Monday, March 10, 2008

A Brown-tail Kill and John Blakeman on Finding Replacement Mates

A yearling Red-tail in Caumett Park has a bite of newly caught prey.

Even though we later learn these two raptors are in one of the Osprey's favorite trees at Caumett Park, the Ospreys obviously aren't back for the season as yet, or this pair of relaxed Red-tails, (note the lower bird has fanned out her red tail), just might have been a dispute waiting to happen. Microbiologist Linda Schiess and I decided to go check out Caumett Park, Sunday, without any optical help in the way of magnification if you can believe it, and the place was crawling with Red-tailed Hawks, flocks of Canada Geese, Red-winged Blackbirds, Robins, lesser groups of assorted other migratory birds plus, my favorite, an escape artist Kestrel in the Gift Shop.

3:13:41PM A Red-tail, whose tail is brown therefore a yearling, is perched near the paved path. All is well for photography as long as I stay on the path. The moment I step off she's gone. But as it turns out, not gone for long, as she's got a kill in mind.

3:15:55PM We've perhaps gone a half dozen yards past the tree the brown-tail was perched in, when towards our side of the mowed grass area coming from the other side, a Red-tail swoops by and pounces on prey in the leafy verge of the tree line.

3:16PM She stands gripping for a few moments.

3:17:00PM Then, BAM, BAM, she lifts up off the ground, prey in talons, and smashes something gray onto the ground repeatedly. BAM! She then flips whatever it is up in the air and grabs it again. BAM! BAM!

3:17:21PM She hops over and looks down.
3:17:31PM The prey flips into the air again, Brown-tail turns and takes a heroic stance, looking left. Has anyone noticed?
3:17:36PM Now she looks front.
3:17:49PM Brown-tail straddles the prey, then leaps into the air and comes down, talons extended. By this time, a small group of watchers has gathered.
3:17:54PM Leaning down, see today's top blog photo, she takes a bite of her prey. Gray prey takes to the air once again albeit stiffly and someone behind me says, "It's a squirrel. I have to leave. I have to leave!" Everyone leaves but Linda and I.

3:17:59PM Brown-tail mantles and watches them go.

3:18:11PM Oops, not dead yet. Get it! Get it!

3:18:16PM Wings up, talons raking.

3:18:20PM MINE!

3:18:26PM Is anyone looking?

3:18:31PM Bang! Smack! Dead yet? One talon is extended. Stab! Stab!

3:18:43PM Get it!

3:18:55PM She pounces. Leaves swirl up.

3:19:11PM She's up on her toes, she grabs, prey flies through air again.

3:19:17PM Finally!

3:19:44PM But a little more bamming can't hurt.

3:19:49PM Take that!
I make the mistake of stepping off the path, desperate for a better look.
3:20:17PM I take another step and off she goes. She hasn't anything in her talons. Her prey has been left behind. She'll be back.
What is the prey by the way? Is it a squirrel? We scurry over to check. Where is it? Linda says dryly, "I think it's that stick."

As you've no doubt seen from the zoomed photos all along, "the prey" is a heavy stout stick. Zoom being an advantage we didn't have at the time with our very long range view, sans binoculars. More fools we, the jokes on us.
It really was quite the display which went on for a good five minutes. I wonder how much longer it would have gone had I not stepped off the path? It did get me to thinking. Killing rocks and sticks is something we've seen very young Red-tails do. I'd no idea that a yearling would participate in imaginary killing at this late age. Strength training? It is a far heavier object than those chosen by just fledged eyasses. Or perhaps the bird I've been calling a she, is really a he, and he's hoping to impress a possible future mate with his strength, speed, prowess, and last but not least--creativity?

Never underestimate a Red-tail.

Speaking of unusual behavior, as I've previously posted, James O'Brian,, saw Isolde of the Cathedral nest, do something he'd not seen her do before. She flew up very very high and then made a beeline into other Red-tail territory. James felt she might well be off to choose a new mate at the time. I felt that might well be the case as she had been being harrassed by other raptors, and mobbed by Crows Isolde needed some help to hold the territory and Red-tails do come up with new mates very quickly. So I emailed John Blakeman with some questions about how Red-tails might acquire new mates so quickly and forwarded along James O'Brian's sighting and theory. I also asked for his thoughts concerning Rob Jett's sighting of the interaction between the resident formel in the territory he watches and the confined female. Here's what Ohio Red-tail expert, Mr. Blakeman had to say---


Yes, perchance, I did see the photos and story on the free-flying RT harassing the enclosed bird. The crucial, revelatory behavior here was the bowing of the wild bird. Red-tails have an interesting intraspecific (same species) threat display, contrasted to threat displays against other species.

To threaten a non-Red-tail, some other bird or animal, a resident bird will flare its hackles (head feathers), open its wings, and stand very erect. This warns any nearby species that the hawk means business and is about to attack if threatened. Eyasses do this when a human approaches them on a nest.

But these flared-wing displays are never used to warn nearby or intruding Red-tails. Instead, the offended resident hawk takes a perch and leans over and assumes a very horizontal posture, with the wings sometimes slightly flared a bit out to the side, and the head just a bit lower than the horizontal back of the bird.

I once had a Red-tail that was illegally taken from a nest as an eyass. It imprinted to the teenager who tried to raise it, before wildlife officers confiscated it. Because it was so severely imprinted to humans, it was given to me to use as a hawk in my education raptor education programs.

I could never figure out if the bird thought it was a human, or if I was a hawk. At any rate, especially in winter and early spring, when breeding hormones were flowing, Goldie (she was one of the local birds at the west end of Lake Erie with a peculiarly golden plumage) would bow right to the ground when I approached her enclosure. If I walked up to her, she would grab my foot or gloved hand. She never figured out why I didn't appropriately retreat when she so clearly displayed her displeasure of my encroaching upon her territory.

My falconry Red-tails, all taken in the fall migration, never display the low, bowing intraspecific threat displays. They know they are hawks and I'm something else.

Goldie, by the way, was the female in my captive breeding program, from whom I learned first-hand how Red-tails behave on the nest and with eggs and eyasses.

Now, just how do hawk widows or widowers attract, gain, or accept new mates, and how does this happen so quickly? The details of all of this will probably be an entire chapter in my Red-tail book -- a chapter I'll have to spend a great deal of time working out. In short, no one really knows exactly how new mate selection and acceptance really works. It's almost always very quick, often within days, or even hours, of the loss of a mate. Was the new mate, a "floater," hanging around at the periphery of the territory, awaiting a mating opportunity? Do floaters, unmated young adults, spend their winters and early springs flying a circuit between the edges of multiple occupied Red-tail territories, on the continual search for new "openings?"

The observation of the new widow skying up and off into the distance, perhaps thereby announcing her availability, is very intriguing. I've never seen this, but I don't get to see nesting Red-tails as continuously has they could be studied -- of all places -- in Manhattan. This is a very reasonable possibility.

There is so much we now know about this remarkable species. But for each new behavior we discern, there are a dozen other antecedents that remain unexplained

--John A. Blakeman

Donegal Browne


Karen Anne said...

I though Isolde had a new beau already? What might have happened there...

Donegal Browne said...

Karen Anne,

Yes, Isolde has a new mate, who appeared within days of Tristan's disappearance. We don't know positively how new mates are chosen or whether the process differs depending on the sex of the remainder hawk. Though I do believe that it does differ. (More on this on the main page.) James O'Brian observed Isolde displaying behavior he'd never seen in her before. She skyed up very high and then headed off with purpose towards 145th St. The next day Rob Schmunk observed the new male with Isolde. James theorizes that Isolde, when she realized Tristan was gone, flew off and chose a new mate. John Blakeman suggests Isolde's unusual behavior may have broadcast to unbonded males that she was available.

I believe the rapid turn over from one mate to the next has to do with the hard realities of Red-tail Hawk territory preservation. Isolde was being harrassed by the traditional Red-tail enemies. She needed a mate as soon as possible in order to preserve the territory.

Karen Anne said...

Thanks, Donna. I think I just got confused. I do know they find new mates quickly. Somehow in reading a blog entry which I can't find now, I thought Isolde was still looking, after the new guy had appeared.

Speaking of survival depending on having a mate, in doing some family history stuff, where my ancestors were Danish small farmers or farm workers, there was one fellow in the 1800s who had married four times, each of his wives having produced a child within a year of the marriage and then died. One child died also.

In the first three cases, with babies and small children to care for, he married again in less than a year. After the fourth, he seems to have given up remarrying, but I did later find him and 2 of the 3 children fortunately together as workers or lodgers on a very large farm. The missing child, my ancestor, was old enough to be out apprenticing elsewhere.

So it isn't just the birds who have to mate quickly for survival.