as symbols of the soul and/or reincarnation. Did you know that the word “pysche” in ancient Greek meant both “butterfly” and “soul”?

But back to the present, and Houston. It was a beautiful afternoon so we all trooped outside, armed with nets, pens, data sheets, and numbered tags purchased in advance from Monarch Watch, a non-profit organization based at the University of Kansas that coordinates monitoring efforts. Soni also took a roll of scotch tape and some microscope slides. She is checking the butterflies for OE (short for Ophryocystis elektroscirrha), a sporozoan parasite. If present, the parasite spores can be seen under a compound microscope (they are much smaller than butterfly scales). If there are enough of them in a caterpillar’s body, these parasites can spell death for the butterfly. Luckily, parasite loads are typically low in migrating individuals – perhaps butterflies weakened by the parasites simply can’t make the long journey.

OEtest
Taking scale sample for OE test

Lots of monarchs were coming around the corner of the Butterfly Center, dipping down to our outdoor butterfly garden and stopping to sip nectar from the blooms (they especially seemed to like wheat celosia and purple porter weed). Then they’d head off towards the Sam Houston statue and on in the direction of Rice University (southwest of us!). We caught 11 butterflies in the garden (and missed many more), tagged them (noting whether male or female), took a scale sample, and released them. Off they flew!

We’ll send in our data to Monarch Watch, and of course we hope that someone will find one or more of our tagged butterflies on the roost in Mexico. It is highly unlikely – given the millions of monarchs at the roost – but tagged butterflies (usually dead ones) do get found and reported. If one of ours is found, Monarch Watch will contact us – and they/we will know that butterflies do migrate to Mexico from our area.

tag team
Tag team

Local butterfly gardeners know that a number of monarchs stay in Houston over the winter. We often don’t have killing freezes here, and the recent craze in butterfly gardening means that there is lots of Mexican Milkweed aka Butterfly Weed around.  This plant, Asclepias curassavica, is a perennial from Central America; unlike our native milkweeds, it does not die back in the winter months. Also, predatory wasps, which take many caterpillars during the summer, are mostly gone – so if it doesn’t get too cold, Houston is a good place for monarchs to spend the winter. However, these butterflies are taking the risk of dying should we have a strong cold snap as we did last year.

Here are two great websites with information about these amazing butterflies and about how to get involved monitoring their migration: Monarch Watch at www.monarchwatch.org and Journey North at www.learner.org/jnorth/.

Great Migrations – New Series Debuts Sunday on NatGeo

Perhaps one of the most compelling segments of National Geographic Channel’s upcoming “Great Migrations” series is the first one, “Born to Move” (premieres Sunday, November 7 on NGC).  In this segment the need to migrate (move) is ingrained in each featured animal as a means to survival.  Featured species include Christmas Island’s red crab (Gecarcoidea natalis), the far-traveling sperm whale (Physeter catodon), and the monarch butterfly’s (Danaus plexippus) annual journey across North America to a single site in central Mexico.  One of the more heartbreaking sagas involves a young wildebeest (Connochaetas taurinus) calf falling prey to Nile crocodiles (Crocodylus niloticus) as its mother watches on helplessly – nature can indeed be cruel, and unfortunately not every story of life terminates in a rainbow.

“Beastly River Battle”
A tragic and violent scene plays out as wildebeest herds attempt to cross a river teeming with crocs.

The footage brings to mind some components of the Frensley/Graham Hall of African Wildlife, which I helped build here at the Houston Museum of Natural Science. In the Okavango Delta diorama, where the theme is “water is life,” we have a plasma screen featuring natural history aspects of the Nile crocodile, some of which I filmed in Kenya’s Samburu River, including footage of the crocs using their group hunting strategy to predate a large impala (Aepyceros melampus) buck.  There is also other footage of crocs predating adult Thompson’s gazelles (Gazella thomsonii) and wildebeest, which is not as painful to watch as the crocs seizing an innocent calf as the mother looks on.

“Moving in Masses” – A zebra foal and his father catch up with the herd
on its way back to the rich green lands of the delta.

In other parts of the African Wildlife Hall we also feature the quintessential Serengeti migrating hoofed mammals, including plains zebra (Equus burchelli) and wildebeest.  Zebras are grazers that may congregate in great numbers in favorable areas.  The zebra’s pattern may serve two functions.  Firstly, when a herd of zebras are observed by a predator the black and white pattern breaks up the outline of individual animals, making it more difficult to pick out a target.  More recently, it has been discovered that the pattern plays a role in triggering and reinforcing herd behavior in the zebra.  For any given Zebra, being in a herd provides more eyes and ears to detect approaching predators; once those predators strike, it is relatively unlikely for any one zebra that it will be the one to be caught.  These advantages outweigh the disadvantage of having such non-camouflaged coloration.  You can witness the zebra’s migration from Botswana’s lush Okavango Delta to the Kalahari Desert in “Race to Survive” (premieres Sunday, November 14).

Great Migrations
Africa: Every spring in Botswana, hundreds of zebras leave the largest inland delta in the world on
a 150-mile slog into hell – a desert of salt and sand – so that their bodies can take in much-needed
minerals. Their stripes help protect them from predators as long as they stick together – blurring
their lines and making them indistinguishable as individual animals.
(Photo Credit: © John Conrad / CORBIS)

The ‘clown of the Serengeti’ or wildebeest, follows the wax and wane of the grasses that sustain them.  Their short-distance migration numbering in the hundreds of thousands is one of the great nature spectacles of our planet.  Harried by predators and the necessity of seeking fresh grazing grounds, the wildebeest manage to mate and give birth while they travel.  Eighty percent of the wildebeest calves (as many as 20,000) are born within several weeks at the start of the rainy seasons and, within minutes, are able to stand and run, traveling with the herd as they migrate.  The vast numbers of newborn far exceed the predator’s kills.  So even though it is heart-wrenching to watch the croc take the life of the wildebeest calf in “Born to Move,” several thousand will survive the journey.  Wildebeest are a keystone species in their habitat, one that if removed, causes the collapse of the community, which revolves around it.

Great Migrations
Africa: White-bearded wildebeest herd: Every year, more than a million wildebeest and
two hundred thousand zebras must chase the seasonal rains, in a 300-mile loop around
Tanzania and Kenya. (Photo Credit: © Anup Shah)

Overall, birds migrate much further than mammals.  For example, wildebeest in East Africa are famous for their annual migration across the Serengeti, which is actually less than 500 miles.  The Arctic Tern in contrast flies 22,000 miles each year on a route that takes it from the Arctic to Antarctic and back again.  When I think of the title of the segment “Born to Move,” I think of many species of birds that are really capable of moving (migrating) very far distances.  This very aspect is highlighted in the African Wildlife Hall’s Saharan Desert diorama where the theme is “perilous migrations”.

As you can imagine, migration has many challenges; the Saharan desert for example is the greatest single obstacle for birds that migrate back and forth between Europe and sub-Saharan Africa.  Covering most of the northern third of the African continent, it takes a songbird 35 to 40 hours to fly across this vast desert.  Many birds fly the desert at night to avoid the intense heat, but there are many other perils birds must face for which they have no solution in their behavioral bag of tricks: traps set by humans, exotic predators such as house cats in unnatural concentrations, tower and window obstructions, environmental extremes such as drought brought on by global climate change, and destroyed habitat every step of the way.  Indeed, migratory birds in the Americas face many of the same perils.

Great Migrations
Nile crocodile with seized Impala buck (horn protruding from water)
in Kenya’s Samburu River, Ethiopian Biome (photo by Daniel M. Brooks/HMNS)

The birds featured in the “perilous migrations” diorama take advantage of the Northern Hemisphere’s annual explosion of food resources, then head south into Africa as fall approaches.  Such migrations offer the advantage of allowing a bird to remain in ‘food-friendly’ seasons.  Whether crossing the Old World or the Americas, a fundamental challenge for migrants is maintaining energy reserves – if a bird runs out of fuel it will perish.  As a result, habitat loss is the greatest threat worldwide for migrants.  Not only must they have suitable habitat in both their nesting and wintering ranges, but along the path in between as well.  During migration many species will stop to ‘refuel’ even in some of the most unlikely environments, such as the Saharan desert.

Featured in the Saharan desert diorama are two birds with contrasting migratory strategies: the lesser grey shrike (Lanius minor) and the grasshopper warbler (Locustella naevia).  Like many other African birds, the shrike nests far to the north in Europe, necessitating a Sahara crossing during migration until it reaches its wintering grounds in southern Africa.  Then it crosses once more for the return trip to Europe.  The warbler migrates a shorter distance through the Saharan desert to stop in central (rather than southern) Africa each winter.

Great Migrations premieres Sunday, Nov. 7 on National Geographic Channel – tune in to this multi-part series learn more about migrations throughout the world; and come by the Museum to view these fascinating animals up close in the Frensley/Graham Hall of African Wildlife.

Genetics and Archaeology: Helping Us Understand the Past

Recently I came across several examples of how genetic information has greatly helped us understand the past. Quite often this data is gathered in the most unexpected places. Consider these examples.

In an article published in December 2009, an international group of scientists addresses the issue of the extinction of North American megafauna traditionally dated some 11,000 years ago. A skeleton of a woolly mammoth on display in a museum never fails to impress us. At the same time, most of us would agree that it is a good thing we don’t have to worry any more about these lumbering giants messing up our evening commute. However, what most of us stop worrying about is when these animals became extinct and why. Most of us, that is, but not all of us. This is where the story of ancient DNA retrieved from perennially frozen soil comes in.

A traditional approach to estimate when and where a species became extinct has been to map and date the last known survivors. The thinking was that knowing when and where the last specimens lived would automatically clue us in as to why they died out. Is this true, however? Do these last known survivors really represent that last ones left standing? Or did we miss them and make wrong assumptions?

Creative Commons License photo credit: rpongsaj

The party line about woolly mammoths was that they survived on remote islands in the far northern regions of Alaska and Siberia, a region referred to as Beringia. That is now old hat. New genetic data tells us a different story. Mammoths may have survived much longer than originally thought in the Alaskan interior. Scratch 13,000 years ago. Now it looks like woolly mammoths may have survived for an additional 2,600 to 3,700 years in parts of Alaska. Mitochondrial DNA was retrieved from perennially frozen soil near Stevens Village in the Yukon Flat. What we have here then is a suggestion that we can establish the presence of certain animals in a region at a certain time in the past. No bones needed. Just animal DNA left behind in the soil and preserved because of the permanent frozen condition of the dirt.

While the researchers were careful to address any shortcomings of their approach (contamination of the soil, migration of more ancient DNA from lower-lying areas to more recent layers closer to the surface), there will be reactions from other members in the scientific community. This may be frustrating to those among us who like to see “the final answer” to questions like these, this dialogue is part of what science is all about. We will have to see if these new results will stand up to the criticism that will come.

As megafauna slowly disappeared from the North American landscape, human settlers were making their presence felt. I have written about the questions of where these earlier migrants into the Americas may have come from. There is very good evidence that the Paleoindians migrated from parts of Asia.

Research into a disease known as multifocal leukoencephalopathy resulted in the discovery of a virus labeled as the “JC virus.”

It turns out that we all have a copy of this virus residing within us. It is harmless to most of us, unless your immune system is compromised. Geneticists studying this virus found that it was remarkably stable and very rarely mutated into a new variety. Moreover, the strain of the JC virus carried by the Navajo today is nearly identical to that carried by the modern inhabitants of Tokyo. The JC virus bolsters an Asian origin theory for the First Americans.

Beringia - Image courtesy of NASA.

As to how Paleoindians arrived into the Americas, genetics can help us focus that picture as well. If one accepts that the Bering Strait was an ancient migration route – and most people have no problem accepting this – then the issue is: exactly what route did they follow? A coastal route and an interior, overland route, often suggested by archaeologists, now both seem to have been used.

North American mitochondrial DNA, collected from contemporary populations, points to two migration routes. In a paper published Jan. 19, 2009, scientists studied various mitochondrial DNA haplogroups, zooming in on two rare groups. One of these (known as D4h3) is found only along the Pacific coast and is mostly in South America, while the second group (X2a) is restricted to northern North America.

The presence of X2a in North America east of the Rocky Mountains may support the idea of an ice-free corridor between two ice sheets covering Canada and parts of the US. Some of the earliest migrants may have followed that route which would have taken them into the Great Plains, where the glacial corridor would have ended. The presence of D4h3 along the Pacific may represent a coastal migration route.

Woolly mammoths leaving their DNA in the soil, viruses carried by all of us and DNA shared through the mother’s family line all help us refine and refute some of the ideas on how the first immigrants arrived in the Americas. I am sure genetics will continue to add to our understanding of this momentous period in human history. Stay tuned.