Tuesday, January 06, 2009

Will this be the year for Pale & Lola?

Pale Male & Lola on Beresford -- Jan 1, 2009

Our friend John Blakeman, the Ohio falconer and biologist, writes:


Soon, diligent hawkwatchers will begin to see the 2009 breeding season commence. Out here in Ohio we’ve already seen a few meager sexual flights. In a few weeks, and especially in February, breeding behaviors will resume in earnest among experienced pairs. Although it’s still hard winter, we can always look forward to spring with the resumption of the breeding behaviors of Red-tailed Hawks, which will start to occur at any time now.

Once again, we’d all delight in having eyasses once again at 927 Fifth Ave. I have a heretofore unannounced explanation for what may have happened last year. If this new perspective is true, there can be great hope that Red-tail reproduction at 927 will gloriously resume this spring.
After learning of the observations of hawkwatchers and falconers here in Ohio during the summer and fall of the past year, it is now clear that the 927 nest was not the only one to fail last spring. In October, at the height of the migration period, when immature Red-tails moving down from Michigan and Ontario should have been in abundance, very few immatures were seen this fall in Ohio.

I and two other falconers spent about six hours on five different days racking up almost 200 miles of travel on each day, all in the search for migrating immature Red-tails. We counted ample and typically high numbers of adults, from about 25 to 40 different adults each day. Ohio did not lack for mature Red-tails this fall. Their numbers were wonderfully high (as they have been in the last 20 years or so).

But we were seeing only one or two immatures on each of these back-roads hawk watching trips. In normal years, the ratio of adults to immatures in October would have been between about three to one, on down to five to one. Three adults to every immature is the usual range. This year, it was ten or twenty adults to one immature. On one day, we saw about 30 adults, and not a single immature.
Something was wrong.

Since October, I’ve talked to a number of my falconer friends in Ohio, along with some information from over in Pennsylvania. These people discovered exactly the same thing. There were very few immature Red-tailed Hawks in Ohio this year, and probably reduced numbers to the east.
The explanation I offer is this. One of my former apprentice falconers, a man who is now an expert master falconer, who also (like so many falconers, for obvious reasons) watches wild Red-tails in his area in eastern Ohio, gave me his explanation for the dearth of immature Red-tails this year.
In October I mentioned the difficulties I was having trying to find wild, migrant immature Red-tails here along the southern shores of Lake Erie, in rather wild areas that normally abound with these and other migrant raptors. My friend said, “John, don’t you remember that horrible wet, windy, rainy snowstorm we had last spring, either in the last week of March or the first week in April?” I said, “No, I don’t.”

My friend said that just before this aberrant weather hit, he was watching a local Red-tail sitting on a nest, one that he could easily scope out near his house. He said that after this weather hit, the female left the nest for excessively long periods of time. It returned and completed incubation, but the eggs became cooled and no eyasses fledged from that nest last spring.

And that’s my explanation, at least for the paucity of immature Red-tails in Ohio this year. In talking with other Red-tail watchers and falconers in the region, we now agree that there had been a general regional nesting failure in the spring of 2008, an event that probably happens once every 10 to 20 years or so. These infrequent failures have no discernable affects on the adult population, as they all easily survive the cold, wet, rainy, windy weather in March or early April. But as with the nest of my friend, two things apparently can happen to terminate successful incubation.

In the worst case, enough snow can fall so as to obscure the hawks’ primary prey, the common field vole. After expending herself laying two or three eggs, a sitting female Red-tail can get rather hungry. If her tiercel mate is having difficulty finding voles under the snow, even for a day or so, she may get hungry enough to leave the nest and go hunt for herself, there by lethally cooling the eggs.
The second egg-killing event probably does not involve the obscuring of prey by snow. If there are persistent strong, cold, rainy winds, even in the best wild nest, too much cold air can get down through the nest and cool the eggs, especially when the mother has to stand up and slice (defecate), or when she stands up to start tearing some prey her mate has brought her for food.
In most years, in all but the most severe weather conditions no lethal egg-cooling events occur. But my falconer friend diligently observed this at his wild nest, noting the absence of the female for short periods of time during the extremely foul (or, anti-fowel) weather.

All of this raises the question (for which I have no definitive answer), were there one or two days in Manhattan last March or April that were extremely windy, cold, and wet? Could the one or two days of really bad weather Ohio had have blown right into NYC? If so, this may well be the explanation for 2008's 927 nest failure.

Someone may have access to NYC weather records from mid March through mid April, and could more accurately determine the possibility of a severe, aberrant weather event there. There is no doubt it happened here. It was closely noted at one Ohio Red-tail nest, and there were very few immatures seen in the state during the summer and autumn. There was a marked hatch failure here last spring, and the only explanation is severe weather, involving mostly excessive cold wind and drenching rain during incubation.

If that’s what happened at 927 Fifth Ave last spring, there is renewed hope that eyasses might again grace the nest structure at that site.

One last point. Many have been concerned that Pale Male, old as he is, might not be able to produce viable sperm. I assert once again that his is highly unlikely. In autumn, I talked to a long-time falconer friend and biologist in Kentucky, raising the question of the healthful age of old Red-tails. This good man pointed out that he had a male falconry Red-tail that he had trapped as an immature bird, in it’s first year, and that he had hunted with it for 34 straight years. All the while it remained in good health and hunted successfully the entire time. In comparison, Pale Male is not geriatric in any sense.

Here’s hoping for 2009, both with my wild Red-tails in Ohio, and especially for the iconic ones at 927 Fifth Ave in NYC.

–John A. Blakeman

PS Please send in answers, if you have any, to John Blakeman's question in bold letters above,