Saturday, October 04, 2008

Sunday Miscellany: White Red-tails, Alex & Me, Golden Eagle, Turtle with Wheels, Eleanor's Cormorant, and the Headless Bunny

Photograph courtesy of Dr. Ruth Boll, DVM
A beautiful "white" Red-tailed Hawk in Utah, being treated for gunshot wounds. Notice her white beak, though still with black eyes. Which is a good thing because beyond being an easily seen target for idiots with guns, the only other issue in being white, is the possibility of unpigmented eyes which reduces the birds chance for survival. Probably because eyes without pigment are more sensitive to light which may interfere with hunting.

These photos come our way from a heads up on the "white" Red-tail site from Jackie of the Tulsa Hawk Forum--

Here is a site we've been exploring; it reports on a number of white/albino/leucistic red-tailed hawk sightings, and offers some wonderful photos. The various degrees of "whiteness" are interesting.

Jackie (Tulsa Hawk Forum)

Alex & Me
How a Scientist and a Parrot Discovered a Hidden World of Animal Intelligence--and Formed a Deep Bond in the Process
Irene Pepperberg

Harper has released some teasers from Alex & Me on their website. Check it out.

SEAN M. HAFFEY / Union-Tribune
Dr. Todd Cecil treats a sick golden eagle that was found on the ground on the Viejas reservation.
Socal from the Tulsa Hawk Forum sends this:

Has anybody read about the Golden Eagle that was rescued here in San Diego County recently? It was on our local t.v. News shows. Poor thing had kidney problems and was very sick. It was delivered to a veterinarian who was nursing it back with I.V. fluids etc., and there were plans to eventually transfer the bird to Project Wildlife, a local wildlife rescue foundation. I haven't heard how the eagle has fared since, but I'll try to find out more and get back to you... Meantime, here are some links to articles and videos:

Ailing eagle rescued on Viejas reservation

By Onell R. Soto
5:29 p.m. September 29, 2008

EAST COUNTY – A golden eagle with kidney problems is recovering at a La Mesa veterinary clinic after it was rescued Saturday night on the Viejas Indian Reservation.

R of Illinois sends us news of Tonka the Turtle



SAN JOSE, Calif. - A screwdriver and some Velcro has changed the life of a once-homeless turtle living on the Peninsula.
When handyman Kohl Williams fitted a three-legged tortoise with a set of toy wheels, suddenly Tonka was off a rolling -- slowly.
Peninsula Humane Society workers think Tonka was bitten by a dog

A gorgeous shot of a Double Crested Cormorant at the Model Boat Pond
by wonderful Central Park Photographer Eleanor Tauber.

The next photo is not for the squeamish, so if you are, don't keep scrolling down.

I went out to the front yard this morning to see if any of the plants had been nipped by the frost last night and discovered this-- A neatly decapitated upper de-pawed bottom section of a Cottontail Rabbit. The head was no where to be seen and I looked for it. I also looked for tracks of a possible predator but the ground is very dry so no luck.

My first thought was that a cat had done the deed. But why would a cat take the head and leave the rest? And it's so neatly done.

A Red-tail flushed off the kill? So she just took the head? Does that make sense? But it doesn't really look like the work of a Red-tail if the technique for rabbits is similar to that used for squirrels. Though as Manhattan hasn't many rabbits I've not seen the leavings from a Red-tail Bunny kill.

As far as I know we have no Prairie Wolves in the neighborhood. And I sincerely doubt it was Rocky the Raccoon, or Fluffy the Opossum.

Any ideas?


Friday, October 03, 2008

BEWARE GLOBAL WORMING! And Is That Stacking or Copulation?

Earthworm with arrow pointing to clitellum
Courtesy of Great Lakes Worm Watch
Now why in the world is there a GREAT LAKES WORM WATCH?

Before you go too far into that thought, I'll let you know that there is also a Canadian WORM WATCH.

A while back I learned that our buddy the earthworm, friend of the vegetable patch gardener, item of fascination for small children, the one invertebrate that many people actually like, was an exotic. Yes, North America hasn't had any land based earthworms since the Ice Age. If we ever had any in the first place which seems to be under discussion. (Or if we only think they all got frozen out and we've got indigenous ones that we don't know about.)

The Earthworms that we have now seem to have came with the Europeans when they arrived with potted plants, horses, and previously dirt ballasted ships.

Now, when I realized that these earthworms were exotics and obviously invasive as they'd spread clear across the country in only a few hundred years, it seemed unique. I'd never heard any thing but good about earthworms from anyone. Unknown for an exotic that spreads. I mean people actually buy earthworms when there is a dearth of them in their gardens. So finally an invasive had arrived that perhaps was taking over an empty niche, doing lots of good, and no harm.

Silly me. I should know better. Well folks, here it is. Earthworms that invade a deciduous forest of hardwood trees, destroy the needed layer of organic "debris" that is necessary for the survival of herbaceous plants, like wild flowers, understory seedlings, tree seedlings, in three to five years.

How do the earthworms destroy it? They eat it all up. And when they eat it up, they destroy an incredibly complex microscopic ecosystem that is thought to have evolved without earthworms. Because when duff and herbaceous layers go, the forest begins to loose it's health as well as many of the formally numerous species that evolved along with and were part of the whole system.

Wait a minute you say, what about all the good stuff worms do? Like aerating the soil? Unfortunately a forest is doing swimmingly without all those worm holes. The worm burrows just cause nutrients to be leached down into ground water, as opposed to being available to the plants.

And you know all the good CO2 removal that forests do, cleaning up after us? A lot of that is done by the microbes and they're being eaten. Ditto, nitrogen grabbing.

The overpopulation of deer has been being blamed for the disappearance of wild flowers and understory from our forests. Maybe. But when the strata in which the plants grow disappears, having been eaten by earthworms, so does the herbaceous layer. The deer are just a whole lot more obvious about being there, than the worms are.

Here's the deal. There is another call out for Citizen Scientists. As Cornell has done previously with Pigeon Watch and Feeder Watch, when information was needed from many micro locales over a broad range. The Worm Watches want to know which species of worms are currently where, when they begin to broaden their range, or change species proportion. That's a tall order when you think about it because they aren't just dipping into a ready made population who already participates in the activity--The people who watch pigeons or watch their bird feeders and can tell the difference between species or color morphs.

Beyond the Great Lakes Area which isn't exactly small, Canada is attempting a National Survey, and Canada has a lot of square inches that could be inhabited by earthworms.

I don't know about you folks but I've never done a lot of species identification when it comes to earth worms, have you?

Well, here's your chance if you're up for it. Learn the most common species of worms--

Key to Reproductively Mature Earthworms

Plus tidbits such as a worm, with a bright orange clitellum, is in heat.

Then there is learning the sampling methods--Flip and Strip, Modified Flip and Strip, and Modified Hand Sorting.

And Great Lakes Worm Watch was looking for partner organizations so Minnesota Worm Watch was created. They send their data to the larger organizations.

And they'll tell you how to create a partner organization to investigate, fill in data sheets, and send it in, basically to CONTAIN THOSE CRAWLERS.


Photograph Courtesy of Charles Juels

Sally wrote in the comments section,

I wonder if those Harris's hawks are actually stacking, or about to copulate? Perhaps coincidence that the male happens to be on top? I have had no luck finding photos of stacking behavior, either.

Hi Sally,

It is tough to find photographs of stacking, isn't it?

I assume part of the problem is that stacking is undertaken usually, only when there is a lack of enough high perches for all members of the family group to stand on.

Where is the lack of high perches most often a problem, while still allowing a viewer to see them do it? In the desert, and that's where stacking takes place--a largely unpeopled environment. Which also means that humans who are there, are easily seen by the hawks who then likely, take off for unhumaned horizons. So even though a human may catch a stack with the eye, there is also the time it takes to pull out the camera and get the shot.

As to whether this could be a pre-copulation photo, I don't think so.

Ordinarily, a female hawk "invites" the male for copulation by leaning forward and tipping up her posterior, placing her cloaca in an easier-to-access position. Upon the males arrival she also will switch her tail to one side. And males during copulation are much further back in relation to the female. They also use the flapping of their wings to remain in the proper tipped back position so they can be cloaca to cloaca with the female.

I've never seen any species of bird copulate, who's start up position for copulation is standing on the female's back, nor is that an "after" position.

I think he's standing on her back for a better view of the hunting area. If you look at the photograph they both seem to be looking at the same thing

In reference to who is on top--the literature says that the higher status or dominant bird is on the bottom. The less dominate will give up his current perch when a more dominate bird comes toward it, every time. Therefore the the closer to the bottom the more dominate the bird.

Now I have seen young Red-tails fresh off the nest, knock their mothers off a perch but I'm figuring that's most likely inadvertent or if it isn't she's giving them some slack as they've yet to learn proper Red-tail manners. I doubt she'd let them do some months down the line.

Is the female always the dominant bird in a raptor pair? Or is it really the most dominant bird on the bottom, or just the biggest one?

Is the biggest bird always the most dominate?

If, there were two, two year old progeny also in the group, (Harris Hawks don't go out on their own until three years of age.), one male and one female, would it always be the young female who stood on Dad? She'd be bigger than he is, but I imagine Dad would still be higher in status than the daughter.

What would answer the question? A photograph of three Harris Hawks in a stack of two females and one male.

Pending enough size difference to know, of course.

And we had quite a hard time finding any photos of a Harris stack, until Catbird found that one.

But I'm going to keep looking and I hope you will too.

Donegal Browne

Monday, September 29, 2008

Stacking Harris Hawks Plus Quicksilver Goes Medieval

Photograph Courtesy of Charles Juels
Harris Hawks, Parabuteo unicinctus's_Hawk
In the United States desert southwest, Harris's hawks sometimes engage in a behavior called 'stacking'. Two or three birds may perch one atop the other.Researchers note that when this occurs, the more dominant bird is actually the one on the bottom of the stack.

The social dynamics are that when a low-status bird is approached by a higher status bird, the low-status bird will abandon a perch. However, a higher status bird will retain its perch,and end up with one or two lower status birds atop it.

They also hunt leapfrog fashion.

The Cut-Off:
One hawk flies straight at the prey. Then a second hawk flies from the direction the prey most likely will run. It tries to intercept(in-ter-SEPT), or cut off, the animal. One by one, the birds in the pack try to intercept the prey until one is able to kill it.

Surprise Circle:
In this plan, several hawks fly toward the prey from different directions all at once. The prey has nowhere to run, and the hawks get an easy meal.

Crawl in and Shoo:
When their prey runs under a bush, the hawks don't give up. One hawk will crawl right into the bush until it "shoos" the animal out. Other pack members are ready to nab the prey, no matter where it runs.

Many thanks to Catbird of the Tulsa Forum for taking up the challenge and tracking down the wonderful photograph of the stacking Harris Hawks and the information on their hunting tactics!

According to the photographer Charles Juels, the picture was a lucky shot. He was about to photograph the female hawk perched an the cactus, when the male flew in and he got them both.

How do I feel reasonably confident about the top bird being male and the bottom one female? It's good old, reverse sexual dimorphism in raptors. She's bigger than he is.

Just how does a parrot process the events of his upcoming day?

For those of you not familiar with him, this is Quicksilver. The African Grey Parrot who lives with us. Silver is just about to turn ten years old and he came to stay at three months of age.

Typical of many African Greys, he can speak in context, and can be loving, infuriating, sweet, utterly uncooperative, mischievous, downright naughty, very funny, menacing, and frighteningly smart. It all depends.

Boy, does it depend.

And by the way, Silver is also an Arts and Sciences education bird who stands in for the parrots who were companion animals during the medieval period of history for our Society of Creative Anachronism demonstrations.

Another of those happened this past weekend at MedievalFest in Fort Tryon Park which abuts the Cloister's Museum in Uptown Manhattan.

And as usual, when going anywhere with a parrot, it was an adventure.

Though birds can communicate with us, and there are similarities in responses at times to those of ours, in actuality, how a bird's mind works and how they arrive at certain conclusions given the same environmental stimuli as a human, can be a mystery.

Though let me add, on the human behavioral side of those who visit the demonstration, most humans don't mind some interesting facts and even enjoy anecdotes about Medieval Parrots, but deep down in their hearts they'd much rather be standing there when a current live parrot talks.

And there may lie a tale.

For days, Silver had been saying, "Wanna go on a trip." He'd seen various preparations being undertaken that precede "trips" and had decided to lobby for being included.

There is positive lobbying and negative lobbying.

The positive is putting in his request now and again, "Wanna go on a trip." The negative is his anxiety that people might leave him which manifests itself in a wish that all members of the family be in the same room at the same time so he can keep on eye on everyone and make sure he isn't left behind. And attempting to make it happen by making things unpleasant if it isn't happening. Or at least that is my assumption about what is going on.

Why the anxiety? Possibly because he may not be entirely sure just who may be going? What if the person leaving, grabs a suitcase and strands him with a family member who isn't going? No matter how many times he's told he'll be going, and he knows it intellectually, his anxiety about possibly being left behind gets the better of him.

Like I said, just why a parrot responds in certain ways to certain environmental stimuli can be a mystery.

Or it could just be whether it's his intellect or his emotions which are controlling his behavior at any given moment. According to the research, an African Grey Parrot has the intellect of a five year old child, but the emotional responses small human aged two. And we know, what they're like. The human age of two isn't called the Terrible Twos for nothing.

Plus lest we forget, Silver is a tame member of a wild species, so there is a third level of induced behavior involved. Behavior that is innate and likely difficult if not impossible to control by intellect. At times no matter what he is thinking, the innate behavior could click into gear and carry him away.

And that's what happened to Quicksilver. After arriving at the Ft. Tryon site, not only one but two of his likely innate responses were triggered.

Now he'd been incredibly happy to get into his carrier, and be part of the baggage that went out the door early Sunday morning. A corner of his carrier cover folded back he watched through the opening, offered his beak to be stroked, made a few comments, and generally showed his excitement by the flashing of his eyes.

(Flashing- a term used for the repeated quick constriction and expansion of the pupil of a parrot's eyes when responding deeply to stimuli.)

Silver was holding his own, through the the whole set up. He sat on his perch, placed upon the table, surrounded by brightly colored copies of paintings of the time period that include parrots and attracted passers-by.

Before long, a mother and two little boys stopped by. Two little boys who were holding wooden swords. As I was asking Silver if he'd could count for the kinds, the youngest boy took a lunge at Silver with his wooden sword missing him by only inches. I had gotten my hand between the sword and the parrot in time so I would have taken the hit, but still.

Sudden aggression by a stranger would set most everyone's autonomic system off. Silver's eyes widened, he stared straight at me, his wings came slightly away from his body, they began little begging flaps and he began repeating the phrase, "Want up", rapidly and with fervor.

I picked him up and we answered a few more questions and Silver firmly refused to not only count but to interact in anyway. He was very nervous and I didn't blame him.

Then it began to rain. Silver hates rain. As it turns out it's known as a species issue. Practically all companion Greys are loathe to be rained on.

Now originally these birds evolved in a rain forest so why does rain completely unglue them?

It's like they go into a mindless panic. They bob up and down, once again wings still curved down but separated from the body. They request going somewhere, anywhere else. They struggle in what looks like fright. And it isn't just the drops hitting them, I realized Sunday, it may also be the sound of rain, the drops hitting surfaces that also gets to them. I knew Silver did not want to be touched by raindrops, but I then realized that he was staring at the ceiling of the tent.

I'd have to test whether the rain hitting canvas was just new and strange therefore scary or whether the plops triggered something that was also triggered by big drops hitting big leaves above him as would happen in the wild. .

The rain is falling and the bird is having a dreadful time. I speak softly telling him, "It's alright, it's alright". With some time, and the lack of anymore visitors due to weather he begins to be calmer, though still nervous. It is still raining.

I'm distracted by something and when I turn back to him,

I see that Lord Grim is telling a story. People are smiling, laughing, and Silver is watching intently. Instead of having a comparable expression to the photo above...

He is wearing an internalized expression. The wheels are turning inside his head. He has now been able to get to a place where he can think. Is he in the moment of the people across the way, or did their energy help him to relax and allow him to mull over the earlier experiences?

Their Majesties Konrad and Brenwen, now Count and Countess, sit in state with the Wizard who has appeared at the Festival for as long as anyone can remember. Many a child's day was made by having their photograph taken with them.
The rain has abated, though the air still hangs with moisture, and Silver wants to go somewhere else. We go for a walk around our area. Fascinated people stop, ask questions, ask if they can pet Silver, that's a no in his current previously agitated state. He's feeling the need to remain sharply vigilant. He has just been "attacked" after all.

Then a young man with the remains of a turkey leg approaches. Silver perks up, and looks downright friendly to the new stranger. He then leans over and helps himself to the remains of the turkey leg. Thankfully, the visitor takes this in good humor.

And the turkey makes a huge difference in Silver's humor as well. He is himself, relaxed and eating with enjoyment. Off a stranger's plate, no less. Why is that comfortable?

He raises up chewing and looks nothing like the bird that acted as if he was about to have a nervous breakdown due to rain. It's all quite mercurial.

We continue on our rounds. Free of the downpour, the visitors are beginning to return to look at the exhibits and demonstrations. Time for us to go back to our post.

See Silver on his perch? Daughter Sam has taken over for awhile, answering questions about medieval parrots generally and this parrot in particular. Notice that Silver is watching the visitors with one eye and making sure he knows where I am with the other. He is more wary since the sword episode when perched there, and won't talk in front of the visitors. In fact if I disappear for awhile he'll become agitated and start to beep, even though Samantha is with him.

Questions around the weapons tables are always in good supply.

Then there is the information concerning the grinding of pigments, and the society itself. So far Silver hasn't begun his rendition of his version of a personal emergency--a perfect imitation of the smoke alarm in the apartment.
I spoke too soon. BEEP, BEEP, BEEP. Truth to be told, it's time for Silver to have a little decompression time in his carrier away from all the stimulus so he doesn't become too stressed.

What stimulus does Silver register while quietly in his box with the curtains closed?

Does he still feel the buoyant energy given off Her Highness, who's family owned an African Grey years ago?
And what is coming from the girls?

I do know that when the ladies sing he listens from within.

Sam is very excited about her painted face.

Just below the bottom horizon of this photograph is Silver's case, with him inside. The others talk unawares. He listens.
There are the masks at the next table to his, which he finds fascinating. Particularly when they go from the table to a child's face, and back again.
I see the cover ripple on the top of Silver's box. He's climbing upside down, and round and round. Time to get him out. He stands on my hand and leans forward and puts his wings out then does short flaps. He's cuing me to perambulate him that direction, toward the trees.

But when we come round the tents to the back. Sam is having her fighting lesson with King Conrad.
And there lies a second tale of behavior within the first tale.
Samantha did an internship at the American Museum of Natural History this summer. At the end she recieved a stipend to help cover her transportation costs for getting back and forth to the museum during the summer.
That weekend we went to an event called Barleycorn, at which there was a silent auction to benefit the Royal Travel Fund. One of the items at auction was a fighting lesson with King Konrad. Sam saw it, dug her stipend money out of her pouch and began to bid.
Why? Because Sam, who is all of five feet, two inches tall and a hundred and ten pounds, maybe, desperately wants to fight heavy weapons well enough to go into battle with and against thousands and thousands of others, by far mostly men, and far bigger than she. She is dying to go into battle in masse and whack people at the Pennsic War. This, after being polearmed square in the chest, knocked off her feet, and sprawled flat on her back, during a practice.
It doesn't matter, from the moment she first saw the thousands of armored fighters sprawled across the plain of the battlefield, she wanted to be out there at least once.
Hence the lesson from King Conrad. She'd already picked the brain of Vicount Sir Edward for strength exercises, so when the opportunity presented itself, and her summer money available in her pouch, she went for it.
At her size she knows she needs all the technique she can garner.

But Silver isn't sure this is a very good idea at all. Beep.

And that guy has a whacker like that little boy. Beep.

Beep. Beep! "Silver, shhh, it's alright."


I come round to the other angle hoping that will help and suddenly a tiny boy, not much older than three or so, walks up and stands hypnotized by what he's seeing. But what if he gets too close and is bopped. Is there a marshall?
Wolfy, who is the youth marshall stands nearby but is he currently marshalling? Beep, beep, beep. I can't really get him without causing a disturbance as I'm holding Beeper Boy.
Good there is Eularia across the way. She sees the little boy. I look around for his parents. Hard to tell. Lots of people watching but who belongs to tiny tot here.

His face is the definition of delight. It's a real Knight in shining armor, standing right there, like a sparkling dream. One does hate to disturb that. And mostly they are just talking through moves and then slowly doing them. It should be fine.
Beep, beep, BEEP! But Silver is becoming more and more convinced that he needs to warn Sam about her position of danger and he won't listen to my reassurances.

Then Vicereine Eularia appears and Silver decides to go to her hand.

And what does she do, she radiates well being, calm, warm fuzzy good feeling at him, or at least that's how I verbalize what she does. And it's just something she tends to do and it, well...
It works. The agitation, slides down, and down,

Though the outside stimuli remains the same.

The rain begins again, and the crowds instead of dispersing, gather to watch the events at hand.

And Eularia keeps radiating and Silver no longer has to keep an eye on me every second.

And when I next look down, the boy has disappeared and a little girl of about the same age has appeared and is hypnotized by Eularia and the parrot.

Which reminds me of a behavioral episode when Samantha was about this little girl's age. You don't have to believe it. And it is anecdotal and even possibly coincidental but it happened and I've always remembered the moment as it was "unusual'.
It was cold out and Sam and I were walking down a Manhattan Street. Sam was cold, and tired, and quite probably a bit hungry. She was very very unhappy about having to walk for a few blocks and she was working herself up to cry.
I looked over my shoulder, as I pulled Sam to the edge of the sidewalk to slow down and wipe her nose and there was the mime, actor, Bill Irwin walking towards us, minding his own business. (He was on Broadway in Fool Moon. He's done TV, movies...) He walked up the sidewalk and as about to pass Sam from behind as she sniffled, he just looked down and smiled at the back of her head. There was no way she could have seen him do it. But instantaneously she looked up, quite sniffling, and smiled too. And everything was better than fine for the rest of the walk. ???
And that's a bit like what was happening to Silver as he sat on Eularia's hand.

Silver looks over at me and he is looking downright relaxed.

Then the lesson is over and the King, all six feet, three inches of him, goes to fight bouts with the other heavy weapons fighters. He can defeat two at a time quite handily.
Silver watches.

And there in the youth arming area are the boys in her fighting level. They too are the size of grown men.
I realize that young males wait for their bouts entirely differently than the females do.

The boys group together while they wait.

Whereas the girls...

...go within themselves.

And when the youth bouts are called and two fighters requested, the boys immediately step up.

As do the girls, but later than the boys.

This male and female fighter are realtively the same age but look at the difference in size.

Sam comes out for a bout.

Silver is back with me and though now more reserved in his vocalizations, he watches Sam with a look of some trepidation.

Again the radical difference in size.

I watch the group, in the arming area, waiting once again for their next bouts and notice that the younger boys have congregated there. No doubt looking forward to their own adventures as fighters in the future. I think back, and don't remember ever seeing very young girls who do the same. There are young girls in the very junior ranks but somehow the arming area, when they aren't fighting, seems to hold no charm for them. A gender specific behavior?

Then it's time for the two girls to fight each other and I notice a third young female looking on fixedly. Is watching, causing her to feel the blossoming of an urge to whack as well?
(The weapons being used here are boffers. Yes, there is a "stick" inside but it is padded with foam. A blow may smart but it won't do any dammage. Rattan weapons which have been know to do damage now and again, cannot be used by fighters under eighteen.
The other young woman still watches with utter focus from beyond the fence.

As does Silver.

Then Sam "looses a leg" to a blow from Allegra. As a point of honor, Allegra then takes her own leg and also goes to her knees to fight.

The young woman on the outside still has that look.

I look at Silver, he is bone tired. Time for a possible longer stay in his carrier for an actual nap. In he goes.

The talking continues.

The fighting is over. The spectators begin to disperse.

A friend arrives for a chat across the barrier.

Sam begins jiving and doing "complaining" bits about her wet t-shirt. She is not at all serious and it's funny. But it is interesting to see the expressions of the other youth fighters. Who can tell the difference when she is joking and when she is serious?

The day is winding down. And the packing up begins.
Quicksilver looks out. He has wrinkles under his eyes he's so tired.
I do wonder what conclusions he's come to while resting and processing the days events. How much does he understand about what has been going on?
And the smallest of the lot-- Did he eat the piece of Brie eventually, also named cheese, he was given when requesting "cheese?
He'd asked for cheese all day, but no one had brought sharp cheddar. And sharp cheddar is Silver's idea of the definition of the thing he is asking for when he says, "Want cheese." And that is likely the smallest of the confusions created by the day in his mind.
Silver watches the park birds begin to fly into trees that could turn into possible places to roost.
He shows absolutely no sign of wanting to join them. Why?
Well, I suppose part of it is, that selected humans, no matter how weird, are his flock. Besides the other birds don't know English and that is the language that he speaks. Language in Greys appearing to be learned and passed generationally rather than otherwise acquired, as different flocks in the wild appear to speak different "languages".
Besides if he went with them he wouldn't get to hang out at the buffet table or cache turkey legs from humans who are delighted that he's doing it.
All in all, sometimes dreadfully rattling but at others likely quite fascinating to be an inter-species embassador, I imagine.