While packrafting the southeastern edge of the Northern Patagonia Ice Field along Chile’s largest river, the Baker, in search of primitive crane flies, Anand Varma and I came across an exciting find.
In a fragmented location only accessible via water, among a lichened-covered forest, we discovered a single wing of the genus Neoderus adhered to the underside of a leaf, between the Northern and Southern Ice Fields. Yes, a single wing is a fantastic find when it comes to primitive crane flies.
Most likely you have never heard of them and that is because primitive crane flies are considered to be one of the rarest groups of flies in the world and only a handful of people have been able to collect them. With only one specimen ever collected in the late 1800s in the southern Chilean fjords, the genus Neoderus can be considered the rarest of all primitive crane flies.
During my last expedition in 2015 I secured four flies, the first and only specimens collected of this genus since its discovery.
stacked image of a Female neoderus sp. hanging on a Nothofagus sp. twig. Photo by R. Isaí MAdriz
With colder temperatures marking the last chance this year to find this rare group, I set off once again to complete what Anand and I started. I decided to target the locality where I found a lone wing two years prior. I loaded my backpack, took my hiking poles (or as my collaborators call them, “my gimpy sticks”, due to the frequency of my ankle injuries) and limped into one of the most pristine creeks I have seen. After a 1100ft climb and bushwhacking across dense forest I arrived to the location.
Upon arrival I removed my hiking boots and proceeded to relieve my ankle pain in the glacial creek. Soon after, I unpacked my 60+lb backpack and identified the perfect configuration for my tree tent, which was strategically located near the creek 6ft above the ground. Below my tent, I set up my “field laboratory” consisting of a stereomicroscope from the early 1980s with generic USB lights secured by duct tape and powered via rechargeable solar battery. This arrangement allows me to collect aquatic insects and immediately identify any promising specimen under high magnification. The dream camp set up of any insect-loving seven-year-old!
Not only does my tree tent provide a dry refuge from sudden rainfall, characteristic to this area, but it is also the perfect barrier from the numerous avian intestinal discharges I am constantly being bombarded with by territorial birds.
With sunset approaching, I decided to have something to eat. I packed all the necessary gear for this short expedition but managed to forget food.
Loose in one of my backpack’s hipbelt pockets, I found a handful of stale trail mix (from sometime since September) and a piece of chocolate.
Lack of aesthetically pleasing or “proper” camping food, seem to be a trend for this site. A couple of years ago, my food bag punctured and got wet while reaching this exact location, leaving me to consume lukewarm soft cheese, soggy bread and broken crackers accidentally blended into a paste-like consistency. Read more about this particular story here.
This time was no different. As I searched the creek looking for the unknown larvae of Neoderus and other aquatic insects, I intentionally separated the largest common stoneflies. I later proceeded to make my “back-country specialty” of au naturel stonefly and stale raisin kebabs on endemic southern beech twigs, complemented with all-you-can-drink glacial melts. A true delight! My other options were: 1) No food or 2) Soggy almonds and common black fly larvae, but the latter are quite slimy and a last resort among the edible insect choices on my list.
With hunger “satisfied”, I set up my blacklight a few feet away from the stream. While waiting for insects to be attracted to the light reflected on a white sheet, I set off into the dark forest in true nerd-like fashion with my rain pants synched up to my mid abdomen, my cuffs tucked into my socks and sporting my night vision goggles in search of nocturnal six-legged gems.
stacked image of a female Neoderus sp. resting on Nothofagus sp. twigs. Photo by R. Isaí MAdriz
Throughout the night, the UV light attracted all sorts of insects, including Darwin’s beetles, half-inch-long parasitic wasps, caddisflies, moths and many midges. Alas, no Primitive Crane Flies.
Soon after midnight, rain drove away most of the insects and continued to pour until mid-morning. With sunrise approaching and a sufficient few hours of sleep, I climbed out of bed, ate a forgotten stonefly still in the “food” container and the piece of chocolate for breakfast, put on my rain gear and limped across the forest in search of the insect I came for.
After wadding through the creek for a couple of hours with no success, I decided to direct my attention to the numerous fallen trees around the forest. Interestingly, a large decaying tree still hangs 8ft high over the creek. Underneath, a Neoderus female. After squealing like a piglet for some time, I proceeded to secure the specimen. Crane flies in general are well known among taxonomists to lose or detach their legs at will. This particular female had all six legs still attached, making it the only pristine specimen in the world.
With my precious find, I headed straight back to camp. Once there, I frantically packed it all up and awkwardly limped back to my vehicle a few miles away, all the while juggling the specimen, my heavy backpack and my “gimpy sticks”.
I drove eight hours back to my headquarters and proceeded to photograph the female. After a long and continuous photography session of 48hours the female finally died, but not before yielding the photographs above. These, along with one poor quality image from 2015, are the only photographs of a live Neoderus in existence. A true reminder of the biological jewels awaiting discovery in the vicinities of the Patagonia Ice Fields.
R. Isaí Madriz identifying aquatic insects in the field. PHOTO BY R. ISAÍ MADRIZ
*The Neoderus specimen in the photographs above belongs to a new species of primitive crane fly. A scientific (peer reviewed) publication is in process to formally describe this species.
For close to two weeks, we will discuss the many threats to the world’s wildlife and habitats, from tropical rainforests to the world’s ocean. Our planet is in the midst of an extensive, well-documented biodiversity crisis. We see a loss of species, habitats, and ecosystems critical to our planet’s health, and to the well-being of all of us—including to Indigenous Peoples and local communities that are directly dependent on healthy ecosystems for their very survival.
A tiger in the Sundarbans mangrove forest. Photo credit: Rubaiyat Mansur Mowgli/WCS.
Recent scientific reports have shown that the extent of terrestrial and marine ecosystems that can be still be considered intact and ecologically functional is dwindling. Threats across the globe today are massive, and include habitat loss and devastation, illegal killing of wildlife and wildlife trafficking, illegal and unsustainable fishing, illegal and unsustainable timber trade, harmful development projects, climate change, and so much more.
The images of devastated landscapes devoid of their natural biodiversity, vast industrial-scale monoculture for commercial agriculture, and largely empty seas are becoming all too familiar and all too dominant. The consequences for biodiversity are clear: ever increasing numbers of species facing extinction and the degradation of the critical ecosystem services that underpin the very health of our planet and our own well-being.
In short, we are moving from a serious erosion of biodiversity to a serious ecological crisis that will impact all of us. And yet how many people know about this conference in Egypt? Or that between this meeting and the next conference in Beijing in 2020, the world will adopt new targets to set the course of biodiversity conservation for the next decade and beyond? But even as we endeavor to expand the constituency for this critical work, we cannot wait to take action.
The expansion of humanity’s footprint both on land and in the sea is staggering and ever-increasing. Photo credit: Julie Larsen Maher/WCS.
More than anything, all of the governments here in Egypt must work and commit to save the Earth’s last intact places: the remaining boreal forests of Canada and Russia; the remaining tropical forests of Central Africa and the Amazon Basin; the remaining grasslands of Central Asia; and the remaining healthy coral reefs found in the tropical belt around the world to identify just some of the most critical biodiversity strongholds.
Just as urgently, we must secure the intact ecosystems and corridors between these place that are so critical for the maintenance of healthy, thriving populations of jaguars, elephants, tigers, sea turtles, parrots, whales, and so many other species threatened by the actions of people.
These intact forests, grasslands, coral reefs, and other intact landscapes and seascapes must be prioritized for many reasons, including because they are the most resilient to the impacts of climate change and increasing development pressures, and offer some of the greatest potential for protecting biological diversity for future generations.
Threats across the globe today include the illegal killing and trafficking of wildlife such as the pangolin. Photo credit: Lucie Escouflaire/WCS
I am excited to be here in Egypt to work through these issues with government officials from around the world, as well as other conservation organizations, indigenous peoples and local community representatives, and so many more. But I am very worried. This treaty, like all treaties, is made up of governments, and they are the ones making the decisions on behalf of all of the inhabitants of our beautiful and fragile planet—the only one we have.
Will the governments of the world talk but not act, show complacency, support business-as-usual, and squabble over minutiae? Or will they be ambitious and bold, and show true leadership and commitment to the future of a healthy planet? Will we be able to look back on this meeting as a watershed moment, when the governments of the world, through the CBD, truly committed to real conservation action, and to saving the magnificent, intact places on earth, for all of us?
Our children and future generations will ultimately be the judge, and they need our commitment, action, and leadership more than ever.
—————————————— Susan Liebermanis Vice President for International Policy at WCS (Wildlife Conservation Society).
A yellow-crowned night heron stalks fiddler crabs in a salt marsh near Norfolk, Virginia.(Photograph: Bryan Watts)
Thalia, it’s called, this upscale neighborhood in Virginia Beach that’s lined with red brick ranches shaded by tall loblolly pines. The community is a few short miles from the mouth of Chesapeake Bay and the Atlantic Ocean beyond. Bounded on the west by Thalia Creek and on the north by the eastern branch of the Lynnhaven River, Thalia is a magnet for human homeowners seeking proximity to water.
It’s also become prime real estate for salt marsh-loving yellow-crowned night herons.
Yellow-crowned night heron in Norfolk, Virginia, just after arriving for the nesting season. (Photograph: Bryan Watts)
Herons in the ‘hood
Like other waterfront spots in the Virginia Beach-Newport News region, “almost every house here has a yellow-crowned night heron nest in its loblolly pines,” says Bryan Watts, director of the Center for Conservation Biology, an organization under the aegis of the College of William & Mary in Williamsburg and Virginia Commonwealth University in Richmond.
Watts is in the midst of a breeding season census of the herons. The resulting data are the linchpin in a study of the herons’ response to the earlier start of spring. The project runs from 2015 through 2018, “but it really began more than 50 years ago,” says Watts, “with the work of the former first lady of Virginia, the late Constance DuPont Darden [1904-2002], who recorded yellow-crowneds’ comings and goings for more than a decade. She left behind an amazing data set on these birds.” Watts is comparing his observations with Darden’s.
Spring is coming sooner not only to the Virginia coast, but to the entire North American Coastal Plain, a region that stretches along the sea’s edge from Texas to Massachusetts. The North Atlantic Coastal Plain was recently named the world’s 36th biodiversity hotspot.
In one corner of that hotspot, Virginia Beach’s Thalia, the loblollies shoot skyward, shading houses – and yellow-crowned night heron nests. “In full nuptial display, the yellow-crowned night heron is one of the most exquisite of all North American wading birds,” wrote A. Sprunt, Jr., in a 1954 edition of Florida Birdlife. “Its soft grays and white crown and cheek patches seem to typify the elfin character of the cypress gloom.”
Although no cypress trees loom over Thalia, the loblolly canopy has the same darkening effect. As Watts states in a chapter on yellow-crowned night herons in the 2011 publication The Birds of North America, “Although occasionally breeding on coastal islands, this species most often inhabits forested wetlands, swamps and bayous of the deep south where poor lighting seems to be the most reliable characteristic.”
Thalia and other neighborhoods in Norfolk host families of yellow-crowned night herons. (Photograph: Bryan Watts)
Homeowners, human and avian
“Poor lighting” couldn’t be more welcome. It’s 7 a.m. in late July, and already temperatures are in the 90s. Watts and I make a loop around Thalia in his truck. We easily find heron nests. The splatters of whitewash below give them away. With more than 30 nests, Thalia boasts the largest colony of yellow-crowned night herons in Virginia.
Some Thalia residents take issue with the herons’ presence “due to the ‘fouling’ of roofs and anything else that’s below the nests,” says Watts, “but most enjoy watching the birds raise their young.”
Yellow-crowned night herons frequently build nests in wooded neighborhoods with parklike appearances and open understories such as those beneath loblolly pines. In Virginia, colonies in residential areas make up more than 80 percent of the yellow-crowned night heron population.
“Pairs seem to prefer to set up housekeeping over rooftops, driveways and roads,” says Watts, leading to some interesting bird-human interactions. Cars parked beneath nests, for example, may be covered with shells from the birds’ fiddler crab meals.
A heron nest is usually placed away from a tree trunk on the outermost fork of a limb. I look straight up at a bundle of sticks above the corner of Dale and Thalia Roads and wonder why it doesn’t come crashing down. The nest’s three young herons, their bodies still more fuzz than feather, seem oblivious to the 50-foot plunge awaiting the merest misstep.
Flimsy as it is, the same “structure” may be used for years. Nests may last an indefinite period without maintenance. “The human houses should be as lucky,” quips Watts.
A parent bird does some nest remodeling, adding a stick here, a branch there. (Photograph: Bryan Watts)
Early arrival of spring – and herons
In 2015, the first year of Watts’ study, yellow-crowned night herons arrived and laid eggs more than 20 days earlier than pairs Darden recorded in the same area in the 1960s. In 2016 and 2017, the trend continued. Each year, the herons arrived and laid eggs a full week earlier, on average, than in 2015. Watts is analyzing this year’s data; the direction, he says, is likely to be the same.
What’s driving the change? There’s a clue in the Thalia neighborhood’s location.
Once upon a time, the locals say, Thalia was “swampland.” Indeed, the marsh plant Thalia, a genus of six species found in aquatic habitats from Illinois to Argentina, may have given the area its name.
A male mud fiddler crab defends his salt marsh territory. (Photograph: Bart Paxton)
Lure of the fiddler crab
Today the mucky marshlands that surround Thalia are home to fiddler crabs that roam over the mudflats, the males waving large claws in a fiddling motion to attract mates, keep intruders at bay or ward off predators. Fiddler crabs live in burrows in the mud, moving onto the flats to find food – bits of algae or decaying marsh plants – when the tide is low. In winter, fiddlers stay deep below the frost line in mud-covered burrows, then in spring emerge by the thousands….
…to the sight of yellow-crowned night heron legs slowly stalking them across the mudflats.
All yellow-crowned night herons are crab-eaters first and foremost, feasting on crabs adapted to their specific locales.
Along the Atlantic Coast, says Watts, “the life of a yellow-crowned night heron is spent in pursuit of one thing: fiddler crabs.” The birds’ hunting times are scheduled at low tide when the crabs are accessible. The herons stalk fiddlers in salt marshes, “running them down on the mudflats,” says Watts. “Females gorge on fiddlers for energy to produce eggs, and breeding pairs feed the crabs to their young.”
The yellow-crowned night heron is primarily an equatorial species, “with four of the five living forms confined to tropical latitudes,” Watts says. The Virginia yellow-crowneds are in the group that migrates north and south with the warm weather each year. The herons’ return in spring is tuned to their crab prey.
When the thermometer rises above 59 degrees Fahrenheit, fiddlers emerge from their burrows and scuttle across the mudflats. “The date in spring when the temperature passes that 59-degree threshold is getting earlier,” says Watts, “extending the season of fiddler availability. Yellow-crowneds appear to be adjusting to the shift in season.
“We have no idea, however, how the birds are aware when the fiddlers are coming out. It’s a total mystery.”
Yellow-crowned night herons “live for crabs,” scientists say. (Photograph: Bryan Watts)
Yellow-crowned night herons are so crab-dependent that more northerly populations, including herons in the Virginia Beach area, depart in the fall when fiddlers return to their burrows for the winter. That happens when the temperature drops below the 59-degree threshold. Then the herons fly to subtropical and tropical latitudes where crabs are active year-round.
For reasons that aren’t clear, yellow-crowneds extended their range northward in about 1925. Although the expansion seems to have leveled off in 1960, the yellow-crowned night heron is rated a species of Least Concern by the International Union for Conservation of Nature (IUCN).
Could climate change affect the herons and their prey enough to change that designation? It’s too early to tell, Watts says.
One indication: where crab populations are faring well, yellow-crowned night herons may be, too.
In the 1980s, Watts and colleagues conducted a study of Virginia yellow-crowneds’ preferred meals. The scientists collected and identified more than 2,000 crab claws under nests, and found that three species – the mud fiddler, red-jointed fiddler and white-fingered mud crab – made up 94 percent of the herons’ diet. The sand fiddler, ghost crab, blue crab, mole crab, toad crab and common mud crab accounted for the other six percent.
There must be a fiddler crab here somewhere. A yellow-crowned night heron waits for an unwary crab. (Photograph: Bryan Watts)
Doyenne of the night herons
The crabs are found in the shallows of salt marshes and mudflats, a fact well-known to Constance Darden. She was passionate about yellow-crowned night herons and their prey. A keen observer of the herons’ habits, Darden kept detailed records in the 1940s and again in the 1960s of their spring arrivals and fall departures in the Norfolk area. She wondered whether the birds might be arriving earlier each spring, and leaving later each fall.
Darden carefully watched the herons from her Norfolk residence in Algonquin Park along Crab Creek, a tributary of the Lafayette River. In 1946, the first yellow-crowned nest appeared on her property. Later, a colony of the birds nested there.
For Connie, as she was known, the heronry became the site of hundreds of hours of birdwatching.
Leftovers from yellow-crowned night heron meals collect beneath the birds’ nests. (Photograph: Bryan Watts)
Basis for new research
Darden’s careful recording of the birds’ habits gave Watts the basis for his current study. “Her invaluable dataset is now housed at the Center for Conservation Biology,” he says.
In the May-June, 1947, issue of The Raven, the journal of the Virginia Society of Ornithology, Darden wrote that “this heron remains in our coastal section from late March to early October. The first nest known to us was found in our yard in Norfolk in a [loblolly] pine tree a few paces from our porch.”
Another nest, noted Darden, “was found in my neighbor’s yard, which embraces the small growth of pines bordering a cove of Crab Creek. This creek is well-named, for it contains an abundance of swimming and fiddler crabs, the latter making up a large part of the diet of these herons.”
The late ornithologist Witmer Stone of the Academy of Natural Sciences in Philadelphia discovered that a quart of fiddler crab shells was often found beneath a yellow-crowned nest. But Darden made her own deductions. “My guess would be that at least three times that amount lay under our tree,” she reported.
Soon after, Darden left Norfolk for more than a decade. She returned in the early 1960s and picked up her story of the herons. Throughout the 1960s, Darden kept careful track of yellow-crowneds’ comings and goings.
“In closing,” she wrote in The Raven, “I shall report what I saw the afternoon of October 17th, 1960. A number of constant ‘quock’ cries brought me running out on our point. Several yellow-crowned night herons were circling the water round and round and one or two more joined them until there were six adult and two immature birds in the group. A laughing gull chased one of the birds and it flew into the marsh, but the others left together heading down the creek to the south. Apparently the start of fall migration.”
More than 50 years later, Bryan Watts hopes to answer Darden’s long-standing questions. The clues, he says, are buried in the muck.
Crab vs. heron: which will win? (Photograph: NPS)
Versions of this article appear in BirdWatching and Oceanography magazines.
Hundreds of canvasback ducks flock to open water on a cold winter morning on Chesapeake Bay. (Photograph: Paul Bramble)
“They came back,” says biologist Donald Webster. “This year.” His voice has a wistful note, wondering if the king of ducks, as the beautiful, crimson-headed canvasback is known, will return to rule Chesapeake Bay again next winter.
In parka, gloves and hat, Webster, waterfowl coordinator for the Maryland Department of Natural Resources (DNR), raises his binoculars near a seawall that runs along the Choptank River near Cambridge, Maryland. The lookout where the Choptank meets the Chesapeake is a mecca for wintering canvasbacks and other ducks.
“Canvasbacks, the waterfowl everyone comes to see, are usually here by Christmas, sometimes by Thanksgiving,” Webster says. “They stay through March, then they’re gone, heading north to nesting grounds.”
Canvasbacks form large groups in winter, especially in areas near food sources. Here, on Chesapeake Bay. (Photograph: Paul Bramble)
Skeins of waterfowl
On this early March morning with calm winds and temperatures that hover around freezing, the canvasbacks’ red heads stand out against winter-dark waters. The ducks glide near the seawall, where a dozen photographers jostle for a quintessential shot of an iconic Chesapeake duck. “This spot is known as the ‘wall of shame,’” laughs Webster, “because it’s almost too easy to get great waterfowl pictures here.”
Chesapeake skies fill with ducks – canvasbacks, buffleheads, greater and lesser scaup, and many others – from December through March. The bay is the Atlantic Coast’s most important waterfowl migration and wintering area. The Chesapeake and its 19 major tributaries, including the Patuxent and Potomac rivers, provide winter habitat for 24 species of ducks as well as Canada geese, greater snow geese and tundra swans on their annual stopovers.
“Long-term worsening of the Chesapeake’s water quality, however, and loss of habitat, especially the grasses so many of these birds depend on, have contributed to declines in wintering waterfowl on the bay,” says Webster.
Canvasbacks in a spot along the Chesapeake that’s protected from winter winds, and where aquatic grasses are ready-to-eat. (Photograph: Paul Bramble)
Seesawing duck and grass estimates
According to a 2016 estimate, the most recent available, some 97,433 acres of submerged aquatic vegetation (SAV) remain in the bay and its tributaries, down from historic levels that may have reached more than 600,000 acres.
There’s good news, however. The 2016 estimate is an 8 percent increase over 2015, and more than twice the SAV in 2013.
In 2011, Chesapeake SAV fell to 48,195 acres, a result of the effects of Hurricane Irene and Tropical Storm Lee. The storms sent a flood of sediment downstream and into the bay. Conditions since, which have been relatively dry, reduced the flow of grass-smothering sediment and helped the SAV recover. More sunlight has reached submerged grasses, allowing them to flourish. In turn, SAV filters runoff, helping keep Chesapeake waters clear.
Several birds watch a canvasback diving for dinner. (Photograph: Paul Bramble)
SAV: A canvasback’s best friend
As recently as 1950, half the continent’s population of canvasbacks – more than a quarter million — wintered in Chesapeake Bay, relying on aquatic grasses as a favored food source.
During Colonial times, as many as one million canvasbacks may have spent wintertime on the bay. In the 19th century, the ducks’ abundance and, to many, good taste made them a favored selection in many East Coast restaurants, says Matt Kneisley, regional director for the Northeast Atlantic Flyway at the Delta Waterfowl Foundation, a waterfowl conservation and hunting organization.
The birds congregate in large flocks on open waters, leading to easy -– too-easy — harvesting. At the end of the 19th century, commercial hunters with batteries of weapons went after rafts of canvasbacks, often killing dozens with one shot. The ducks were shipped by boxcar to markets from Baltimore to Boston. Such “market hunting” was outlawed with the passage of the Migratory Bird Treaty Act of 1918.
“Canvasbacks were a favored quarry of market hunters because their meat was considered the tastiest of all the ducks due to their consumption of wild celery,” writes Guy Baldassarre in the 2014 edition of Ducks, Geese and Swans of North America.
Adds Kneisley, “Large beds of wild celery, a canvasback favorite, once attracted thousands of these ducks to an upper bay area known as Susquehanna Flats.” The decline in the Chesapeake’s water quality greatly reduced the amount of wild celery bay-wide, however.
The ducks switched their foraging efforts to small clams on the Chesapeake’s shallow bottom. A less nutritious diet of shellfish such as Baltic clams may affect canvasbacks’ winter survival rates, scientists believe.
Canvasbacks shed water after diving for food. How many of these ducks winter on the Chesapeake? To find out, scientists conduct an annual count. (Photograph: Paul Bramble)
Annual bird counts, Webster says, “give us a very good picture of how declines in SAV have affected wintering waterfowl.”
Half a century ago, four to five million ducks, geese and swans spent time on Chesapeake Bay during the winter. Now, that number is less than one million, according to results from the 2018 Midwinter Waterfowl Survey. The nationwide count has taken place annually since the 1950s.
Along the Chesapeake and nearby Atlantic coast, aerial survey teams of pilots and biologists from the Maryland DNR and the U.S. Fish and Wildlife Service make visual estimates of the region’s waterfowl. In 2018, the teams counted some 1,023,300 ducks, geese and swans, higher than the 812,600 birds observed in 2017 and above the 5-year average of 851,980.
“Cold weather and accompanying ice and snow to the north will typically push birds south as they search for food and open water,” says Maryland DNR Wildlife and Heritage Service director Paul Peditto. With December’s frigid temperatures and iced-in lakes in northern states, ducks were on-the-wing to points south.
Estimates of Chesapeake canvasbacks in 2018 were 60,000; in 2017, 75,100; in 2016, 19,800; and in 2015, 64,200. Sixty years earlier, in 1955, 225,450 canvasbacks were sighted. The last time the canvasback count exceeded 100,000 was in 1967: 133,100.
Nonetheless, says Webster, “Chesapeake Bay is one of the best places on Earth to see waterfowl in winter, and as they migrate in and out in late fall and early spring.”
Most waterfowl migrate along corridors, the well-known “flyways.” Four major routes pass through the United States: the Pacific Flyway, which runs north-south along the West Coast; the Mississippi Flyway, which leads from the bays of northern Canada and the Arctic to the Gulf of Mexico; the Central Flyway from northwestern Canada to Central America and the Yucatan Peninsula; and the Atlantic Flyway, which funnels waterfowl from central and eastern Canada along the Atlantic Coast to Florida. Chesapeake Bay is a major duck stop along the Atlantic Flyway.
A lone canvasback hen in a crowd of potential suitors. (Photograph: Paul Bramble)
Many of the Chesapeake’s wintering ducks began life in the prairie pothole region, which extends from the Midwestern northern tier states into Canada. There, about half North America’s ducklings hatch.
When the Wisconsin ice sheet of the last glacial period retreated northward some 15,000 years ago, tens of thousands of landlocked icebergs were left in its wake, writes Michael Furtman in On the Wings of a North Wind: The Waterfowl and Wetlands of North America’s Inland Flyways.
These small icebergs melted into the soil. As they faded, Furtman states, “they became the foundation of the prairie potholes. An estimated 10 million glacially carved depressions once pockmarked the landscape of the prairie pothole region of the United States and Canada.”
As climate warmed, the potholes evolved into a habitat so enticing that more than 130 bird species have used a single pothole in one year. Ducks were likely among the first residents. With millions of potholes from which to choose, waterfowl had plenty of room to find nesting sites.
“The diversity of potholes, ranging from small spring ponds to large permanent wetlands, provided ducks with the habitats necessary for each stage in their breeding and brood-rearing cycles,” Furtman states.
But as undisturbed land in the region gave way to agriculture, the number of potholes decreased, especially over the last 40 years. In North Dakota’s pothole region, where as many as 100 of these basins per square mile once existed, “60 percent of the original five million acres of wetlands has been lost,” Furtman reports. “Ninety-five percent of that loss is attributable to agriculture.”
Will the Chesapeake always welcome wintering canvasbacks? (Photograph: Paul Bramble)
If increasing agriculture isn’t challenge enough for waterfowl, rising global temperatures may result in more frequent and severe droughts in the prairie pothole region. The effect on breeding ducks would be devastating, says Webster.
“Decades ago,” he remembers, “the Chesapeake was full of canvasbacks. But no more. I’d like to see the days come back when canvasbacks’ red heads bobbed on the water as far as you could see.”
Canvasbacks and the many other ducks that winter on the Chesapeake have come a long way, Webster says. “The least we can do is show them some hospitality by making sure their environment — here, and on their breeding grounds — is healthy.”
Otherwise, the spectacle along the Choptank River may vanish, the seawall indeed becoming a wall of shame as the last canvasback’s wingbeats fade into silence.
The last Chesapeake canvasback? We need to do our part to help the “king of ducks” grace the bay each winter. (Photograph: Paul Bramble)
Brown anoles are one of the most successful species on the planet. These resilient creatures have settled throughout a large portion of the Western Hemisphere, even landing in such distant places as Hawaii and Singapore by hitching rides across the Pacific in shipments of ornamental plants. In the southeastern United States, they are actually displacing native green anoles, driving them higher into the trees. These cold-blooded creatures are happy almost anywhere, from shady forests to sun-drenched beaches.
“In The Bahamas, it would blow your mind how common these things are,” said Michael Logan, a post-doctoral fellow at the Smithsonian Tropical Research Institute in Panama, who studies them. “Pick any bush along the side of the road, look closely, and I’ll bet the bank you see a brown anole — or three — in there.”
You would think that with so many brown anoles covering so much of the planet there would be a lot of genetic variation within the species. Some lizards would be larger or smaller, faster or slower, lighter or darker — meaning that, by chance, a few anoles here or there would be adapted to new challenges, like climate change, and they would pass on these traits to a younger generation of climate-tolerant lizard. But new research suggests that isn’t happening.
Brown anole. Photo: Thomas Brown
The findings, recently published in the Proceedings of the Royal Society B, could have significant implications for the future of all cold-blooded species — the anoles, as well as other reptiles, amphibians and fish — whose body temperatures vary with that of the outside environment. Studying these species, known as ectotherms, can help scientists better understand the perils of global warming because their lives are so precisely connected to fluctuations in temperature.
“It was surprising to find such low genetic variation in traits that are important under climate change, such as the body temperature at which lizards run the fastest,” a trait essential to outrunning predators, Logan said. “So how have these guys invaded and adapted to such disparate regions of the globe if they lack what’s necessary for genetic adaptation?”
That’s a question still in need of an answer, although one possible explanation is that generations of anoles have faced challenging environments, and as the species evolved to meet these challenges, it wound up in something of a genetic cul de sac. The result is little variation among brown anoles. Logan explained how, over time, evolution yields very limited variability in certain traits.
“A trait like ‘number of limbs in tetrapods’ — amphibians, reptiles, birds, and mammals — is almost entirely determined by genes,” Logan said. “But because there is no variation in those genes among individuals — nearly all tetrapods are born with four limbs.” He added that “selection cannot act on a trait that has no variation.”
Michael Logan gathers research data in Great Exuma, Bahamas on brown anole lizards. Photo: Christine Miller
For their study, the scientists captured adult lizards from two very different habitats, one cool and forested, the other a hot, sun-soaked peninsula. They then bred the anoles in captivity and raised their offspring in the same laboratory setting.
“We did this because any differences between the populations would be due entirely to genetics,” Logan explained. “In other words, we controlled for ‘nurture’ so we could see if ‘nature’ played a role.” He said there were marked differences between cold-weather lizards and warm-weather lizards, despite growing up under the same conditions.
Using a high-speed camera, they filmed the lizards running across a wooden dowel rod after exposing them to different temperatures. They used gel packs and heating lamps to create temperatures from around 70 degrees F to around 120 degrees F, recording their responses. Predictably, the warm-weather lizards performed better at higher temperatures, but neither group displayed a lot of genetic variation.
“Our results suggest that natural selection may have used up all the available genetic variation to get these populations adapted to their thermal environments in the first place, leaving them with nothing to evolve further as the global climate continues to change,” Logan said.
Brown anole. Photo: Pixabay
The study showed that thermal traits have a genetic basis “because they differ between populations when we control for the effects of the environment,” he added. “But we also show that within each population these traits lack genetic variation, which means they can no longer evolve in response to selection.”
The brown anole, because of its large population and ability to colonize novel environments, is unlikely to be especially vulnerable to climate change — although it turned out to be more vulnerable than expected, he said. But the study raises troubling questions about the fate of other species in a warming planet.
Other species tend to cover a more limited area than the brown anole, and they tend to live only in one kind of thermal environment, Logan said. “If the brown anole with its success as a global invader lacks the necessary genetic variation to evolve rapidly, what does that say about the rest of biodiversity?” he said. “Species that are less prolific and more specialized should have even less genetic variation for selection to act on.”
Evolutionary biologist Shane Campbell-Staton, a postdoctoral fellow at the Universities of Montana, Missoula and Illinois, Champaign-Urbana — who was not involved in the study — said the research provides a critical link to understanding how cold-blooded creatures respond to changing temperatures.
Collared lizard. Photo: Pixabay
“There have been several studies that have shown that extreme weather events and rapid shifts in the environment can cause selective events — organisms with greater resilience to droughts, heat waves or cold snaps are more likely to survive and pass their genes on to the next generation,” Campbell-Staton said. “However, as [the study] points out, evolution — which occurs across generations — can only happen if the traits that allow survival can be passed on to offspring.” With the brown anole, “the traits under selection in high temperature environments don’t seem to be passed from generation to generation very efficiently, meaning that adaptive evolution of those traits would presumably happen on a much slower time scale than the anticipated changes due to global warming,” Campbell-Staton added.
This mismatch “could potentially be a disastrous combination,” Campbell-Staton said. “It means that as the planet warms over time, selection on thermal performance may increase — meaning more individuals may die in a given generation — but the offspring of the survivors may only be slightly better fit to deal with continually rising temperatures, or no better off at all. The end result of this mismatch, if temperatures continue to rise, would inevitably be extinction.”
While the study isn’t directly applicable to warm-blooded humans, “it is clear that many species around the world, including the plants we depend on for food and oxygen, the insects that pollinate those plants, and many other ectothermic species that are important players in ecosystem health could be drastically affected,” Campbell-Staton added.
For species with small home ranges, lacking the ability to migrate, evolution should provide “their main avenue of escape,” from the effects of global warming, Logan said. But this study “hints that many of the species we love and care about may not be able to mount a rapid evolutionary response to climate change.”
Marlene Cimons writes forNexus Media, a syndicated newswire covering climate, energy, policy, art and culture.