Eric Dinerstein

Eric Dinerstein

Eric Dinerstein is Director of Biodiversity and Wildlife Solutions at RESOLVE. Previously, he was Lead Scientist and Vice President for Conservation Science at the World Wildlife Fund. His areas of specialty include tropical mammals, large mammal biology, biogeography, bats, rhinos, seed dispersal, and community ecology. With the World Wildlife Fund, he led many of the organization's most important scientific projects, including the Global 200 Ecoregions, examples of which form the basis of his book Tigerland and Other Unintended Destinations. Dinerstein is also the author of The Kingdom of RaritiesThe Return of the Unicorns: The Natural History and Conservation of the Greater One-Horned Rhinoceros and What Elephants Know: A Novel, among other articles and publications.
He attended Northwestern University and Western Washington University, and did his post-graduate studies at the University of Washington (Organization of Tropical Studies) and the National Zoological Park's Conservation and Research Center.

Photo credit: Flock/bandada by user Rafael Edwards

Raven's Roost

Ravens are hardy birds and remain in the Maryland region through the winter.
Photo by Doug Brown, used under Creative Commons licensing. Ravens are hardy birds and remain in the Maryland region through the winter. Photo by Doug Brown, used under Creative Commons licensing.

Originally published by Village News, a publication of the community of Cabin John, MD. By October, most of the birds that breed here in the East have taken wing to warmer climes—South Carolina, Florida, the Caribbean, Central America, or even the Peruvian Amazon—to pass the winter in places where bugs, caterpillars, and fruits are still plentiful. Only hardy species remain behind, well adapted, by dint of feathers and extra fat, to cope with the freezing temperatures and fierce winds of winter. One of the pleasures of a crisp, clear November day in Cabin John is spotting a pair of large black birds roosting on the water tower’s railing at the top of the hill. Watching over us from the highest vantage point in our hamlet is the largest perching bird in the world—the Common Raven. When they fly off from their perch, it’s easy to distinguish the Common Raven from the ubiquitous crows of the neighborhood. Ravens are larger than crows and with a more robust bill, and a longer wedge-shaped tail. But it’s the vocalization that most memorably sets them apart: once you learn to recognize the Raven’s loud croak you will never forget it. And it’s a useful field ID to know: you can travel almost anywhere in the wilds of the northern hemisphere, from the coast of Siberia, to the slopes of Mt. Everest, across to Spain, and much of North America down to southern Mexico to find this species. The Common Raven has one of the widest ranges of any perching bird. In the United States, the Common Raven was once a bird of the wilderness, but it has over the decades made its way into areas where settlements are interspersed with forest. That this denizen of remote regions uses our water tower as a winter roost gives me great comfort: the Raven’s discriminating eye evidently sees wilderness worthy of occupation as close by as the shores of the Potomac and Cabin John Creek. It’s rare to see ravens inside the Beltway, so our pair are something special; perhaps not the first amenity a real estate agent recites in touting the benefits of “Cabin John living,” but a highlight to anyone who cares about nature. The first introduction many of us had to ravens was in Poe’s most famous poem. But his take, both melodic and macabre, made the talking bird a frightening subject. Along with other members of their family (the Corvids), crows, jays, and magpies, ravens may be the most intelligent of all birds and they have among the largest brains of any bird. The raven’s cultural significance is well established among tribes of Northwest Indians who consider the bird a god figure and trickster, perhaps in recognition of its cleverness, and include representations of it in their totems. I have also seen ravens in Bhutan, where it is the national bird and where the monarchs wear a crown depicting a raven. Ravens pair for life and are long-lived among wild birds, perhaps reaching 20 years of age. Their intelligence, wide global range, broad diets, and adaptability to a variety of habitats are some reasons why ravens, crows, the American blue jays, and magpies are so abundant. But Nature always has surprises in store. In 1999 the first instance of West Nile Virus (WNV) was recorded in the U.S. and the disease affected many bird species but especially hit hard were members of the Corvid family and many birds simply disappeared to the consternation of ornithologists. By 2002, WNV had become widespread in the eastern U.S. and for a while, it was hard to even find the once-ubiquitous crows, let alone a raven. Somehow, our neighborhood ravens survived, or their offspring did, or a new pair moved in to take the place of the departed. Either way, we should be delighted to have them back. And for the record, I prefer the wild raven’s deep croak—the sound of wilderness—to the talking version’s “Nevermore.”
Photo credit: Flock/bandada by user Rafael Edwards

Restoring the Monarchy to Cabin John

A monarch butterfly in DC.
A monarch butterfly in DC. Photo by crystalndavis, used under Creative Commons licensing. A monarch butterfly in DC. Photo by crystalndavis, used under Creative Commons licensing.

Originally published by Village News, a publication of the community of Cabin John, MD. For many of us, perhaps the first butterfly we were able to identify was the Monarch. They were our companions of summer with their bright orange and black wings floating over flower-strewn gardens, as if this Earth was indeed their dominion. In recent summers, though, the children of Cabin John and much of the eastern U.S. would have been lucky to see more than a handful. The Monarch (Danaus plexippus), once one of the most abundant butterflies of North America, has suffered a tremendous population crash over the past twenty years. On their wintering grounds in the highland conifer forests in the state of Michoacan, Mexico, as recently as 1996 they once numbered as high as 1 billion individuals. Since then they have plummeted to only 33 million counted in 2013. That may still seem like a lot of butterflies. But to put in perspective, imagine if the human population had declined by 92% over the same period!
Monarch larvae. Photo by Nicole Castle Brookus, used under Creative Commons licensing. Monarch larvae. Photo by Nicole Castle Brookus, used under Creative Commons licensing.

There is so much beyond their beauty and their association with summer that is worth preserving; they have an important ecological role as pollinators of many flowering plants. Monarchs are also a wonderful example of mimickry, a relationship formed with the similar-marked Viceroy butterfly that we learn about in biology textbooks (although the textbooks need updating—see my column next month). Since Monarch females lay their eggs on milkweed plants, and milkweeds only, they depend on its availability throughout the range. The brightly striped larvae look like they have dancing shoes on, many pairs of them, and walk all over the leaves, ingesting the tissues loaded with cardiac glycosides that make the caterpillars and adults distasteful to almost all birds and other would-be predators. And then there is their intrepid migration, more on the order of birds than insects. Amazingly, some individuals fly as far as 3,500 miles from the northernmost part of the breeding range in the U.S. and Canada to their wintering ranges in Mexico. The trip back north is even more remarkable: returnees only travel part way before they lay their eggs on milkweed, often in Texas and neighboring states, and are replaced by a new generation heading further north to their ancestral point of origin. Often it takes five or six generations to reach our backyards from Michoacan, adding more drama to their remarkable story.
Monarchs are known for their impressive migration. Photo by Tarnya Hall, used under Creative Commons licensing. Monarchs are known for their impressive migration. Photo by Tarnya Hall, used under Creative Commons licensing.

For decades, ecologists north of Mexico pointed fingers at Mexican officials as responsible for the precipitous decline in monarch populations. They turned a blind eye, we said, to illegal clearing of the oyamel fir forests where the monarchs cluster in winter in great numbers and where poor villagers eked out a leaving through timber harvesting or rustling. But now, with these areas better protected, Mexicans have a right to point the finger back at the gringos. At a conference last February in Washington, DC, I was lauding ex-President Salinas for his country’s unparalleled biodiversity and the steps they had taken to protect it. Then I brought up the monarchs. Before I could say more he replied, “But it is American farming practices that are to blame for reducing the number of Monarchs.” And he is right. Conservationists, Mexican and American, attribute the disappearance of mikweed host plants to new agricultural practices in the Midwest—and along the Monarch’s main route to and from Mexico—where genetically modified seeds are bred to resist herbicides that eliminate milkweed nearby. Once established, the farmers can spray Roundup with abandon and kill any wild milkweed that lives between the regimented crop rows. Increased use of these genetically modified crop strains and herbicides in fields of the two most planted crops, corn and soy beans, are correlated with the steep decline in Monarch populations between 1999 and 2010. The leading expert on monarch populations, Dr. Chip Taylor, estimates the loss at 120-150 million acres of the monarch’s milkweed habitat across much of the cornbelt in the Midwest. The solution is to restore milkweed on a grand scale, to provide stepping stones, or way stations of “milkweed habitat” where returning generations can stop and breed as they make their way back north to us. There are several groups working nationally to spearhead this noble effort. What can we in our little hamlet of Cabin John do to restore monarchs to their rightful place? The first step is to be honest with ourselves. It’s not fair to blame just corn and soy bean farmers in the Midwest—we are a nation of Roundup users. So the first step is to stop using this dangerous chemical and other pesticides (including herbicides and insecticides) that kill a wide range of plants and beneficial insects and endanger our own health. (Pulling weeds is a chore; we have had great success with mixing a gallon of vinegar with a pinch of salt and a few drops of dishwashing detergent. If you drip the mixture on the offending weed’s root area it will be dead in a few hours, especially on sunny days. Try it!).
Asclepias tuberosa is one of the most popular milkweed species. Photo by squamatologist, used under Creative Commons licensing. Asclepias tuberosa is one of the most popular milkweed species. Photo by squamatologist, used under Creative Commons licensing.

The second step is to get our own hands dirty—by planting milkweed to foster suitable habitat for Monarchs. Many neighbors already do this by planting the beautiful butterfly weed (Asclepias tuberosa), the showiest of the milkweeds. Its bright orange flowers are a magnet for many kinds of butterflies including nectaring Monarchs. Even better is for all of us in our yards to plant some common milkweed as monarch waystations. If you have never put your nose in a bright pinkish-green ball of common milkweed flowers (Asclepias syriaca), you have missed one of the most fragrant floral scents in nature. The perfume is intoxicating. The plant’s foliage may not be exceptionally attractive, but there are other milkweeds in the genus Asclepias, such as swamp milkeed, A. incarnata, obtainable in nurseries, that have attractive foliage and flowers. Even better, if you have never inhaled the fragrance from sand vine (Cynanchum laeve), also called honey vine or climbing milkweed vine, another member of the family, you have not experienced the joy of native gardening. For nearly six weeks of summer, sprays of small white vanilla and honey scented flowers attract pollinators by the score and are also hosts to monarch caterpillars. I have pods to give away to interested gardeners who would like a more ecologically beneficial and fragrant alternative to the destructive Chinese or Japanese wisteria or trumpet creeper vine. We can go further to ensure that future generations of Cabin John residents enjoy Monarchs by volunteering to do a bit of butterfly gardening. The noted writer Michael Pollan observed that, “a lawn is a garden under totalitarian rule.” But even some of our local gardens are so predictable: azaleas, rhododendrons, hosta, etc. etc. etc. What if everyone in Cabin John devoted 10% of their gardens to plants that butterflies need for nectar and their hungry caterpillars need for sustenance? We would shift from a lawn-dominated ecosystem to the East Coast’s first community butterfly reserve. Community spaces, like the Clara Barton school yard, the Cabin John shopping center by the side of the co-op, or even the new green strips along Macarthur Boulevard could be planted with butterfly plants that would add beauty and color to our neighborhood roadway and wouldn’t need mowing. The natural vegetation of this part of Maryland is forest and the only way to suppress its return to your yard is through chemicals, mowing, and weeding. Why not reduce the chemicals, fertilizer, and mowing by, at least in a small section of your yard, giving the Monarchs a chance to be your neighbor once again? At least nationally, the Obama administration is with us, appointing a task force to address the decline of the Monarch butterfly and avoid the necessity of listing it as an endangered species. Monarchs won’t go extinct as a species but the spectacular phenomenon of this long-distance migration by the eastern population might disappear in our lifetimes. Picking up a dozen milkweed plants at the nursery and giving them a sunny spot in our gardens will provide food and a home for these most attractive natives. And if every yard would hold some milkweeds we should soon be able to see the graceful dance of the Monarchs once again.
Photo credit: Flock/bandada by user Rafael Edwards

Bogeymen of Nature

Eastern rat snakes have a bad reputation. Photo by D. Gordon E.
Eastern rat snakes have a bad reputation. Photo by D. Gordon E. Robertson, used under Creative Commons licensing. Eastern rat snakes have a bad reputation. Photo by D. Gordon E. Robertson, used under Creative Commons licensing.

Originally published by Village News, a publication of the community of Cabin John, MD. In one respect, the Eastern rat snake is the great white shark of the Potomac River’s towpath. Just as the sheer thought of the marine predator keeps swimmers out of the water, the sight of an Eastern rat snake diverts many strollers from a riverside walk from May until autumn. There is one major difference: you are a million times more likely to encounter on the towpath an Eastern rat snake, one of the most common reptiles in our woods, than a great white along the Maryland coastline. In fact, the global population of the great white shark, put at less than 3,500 for this ocean-going predator, is likely less than the number of wild tigers in all of Asia’s forests. The native Eastern rat snake looks ominous with its black skin and near six-foot span. It poses no threat to humans, however, and is a skilled hunter of small mammals such as mice and rodents. Harmless or not, the mere sight of one sends many walkers the other way. Why is that? Why do humans fear snakes, spiders, and scorpions more than modern day concerns like nuclear fallout or climate change? One answer is suggested in an intriguing book, entitled Sunrises, Serpents, and Shakespeare, by Gordon Orians. His central theme is that the emotional make-up of modern humans has been strongly influenced by evolution through natural selection during our ancestors’ early days in the African savannas. Back then, constrictor snakes like pythons—which catch and crush their prey before swallowing them—and venomous snakes like cobras and vipers posed significant mortal threats and so our ancestors who were able to quickly recognize and avoid them left more offspring who survived than those early uprights who tread on or too close to a deadly serpent. Our evolved ability to recognize snakes in the wild and attendant fear at their sight, has served humans well, and thus we maintained this vigilance—even a genetically predisposed ability to detect the flecked scale patterns of many poisonous varieties—as well as, in our conscious minds, a deep anxiety about them. In the Indian subcontinent, this cautious response is appropriate, as more than 50,000 people die each year from venomous snakebites. Some public health officials even wonder why more tropical medical research is not directed to producing more anti-venoms to address this prime health hazard. People strongly dislike snakes of any kind typically, but they don’t like rats much either. Imagine the reaction a Cabin John homeowner has to a single rat scurrying out of the garbage can. Now what if you drove onto your yard at night and the headlights illuminated hundreds of rats on the front lawn? All of a sudden, having natural predators around like the Eastern rat snake appears in a whole new light. They offer as valuable a community service as our local exterminator provides (a shout-out to Mr. Bugs!), and the rat snake works for free. Eastern rat snakes range south to the tip of Florida and occur in the Everglades. It is in this magnificent ecosystem that a new chapter is being written that will soon find its way into the ecology textbooks. Floridians tired of their pet pythons, Burmese or otherwise, have released them into the swamps of south Florida, where they have proliferated (no chance of them moving north to the Potomac because they cannot survive frost). According to local ecologists, there may already be thousands of pythons in the Everglades, so numerous that it is now virtually impossible to eradicate this large constrictor. Consequently, bobcats, raccoons, and other middle-sized predatory mammals have all but disappeared. Sometimes, when invasives take over, we see the runaway ecological change in the composition of an ecosystem rather than the checks and balances of one population keeping another at bay but not eliminating it. Snakes have an outsized effect on the human psyche and a profound one on wild nature, and sometimes both. I was bicycling home to Cabin John along the towpath from D.C. recently, thinking about how common rat snakes had been this year along the Potomac when I had to come to a screeching halt near Lock 6. Lying perpendicular to the trail was a nonchalant Eastern rat snake. I waited patiently and then finally told it to check out the August issue of the Cabin John News and in the meantime to please slither to the side of the towpath. The snake obliged and continued its hunt for smaller mammals than me.