Birds Hitting Windows in Philadelphia

Like in other cities, buildings in Philadelphia's Center City have reflective glass surfaces that fool birds so that birds die in window strikes. Two researchers that have been studying the problem estimate that about 1,000 birds die each year in their four-block study area on Market Street. Most of the victims are migratory songbirds such as Ovenbirds and White-throated Sparrows, but they also include American Woodcocks and Wild Turkeys. Possible solutions, like elsewhere, involve shutting lights off at night during periods of heavy migration and incorporating designs that make glass surfaces more visible to songbirds:

Films applied to the glass to make it visible are one idea. At Temple University, art students held a competition to come up with attractive and effective designs. The winning version resembled sheet music with the notes shaped like birds.

Another student cut translucent film into the shape of molecules for the chemistry building's windows.

A New York company, SurfaceCare, provided a film with small, almost imperceptible, black stripes for the Bear Country exhibit at the Philadelphia Zoo, which, like many other zoos, has a combination of glass enclosures and trees. The bird strikes stopped.

SurfaceCare owner Marc Sklar is looking at new technologies, including glass that has elements in the ultraviolet light spectrum, which humans can't see but birds can.

Christine Sheppard, a bird collision expert with the American Bird Conservancy, has been testing prototypes of bird-friendly glass at a bird-banding station near Pittsburgh. She said the results could be used to write guidelines for architects.

"Nobody wants to kill birds," she said. But, still, "nobody wants more rules and regulations." Her goal is to educate.

"There are lots of beautiful buildings that are very bird-friendly," she said. "You can be creative and do architecture that will win awards" and still not kill birds.

Recently, the national green building certification program - Leadership in Energy and Environmental Design (LEED) - began a pilot program that gives buildings points for having bird-friendly windows.

"So-called green buildings . . . are never green to me, no matter what their LEED award, if they kill birds," Muhlenberg's Klem said.

Chicago and San Francisco require that new buildings and major renovations incorporate bird-safe elements.

Minnesota requires that all state buildings turn off lights during migration. Michigan's governor issues an annual proclamation declaring migration "safe passage" dates and asking that buildings remain unlit at night.

A year ago, Illinois Congressman Mike Quigley introduced national legislation, still pending, to mandate bird-friendly construction for federal buildings.

Birds and Fireworks

Last year, thousands of blackbirds died on New Year's Eve in Beebe, Arkansas. This year it happened again, though in smaller numbers.

"Well, there was just birds falling down on the street and people dodging and missing them," Taylor said. "And we were down the street picking them up. We got called out by the chief and we all [came] out trying to pick them off the street."

Taylor added that the Game and Fish Department took about 30 of the nearly 100 birds for testing to try to determine what happened.

Fireworks were blamed for the deaths of thousands of blackbirds last year, but it's unclear whether fireworks were the cause this time. Police imposed an impromptu ban on fireworks when the birds began falling this year.

Lt. Brian Duke of the Beebe Police Department told ABC this year wasn't nearly as bad as last year, when the birds covered the streets of Beebe. This year, they were concentrated in a smaller area and the birds were cleaned up quickly. There haven't been any reports of people being hit by a falling bird.

Biologists said last year's kill was caused by birds who were spooked off their roosts by the loud explosions and began flying into homes, cars, telephone poles and each other.

Apparently the problem of birds being startled by fireworks is not limited to Arkansas.

It turns out that birds are easily startled by fireworks. A study in the November/December issue of Behavioral Ecology used weather radar to track birds disturbed by New Year’s Eve fireworks for three years in the Netherlands. They found that thousands of birds took to the skies shortly after midnight and didn’t settle down again until 45 minutes later.

The scientists estimated that hundreds of thousands of birds, including several species of migratory waterfowl, were disturbed by the fireworks each year in the Netherlands alone. “The unexpected loud noises and bright lights fireworks produce are probably a source of disturbance for many species of domestic and wild animals,” the scientists wrote.

Most of the time, birds won’t die from the fireworks displays, as they did in Arkansas, the researchers note. But they still suffer from disrupted sleep, interrupted feeding and the energetic costs of flight and resettlement.

This is such a consistent problem that perhaps the presence of large bird flocks should be a consideration in the timing and location of fireworks displays.

Fishing Line and Birds

At one time or another, we have probably all seen a bird hampered by fishing line, with the line wrapped around its legs or tangled elsewhere on its body. This is a widespread problem, especially since plastics line fishing line persist in the environment.

The problem is not new — or limited to Prospect Park. Birders in other city and state parks report similar cases. The Ocean Conservancy in Washington points out that monofilament fishing line, which is made from an individual fiber of plastic, has been in use since World War II, and as the decades pass, it has accumulated in the water and on land. For a quarter-century, the conservancy has organized coastal cleanups throughout the world on a single day in September. Over that time, 1,340,114 pieces of discarded fishing line have been collected, according to the group.

“Plastics in general are the most persistent forms of marine debris,” said Nicholas Mallos, a conservation biologist with the conservancy. “Once monofilament line becomes loose in the marine environment, it poses a serious threat.”

Birding groups and wildlife experts say that most fishermen and women are quite likely unaware of the impact on wildlife. The solution, they contend, is more education, as well as the availability of secure receptacles for old fishing line and hooks. Open trash cans easily overflow, they say, and the wind blows the line away.

Killing Songbirds for European Cuisine

In yesterday's Loose Feathers, I linked to a report on an incident in which Hungarian officials seized a shipment of about 10,000 illegally-killed songbirds. The dead songbirds were most likely headed for restaurants in northern Italy. Traffic in wild songbirds is unfortunately routine in Europe, even though it is officially illegal in most of the EU. The most famous of the trafficked songbirds is probably the endangered Ortolan Bunting, part of Francois Mitterrand's last meal. However, many other species are also involved. Conservation organizations in Europe are doing their best to curtail the trade in songbirds, with mixed success so far.

Bee-eater / Photo credit: BirdLife Cyprus

Cyprus has been a center of songbird trapping, particularly during migration seasons when many birds are passing through the island on their way to and from mainland Europe. This fall almost 867,000 birds had been killed by mid-October.

The toll is estimated on the basis of field data from BirdLife’s ongoing field monitoring of trapping activity with mist nets and limesticks, part of a systematic surveillance programme. This latest estimate – 866,905 birds- represents the number of birds killed between Thursday 1st September and Sunday 9th October 2011. The trappers are after Blackcaps and other songbirds, which will end up as illegal, and expensive, ambelopoulia delicacies served up in law-breaking restaurants, allowing the trappers to make huge profits. The first estimate for the autumn 2011 season, posted on September 12th, was for almost 90,000 birds, but trapping has gained pace since then. The estimate will be updated every Monday until the end of October.

BirdLife Cyprus is asking birdwatchers and other wildlife lovers to sign an online petition asking the government of Cyprus to intervene. So far over 15,000 people have signed.

Injured Hawk Rescued and in Treatment

Last week, observers in San Francisco Botanical Gardens spotted a Red-tailed Hawk that had a nail stuck through its head. It seems that the nail must have been fired from a nail gun. For most of the last week, the hawk eluded rescuers, but last week, it was finally caught.

The juvenile bird was trapped Saturday evening at the San Francisco Botanical Gardens. It was immediately transported to the wildlife center where specialists stayed late to receive it, Dmytryk said.

WildRescue had been notified of the injured bird nearly a week ago and had tried to trap it several times last week without success.

But observers got close enough to the bird to see the nail extending from its cheek through the front of its head. They said the hawk appeared to be in pain.

Dmytryk's group had been using a trap called a bal-chatri, a trap made of wire mesh, to try to catch the injured hawk.

According to the report, the nail dropped out while the hawk was being taken to the wildlife center. The bird is currently alive and recovering.

There is a reward for information about the shooting since it is a federal crime to kill or injure birds without a take permit (or a hunting license in the case of game birds). I think it is terrible that someone would injure the hawk (deliberately or not) and then leave it without trying to get help for it. Fortunately, the hawk appeared to be able to hunt and eat, but it could easily have been otherwise. These are wild birds and deserve to be treated humanely and with respect.

Pelicans Dying from Puncture Wounds

By Jayson Mellom / TheTribuneNews.com

Some Brown Pelicans on California's Pacific coast have been appearing on beaches with odd puncture wounds, in some cases very large ones. Initially these were reported as possibly being the result of a knife attack.

Fifteen pelicans have died in recent days as a result of their chest wounds. Three were brought into the Pacific Wildlife Care center in Morro Bay on Thursday.

Two of the birds had to be euthanized because their injuries were so bad, and a third is being treated. Jeanette Stone, center director, said the wounds are more serious than the typical injuries pelicans receive from fishing hook and line entanglements....

A veterinarian examined the dead pelicans and found one to have wounds consistent with being caused by a knife or other sharp object. Wardens are continuing their investigation.

“We can’t rule out foul play,” Warden Sean Kenady said.

Now the state game wardens think the wounds may be the result of competition with sea lions.

Warden Sean Kenady said a kayaker saw a sea lion repeatedly pull a pelican under water until it failed to resurface. The department also got an email from the animal rescue group, Wild Rescue, which said its members had seen that behavior in the past....

Wardens think the injuries occurred when both animals were in a feeding frenzy on baitfish, with the pelicans feeding from above and the sea lions from below. The sea lions may have attacked the pelicans because they were competing for the same food source.

I would not have thought of pelicans and sea lions as being direct competitors, but they do share some habitats and both rely heavily on fish. So this explanation does make some sense. Confirmation (or refutation) of this explanation will come whenever the necropsies are completed.

Alaskan Birds with Beak Deformities

An unusually high number of birds with beak deformities have turned up around Alaska, according to the USGS. According to a statement issued by the agency, the birds most affected have been Black-capped Chickadees and Northwestern Crows.

In birds affected by what scientists have termed “avian keratin disorder,” the keratin layer of the beak becomes overgrown, resulting in noticeably elongated and often crossed beaks, sometimes accompanied by abnormal skin, legs, feet, claws and feathers. Biologists with the U.S. Geological Survey’s Alaska Science Center published their findings in this month’s issue of The Auk, a Quarterly Journal of Ornithology.

“The prevalence of these strange deformities is more than ten times what is normally expected in a wild bird population,” said research biologist Colleen Handel with the USGS, “We have seen effects not only on the birds’ survival rates, but also on their ability to reproduce and raise young. We are particularly concerned because we have not yet been able to determine the cause, despite testing for the most likely culprits.”

The disorder, which has increased dramatically over the past decade, affects 6.5 percent of adult Black-capped Chickadees in Alaska annually. Beak deformities in this species were first observed in the late 1990s and biologists have since documented more than 2,100 affected individuals. Increasing numbers of other species have also been observed with beak deformities throughout Alaska, British Columbia, and Washington. An estimated 17 percent of adult Northwestern Crows are affected by avian keratin disorder in coastal Alaska.

A variety of other Alaskan species have also been found with beak deformities, though not to the same extent as Black-capped Chickadees (pictured above) and Northwestern Crows (pictured right). An online gallery shows images of those two species, plus American Kestrel, Common Raven, White Pelican, Downy Woodpecker, Red-breasted Nuthatch, European Starling, Northern Flicker, Steller's Jay, Rough-legged Hawk, Red-shouldered Hawk, Red-tailed Hawk, Red-winged Blackbird, Yellow-rumped Warbler, Black-billed Magpie, Black-crowned Night Heron, Orange-crowned Warbler, and Clark's Nutcracker.

According to the USGS, beak deformities can have a variety of causes, so more research is needed. Possible candidates include pollution, poor nutrition, and diseases. Deformities have sometimes been traced to specific pollutants such as agricultural runoff.

To learn more, you can explore the USGS beak deformity website, which includes a section on how to help (if you live in Alaska or the Pacific Northwest) and links to articles the research team has published about the beak deformity problem. The two recent Auk papers are both downloadable at the last link.

Feverish Song Sparrows

Researchers are studying how western Song Sparrows respond to infections that might cause a fever.

As anyone who has suffered from a cold or flu knows, a high temperature is an unpleasant but important side effect of the body's immune reaction when fighting off pathogens. Laboratory studies, in which the immune responses of animals could be observed in detail, have shown that these responses display significant variations.

Why doesn't every organism defend its body at the maximum possible level of intensity? New immunological theories presume that immune responses are "costly," that is they compete with other energy-consuming processes such as partner selection, territorial behaviour and reproduction. Each individual has limited resources and must, therefore, enter into compromises, so-called trade-offs. This could explain why different species with different living conditions also display variations in their immune responses.

Apparently Song Sparrows do respond with fevers, but only at night, and more vigorously in southern areas. The really cool part of the study is that they found a way to study the birds' responses while the birds were in the wild.

Jim Adelman, a doctoral student at the University of Princeton, and a staff working with Michaela Hau and Martin Wikelski at the Max Planck Institute for Ornithology in Radolfzell have now succeeded in measuring fever and illness-related behavioural changes in various populations of a North American bird species living in the wild, the song sparrow (Melospiza melodia). For the tests, individual sparrows were caught in South California and in the northern state of Washington. To stimulate the immune response in a standardised way, both groups were administered a small dose of bacterial cell walls which causes fever for a limited period of around one day. A control group was left untreated. Following the administration of the injection, a small transmitter weighing approximately 0.5 grams was attached to the birds' backs and transmitted data on both their temperatures and activities over a 20-hour period.

Interestingly enough, the "injected" sparrows showed barely any increase in temperature during the day. However, during the night when, based on their natural biorhythms, birds reduce their metabolism and their temperatures by three to four degrees, clear differences emerged between the two populations: the Californian sparrows recorded a body temperature of over two degrees Celsius higher than the animals in the untreated control group of this population. As opposed to this, the temperatures of the more northern population increased by at most one degree and only during the first half of the night.

The lower fever temperatures of the northern sparrows is explained by their shorter breeding season. Since they need to devote more resources to breeding to cope with a shorter season, they may have less energy left over for producing a fever in response to infection.

Why Are Pelicans Dying in California?

For the second winter in a row, hundreds of Brown Pelicans have died or been sickened along the coast of California for reasons that remain unclear.

When found alive, the birds appear hungry and disoriented. But necropsies performed on dead pelicans found that they had been eating, so the casualties don't appear to be from lack of prey. But their stomachs did contain unusual prey, like squid—not the sardines and anchovies they normally dine on.

Many of the pelicans also appear to have some sort of unidentified residue on their feathers, which may affect the feathers' insulating ability. "When we wash them, you can tell something is coming off. The water is discolored, like when you wash really dirty clothes," Jay Holcomb, director of the International Bird Rescue Research Center (IBRRC) in Cordelia, Calif., told The Mercury News. "That's not normal."

Scientists don't know where this residue is coming from or what it is exactly, but so far theories include side effects from red tide or pollution runoff into the ocean.

Unfortunately the agency responsible for managing wildlife, the California Department of Fish and Game, has no money for an investigation because of the state's budget crisis.

Wildlife rehabilitation organizations, such as the International Bird Rescue Research Center, have been doing their best to rescue and treat sick pelicans. The IBRRC alone has handled 435 sick pelicans since the start of January. However, there have been so many sick pelicans that the groups' resources have been strained to the limit, especially for supplying food for so many pelicans at once.

Tasty Morsels

Since the weekend's blogging so far has been devoted to dead things and the birds that eat them, I decided to carry on the theme for another day. Someone on another site described me as morbid on Friday simply because I posted links to a leopard seal catching a pintail and this strange creation. To me, those are not morbid at all. Predation is an important part of the natural world, and the remains of dead animals can be interesting for a variety of reasons. Occasionally I find dead animals on my walks, and when I do, I usually try to figure out what they were and how they might have died.

Here a few images from dead things that I found recently. The first is a dragonfly at Buck Gardens in Far Hills, NJ. I am not sure how it ended up in the water, or why it stayed there for so long without something eating it. (The ponds are well-stocked with frogs and other potential dragonfly predators.) I am not entirely sure of the species, either. The best match I have found so far is Autumn Meadowhawk.

The thriving mosquito population in Lord Stirling Park made it very difficult to concentrate on warblers flitting in the treetops. One bird, at least, made itself easier to watch by lying in pieces on the ground.

It may not be entirely evident from this photo, but in the field I could recognize this as the wing of a Blue Jay. There does not seem to be much meat left on this wing; it has been picked clean except for bones and feathers. Of the predators likely to be in the park, Cooper's Hawk seems the most likely to have killed and plucked this jay. Sharp-shinned Hawks prefer smaller birds, and the other possible hawks prefer mammals, reptiles, or amphibians. Owls tend to swallow their prey whole rather than leave a mess like this. A mammalian predator is possible, but the spatial distribution of body parts suggested that they were torn off and dropped from high in a tree over the boardwalk.

There were other leftover body parts. Feathers were scattered here and there, and next to the boardwalk was the jay's head. Feathers were still stuck to the face and crown, but they had been ripped off the back of the head, so that the skull and spinal cord were visible.

Sadly, there seemed to be little left for a vulture to snack on.

Photo Study of a Dead Cuckoo

Yesterday, I saw a Black-billed Cuckoo. While not a rare species, it can be a difficult bird to find, even during migration. Unfortunately it was deceased. This cuckoo was lying in the bushes outside my cousin's house.

The cause of death is unclear. There were no visible wounds, which rules out a predator, like a raptor or a cat. However, its neck is broken, and there is some sort of shiny fluid around the bird's face (visible more clearly in the photo below). It may have crashed into one of my cousin's front windows and died from impact. A second possibility, since there was heavy migration the previous night, is that the bird died from exhaustion and broke its neck upon hitting the ground.

This was an immature Black-billed Cuckoo, which is apparent from the buffy shading on its neck. The long tail feathers also do not have as bold of a black and white pattern as would be expected on an adult. Yellow-billed Cuckoos, by the way, have much larger white spots on their tails, making the tail pattern an easy way to identify a perched cuckoo if you cannot see its bill.

While Black-billed Cuckoos have much less rufous on their wings than Yellow-billed Cuckoos, they still retain some. Their rufous is hard to see in the field, as it blends in with the dominant brown, but in the hand it shows much better.

In contrast to the dark upper wing, the underside is creamy white.

I was sorry to encounter such an awesome bird in such unfortunate circumstances. However, it was interesting to see some of its features up close, in a way that is rarely possible outside of a banding blind or a museum collection.

For larger images and a few more photos, see the cuckoo set on my Flickr account.

Birds Dying in Western Australia

Pacific Black Duck / Photo by interllectual

Over the weekend, there was a rash of bird deaths in Western Australia, at a landfill site south of Perth. The description of the symptoms sounds horrible:

DEC Pollution Response Unit environmental hazards manager Ken Raine said birds were seen frothing at the mouth and staggering around at the tip yesterday before scores of dead birds were discovered within a kilometre radius of the landfill site.

By today the body count had climbed to more than 200 with ibis, silver gulls, pacific black ducks, a raven and a pelican among the dead....

Some seriously ill birds have also been found among the bodies and are being monitored in a bid to determine the cause of the mass deaths.

The DEC's investigators are now blaming the deaths on a pesticide, Fenthion, but have not determined who dumped it at the landfill or why.

DEC pollution response manager Ken Raine said samples had been taken from waterways to check for contamination and the rubbish tip had been covered with sand while investigations were continuing.

Fenthion is a broad-spectrum organophosphorus insecticide used to control horticultural pests such as fruit fly and aphids as well as mosquitoes and other insects.

It is an active ingredient in a number of products sold at hardware stores, including fly baits and fruit fly sprays. It was not known yesterday how much poison would have been needed to cause so many deaths.

A DEC spokeswoman said if the birds were deliberately poisoned it was an offence under the Wildlife Conservation Act, with fines of up to $4000 for each bird species affected. Illegal dumping of pesticides was covered by the Environmental Protection Act.

A year ago, about 200 gulls died near the same location from an unknown cause. In 2007, lead poisoning killed about 4,000 birds in Esperance on Australia's southern coast.

Fenthion is currently legal in Australia but under review by the Australian Pesticides and Veterinary Medicines Authority. Australia's Northern Territory advises disposing Fenthion away from waterways, which seems not to have been done in this case. Fenthion has been found to be highly toxic to several native Australian bird species.

For those who are curious, Fenthion has been used in the United States to control mosquitos, especially in the aftermath of initial West Nile Virus outbreaks, and in dog shampoos. While it is primarily an insecticide, it is also highly toxic to birds and sometimes used as an avicide (the "Rid-A-Bird perch"). Even when used as an insecticide, its application can result in bird deaths; the American Bird Conservancy lists several incidents of mass bird killings. Due to concerns over its toxicity to humans, it was withdrawn from the U.S. market in 2004 and the EPA canceled its registration.

Grackles Dying

As a commenter noted yesterday, a neighborhood in Staten Island experienced a scary situation when birds started dropping from the sky and dying.

More than 50 birds plummeted to the pavement in Bay Terrace about 3 p.m., causing frightened residents to scramble indoors.

"It was like Alfred Hitchcock's 'The Birds,'" said Donna Toti, 50. "Birds were just falling out of the sky. They would land, lie on the ground, flap and die."

The birds - all believed to be Purple Martins - landed within the Port Regalle development near the intersection of Wiman Ave. and Tennyson Drive. Some appeared to die in the air; others expired in the moments after they hit the pavement, authorities said.

"When we pulled in, most of the birds were on the ground, floundering and foaming at the mouth," said FDNY Battalion Chief John Giacella.

Giacella suggested that because all the birds were the same species they likely got ill from something they ate. But he noted that he was far from certain.

Health department officials collected the birds last night and were sending them to a lab for testing.

I have seen other stories with birds mysteriously dropping from the sky. In those cases the cause turned out to be poison, like a recent case somewhere in Texas. Last year in Australia, dead birds started appearing around a town because of lead poisoning.

The dead birds that the story refers to as "purple martins" are clearly common grackles. (Note the curved bill, yellow eye, and wedge-shaped tail). Grackles, like other blackbirds, tend to gather in large flocks for roosting and foraging during the winter. Because the flocks are so large, often numbering into the thousands, they are sometimes seen as pests and are targeted by pest control. Also, blackbirds feed on the ground like starlings and pigeons, two other species sometimes baited with poisoned food. Whether deliberate poison was the cause of this mass death remains to be seen.

Seabirds Dying in the North Sea

This fall there have been several instances of mass deaths of seabirds in the North Sea. Their mortality has come to light when corpses washed ashore in Scandinavia and elsewhere. Most affected birds have been alcids.

The discovery of thousands of dead and dying auks, mainly razorbills, around the coasts of Denmark, southern Norway and Sweden, in September and October, didn't arouse widespread UK attention because there was comparatively little evidence of problems on this side of the North Sea.

But alarm bells rang after the latest British Trust for Ornithology BirdTrack Update referred to "a large wreck of auks seen along the north and east coasts, and as far afield as the Oslo fjord … All of these appear to have starved - and most were adults."

This disaster was of UK significance because, after the breeding season's end, Scotland's razorbills head for Scandinavian waters. This was underlined by numbered rings on several corpses: one started life on the Shiant isles off Lewis in the Outer Hebrides in 1982; another on the Isle of May off Fife on the mainland's east coast in 2000.

In addition to the razorbills, large numbers of guillemots and puffins have been found dead. Similar incidents have occurred elsewhere in the North Atlantic over the past several years. The cause of death in all cases appears to be starvation.

What caused particular concern, however, was that the birds were in an emaciated state - indicating failure to catch sufficient small fish to fuel their life on the open sea - and almost all were adults....

Kjell Isaksen, the Oslo municipality's biologist and wildlife manager, said "massive" number of dead and dying razorbills were washed ashore in his area. "Razorbills and guillemots were also seen on lakes far inland or found grounded on fields."

He had examined externally 60 per cent of 500 dead razorbills picked up locally and noted they were "only skin and bone", so emaciated he was surprised that birds originating in Scotland had been able to reach Norway. The conclusion in every case was "death by starvation."

The immediate cause of the food shortage has not yet been determined; the answer depends in part on where the birds died. Factors like overfishing and climate change would probably be immediate suspects; pollutants, disease, or perhaps invasive species could also play a role. In any case, the mass bird deaths are a sign that something is seriously wrong and needs to be corrected.

Injured Swift

Occasionally I receive a question by email about what to do with injured birds. Field of View, a blog maintained by the magazine Birder's World, offers one way to deal with the situation:

I decided to take it to the Wisconsin Humane Society. (Last month, Chuck, Ernie, Jessica, and I participated in the society's Avian Odyssey to support its Wildlife Rehabilitation Center.) Thanks to the center, I knew what to do.

The good folks at the center coordinate a program in Milwaukee each spring and fall that rescues birds that hit windows. They call it WIngs: Wisconsin Night Guardians for Song Birds. At a training session for volunteers, wildlife manager Scott Diehl described how to transport an injured bird: Put a cloth towel in the bottom of a paper grocery bag, put the bird inside, and close the top of the bag. (The towel gives the bird something to cling to.) And on the drive to the rehab center, turn the radio off to avoid further stressing the bird.

Read the rest.