What Does a Parrot Know About PTSD? By CHARLES SIEBERT

Aside

Untitled-2What Does a Parrot Know About PTSD?

An unexpected bond between damaged birds and traumatized
veterans could reveal surprising insights into animal intelligence.

Inside one mesh-draped enclosure, Julius, a foot-high peach-white Moluccan cockatoo with a pink-feathered headdress, was madly pacing, muttering in the native tongue of the Korean woman who, along with her recently deceased husband, had owned him. Next door, a nearly three-foot-tall blue-and-gold macaw named Bacardi, abandoned by a truck driver who was spending too much time on the road, kept calling out for someone named Muffin, before abruptly rising up and knocking over his tray of food to surrounding squawks of delight. Across the way, Pinky, a Goffin’s cockatoo, the castoff of a bitter custody battle between his original female owner and the husband who threatened to spite her by cutting off her beloved pet’s wings, was mimicking a blue jay’s high-pitched power-saw plaint. More screams rang out and then, in the ensuing silences, random snippets of past conversations: ‘‘Hey, sweetheart!’’ ‘‘Whatever.’’ ‘‘Oh, well.’’ ‘‘Whoa! C’mon man!’’ Soon, from a far corner, came the whistling, slow and haunted, of the theme from ‘‘Bridge on the River Kwai.’’

‘‘They had me loaded up on so many kinds of medications, I was seeing little green men and spiders jumping out of trees,’’ Love continued, as a six-inch-tall female caique parrot from the Amazon Basin named Cashew dutifully paced across her shoulders. Back and forth she went, from one side to the other, in determined, near- circular waddles.

For the next 10 minutes, Love, her eyes closed, her arms still at her sides, continued to engage in one of the many daily duets she does with each one of Serenity Park’s winged residents, listing her shoulders up and down like a gently rocking ship, Cashew’s slow, feather-light paddings all the while putting Love further at ease. Now and again, Cashew would pause to give a gentle beak-brush of Love’s neck and ear, and then crane her head upward toward Love’s mouth to receive a couple of kisses. She made a few more passes, back and forth, then abruptly climbed atop Love’s head. Smiling broadly, Love let her loll around up there on her back for a time, Cashew using the same upward scooping wing flaps that caiques employ to bathe on wet rain-forest leaves.

In the wild, caiques, diminutive dollops of luminous yellow, white and deep blue-green, fly in huge, tightly knit flocks whose collective wing feathers make a singular whirring sound above the rain-forest canopy. Cashew, however, for reasons unknown, had her wings overclipped by her former owner, who had bought her as a pet and then abandoned her. So each day now, Love helps her learn how to take to the air again.

The flight lessons are usually administered at the end of Love’s daily rounds. Each morning at dawn, she arrives at Serenity Park from her boat at the marina. For the next four to five hours, she, like the six other veterans in the work-therapy program there, brings food and water to the parrots, cleans their cages and nuzzles and coos and talks and squawks with them. Love, by far the most animated of the veterans that I met at the park, flits from enclosure to enclosure, miming each bird’s movements, mimicking their individual voices and attitudes and, as with Cashew, tries to restore what was taken from them.

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Phoebe, Dino and Kiki, three umbrella cockatoos. CreditJack Davison for The New York Times

She had only to say her student’s name once that day and Cashew was upright in Love’s right palm, a knowing head tilt signaling her readiness. Love set Cashew on a nearby perch and with the thumb and forefinger of both hands took hold of each wing by the tip and moved them up and down a few times as though priming a pump. She then extended an index finger, held Cashew briefly aloft and with a quick thrust upward let her fall free. Some frantic flailing quickly morphed into firmer flaps, Cashew’s wings finally gathering just enough air for her to gain the netting on the far side of her large mesh home. ‘‘You see,’’ Love said, beaming. ‘‘She can actually go a little distance.’’

Taking hold of Cashew once again, she cupped her against her cheek. ‘‘Their spirit gives me the will to get up and do it another day. They’re all victims here. Kind of like what the veterans have been through, in a way.’’ Love lowered her hands and watched Cashew roll over once more on her back, a play position known as wrestling that is peculiar to caiques. ‘‘They don’t belong in captivity,’’ Love said, rubbing Cashew’s white breast feathers. ‘‘But they have a real survivor’s mentality. These forgotten great beams of light that have been pushed aside and marginalized. I see the trauma, the mutual trauma that I suffered and that these birds have suffered, and my heart just wants to go out and nurture and feed and take care of them, and doing that helps me deal with my trauma. All without words.’’

Abandoned pet parrots are twice-traumatized beings: denied first their natural will to flock and then the company of the humans who owned them. In the wild, parrots ply the air, mostly, in the same way whales do the sea: together and intricately. Longtime pairs fly wing to wing within extended, close-knit social groupings in which individual members, scientists have recently discovered, each have unique identifiable calls, like human names. Parrots learn to speak them soon after birth, during a transitional period of vocalizing equivalent to human baby babbling known as ‘‘subsong,’’ in order to better communicate with members of their own flocks and with other flocks. This, it turns out, is the root of that vaunted gift for mimicry, which, along with their striking plumages and beguilingly fixed, wide-eyed stares, has long induced us to keep parrots — neuronally hard-wired flock animals with up to 60-to-70-year life spans and the cognitive capacities of 4-to-5-year-old children — all to ourselves in a parlor cage: a broken flight of human fancy; a keening kidnapee.

There were 34 parrots at Serenity Park when I was there last summer — representing a range of the more than 350 species in the psittaciformes order — a majority of them abandoned and now deeply traumatized former pets that had outlived either their owners or their owners’ patience. A parrot separated from its flock will flock fully and fiercely to the attentions and affections of its new human keeper. And when that individual, for whatever reason, fails to uphold his or her end of such an inherently exclusive relationship, the effects are devastating.

Up and down the aviary-lined corridor of Serenity Park are the winged wreckages of such broken bonds. On and on they go: the ceaseless pacing and rocking and screaming, the corner-cowering, self-plucking and broken-record remembrances. And yet at Serenity Park, the very behaviors that once would have further codified our parrot caricatures — ‘‘birdbrained,’’ ‘‘mindless mimicry,’’ ‘‘mere parroting’’ and so on — are recognized as classic symptoms of the same form of complex post-traumatic stress disorder afflicting the patients in the Veterans Administration Medical Center. They’re also being seized upon as a source of mutual healing for some of the most psychologically scarred members of both species.

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Bobbi, a Goffin’s cockatoo who was kept in a kitchen drawer by her former owner.CreditJack Davison for The New York Times

‘‘The problem with parrots is that they’re so intensely attuned,’’ Lorin Lindner, the psychologist who founded Serenity Park, told me one afternoon as we stood watching Julius pace back and forth, speaking in Korean. ‘‘Parrots have so many social neurons. Their brain is filled with the capacity to mirror their flock. It’s so crucial for survival to be able to know what the flock is doing, to know what the danger signs are, when they have to get together, when night is falling and they are called to roost. They’re so attuned to being socially responsive that they can easily transfer that to us. They have the ability to connect, to feel this closeness with another being, another species.’’

Listening to Julius that day reminded me of a story I read not long ago in the journal Current Biology about a 22-year-old male Asian elephant named Koshik that resides at the Everland Zoo in Yongin, South Korea. Separated from the two female Asian elephants he was raised with in captivity, Koshik lived alone at Everland for seven years, a period during which he construed a way of speaking perfectly intelligible Korean words by sticking his trunk in his mouth and then using his tongue to shape his own plosive trumpetings into the language of the zoo’s workers and local visitors. Such ‘‘vocal learning,’’ the researchers who wrote the paper concluded, isn’t an attempt to directly communicate with us so much as it is a way for a highly social species like the elephant ‘‘to cement social bonds’’ with the only other species available.

It’s one of those unlikely natural outcomes of the so-called anthropocene, the first epoch to be named after us: the prolonged confinement of intelligent and social creatures, compelling them to speak the language of their keepers. And now, in yet another unlikely occurrence, parrots, among the oldest victims of human acquisitiveness and vainglory, have become some of the most empathic readers of our troubled minds. Their deep need to connect is drawing the most severely wounded and isolated PTSD sufferers out of themselves. In an extraordinary example of symbiosis, two entirely different outcasts of human aggression — war and entrapment — are somehow helping each other to find their way again.

Lindner, a 59-year-old native of Queens, N.Y., knew little about parrots when she first came to Los Angeles in 1976 to finish college and go to grad school in behavioral sciences at U.C.L.A. Then one day in 1987, a week before Christmas, she received a call from a friend who knew of her deep affection and affinity for animals. ‘‘He was looking for someone to take this female parrot he heard about named Sammy,’’ Lindner recalled. ‘‘She was living alone in a Beverly Hills mansion. The owner had put the house up for sale and decided to leave Sammy behind. The bird matched the place’s décor, and he thought the new owners might like that. He was sending his driver over once a week to feed her. When I went to get her, the feces in her cage were piled up in a pyramid that reached her perch.’’

The following year, Lindner started a private practice in Westwood and began to do pro bono work with the increasing number of homeless veterans she encountered in the community, many of them living at that time in encampments under the nearby 405 freeway while awaiting appointments at the West Los Angeles V.A. medical center. Overwhelmed by their stories, she began devoting herself full time to veterans, eventually enlisting the backing of the state to head a nonprofit homeless-veteran-rehabilitation program, known as New Directions, at a residential treatment center.

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Lilly Love with Julius, a Moluccan cockatoo.CreditJack Davison for The New York Times

Spending more and more time at work, Lindner soon decided to take in another orphaned cockatoo named Mango as a ‘‘flock mate’’ for Sammy. Before long, she was tending to both New Directions, which was relocated in 1997 to a newly refurbished building on the grounds of the V.A. center, and a sanctuary for homeless parrots that she started that same year with a friend on a four-acre plot an hour-and-a-half drive north in Ojai. One morning, near the end of 1997, Lindner found herself leading yet another veterans’ group-therapy session that was getting nowhere.

‘‘The guys are sitting around, all stoic, arms crossed, not saying anything,’’ she recalled. ‘‘They’d been like that for a number of weeks. So for a change, I took them up to Ojai to help build some new aviaries there. All of the sudden these same tight-lipped guys are cuddling up to the parrots and talking away with them.’’

Lindner was soon repeating the same exercise with other veterans. The transformations she saw in both species were so pronounced that she promptly set about persuading the V.A. to allot her the grounds of an old outdoor basketball court just down the hill from the medical center so she could move the birds from her Ojai sanctuary and start a work-therapy program there. (Veterans are paid a stipend to work in the sanctuary; some, like Love, volunteer their time.) She began with two 25-foot-high aviaries; there are now nearly two dozen. Some hold as many as three or four birds, like Kiki, Phoebe and Dino (a.k.a. the Three Stooges), a now inseparable troika of umbrella cockatoos who spend their days cuddling and grooming one another. Others contain just one bonded pair like Mandy and Kookie, a female and male eclectus parrot couple, a species native to the Solomon Islands, or Jester and Tango, one Harlequin and one green-wing macaw, who never leave each other’s side. And then there are the quarters of the inveterate loners, birds still caught somewhere between their inherent, wild selves and their captive ones: Cashew, Bacardi or Julius, who is afraid of other parrots because, as Lindner explained, ‘‘he doesn’t think he is one.’’

As I stood talking that day with Lindner, who is warm and effusive, with long blond hair and bangs, I watched Jim Minick, a former Navy helicopter-squadron member who did three tours of duty overseas and suffered severe upper-body injuries in a fall from his chopper, get his fingernails cleaned by Bacardi, the blue-and-gold macaw. In another enclosure, Jason Martinez, a wheelchair-bound Army veteran, sat alongside Molly, an African gray, resting on her perch, the two of them just staring at each other.

Love approached. She was holding an elderly Goffin’s cockatoo named Bobbi, a bird kept most of her life by her owner in a kitchen drawer. She looked like a tiny plucked blue chicken, her only remaining plumage some straggly wing and tail feathers and a frayed skull cap of the ones she couldn’t reach with her beak to mutilate. Love held Bobbi aloft on her index finger and then went dashing down the path between the compound’s two rows of aviaries, shouting, ‘‘Fly, Bobbi, fly,’’ giving her fruitlessly flapping charge at least the semblance of flight.

‘The parrots get what the veterans are going through and, of course, the veterans get them, too, because, hey, they are all pretty much traumatized birds around here.’

‘‘You can look in their eyes,’’ Love said, returning with Bobbi, ‘‘any of these parrots’ eyes, and I myself see a soul. I see a light in there. And when they look at you, they see right into your soul. Look around. They’re all watching. They notice everything. It’s intense.’’

I turned to take in a multitiered array of stares, feeling at once beheld and uplifted by creatures a fraction of my weight. I couldn’t place it at first, the slow-swiveling sideswipe of their gazes, the way they’ll dip their heads below their own bodies and then crane smoothly upward, like a movie camera pulling focus. And then it came to me: They reminded me of those C.G.I. velociraptors in films, except that the scales have turned to feathers and the stunted forelimbs to vibrant wings. Time, all at once, lurched wildly backward and ahead, depositing me right back where I’d been, in that moment, and yet deeper and more present.

‘‘God is a parrot,’’ Love said. ‘‘I know that now. God supposedly interprets and mimics what we do on earth, right? Is a reflection of us? So I believe God, if she exists, must be a parrot.’’

Animal-assisted therapy is hardly a novel prescription, having been employed at least since the 18th century, when the York Retreat for the mentally ill opened in England in 1796 and began allowing patients to roam the outside grounds among farm animals. At his office in Vienna, Sigmund Freud regularly had his chow Jofi on hand during psychoanalysis sessions to reassure and relax his patients, allowing them to open up more readily. The U.S. military used dogs as early as 1919 as a therapeutic aid in the treatment of psychiatric patients at St. Elizabeth’s Hospital in Washington. Still, what distinguishes the mutually assuaging bond that the veterans and parrots are forming at Serenity Park is the intelligence — at once different from ours and yet recognizable — of the nonhuman part of the equation.

There is abundant evidence now that parrots possess cognitive capacities and sensibilities remarkably similar to our own. Alex, the now-deceased African gray parrot studied for years by his longtime companion, Dr. Irene Pepperberg, a psychology professor, is regularly held up as the paragon of parrot intelligence. His cognitive skills tested as high as those of a 5-year-old child. He mastered more than 100 words, grasped abstract concepts like absence and presence (Alex excelled at the shell game) and often gave orders to and toyed with the language of researchers who studied him, purposely giving them the wrong answers to their questions to alleviate his own boredom. Alex was also given to demonstrating what we would characterize in ourselves as ‘‘hurt feelings.’’ When Pepperberg returned to Alex one morning after a three-week absence, he turned his back on her in his cage and commanded, ‘‘Come here!’’

 

Of a Feather

CreditJack Davison for The New York Times

Stories like these are, in fact, legion among those who keep and work with parrots. Dr. Patricia Anderson, an anthropologist at Western Illinois University, told me that her expertise in anthrozoology, the study of human-animal relations, is daily tested by her own cadre of adopted, orphaned parrots, including the first bird she decided to take in nearly 30 years ago, a Quaker, or monk, parrot named Otis.

‘‘He was so bright,’’ Anderson told me. ‘‘I taught him to say ‘thank you.’ Very anthropocentric of me, I know, but he generalized it appropriately to anything I ever did for him. He never said it randomly. He only said it when I did something for him, so it appeared to have meaning to him. There appeared to be some cognition going on, and this totally blew my mind.’’ Anderson read extensively about parrots and learned that anytime she left, she should say, ‘‘I’ll be right back.’’ ‘‘I started saying that, and then whenever I began to put my shoes on in the morning to get ready to go to work, he’d say: ‘Right back? Right back?’ ’’

Though the avian cerebrum possesses only the tiniest nub of the structures associated with mammalian intelligence, recent studies of crows and parrots have revealed that birds think and learn using an entirely different part of their brains, a kind of avian neocortex known as the medio-rostral neostriatum/hyperstriatum ventrale. In both parrots and crows, in fact, the ratio of brain to body size is similar to that of the higher primates, an encephalization quotient that yields in both species not only the usual indications of cognitive sophistication like problem-solving and tool use but also two aspects of intelligence long thought to be exclusively human: episodic memory and theory of mind, the ability to attribute mental states, like intention, desire and awareness, to yourself and to others.

Nature, in other words, in a stunning example of parallel or convergent evolution, found an entirely other and far earlier path to complex cognition: an alien intelligence that not only links directly back to minds we’ve long believed to be forever lost to us, like the dinosaurs’, but that can also be wounded, under duress, in the same ways our minds can. In one recent psychiatric study conducted at Midwest Avian Adoption and Rescue Services, a parrot sanctuary and rehabilitation facility in Minnesota, a captive-bred male umbrella cockatoo who had been ‘‘exposed to multiple caregivers who were themselves highly unstable (e.g. domestic violence, substance abuse . . . addiction)’’ was given a diagnosis of complex PTSD. ‘‘When examined through the lens of complex PTSD,’’ Dr. Gay Bradshaw, a psychologist and ecologist and an author of the study, wrote, ‘‘the symptoms of many caged parrots are almost indistinguishable from those of human P.O.W.s and concentration-camp survivors.’’ She added that severely traumatized cockatoos ‘‘commonly exhibit rapid pacing in cage, distress calls, screams, self-mutilation, aggression in response to . . . physical contact, nightmares . . . insomnia.’’

Veterans, of course, share similar psychological scarring, but whenever I asked any of them how it is that the parrots succeed in connecting where human therapists and fellow group-therapy members can’t, the answer seemed to lie precisely in the fact that parrots are alien intelligences: parallel, analogously wounded minds that know and feel pain deeply and yet at a level liberatingly beyond the prescriptive confines of human language and prejudices.

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Cashew, a caique.CreditJack Davison for The New York Times

‘‘They look at you, and they don’t judge,’’ Jim Minick, the badly injured helicopter-squad member, told me. ‘‘The parrots look at you, and it’s all face value. It’s pure.’’

One afternoon at the sanctuary, I went up the hill to the V.A. hospital to talk with Leslie Martin. A clinical social worker and a director at the center’s trauma-recovery services, she often recommends parrot therapy for patients, including those who are ‘‘treatment resistant,’’ like Lilly Love. I asked Martin if the primordial nature of the parrot’s intelligence might have a particular effect on certain veterans. ‘‘Everyone knows these animals are very sensitive, like children,’’ she said. ‘‘The pure, primitive nature of their feelings, their emotions, activates your primitive brain. And then when they speak to you, it’s a real high.’’

Previous studies have shown that effective trauma therapies can help the brain construct neuronal bypasses around the scarred areas of a traumatized brain. ‘‘They’re only just starting to do research on this now, but there are phenomena that are operating in the prefrontal cortex,’’ Martin said. ‘‘There are some physiological and chemical changes happening that are real, that are measurable.’’ Lindner says she would like to one day enlist researchers to study the brain science behind the efficacy of parrot therapy and whether it is the parrots themselves that are helping the veterans or whether there are other variables at work. For now, however, she uses as her measure the nearby veterans’ garden just across from Serenity Park. For years, afflicted veterans were brought to work in the garden as a way of treating their trauma, essentially working in the same tranquil setting as the veterans at Serenity Park, the one obvious difference, of course, being the parrots. Lindner said she thinks that, using conventional measures of improvement for veterans suffering trauma — the ability to stay clean and sober; keeping up with their case-manager appointments; reuniting with family; finding gainful employment, and so on — the veterans who have been working with the parrots are doing better than those who spend time working at the garden.

‘‘There’s definitely something different going on at this place,’’ Lindner said. ‘‘We know that what’s preserved across species, all vertebrates truthfully, is the ability to feel compassion. As for birds and humans, we both have sympathetic nervous responses. We react the same way to trauma on the physiological level and in terms of the reparative nature of compassion and empathy. That’s what is doing the healing. That’s what is bringing the broken halves together. We don’t know what the actual healing factor is, but I believe that it has to do with mental mirroring. That the parrots get what the veterans are going through and, of course, the veterans get them, too, because, hey, they are all pretty much traumatized birds around here.’’

One afternoon at Serenity Park, a white pickup truck roared to a stop behind the work shed. Lindner emerged from the passenger side with a wooden box containing the ashes of her first parrot, Sammy, who died last March after living with Lindner for 27 years. Sammy was to be buried at the park later that day. The truck was driven by Serenity Park’s manager, Matt Simmons, a tautly built, square-jawed 43-year-old, who came to the sanctuary in 2006 after making little progress as a patient in traditional group therapy at the V.A. When his therapist first instructed him to visit the aviary down the hill, Simmons thought he was going to be ‘‘dealing with chickens,’’ he later told me. What he found instead was himself, through the eyes of the park’s winged trauma victims. He began devoting his days to caring for the parrots, forming attachments that gradually drew him out of his sense of isolation and mistrust and allowed him, in turn, to start connecting with people as well. He and Lindner grew increasingly close, and in 2009 they were married at the sanctuary. Sammy was flower girl. Lindner held a bridal bouquet made of fallen parrot feathers.

‘Parrots have so many social neurons. Their brain is filled with the capacity to mirror their flock.’

Simmons built his first computer in grade school. He joined the peacetime Navy right out of high school, he told me, to spite his father, who wanted him to go straight to college and then law school. He scored so high on his recruitment aptitude tests that the Navy wanted to assign him to a nuclear submarine. Simmons managed, instead, to secure what he believed would be a relatively easy tour as a yeoman — essentially an administrative and clerical position — on an aircraft carrier, until that ship made a sudden turn in early 1991.

The PTSD stemming from his time in the Navy wasn’t formally diagnosed for another two years. A friend suggested that he visit the West Los Angeles V.A. for help. Simmons told me that until then, he had no idea that what he was experiencing had to do with his military service. The regimen of new drugs that were prescribed by a psychiatrist there proved ineffective, and he grew increasingly closed off in therapy sessions that were dominated at that time by long-ignored Vietnam veterans with issues entirely different from those associated with the Gulf War. ‘‘I told my therapist this,’’ Simmons said, ‘‘and he basically said that if I didn’t go down and help out at the sanctuary, he was going to stop treating me.’’

Simmons instantly connected with the yellow-headed Amazon, Joey, who had adopted and raised from infancy two other birds at the sanctuary — a pair of female lilac-crowned Amazon parrots that had fallen from their nest — regurgitating his own food to feed them. For a male parrot to raise two females from another species is a rare display of altruism, Lindner told me, a behavior long thought to be exclusive to humans and other primates.

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Kookie, a green eclectus.CreditJack Davison for The New York Times

‘‘Joey came to Serenity Park around the same time I did,’’ Simmons told me. ‘‘That’s the first thing we had in common. I had learned that yellow-headed Amazons are not that friendly, so when Joey made an effort to befriend me, that meant even more. We were different species, but we got each other. I was shy, burned by humans, isolated, angry. Joey had what seemed to me the same attitude. So we bonded. He let me touch him. Only me.’’

Within weeks of his arrival at Serenity Park, Lindner told me, Simmons had pretty much taken over the place. He was up at 3 a.m. every day in the New Directions kitchen, preparing breakfast for all the veterans. Then he came down to the sanctuary and worked there until 6 in the evening, clearing out the compound, building new aviaries and expanding the existing ones.

When I asked Simmons to describe what happens to him when he is with a parrot, he instantly went into one of his signature high-speed soliloquies. ‘‘Here we go,’’ he said. ‘‘Write it down. There are things I have seen that will never leave me. There’s this huge sack of guilt and shame and pain that I carry with me, and I got it when I was 18 years old in Bahrain. Now, when I’m with a parrot, it’s not a total time-change thing, but I do have to act like a 12-year-old boy again. And here’s why. Because parrots are not domesticated animals. They haven’t been bred for hundreds of years to be at my feet.’’ Simmons paused for a sip of Coke, the third one of the night. ‘‘So in order to have a relationship with a parrot, that parrot has to select me. In order for that to happen, that parrot has to be comfortable. I have to come in open and quiet and calm. Much like that 12-year-old boy that met the mean dog next door and never had a problem. Much like that 12-year-old boy that went hiking and saw a mountain lion. I’m acting like the 12-year-old boy again around the parrots, and what that does is help me confront my trauma rather than carry it around. Because now I’m with a psychiatrist, and I’m talking about how this bird didn’t feel so good today and wasn’t very comfortable and was kind of hiding in the back of the cage, and the psychiatrist goes, ‘Hmm, you’re starting to talk about emotions.’ I’m talking about how the bird was feeling, but I’m also transferring my own emotions. So being with the parrots allows me to take that third-person look at my own trauma, which you can never do when you’re whacked out on Vicodin and Budweiser and living under a cement highway bridge.’’

We often think of empathy as a skill rather than the long-ago, neuronally ingrained bioevolutionary tool for survival that it actually is: the ability to inhabit the feelings of fellow beings (the word empathy derives from the Greek en, which means ‘‘in,’’ and pathos, meaning ‘‘suffering’’ or ‘‘experience’’); the ability to feel, for example, their fear over a threat; or thrill over a newly found food source; or sorrow over a loss, which has as much to do with the fabric of a community as any other. Empathy, in this sense, can be thought of as the source of all emotion, the one without which the others would have no register.

The more time I spent at Serenity Park last summer, the more I came to think in terms of the expansive anatomy of empathy. And not just the shared neuronal circuitry that has now been mapped across species, from us to the other primates to elephants and whales and, we now know, to creatures with entirely different, nonmammalian brains, like crows and parrots. I thought, as well, of the extraordinary capacity conferred by that circuitry to recognize and respond to the specific infirmities, both psychic and physical (although those are essentially one and the same) of another species.

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Matthew Simmons with Kiki and Phoebe.CreditJack Davison for The New York Times

I got a sense early on at the park of which parrots and veterans seemed most drawn to one another. The way, for example, Simmons said that the lilac-crowned Amazon, Dagwood, came to life around Jim Minick, the former Navy helicopter crewman. But I learned only later about the true depth of such bonds.

‘‘You know, Jim does a great job of hiding how wounded he was,’’ Simmons told me. ‘‘He has tattoos all over the elbow he can’t use anymore, and he won’t talk about it, but at one point he was sitting on the edge of the bed with a shotgun in his mouth and tears rolling down his face. On that same night, he drove his car into a tree, drunk out of his mind. So he comes to Serenity Park, and Jim doesn’t know the history of any of the birds, and which bird loved him at first? Dagwood, the one with a screwed-up wing and a crooked beak. There’s no way to explain it.’’

Jason Martinez, who suffered traumatic brain injuries parachuting into Afghanistan and now suffers from epileptic seizures, was immediately drawn to Molly, an African gray, the only parrot at Serenity Park, he learned only later, with epilepsy. And then there were the daily cheek-to-cheek murmurings between the bedraggled, drawer-bound Goffin’s cockatoo, Bobbi, and a blond 21-year-old ex-Marine named Josh Lozon.

‘‘Let’s talk about Josh,’’ Simmons said. ‘‘A good-looking guy with curly hair. He’s a little scary. He’s so broken, all of his wounds are still hidden. Who gets along with him best? Bobbi, mostly naked, bleeding from her remaining feathers. A bird who looks like a damn pterodactyl that went through a buzz saw.’’

Of all the veterans I encountered at the sanctuary, Lozon was by far the most skittish. The one time I was able to chat with him at length was when I found him early one morning atop an elevated wooden porch, one flight above a work shed, scrubbing the bars of an empty bird cage with a brush. My decision to head up the narrow steps that lead to it effectively trapped him up there.

He joined the Marines, he said, because he ‘‘wanted to hurt somebody.’’ He told me he received an exceptional score on his recruitment aptitude test, which landed him an office job working with computers, a post suited to his intellectual abilities but not his disposition. Sent to the V.A. for evaluation after frequent episodes of insubordination and erratic behavior, he was prescribed mood stabilizers and antipsychotics, neither of which, he sheepishly confided, he was presently taking, thanks to Serenity Park.

He was not able to put into words what exactly went on between him and the parrots. All he kept saying was, ‘‘It’s something about the cages.’’ Feeling his growing discomfort, I descended the stairs. Back on the ground, I looked up at Lozon, who was peacefully cooing and chirping back and forth with Koko, the Australian Adelaide rosella. He suddenly looked down at me. ‘‘They’re in these cages and helpless,’’ Lozon said, ‘‘and it’s not their fault.’’ He paused, and I started away. ‘‘But for me,’’ he continued, ‘‘I think it’s also that when I’m alone with them in those cages, I feel I don’t have to conform to what everyone expects of me. I’m free to be an animal again.’’

In the late afternoon on my last day at the sanctuary, I seemed to be the only one around. I passed Koko in his cage, sounding his particular strains of the park’s ongoing symphony of stranded human speech. I thought then of the numerous anecdotes people have told of wild-parrot flocks learning, via ‘‘cultural transmission,’’ to speak the human words taught to them by reintegrated former pets. In the parks of Sydney, Australia, where there are native wild-parrot flocks, people regularly overhear a ‘‘Hello, darling’’ or ‘‘What’s happening?’’ sounding from the trees above. The early German naturalist explorer Alexander von Humboldt wrote of encountering, during his travels in South America toward the close of the 18th century, a parrot that was the last living repository of the language of the extinct Atures Indian tribe.

All alone now among the sanctuary’s parrots, I got a sudden glimpse of a possible future. One long beyond us and our traumas. A world of winged dinosaurs, soaring and chatting back and forth, their different local dialects inflected here and there with the occasional broken shards of a long lost one: ‘‘Hey, sweetheart.’’ ‘‘Whoa! C’mon man!’’ ‘‘Whatever!’’

Nearing Serenity Park’s exit, I decided to turn back and step inside Cashew’s quarters for a moment. I had only to nestle close to her perch and she immediately hopped on my back. Crisscrossing my shoulders as I had watched her do with Lilly Love, she stopped at one point for what I assumed would be the parrot equivalent of a kiss. Instead, she began to clean my teeth: her beak lightly tapping against my enamel, the faint vibrations strangely soothing. Immediately afterward, she took a brief nap in my shirt’s left breast pocket — it felt as if I’d grown another heart — then re-emerged and crawled to the top of my head. She strolled about there for a time before plucking out one of her own deep blue-green feathers and then descending to gently place it on my left shoulder. I have it still.

I Saw that you were Perfect….

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I saw that you were perfect quoteInspired by an amazing friend who only adopts Angels with Special needs …

Luci Salzman

 

On the Bright Side – The Benefit of Light from Avian Enrichment

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On the Bright Side – The Benefit of Light

In the wild, the sun dictates not only the seasons but also the biological cycles of birds. The length of the day influences when your bird will molt, breed and migrate amongst other things. Our parrots need to experience the same light and dark cycles as their cousins in the wild.
Our companions wild counterparts are exposed to natural sunlight daily which offers many benefits over the typical household lighting. Exposure to natural sunlight:

Stimulates the production of Vitamin D which is essential in activating the absorption of calcium necessary for bone and physical development.

Promotes skin health and feather quality.

Stimulates breeding activity.

Strengthens the immune system.

Improves mental disposition.

Increases playfulness and activity levels.

Invigorates appetite.

Birds deprived of exposure to UV light often develop undesirable behaviors and can become depressed and lethargic.

Our parrots need to be exposed to natural sunlight or full spectrum light daily. Optimally, this should occur while in an outdoor cage or aviary. Birds do not get the benefits from light that is filtered through windows as glass blocks up to 90% of the beneficial UVA and UVB rays. If it is not possible due to climate or work schedules to allow your bird outdoor time then the next best thing is to expose your bird to artificial full spectrum light.

In order to obtain the necessary lighting, it is recommended that you use full spectrum bulbs with a CRI (color rendition index) value of 92 or greater. It is best to hang the light fixture approximately 18 inches above the cage as artificial UV light does not travel far from it’s source. The length of time your parrot should be exposed to full spectrum light depends on where your parrot originated from geographically.

If your bird species originated from near the equator, it will need 12 hours of light and 12 hours of dark. Those species further from the equator will need shorter periods of exposure time. Some experts recommend only 4-6 hours of full spectrum lighting per day. You may wish to use full spectrum lighting with a timer in order to mimic natural conditions throughout the year.

Using Full Spectrum Lighting With Birds

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Using Full Spectrum Lighting With Birds
from Wildlife Rehabber

Patrick R. Thrush © 1999 (reprinted with permission from author)

One of the most commonly asked questions by birdkeepers about cage lighting concerns the effective and proper usage of full spectrum (or FS) lighting devices. Little ‘fact’ exists as to the type of lamp to be used, the correct distance of the lamp assembly to the cage or flight, and the effective life of the device. Much of what is being spread about as lighting ‘fact’ is directly translated from practices used in the keeping of reptiles. Birds and reptiles have completely different illumination and dietary requirements; it is an error to translate the application of lighting for reptiles to practice with birds. This article seeks to dispel myth about lighting practice and efficiency, and enable the aviculturist to make informed and cost effective lighting decisions.

To fully understand what is meant by full spectrum lighting, we must first divide the category into two parts: a) General Illumination, and b) Specialty Illumination. A general illumination lamp that may be properly termed full spectrum has a CRI (color rendition index) of greater than 90, and a Color Temperature of >5000K (1). The FS designation here only alludes to the range of light visible to the human eye, as it closely emulates natural sunlight and color balance. These devices are not intended as a source of UV irradiation, but do produce small amounts of UVA as a byproduct of their operation. Specialty illumination devices, such as the pet series (Vitalite, et al.) and tubes for seasonal affective disorder (Ott, et al.) contain varying amounts of ultraviolet light in the near (UVA) and possibly middle (UVB) ranges in addition to meeting the general illumination criteria. The de facto standard UVA/UVB ratio is 28:11. Depending on the result required from FS solutions, various distances are used to maximize their effects. This becomes of great importance for the consideration of the birdkeeper in choosing a proper lighting solution.

A major study of general lighting practice employed by birdkeepers revealed that on the average, the popular distance from bird to light was 14-18″ (2). Often, to achieve this distance the lighting source is placed several inches above, or directly on top of the cage. A 14-16″ (or any other arbitrarily set) concept of lighting placement is relevant only to the effective ultraviolet output (irradiance) of a lighting device. Some FS specialty fluorescent devices designed for pet application (reptile, bird, aquarium, etc.) produce small amounts of the middle range of ultraviolet light, known as UVB along with greater amounts of the near range, UVA. There is a specific segment of the UVB range which is the active “vitamin synthesis” component of ultraviolet light. Unfortunately, the output of these devices in this range is very weak compared to the total visible spectrum of light which they produce.

There are sound reasons for this, which will be explained as the article progresses. To gain a further knowledge of lamp construction, the author directs the reader to information on fluorescent light design which is available at the author’s Birds & Light website (3). For now, accept the fact that the UVB irradiance is much weaker than the visible light output (<0.5%), is unbalanced negatively in relation to natural sunlight levels, and does not travel as far from the lamp as visible light. With this in mind, the popular concept has been to place the lighting source as close as possible to the bird to achieve useful exposure for natural pre-vitamin D (cholecalciferol) synthesis (4). Unfortunately, several sets of problems begin to present themselves by doing so. To begin, output of the light changes as the device ages. The lumen (brightness) output of the visible portion of the light may change only 10-20% over the entire lifetime of a lamp. If one operates the device for two years at an average of 12 hours per day, 8760 hours of use on the lamp has occurred.

By this time, at least 10-15% of the visible light output of the lamp has decreased, and there have also been primary color shift changes due to phosphors within the lamp degrading unevenly. It is time to replace the device to achieve a balanced lighting perspective, regardless of whether the manufacturer states the rated lamp life at 16000 or 20000 or 30000 hours. These figures do not reflect an efficient or balanced output of the device, they simply mean that the lamp is likely to cease working altogether at this time. As will be noted in further discussion, the maximum benefit of FS can only be realized when the output of the lamp assembly still maintains balanced color ratios.

The phosphors which produce ultraviolet light are different from the mixture employed to produce visible light. They degrade at a much quicker rate. This means that the "vitamin" range of light steadily decreases in a 3:1 ratio to the visible output, and not equally across the UV spectrum. There will still be amounts of UVA (not part of vitamin synthesis, but visible to your bird) long after the UVB range has disappeared from the lamp output. Therefore, after about 3000 hours of operation, levels of UVB irradiated from the lamp will have decreased by approximately 20%.

Compare this to the 10% loss of visible output at 9000 hours, and consider that the UVA/UVB portion of the lamp only constituted about 1% of the total output of the lamp when new. This is roughly 250 days of use, after which the bird would have to be sitting directly on top of the fluorescent tube itself to receive benefit, if any. A few devices may output Vitamin D specific wavelengths (295-300 nm) a little longer depending on the original quality of the device but none over a year, and efficiency will have degraded after six months to where the device is generally useless in playing a part in the Vitamin D synthesis process. The most popular device for avian lighting, Vita-Lite by Duro-Test, maintains its integrity within these parameters, and after 3000-4000 hours functions basically the same as any high quality general full spectrum for avian use at standard illumination distances (5).

Another problem concerns avian visual and endocrine disturbances from the visible and UVA output of the lamp at close range. Birds have tetrachromatic vision, meaning that UVA is part of their "color" perception range, along with blue, green, and red (6). The author invites the reader to take a fluorescent lamp assembly and sit with it about a foot or two away from his/her face for twelve hours and then assess if they believe this to be a pleasant experience. Light plays an even more important role for birds than for humans in metabolic control. Avian forms gather information about light quality from the retina. This information is then relayed back to the pituitary gland. The Harderian gland around the eye also transmits information about light duration (photoperiod) and wavelength to the pineal gland.

Taken together, these two pathways set the pace for all subsequent endocrine regulated metabolic processes. Improper lighting can bring on varied health problems; behavioral and breeding disorders which are often attributed to other sources. These symptoms and problems include but are not limited to: lack of strength and endurance; feather and toe picking; restlessness and agitation; decreased immune response; abnormal sex ratios in breeder situations. Therefore, how could one even consider an arbitrary close distance appropriate for the health and environmental comfort of their bird?

Concentrations of UVB in fluorescent tubes can be increased, but due to the amount of barium based phosphors involved, these devices are no longer lamps which can produce a suitable visible spectrum. When manufactured in this manner, the lamp becomes either a reptile series lamp or tanning (erythemal) device, and must necessarily be regulated or controlled in exposure to prevent damage to humans and animals. The effective life span of these devices is also short, as noted by the previous discussion. Reptiles and birds have a safety mechanism that uses Vitamin A within the cornea and lens to filter out and make harmless "normal" levels of UVA/UVB; humans do not have this protection. Unnecessarily increasing the UVA/UVB to peak levels may cause problems to present themselves in the form of retinal degeneration, cataract formation, and calcium/bone disorders.

This problem may be compounded if your bird's diet is deficient in Vitamin A, and this protection is weakened. It is for this reason that not many years ago cataract formation was a standard outcome in specialty lighting for both birds and reptiles. Some improvement of avian diet has occurred in the intervening years, but the path to proper nutrition for many species is still being researched. Most pelletized diets, and a balanced natural diet contain cholecalciferol or calciferol, a precursor to Vitamin D3. The presence of UVB is not necessary for birds to convert this form to usable and sufficient levels of Vitamin D. Given this, use of the reptile series lamps is not appropriate for general aviculture. Unless the bird has a Vitamin D deficient calcium metabolism problem or is overproducing eggs and depleting calcium, reptile series and high output UVB devices should never be considered except as a temporary treatment procedure.

To summarize what we have covered so far:

1. UVB is a very small component of some "full spectrum" specialty series lights. There is no UVB present in general lighting "full spectrums".

2. UV light does not travel far from its artificial source, and must be placed close to the bird to be effective. This distance shortens in direct relation to age in hours of the lamp.

3. The UVB component is short lived, compared to the usable life of the device itself.

4. Placing a device right on top of a bird is uncomfortable and a disturbance to its visual acuity and metabolic process.

5. Proper levels of nutrition containing cholecalciferol/calciferol supplement remove the need to provide UVB sources in lighting.

6. Replace the tubes every 2 years, or if marked flicker, loss of brightness, or color skewing occur before this time.

7. Never use reptile or high output UV devices except as treatment devices at the instruction of a qualified avian veterinarian.

With these facts in mind, a lighting system composed of a high quality, reasonably priced general FS, or specialty FS solution is appropriate. This may consist of a Vita-Lite, Lumichrome 1XC, Chroma 50, Chromalux, etc. Any lamp with a CRI of greater than 92, and Color Temperature of 5000-5800K will suffice. Costly solutions such as Ott, etc., offer no demonstrable scientific benefit over a comparable Vita-Lite installation (7). For practical purposes, nothing smaller than a 2' double tube assembly should be used. Whatever the length, a dual tube configuration should always be employed. This fixture should be suspended a distance of at least two feet from the top surface of any cage or flight assembly. With a dual tube 48" assembly, up to four feet will suffice, ceiling height for multiple tube 96" fixtures.

Under no normal circumstances should a light housing be placed closer than two feet from the top of a large cage or flight. If it is an ample working illumination level for humans, it is adequate for the bird, as the same rules of general illumination apply to both. If it is too bright in the illuminated area, height may be increased. Protection of the device itself may be accomplished by the use of an Acrylite OP-4 cover (material available at most large sign companies), or a 3/8" to ½" mesh hardware cloth wrapping. Special precautions need not be taken, as the risk of any zinc toxicity to the bird from this kind of application does not exist.

Use good judgement in routing electrical cables and suspension chains. All lighting systems should be on a timer to maintain a consistent photoperiod of approximately 12 hours per day. This timing should coincide with the natural rising of the sun in the mornings. Adjustment should be made to provide for daylight savings time changes. This timing is to be applied to non-breeders. Breeding cycles and yield may be manipulated to greater potential by gradually increasing the timing to approximately 16 hours per day, depending upon species and season.

Again, unless you are supplementing a bird with metabolic problems, the "closer is better" rule is neither beneficial or cost effective to the aviculturist. The real effect of lighting upon general health, new molt, feather appearance, and behaviors is brought about by a balanced avian visual spectrum. Supplement artificial lighting whenever possible with natural unfiltered sunlight, and feed a high quality balanced diet. This will meet all of your bird’s requirements for lighting and nutrition.

NOTES

(1). Natural sunlight at high noon in the equatorial regions is considered a CRI (color rendition index) 100. The combination of sunlight and skylight combine to form a Color Temperature of 5500K. A lamp with a CRI 94 or greater is recommended.

(2). This Internet study was conducted by the author in the first quarter of 1999, and contained a representative sample of 500 aviculturists from all levels of competence. A sample this size allows for a 96% confidence level that the answers gained are statistically valid, and are typical of general birdkeeping practice.

(3). http://www.users.mis.net/~pthrush/lighting/

(4). MacLaughlin, J. A., Anderson, R. R., Holick, M. F. 1982. Spectral character of sunlight modulates photosynthesis of pre-vitamin D, and its photoisomers in human skin. Science 216:28 May. pp.1001-1003; Gehrmann, W. H. 1987. Ultraviolet irradiances of various lamps used in animal husbandry. Zoo Biology 6:117-127

(5). Lamps and Lighting: A manual of lamps and lighting application. 1983. Third Edition. Cayless, M. A., Marsdep, A. M., Eds. Edward Arnold: Baltimore; Duro-Test Corporation Commercial Engineering Technical Specifications E1-10 & 40T12 R.S.

(6). Vision, Brain, and Behavior in Birds. 1993. Zeigler, H. P., Bischof, H. J., Eds. MIT Press: Cambridge, MA.

(7). Dr. John Ott worked with Duro-Test in the late 1960's, to develop and produce the Vita-Lite. He later spun off his own company incorporating FS lamps into specialty lighting housings. He sold out his interests and rights to that company, Ott Biolite in the early 1990's.

Why Birds’ Eyes Are So Different From Ours

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Why Birds’ Eyes Are So Different From Ours
12th April 2013 by Susan Orosz, PhD, DVM, Dipl ABVP (Avian), Dipl ECZM (Avian)

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Birds are highly visual animals with unique features and adaptations that allow them to fly. As they begin to migrate, they use visual cues to help guide them. Their eyes can change focus rapidly using an active process called accommodation. Birds also see ultraviolet light, and they have enhanced visual acuity because of different mechanisms, including a one-to-one projection of receptor cells to ganglion cells in the retina.

Avian Ocular Anatomy & Physiology

Birds are the most visually dependent class of vertebrates. Even though humans are highly visual, the information transmitted to our brains is only 40 percent of that transmitted by pigeons and chickens. Birds of prey have even greater visual acuity. Pigeons can discern subtle color differences, and other avian species are able to record and remember over 6,000 images of caches where food is stored.

Eye position in birds can be lateral in the skull or directed frontally, particularly in predator species such as raptors. Species with laterally placed eyes, such as parrots, have a larger visual field (300o for pigeons) versus frontally directed eyes (150o for barn owls). However, as the visual field increases, binocular vision decreases. In binocular vision, both eyes focus on the same object, and eye movement is coordinated. Monocular vision occurs when only one eye is focused on one object at any particular moment. That type of vision is the norm for our parrots.

The eyeball consists of the small anterior cornea, a variable intermediate region, characterized by scleral ossicles and the posterior sclera. These sclera ossicles provide the rigid shape to the eyes of birds, which is not the way mammal eyes get their shape. Types of eyeballs include:

Flat eyeball — diurnal birds (active during the daytime) with narrow heads; a short bulbar axis results in a small visual image on the retina and lessened visual acuity.
Globular eye—diurnal birds with wider heads, including passeriforms, most parrots and birds of prey; a cone-shaped intermediate region results in greater visual acuity
Tubular eye—nocturnal birds of prey; the intermediate region is relatively elongated.
The shape of the avian retina is relatively flat, meaning that its surface lies near the point of focus for all directions of incident light. The wall of the eyeball consists of:

Outer fibrous tunic — cornea and sclera
Middle layer — vascular layer
Inner layer — nervous (retinal) layer
Fibrous Tunic

The outermost layer, or fibrous tunic, maintains the shape of the eye. The cornea is relatively small, particularly in underwater swimmers. It is strongly curved in tubular and globular eyes. The refractive index between the air and the cornea is relatively larger compared with that between the water and cornea, and is nearly the same underwater.

The sclera in birds is reinforced with a continuous layer of hyaline cartilage, except at the scleral ossicles. These ossicles form a continuous ring of overlapping bones that support and form a base of attachment for the ciliary muscles. Mammals maintain their eye pressure with the fluid that is made internally. Birds also make fluid in their eyes, and this fluid is drained out by the scleral venous sinus, or canal of Schlemm. This sinus is at the sclerocorneal junction or limbus of they eye, and it needs to stay open to drain fluid or it will cause an increase in pressure like in mammals that get glaucoma.

Vascular Tunic

The middle layer of the eye consists of a continuous layer — the vascular tunic. It is composed of the choroid, ciliary body and iris. The choroid tends to be thick, highly vascular and darkly pigmented, and it provides a significant portion of the nutrition to the eye. The tapetum lucidum, a highly reflective surface in many species, has been observed in only a few species of birds —the goatsuckers, which are nocturnal. The choroid continues as the ciliary body and then the iris.

The ciliary body suspends the lens with its processes, the ciliary processes and its fibers, the zonular fibers that encircle the lens. The ciliary processes are pressed firmly against the lens with its muscles that provide accommodation. These muscles are striated in birds, and they are directly attached to the lens capsule. This unique feature allows birds to rapidly adjust their vision as they fly. These muscles are most highly developed in hawks because they require rapid accommodation as they descend in a dive to hit their prey target with great accuracy.

Accommodation is much different in birds compared with mammals. In mammals, the ciliary muscles result in a passive change of the thickness of the lens. Birds, however, use a variety of active mechanisms for accommodation of the lens. These mechanisms include:

Using the posterior sclerocorneal muscle to force the ciliary body actively against the lens to change its shape
Using the anterior sclerocorneal muscles to distort the center of the cornea (hawks, owls)
Having a softer lens with powerful sclerocorneal muscles to force the lens to bulge through the pupil (diving birds). Water reduces vision because there is no longer corneal refraction, which accounts for 20 diopters.
The iris is often dark but may be highly colored. Male cockatoos often have a black iris, while females have a brown one.

The pupil is commonly rounded; pupils with an irregular margin may result from avian leukosis. Pupillary size is regulated by striated, rather than smooth muscles — the sphincter and dilator muscles of the pupil. Movement and size are rapidly changed in birds, but because of willful movement, a bird’s pupils often not respond to light in a pupillary exam because of stress. Birds also have the ability to regulate the quantity of light reaching the retina by migration of pigment in special cells embedded into the retina. With light adaptation, the pigment migrates to shield the receptor cells.

Lens

As indicated, the lens of birds is softer than that of mammals to provide rapid accommodation. Part of this softness results from the lens vesicle, which is fluid-filled. It lies between the annular pad (Ringwulst) and the body of the lens. The annular pad encircles the equator of the lens and is most pronounced in diurnal predators. In primates, the lens filters light below 400 nm, making it impossible to detect ultraviolet light. On the other hand, birds are able to visualize wavelengths down to 350 nm, allowing them to visualize many things we cannot. They are able to discern males from females in what we think are sexually monomorphic species. They can detect ripeness of food items because of this quality and hawks can visualize urine trails of mice. Now that is something very different than mammals and provides them with unique abilities to see things that we cannot see.

Retina

The retina of birds is relatively thickened and does not contain blood vessels, as occurs in mammals. This allows the entire space to pack in more “pixels” to see with. The retina consists of a non-nervous pigmented epithelium and a nervous layer composed of rods, cones, bipolar cells and ganglion cells. The ganglion cells collect to form the optic nerve at the optic or blind spot.

The rods and cones are the receptors in the retina. Rods are sensitive to the intensity of light, so nocturnal birds have mostly rods. In order to increase sensitivity to low amounts of light, several rods synapse with a single bipolar cell and several bipolar cells synapse with a single ganglion cell. However, the sensitivity of the owl’s eye may be due to its ability to gather more light (2½ times brighter than humans). Their ability to hunt in near darkness may result from their sense of hearing.

Cones are responsible for visual acuity and color vision. In diurnal passerines and predators, one cone synapses with a single bipolar cell, which synapses with a single ganglion cell. This one-to-one projection to the brain greatly enhances visual acuity, or the sharpness of detail.

Factors that affect visual acuity include:

Relatively large eye
Accuracy of focus on the regions of the retina because of the shape of the eye (ie, tubular)
Magnifying capacity of the fovea
Absence of blood vessels
The visual acuity or one-to-one projection of receptor cells to ganglion cells
Amount of contrast between an object and its background
The central area of the retina is the place of maximal optical resolution and may have a fovea. This fovea is commonly deeper than that of primates, thereby increasing visual acuity. The fovea may have one of three arrangements:

A single, round central area in each eye, close to the optic axis. A horizontal central area is present in water birds and those that live in open plains, which allows the eye to fix the horizon at its reference point.
Two foveate areas — one in the central area and a laterally situated temporal one. This is common in fast-moving birds, which require accurate perception of distance at relatively high speeds.
A single foveate area temporally placed, as in owls.
Color Vision

There are three visual pigments in birds, with a possible fourth, that are sensitive to near ultraviolet wavelengths. In birds, cones additionally have an oil droplet within them with five different absorbency spectra. The droplets’ function is not entirely known, but they may directly produce color vision or may enhance contrast by acting as intraocular filters. For example, yellow droplets could remove much of the blue from the background, increasing contrast between an object and the blue sky.

Susan Orosz, PhD, DVM, Dipl ABVP (Avian), Dipl ECZM (Avian)
About Susan Orosz, PhD, DVM, Dipl ABVP (Avian), Dipl ECZM (Avian)

Susan Orosz, Ph.D., DVM, Dipl. ABVP (Avian), Dipl. ECZM (Avian) Dr. Orosz is a board-certified specialist in avian medicine and surgery, both in the United States (ABVP, Avian) and in Europe (ECZM, Avian). She is known internationally through the advances made for the health care of birds, books and articles she has written, and her lectures to veterinarians and bird owners alike.
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