Grassland birds

In a hay meadow near Brunswick, Maine:

Bobolink, taking a break from his jumbled singing flights over the field.

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Savannah sparrow, keeping an eye on neighboring males.

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According to the North American Breeding Bird Survey, neither species has been faring well. The bobolink has declined by about 2% per year since the 1960s. The savannah sparrow’s decline is about 1.25% per year.

North American Breeding Bird Survey trend for bobolink, then savannah sparrow (“index” on the vertical axis is a measure of the number of birds seen along annual survey routes):

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sav graph surveywide

These declines are typical for meadow species in North America. According to a review by ornithologist Jon McCracken, birds that nest in upland grasslands have, in the last century, “experienced the most pronounced declines of any other group of birds on the North American continent.”

In the last few decades, intensification of agriculture — earlier hay-cutting, more frequent hay-cutting, conversion of grass to alfalfa — has drastically reduced breeding success of these species. Before that, in the mid-1900s, regrowth of forests on former agricultural land was the main cause of the decline of grassland birds. This followed the 1800s and early 1900s, the heyday of hay in eastern North America. Early European colonists cleared large areas of forest, opening grassland. Then, as American agriculture moved to the midwest and heating oils replaced firewood, grasslands in eastern North America declined as forests regrew (and grasslands in the midwest declined as they were plowed for grain crops).

Given the great variability of grassland acreage over the last centuries, the “right” or desirable amount of bird-friendly grassland in the region is obviously hard to state. But the combined effects of early hay cutting (goodbye nests) and land conversion (hello alfalfa fields and housing subdivisions) suggests that, if we want to maintain populations of these species, we’ll need more (and better) grassland than we now have. The economics of farming makes this a significant challenge. Stiff competition from industrialized meat and milk businesses mean that hay meadows are not money-makers, hence the long-term decline.

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Fiddlehead gastronomy

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You know you’ve arrived in Maine when the supermarket has a fern fiddlehead special in the produce section:

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And Portland restaurants find ways of preparing the ferny curls with chard and dressing:

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And, a few weeks later, when the wild ferns have fully unfurled, the remnant kitchen fiddleheads are roasted and turned to soup:

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Ferns are well defended both mechanically (tough to chew on) and chemically (how many insects do you see munching on fern leaves?), so they seldom appear on human plates. After a long winter, though, anything green looks good to vitamin-starved mammals, so people cut the young unfurling fronds of ostrich fern — fern furls curtailed forever, very poignant — and eat them raw, lightly steamed, or roasted. Ferns can bear a small amount of harvesting, but repeated cutting will kill the plant.

Ferns are also harvested for food in Korea and Japan, always as fiddleheads. I’d be interested to know of examples from other cultures. In the non-human realm, the European woodmouse loves to chew on ferns, perhaps echoing the dietary preferences of sauropod dinosaurs?

Lesson from Carthage: How to catch an octopus, defeat an empire

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Almost all that remains of the ancient city of Carthage is a small harbor on the peninsula outside Tunis. The Romans leveled and burned the rest of the city at the end of the Third Punic War. Many more recent cities have since been built over the rest of the Carthaginian remains. “Carthage” is now an upscale suburb of Tunis.
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From Google Maps:

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The harbor is now a fishing port, used by the small, colorful boats that are common in many Tunisian ports.

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Stacked along the dock were piles of ceramics, each threaded with ropes or netting. These are octopus traps. Thinking they have found a good rock nook, octopuses slide inside the submerged containers. When the fishermen pull on cords, the jostling alarm causes the octopus inhabitants to hunker down. Fear is their undoing. There is an unfortunate echo of the two-thousand-year-old history of this harbor, as the Carthaginians used a similar strategy of holing up, one that the Romans overcame, ending Carthage’s rule.

Now, though, the harbor is peaceful, inhabited by fish-scrounging cats, a few local kids at play, and fishermen joking as the stow their pots.

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Birding at the Bardo

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Some of the world’s best preserved Roman mosaics are housed at the Bardo Museum in Tunis, Tunisia, and the Archaeological Museum in El Jem, just a little south of Tunis. They date from the time of the “Roman African Province,” 146 BCE–435 CE, a time of great prosperity (for some). After the defeat of the Carthaginians, what is now Tunisia become a trading and agricultural hub in the Roman empire. The wealthy built many large, lavish houses, some of which were eventually buried under sands and rubble until the last century. Now, they stand in fabulous museums in Tunisia.

The mosaics are often huge, several meters in both dimensions. A few are comprised of geometric designs, but most show scenes from mythology and everyday life. The mosaic artists’ work is remarkable for its attention to the particularities of natural history: local birds, fish, and other species are represented with skill and often a touch of humor.

A painful beach scene:

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Some ornithology: swallow, hoopoe (fairly common in rural areas, even today), crane, owl (standing as a symbol of defeat over envy, according to the signage), a peacock, moorhen, quail, what appear to be some thrushes ready to be made into pie, and, finally, a bird being made into pie.

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Sadly, the museums are empty of visitors. We walked through hall after hall, alone save for museum employees. The same is true in much of Tunisia. A country whose coasts were thronging (and thonging) beach holiday resorts and whose cultural sites were popular destinations for history and archaeology buffs now receives few foreign visitors. Miles and miles of beach hotels stand completely empty, as if the Rapture had taken away all the lovers of blue seas, discos, and seafood. Historical sites — Roman, Carthaginian, Byzantine, French colonial — are visited by local schoolkids and few others. Two bombings by extremists succeeded in closing down a thriving tourist economy. The terrorists got exactly what they wanted: travel warnings from Western countries that stemmed the flow of foreign money to the only remaining Arab Spring democracy.

We tolerate all kinds of risks in life, but if a minuscule risk comes from a jihadist, our governments capitulate, promulgating the message of fear, enclosure, avoidance. Travel in the last years in the West Bank and Jerusalem, and now in Tunisia, all areas flagged as “dangerous” by State Department warnings, suggests to me that a more productive approach might be one of informed engagement.

To whet the appetite, the Roman amphitheater at El Jem. Seating for 35,000. Gladiator and animal rooms still intact. Walk right in…only a nesting kestrel in the high arches and some schoolkids for company:

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Photo credits: David Haskell, Katie Lehman

Sebkhet Halk el Menjel

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Underfoot: the crunch of thousands of shells. On the nose: a tang of salty algae. In the eyes: dust thrown here from the Tunisian deserts and over-plowed olive plantations to the south.

The lake was a surprise, a silver sheet interrupting a day’s drive through scrub and bare soil. As we approached, the sheet expanded, nearly thirty thousand acres of shallow water.

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On the southern shore, shells were blown into drifts, a molluscan gravel onto which the wind also piled the discards of humanity.

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Looking down into the lake, at first we saw only multicolored bivalve shells. Then, motion: turning, spinning, leaping. Tiny shrimp-like creatures, almost translucent.

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These brine shrimp (Artemia, see a pair just to the right of the black pebble above) are among the few animals that can survive the hyper-saline waters of this lake. They feed by filtering specialized halophile bacteria and algae from the lake’s shallow waters.

Birds, including thousands of flamingos, are drawn by the abundance of shrimp. Like the shrimp themselves, flamingos filter the water for their food, pumping tongues through sieve-like beaks. Long experience with humans has taught the birds to stay away from the lake edges, but we approached close enough to hear the sluicing sound of shrimp-filled water squiring through lamellae in flamingo beaks.

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This lake is one of many “Sebkhets,” salt lakes, in central Tunisia. The water seems to taunt the donkeys, camels, and goats that live around them: great expanses of liquid in a parched land, yet utterly undrinkable. To the north, more abundant Mediterranean rains turn the land green and hospitable. Further south, the taunting ends where the Sahara begins.

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Photo credits: David Haskell, Katie Lehman

Nature writing cult…

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“They are haunted by visions. They are visited by strange dreams. They are – like Muhammad on Jabal al-Nour and George Fox on Pendle Hill – vouchsafed revelations in high places. They are the nature writers, and they bring us wisdom from the wilderness.

The question is, why do we listen to them?”

This from Richard Smyth’s latest piece in the New Humanist, The Cult of Nature Writing. I was delighted to be interviewed for the essay and I’m greatly enjoying Richard’s insight and wit.

“Go birdwatching or bug-hunting; take a hike. Experiences of this kind shouldn’t require the mediation of a prophet.” Yes, indeed. Let’s take off the prophet’s robes. Then, perhaps, write a short essay about what the defrocking experience teaches us about chickadee physiology?

The dawn of the Age of Ideonella

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Fellow humanoids, our task is nearly complete. We’re now annually making more than 50 million tons of polyethylene terephthalate or PET plastic. We’ve been at it a while: The land is garlanded, the oceans spiced. Thanks to us, the food supply for the Earth’s next overlord is almost ready.

Ideonella sakaiensis, a species of bacteria that seems to have evolved inside a PET recycling facility, is now ready to start eating. Shosuke Yoshida at Kyoto University and his colleagues report in Science that the species possess two enzymes that allow the bacteria to use PET plastic as their only source of carbon. The bacteria glue themselves to the plastic and secrete the first enzyme. They then draw the ooze that results from this digestive process into their cells where the second enzyme finishes the work. The whole process takes six weeks, an eternity in the bacterial world, but we can expect efficiencies to develop as the bacterium develops a better work ethic.

Only 14% of plastics worldwide are recycled, so Ideonella arrived into a world that any astute student of biotheology would surely recognize as designed specifically for the eventual evolution and triumph of the species.

In a commentary on the paper, Uwe Bornscheuer of the Department of Biotechnology and Enzyme Catalysis, Greifswald University, states that if the leftovers of the bacterial digestive process “could be isolated and reused, this could provide huge savings in the production of new polymer without the need for petrol-based starting materials”. In other words, we’ll be able to keep making PET plastic even when the oil runs out. Ideonella will no doubt be thankful.

David George Haskell

March 11, 2016

Spotted salamanders (guest post by Saunders Drukker)

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I’m delighted again to share a guest blog post written by Saunders Drukker. Saunders is an Ecology and Biodiversity major at Sewanee (Class of 2017).

Spotted salamander, Ambystoma maculatum

In my last post on this blog I wrote about how winter was a time of increased activity for the forest dwelling amphibians that inhabit the Cumberland Plateau. Late February is the most active time of all. Towards the end of winter, when relatively warm rains begin to fall, amphibians of all types migrate through the hardwood forest of the Cumberland Plateau and set up temporary residence in water-filled depressions known as ephemeral ponds. Among the animals moving are animals like Upland Chorus Frogs Pseudacris ferriarum, Four Toed Salamanders Hemidactylum scutatum, and Marbled Salamanders Ambystoma opacum. However, the greatest migration is undertaken by the Spotted Salamander Ambystoma maculatum. This relatively large salamander spends the summer and fall in brumation, escaping the dry and the heat in underground retreats, waiting for ecological signals of the breeding season. When the cue of warm rain comes, the salamanders emerge in the thousands to return to the same pools they were born in, where, like their parents, they will engage in the same ritualistic breeding activity.

Ephemeral wetland, near Brakefield Road in Sewanee

Spotted salamander emerging from leaf litter

Spotted salamander emerging from leaf litter

Spotted salamander walking across forest floor

The males are the first to enter the pond. Here, even without females to impress, they swirl around in the leaf litter at the bottom of the pond, dropping spermatophores (see video taken at the pond on Brakefield Road here). The female salamanders arrive a week or so later. Upon entering the pond the females are swarmed by eager suitors, each waving his pheromones in her face, and gripping her with their legs so as to entice her to pick up their spermatophore, thus passing on their genetic material. After fertilization, the females attach their eggs to a submerged branch, where they swell with water to form a firm gel-like mass. Females come and go fairly regularly, completing their purpose and leaving the pond to return to their forest home. Males tend to stay longer, attempting to breed multiple times, giving themselves a better chance at reproductive success. As the eggs hatch, the pond is filled with thousands of small, gill-flaunting larvae, who in a few weeks will leave the pond on a rainy night to find a place to spend the summer.

Spotted salamander egg mass

Emigration of young salamanders from the pond represents a huge transfer of biomass from an aquatic ecosystem to a terrestrial one. This transfer is one of the most significant roles of amphibians in food webs and ecosystems. These salamanders make up a huge portion of the forest’s vertebrate biomass, and engage in one of the largest movements in the eastern forests of America, and certainly one of the largest here in Sewanee.

Trail markers as whetstones?

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Some interesting toothwork on trail markers in North Alabama: Almost every metal sign on the trails at the Land Trust of North Alabama’s Monte Sano Preserve is incised with dozens or hundreds of striations.

The artist? Gray or fox squirrels? We saw plenty of grays. Perhaps night-working flying squirrels? I’d welcome your thoughts!

Rodent incisors grow continually through their lives, a self-renewing mechanism necessitated by the walnut cases, seed husks, and other rock-like coatings with which plants so inconveniently wrap their progeny. These ever-growing teeth need continual shaping and sharpening. Might this be the reason for the rodents’ attention to the trail markers? I’ve seen similar markings on horn and bone. But these biological remnants are calcium-rich, unlike aluminum trail signs. It would be interesting to hang some files in the woods and watch the evolution of dentistry.