There’ll Be Bluebirds Over

The American composer of “There’ll be Bluebirds over the White Cliffs of Dover” either had the excuse of poetic license or didn’t know that bluebirds are absent from the British Isles. But the song became one of one of Dame Vera Lynn’s signature performances for stirring patriotic hope in 1942.

There are three species of bluebird in North America (all thrushes). Someone who grew up in Tidewater Virginia doesn’t remember seeing Eastern bluebirds here in the 1960s, probably because urban sprawl and competition from introduced species robbed them of natural cavities to make home. But no longer.


Male Eastern bluebird (photo: Inge Curtis)

The friendly songsters are now common in local meadows and suburban gardens thanks to human interference, sponsored by the Virginia Bluebird Society and kindly people who provide nestboxes. The best boxes are not the kind found in knickknack stores, gaily painted (for predators to find) and with a perch close to the entrance hole (to help predators look inside). Constructed of rot resistant cedar, an ideal box has a 1.5” entrance hole protected by a wire mesh predator guard and a snake guard on the pole. While these safeguards are not 100% effective, most broods reach the fledgling stage for the most dangerous days of their lives.

Bluebirds are nesting in two of our four boxes, each with five sky blue eggs. I don’t peep inside again until the chicks have flown after gorging on countless insects and arachnids brought by doting parents. Then, I clean out old nests that might harbor parasites, and usually find the lodgers have made new ones of pine straw and small sticks a few days later for a second brood. Even if I trained for months using forceps to weave the straw I doubt I could craft anything that would pass a bird’s inspection.

Our third box is still vacant and the fourth has a house wren sitting on brown speckled eggs.

Bird eggs are among the most beautiful objects in nature. They are delicate works of art, sometimes decorated with pigments as if squirted from paint guns in the oviduct on the day before laying. It is no surprise that ground-nesters have camouflaged eggs or that eggs laid further north tend to be darker to absorb more heat. We might expect cavity nesters, such as owls, kingfishers, woodpeckers, and wood ducks, would have pure white or buff eggs as coloring provides no obvious advantage. The colors of bluebird and wren eggs are among the exceptions, which goes to prove that nature hates uniformity and ruins our simple hypotheses.

Box taken over by house wrens

Adopted by house wrens

Data from over 4,500 nestboxes on 410 trails across Virginia are compiled by the Bluebird Society. Our local chapter of Master Naturalists monitors a few hundred boxes in parks and around golf courses every week between March and July. On a trail where I help to monitor 41 nestboxes, there were 63 bluebird fledglings in 2018  (a wet spring) and 97 last year, plus a few broods of chickadees and tufted titmice. Nestboxes raise thousands of extra birds.

This year the coronavirus pandemic disrupted our survey, but not the breeding season, which may even benefit from less human traffic and noise. But human nature doesn’t seem to change as I heard that three of our boxes have been vandalized. Who could do that to bluebirds?


Posted in Birding, garden, Nature | Tagged , , , , , ,

Pepysing back at the 1665-66 plague of London

I aimed for a weekly post about the health of the natural world, but here I am dwelling on coronavirus again. Is anyone undistracted by this pandemic?

This time I dusted off my copies of Samuel Pepys diaries in which he recorded the bubonic plague in the city I grew up in. Londoners were familiar with the scourge. The Black Death carried off most of the population across Europe in the 14th century and made other appearances. Although believed to be carried in the air (‘miasma’), human contact was a known agency too. Inbound merchant vessels had to rest at anchor for 40 days before disembarking (a number straight from the Bible). Plagues then took months to sweep across the known world in merchant sailing ships as we became more connected by trade, but it only takes a few hours or days by air travel today.

Pepys wrote in August 31, 1665: “the plague everywhere through the kingdom almost. Every day sadder and sadder news of its increase. In the City died this week … 6,102 of the plague. But it is feared the number of the dead this week is near 10,000”. He had little confidence in statistics because the poor were often unrecorded and Quakers forbade tolling the bell for their losses. Nor will the true number of coronavirus deaths be known for a long time.

Two weeks later: “To hear that poor Payne, my waiter, hath buried a child, and is dying himself. To hear that a labourer I sent but the other day to Dagenhams is dead of the plague and one of my watermen …” Epidemic is merely numbers until its meaning is wrought in suffering people you know and care about. Willful ignorance and denial of science we currently witness in the news will surely be tested with the fire of personal tragedies to come.

Church on the hillA shipment of cloth from London to a tailor in Eyam, a small village near Sheffield, carried infected fleas in 1665. Dreaded buboes erupting with pus appeared on the skin of villagers. The Eyam community led by an Anglican priest is hailed as an example of self-sacrifice where quarantine was imposed to avoid spreading the contagion outside.

Beautiful myths grow up where facts are scarce. The priest sent his children away and the poor could not afford to go. But it is a fact that only a quarter survived, and maybe the odds in neighboring villages benefitted from ‘lockdown’. According to a math model, quarantine may have made matters worse for Eyam by prohibiting dispersal if closer contact led to a more deadly pneumonic (pulmonary) plague. If there is a hero in the story, it is the priest’s wife because she stayed and died.

We constantly ask how the current ‘plague’ will end, and when?  In Eyam it burned out by running out of victims (from herd immunity?), but no one imagined it would take a literal fire in London.

Pepys wrote on September 2 of the following year: “With my heart full of trouble, to the Lieutenant of the Tower (of London), who tells me that it began this morning in the King’s baker’s house in Pudding-lane, and that it hath burned down St. Magnus’s Church and most part of Fish Street already … and did tell the King (Charles II) and the Duke of York what I saw; and that, unless his Majesty did command houses to be pulled down, nothing could stop the fire.” It seemed perverse to add to the physical and economic destruction but in the end was the best policy.

Sometimes we have been lucky in history with leaders who rose to the challenge of crises with coordinated, compassionate and effective responses. This time we have seen dithering politicians scared that bold responses might dent their standing and blind to the bigger picture. This coronavirus emergency is terrible and a vaccine is an urgent goal, but unless its roots in careless stewardship of nature are acknowledged the ancient cycle of plagues will be repeated, because everything is connected.

Posted in Environment, Health, History | Tagged , , , , , , ,

Latent impact of COVID-19 in pregnancy?

There was a time when the womb was regarded as a pristine environment for a ‘fetonaut’ to travel safely for 9 months until birth, protected by a shield-like placenta. No longer. The effects of smoking, thalidomide and binge drinking show it is all too vulnerable to external threats.

This realization was extended by David Barker, an epidemiologist whom I met but only once at a Swiss symposium on evolution and health. He was head of a research unit at the University of Southampton and then winning over detractors to his belief that prenatal malnutrition has delayed impacts until midlife or even later.

From searching British medical records, he found low birth weight predicted heart disease, stroke and high blood pressure in adult life, some of the most common medical blights. His critics dismissed the connection as mere correlation—not causation— but as years rolled by there was confirmation from other sources and connections with obesity and diabetes type 2.

At first called the Barker hypothesis, it is now known as the fetal origins of adult disease and as spurred research into late effects beyond those he studied.

pregnant woman ClipartAdverse health effects were also found among Dutch people born to mothers subsisting on a forced daily diet of under 1,000 calories in the last year of World War II. More harms were reported in children conceived around the time of the Chernobyl nuclear disaster and a famine during Chairman Mao’s ‘Great Leap Forward’.  They imply that health and vitality are molded by our environment as well as genes at tender stages that go unseen.

A gravid womb is not like an unmanned space capsule controlled from afar and tossed by storms of plasma from the solar corona. Like an astronaut, a fetus can make adjustments to adapt to changing conditions and improve its safety. This so-called developmental plasticity evolved to increase the chances of survival in times of food shortage. Sometimes called a thrifty phenotype, the baby who emerges is adapted to thrive in the meager circumstances he or she is born to. But if a mismatch exists between prenatal poverty and postnatal affluence the resulting catch-up growth, although apparently welcome, may come at a price if adaptations made in the womb are no longer appropriate.

Adaptations to low oxygen and stress hormones can also play a role, either independently or with malnutrition, and the effects on cell biology and physiology are multifarious and complex. The root of the problem is likely epigenetics in which genes are switched on or off in different cells and states but the sequence of letters in the DNA code are unaltered. Rather insidiously, some epigenetic changes can be inherited by the children and even grandchildren of those originally affected.

So, what has that got to do with the COVID-19 pandemic? Major economic interruptions, like the Great Recession from 2007 that lasted a decade, are known to cause persistent mental and physical health problems, especially among racial and ethnic minorities. But what about acute pandemics that last only months?

Douglas Almond, a health economist at Columbia University, studied people conceived in 1918 and 1919. They suffered far more disadvantages in life if conceived during the flu pandemic than a few months earlier or later, even after adjusting for social class, etc. He reported, “(they) attained lower educational achievement, income, and socioeconomic status … 15% less likely to graduate high school, 15% more likely to be poor, and 20% more likely to be disabled as adults.”

There will be a huge sigh of relief, of course, when COVID-19 is conquered by vaccines, but that won’t be the end of the story. There are likely to be long-term negative consequences for the generation of innocents currently in utero.

This shouldn’t unduly alarm women currently pregnant because the projection is demographic, and the great majority of babies will be fine. The cohort conceived in the flu pandemic a century ago produced as many outstanding people as other generations, men and women like Richard Feynman, Katherine Johnson, Nelson Mandela and Edmund Hillary. Some of them were doubtlessly born in acutely affected communities. But the fetal origins hypothesis urges more research on the unborn to mitigate the chronic personal and societal health impacts of infection.


Posted in Health | Tagged , , ,

A Day in Dharavi

That day slept in deep memory until Dharavi appeared in news reports about the threat of COVID-19. It wasn’t a Westerner’s curiosity about the plight of poor people that brought me in 2003 after an engagement in Mumbai; it was an introduction to a medical practitioner who worked in the slum. She cared for patients of all kinds, but after flooding from the monsoon she was treating dengue virus. I came with questions.

Mumbai, India

Not a million miles from Dharavi

A first visit to India is an overpowering experience. The immense crowds, poverty, religious spirit, stoicism, heat, and intense colors.

Dharavi squats between arteries of the rail network. As a visitor, I felt the alien I was, but the stares I received, mostly from teenagers in t-shirts, were invariably friendly and I never felt as threatened as in some American inner cities. It’s a community of many religions and none, so creed is less likely to explain low crime than the narrow wealth gap compared to our cities. A millionaire in Dharavi would be incongruous.

The biggest slum in Asia with half a million people crammed in a square mile wasn’t on the tourist trail then, although I hear of tours for inquisitive trekkers today, maybe encouraged by Slumdog Millionaire earning Best Picture at the Academy Awards. It would be a naff voyeur who came to photograph poverty, and some tour companies observe a strict ethical code.

Dharavi defies common notions of slum-living. It’s true that people live cheek by jowl in concrete homes under corrugated roofs beside narrow passageways for noisy streams of pedestrians and auto rickshaws. Overhead there is a tangle of power lines that would look alarming to engineers, polluted waterways horrify environmentalists, and piles of trash condemned by public health departments at home. There is an odor in the air, but it’s not fetid. Some children go barefoot, but most residents take pride in personal appearance and sloth is foreign to them. A beehive is an apt metaphor for the industry inside the maze. There are potteries, tanneries, tailors, shoemakers, food stalls, and recycling enterprises. Some lawyers and doctors reside there, including the one I visited. It is a vibrant community.

Above all, the crush of humanity was the most lasting memory. It’s hard to imagine how people can keep a safe social distance to avoid infection with the coronavirus or find access to facilities for frequent washing of hands. The risk of contagion is acute, and a reminder of the thousands who died of plague there in the 1890s. Remember Dharavi and places like it.


Posted in Health, Memoir | Tagged , , , , ,

Why So Many Hollow Trees?

According to legend, Robin Hood and his Merry Men hid from their pursuers in a hollow tree in Sherwood Forest during the harsh reign of King John (1199-1219). The tree still stands, albeit courtesy of props and wires, and called the Major Oak. Another veteran had hollowed out enough by the 18th century to provide room for seating 20 people with a plank floor and door. Thought to be over 1,000 years old, the Bowthorpe Oak survives in Lincolnshire. Across the Atlantic ocean in the same century, Jacob Marlin and Stephen Sewell were the first white pioneers to settle in the Greenbrier Valley of WV. When they fell out over a religious argument, Sewell separated to make a home in a hollow sycamore tree (later he was killed by Indians).

Southern red oak

Hollowed Southern red oak

A financial loss to lumber companies, hollow trees win our curiosity, even affection, as natural works of art and have inspired storytellers. Albert Bigelow wrote the children’s book, The Hollow Tree and Deep Woods Book (1898), which introduced as major characters Coon, Possum and Old Black Crow who struggled to live together amicably in the same tree.

My curiosity has been stirred by trees in our yard. If the angle of a side branch creates a cup for water and debris to accumulate or if a limb is torn down by a storm or sawn off doesn’t heal over, the rot starts as specialized fungi invade the heartwood to digest cellulose and lignin. They are followed by beetle and insect grubs that nibble channels and chambers, and they in turn become the menu for woodpeckers (7 species here) that carve out larger holes for nests. A growing menagerie includes invertebrate (called saproxylic), bird, bat, racoon, and even human occupiers.

Red maple

Hollow filled in a red maple

Trees that are not stressed by storms to breaking point can reach great ages from the strength of their shell of living sapwood, but they are often felled in parks for public safety. I minimize rot and hope to save mine by filling hollows with polyurethane foam, and apply a thin coat of tar to blend with the bole and provide waterproofing. Regrettably, some of the critters I like are thereby made homeless, or would be if I didn’t make nestboxes (next post)

A Swedish study of oak trees (Quercus robur) found <1% had hollows at under 100 years old, rising to 50% at 200 to 300 years, and all were affected at greater than 400. I recall few hollow trees in England and Scotland, except for rare veterans. Yet, here in Virginia I see them everywhere, and often in relatively young trees. A local dendrologist (academic tree expert) told me it is impossible to tell the age of the oldest trees because the inner rings of heartwood always rot out, although hardly a single specimen is more than 200 years old.

Why are hollows more prevalent here than in northern Europe? If a greater abundance of fungi and bugs exists in our warm and moist climate, trees with a natural insect repellent ought to be better protected. I asked a friend in Melbourne about Australian gum trees because eucalyptus oil is a powerful repellent (I spray it to deter insects and ticks). She replied, “I’ve seen lots of old dead trees with high up hollows where birds and possums nest, and quite a few living giants with a hollow at the base (such that a person can stand inside them, how the trees remain  standing is a miracle), and plenty of fallen trees/logs with hollows in them.” There dies a beautiful hypothesis. But I have another.

The same Swedish researchers noticed the fastest growing trees were most vulnerable, much more than oaks which age slowly and seldom have hollows until past middle age, like the famous “great trees” listed by the Woodland Trust. Trees grow faster in the mid-Atlantic climate, which probably means that less lignin, a hydrophobic, cross-linked polymer, fills spaces in cell walls. I’d be glad to hear a better explanation.

Posted in Environment, Nature, Trees | Tagged , , , , , , , , | 2 Comments