Category Archives: City living

How birds avoid cuckoos

By John Upton

One of nature’s more ridiculous sights is that of a pair of adult birds rearing an oversized cuckoo chick.

Cuckoos are members of a large family of birds, some of which have done away with chick rearing, instead depositing their eggs in the nests of other species. This is called brood parasitism.

The parasitized birds rear the cuckoo chick as if it were their own, even as it grows to dwarf them in size — and as it pushes any other chicks from the nest to certain death.

Illustrated by Perry Shirley.
Illustrated by Perry Shirley.

(Ever noticed a dead chick beneath a tree and wondered how it fell out? Next time look up for a nest, and wonder whether a cuckoo is being raised therein.)

It seems that the the parental compulsion to raise young is so strong that the parasitized birds remain blind to the possibility that the brood contains none of their own DNA.

While many bird species remain oblivious to what would seem to be obvious signs that they are raising an unrelated chick, selection pressure has of course led to the evolution of some defenses against brood parasites.

Scientists compared defensive strategies developed by barn swallows living in China with those in Europe and found that they developed different defenses.

In Europe, martins and barn swallows, which seem to be better than some similar species at avoiding cuckoos, prefer to build their nests indoors. That’s where cuckoos are less likely to strike; they prefer open areas and avoid human habitation.

“Suitable cuckoo hosts breeding close to human habitation enjoy a selective advantage from breeding indoors,” the researchers wrote in a paper published in the journal Behavioral Ecology and Sociobiology. “These findings suggest that birds benefit from association with humans in terms of reduce risk of parasitism.”

The scientists say it’s harder for the barn swallows to build nests indoors in China. There, they have developed an alternative trick that’s largely lacking among their European counterparts: A Chinese barn swallow will often recognize a cuckoo egg. So when a cuckoo egg shows up in its nest, it will toss it over the side.

“These findings suggest that barn swallows in China have gained egg rejection behavior because they cannot avoid parasitism when breeding outdoors.”

Watch a Reed warbler feed a much larger cuckoo chick:

Parasite hijacks cells, dulls fear

Cats, such as Poppy here in Oakland, are the definitive hosts of Toxoplasma gondii / Kamala Kelkar

By John Upton

Toxoplasma gondii is a wily parasite that’s beautifully adapted to the urban environment. The protozoans pass between rats, house cats and humans with aplomb.

Once inside a rat, the single-celled stalker diminishes its host’s fear of cats, which helps it spread from the hunted to the hunter. From the cat, the parasite passes into kitty litter, where it can infect new rats and enter humans through litter-tainted food or licked fingers.

Perhaps one quarter of the world’s human population is infected. Consequences are seemingly slight: Temporary flu symptoms and a lifetime of benign infection. But inside the central nervous system the disease could trigger depression and schizophrenia and reduce reaction times. Infected humans are more likely to crash their vehicles than those who are uninfected.

Researchers have honed in on a deft trick used by the parasite to spread through the body and commandeer parts of its hosts’ brains. By affecting brain function, the protozoans could help cats catch infected rats.

T. gondii under a microscope / Flickr: OmarCerna

The protozoans bust into dendritic cells, which play major roles in the immune system. Research published last week in PLOS Pathogens reveals that the protozoans trick the infected cells into producing a compound dubbed GABA.

Production of GABA excites the infected cell, encouraging it to move around the body and aiding in the parasite’s migration into the brain.

GABA is also a neurotransmitter; it stifles sensations such as fear and anxiety.

“For toxoplasma to make cells in the immune defence secrete GABA was as surprising as it was unexpected,” said Antonio Barragan, researcher at the Center for Infectious Medicine at Karolinska Institute and the Swedish Institute for Communicable Disease Control, “and is very clever of the parasite.”

Birds bludgeoned by buildings; criminal case dismissed

After a prosecution began, developers spent hundreds of thousands of dollars preventing birds from colliding into Consilium Place in Toronto. Courtesy / CBRE

By John Upton

Despite inadvertently killing hundreds of birds that collide with their high-rise buildings every year, developers were acquitted last week by a Canadian judge of alleged environmental crimes.

The landmark case against Menkes Developments highlighted the cruel effects that reflective skyscrapers have on birds. Birds can mistake the windows for stretches of uninterrupted skyscape and fly blithely into them, with often fatal consequences.

The problem is vast and widespread. The U.S. Fish & Wildlife Service estimates that 100 million to 1 billion birds are killed by flying into buildings every year in the United States alone. (By comparison, the same agency estimates that cats kill 40 million birds yearly in the U.S. and that nearly 200 million are killed by electrocution.)

In response, some cities, such as San Francisco, require developers to protect birds by making their windows easier to see with avian eyes. This can be done by etching or frosting the glass, painting the windows with UV patterns that are more easily spotted by birds or by building architectural features across them.

Canada warblers are vulnerable to dying during collisions with windows. / Flickr: Jeremy Meyer

Similar laws apply in Toronto, home to Menkes Developments’ Consilium Place, which was at the heart of the recent case. But the laws there only apply to new construction.

In dismissing the criminal charges, which were brought by attorneys for bird activists, a judge ruled that developer could not be held responsible for the deadly reflection of sunlight — and that it made no effort to harm birds.

The outcome was not a total loss for bird populations or bird lovers. In response to the lawsuit, the office complex in 2011 was coated with film in a successful bid to reduce the number of birds that unwittingly fly into it.

“The number of collisions is dramatically down,” Ecojustice lawyer Albert Koehl told The Star newspaper, “so there are obviously solutions that do work.”

Americans allowed to destroy protected bird nests, thanks to previous president

By John Upton

Homes are not merely places where we rear and raise children. Houses and apartments provide shelter from the elements; seclusion for amorousness; and kitchens where we can store and prepare food.

So it goes with bird nests. The most obvious uses of these homes, be they bundles of twigs, hollowed out trees or even gaps between boulders, are to provide places where birds can rear and raise chicks. But nests can also provide avian tenants with shelter from the elements; places to groom and romance their feathery mates; and camouflage and protection from predators.

Pale Male / Courtesy:

The resonating effects of the loss of a bird’s home have been on clear display during the past decade in New York City. In late 2004, as New Yorkers hurried between heated stores, offices and homes in the weeks before the holiday season, residents of 927 Fifth Avenue had grown decidedly fed up with a pair of red-tailed hawks that nested on their building’s façade — and with the flocks of human fans that they attracted. So while Pale Male and his mate, Lola, were out and about one day, the residents destroyed the birds’ 400-pound window-ledge nest. Vigils and protests ensued, and within a month the exclusive apartment building’s co-op had capitulated and agreed to allow the birds to return.

But it was not the same. Pale Male and various mates had produced two to three chicks at 927 Fifth every year since 1995. After Pale Male and his mate rebuilt the nest, however, he lived for years as an empty nester. Despite successfully wooing a mate, not a single egg hatched in the nest until 2011, taking a bite out of the city’s burgeoning urban raptor population. Conservationists blame Pale Male’s fatherhood failures during the breeding seasons from 2005 to 2010 on the stress of losing his home during that cold wintery month.

It wasn’t just the city’s red-tailed hawk population that took a hit from the co-op’s wildly unpopular actions. In granting the wealthy and well-connected residents permission to destroy Pale Male’s home, President George W. Bush’s administration rewrote the nation’s rules around how the nests of protected birds can be treated. The Migratory Bird Treaty Act of 1918 protects “migratory birds,” including red-tailed hawks and approximately 1,000 other species, “or any part, nest, or egg of any such bird.” But Bush’s U.S. Fish & Wildlife Service told the co-op that it didn’t need a permit to destroy the nest, so long as no eggs or birds were present when the nest was cleared out. Under the ruling, a nest in that scenario was defined as “inactive,” and therefore unprotected.

That means an American can now destroy the nest of a species of bird that’s protected under the Migratory Bird Treaty Act. If you want to do it, you need only wait for the non-breeding season and then strike while the residents are off foraging or hunting. No biological expertise is necessary.

But if you’re into inflicting such misery on birds, you might want to do it soon.

Conservationists filed a petition last month with President Barack Obama’s Fish & Wildlife Service, seeking a new interpretation of the law. San Francisco-based nonprofit Wild Equity Institute wants the federal government to tweak some definitions of words in the Migratory Bird Treaty Act and to make it clear that permits are required before a nest of a protected species can be destroyed, regardless of who might or might not happen to be at home at the time.

“It’s a modest petition,” Wild Equity Institute executive director Brent Plater told me. “We’re just asking the Obama administration to put the law back to where it was for decades.”

It took nearly a decade, but Pale Male and a new mate are raising chicks again in a nest on a window ledge at 927 Fifth:

How to save imperiled native bees — video

By John Upton

Much of the world is in a crisis that most of the world knows nothing about: Native pollinators, the bees, bats, butterflies, hummingbirds and other creatures needed by crops and wild plants, are disappearing.

While reporting for Grist over the weekend on an effort to tally bees, named The Great Sunflower Project, I interviewed Oakland bee-lover Celeste Ets-Hokin at her pollinator garden. I threw together this two-minute video, in which Ets-Hokin describes the pollinator problem and explains how easy it is to help.

Racing pigeons juice city populations

Stray homing pigeons appear to be boosting feral populations / Flickr: mugley

By John Upton

Visit any of the world’s cites and you will almost certainly encounter hordes of the world’s most ubiquitous and well-adapted avian urban dwellers.

The humble rock dove, or pigeon, is derided as a flying rat, spreader of disease and graceless depositor of mounds of guano. But it is also a prized domestic species that has been bred for nearly 5,000 years as a food source, message deliverer, racer, and show bird boasting a startling array of plumages and physiques.

It is this very popularity that has seen the species transported around the world, where captive and racing birds have escaped into the wild to establish vast feral populations amid the same irritated humans who were responsible for its spread.

Cities suit rock doves superbly. Before they were domesticated, the birds nested along cliffs in Europe, North Africa and parts of Asia. Today, buildings in cities provide plentiful cliff-like environments for their nests; humanity’s wont to waste grants them plenty of grain and other food; and the hostile nature of cities for most large animals protects them from predation, although raptors are increasingly moving into cities to feast on their meat.

Feral rock dove populations are virtually immune to human-led efforts to snuff them out. And new research suggests that pigeon racers could be constantly fueling the wild populations with physical prowess-imbuing genes, helping to spawn today’s urban super-pigeons.

University of Utah researchers studied the genes of hundreds of domestic and free-living pigeons in the United States in an effort to map their family tree. What they discovered, and reported in February in the journal Current Biology, was a free flow of genes from specially bred racing pigeons into the wild.

Anywhere from five to 20 percent of racing pigeons fail to complete any given race. Some fall prey to predators. But others may simply get lost, or choose to not return home, and then blend into wild populations, where they coo and carry on and breed with feral lovers.

“[Racing homers] are bred for speed, endurance and navigation ability,” researcher Mike Shapiro told me. “They’re great flyers, unlike many of the ornamented or other exhibition breeds, so it’s not too surprising that they do well in the wild.”

All free-living rock pigeons in North America are feral, having first arrived some 400 years ago, with modern racing pigeons appearing a couple of centuries ago, Shapiro said, meaning that all of the continent’s populations must have been established by domestic breeds at some point.

“We hypothesized that they probably had major genetic contributions from racing homers because the breed is so popular and they, perhaps more than any other breed, have ample opportunities to fly free and escape,” Shapiro said. “This hypothesis is supported by our genetic data.”

Next time you see a broken-legged pigeon plunging its filthy face into trash strewn by the side of a busy street, spare a moment to give thanks to pigeon racers for potentially growing the species’ vigor. After all, these dumpster divers help push our wasted French fries and other food scraps up a nascent food chain and into the stomachs of the awe-inspiring hawks and Peregrine falcons that also inhabit our cities. That seems better than leaving the food to rot – and belch out its hydrocarbons as climate-changing methane.

Some of the pigeon breed studied by University of Utah researchers / Courtesy: Current Biology

[This pigeon story was requested by reader John Fleck. Request your own here or on my Facebook page!]

French fry to falcon — a modern food chain

By John Upton

A hunk of potato planted in a field sprouts into a leafy plant. A potato swells in the soil beneath the low canopy, fostered by water, fertilizer and pesticide, before it is torn out by a tractor and scrubbed and sliced by machine. A sliver of it tumbles into a plastic bag that is filled, sealed, frozen and trucked to a downtown fast food store.

When I was reporting for the Bay Citizen last year, editor Jonathan Weber snapped this falcon feasting on a pigeon outside our newsroom windows

The French fry is boiled in oil and lands in the bottom of a cardboard holster. The customer’s gluttony is satiated before his super value meal is done and the chip lands near a trash can, spinning in a waterfall of leftovers and packaging. It is grabbed by a rock pigeon which, hours later, is snatched up by a Peregrine falcon and fed to fledglings in a nest on an office building’s roof.

Peregrine falcons were nearly wiped out in the United States by the 1970s, their shells made fatally fragile by DDT sprayed to keep mosquitoes at bay. The poison bioaccumulated in the food chain and became concentrated in the falcons. The remarkably large raptors recovered spectacularly after the chemical was banned and American Peregrine falcons were removed from lists of endangered species in the 1990s.

As the populations recover, they have mastered the city environment, nesting on buildings and bridges. By preying heavily on the ubiquitous pigeons that eat our voluminous waste, they have established a food chain that runs from farm to trash to scavenger to urban predator.

But new and old threats nag at these birds all around the world.
Old: Falconers steal chicks from nests to be reared as hunters (and, increasingly, for lucrative commercial purposes – landfills hire falconers to scare away seagulls).
New: Toxic flame retardants used in furniture seep as dust into the environment and have been discovered bioaccumulating at high levels in Peregrine eggs.

The flame retardant threat is pronounced in California, where a strict law based on outdated science mandates the use of such chemicals at certain levels. Last week, Gov. Jerry Brown ordered a review of the 37-year old law in a bid to protect human health and wildlife. The review, by the California Bureau of Electronic and Appliance Repair, Home Furnishings and Thermal Insulation, is expected to establish a new industry standard that will be adopted as law by other governments.

The threat of poaching, meanwhile, is as established as the milleniums-old sport of falconry. To help curb that threat, scientists often try to keep vulnerable locations of nesting falcons a secret.

Here is a video from YouTube of commercial falconer Steve Vasconcellos keeping gulls away from a dump at Half Moon Bay, California. Vasconcellos was in talks with the San Francisco Giants to scare seagulls away from the waterfront ballpark, but the franchise’s operations manager recently told me the team had balked at the price tag, which I understand would have been well over $100,000 a year.