John Blakeman offers the following helpful advice on this topic, and asked me to pass it along. How much trouble would it be to report age classes of raptors? Bill Whan, Columbus p.s. Also below, after his contribution, I send along a recent bird report from the UP, which is relevant to the raptor discussion and has a lot of suggestive latitude-related information. As a master falconer (flying red-tails) and life-long Ohio raptor student (formerly banded, re-habbed, etc.), I have several observations regarding the reported reduced numbers of Ohio winter raptors. First, regarding rough-legs. Their irruptions out of Canada are almost exclusively related to the state of lemming and other small rodent populations. When these are high, as apparently now, there is no hunger motivation for the birds to move to more wooded lower latitudes. This year, small rodent populations must be adequate in Canada, holding these hawks at higher latitudes. The converse can be said for red-tails. Now Ohio doesn’t have lemmings, but meadow voles (Microtis pennsylvanicus) are the sustenance diet for most winter red-tails in Ohio. Yes, experienced adults can persist on other prey, but the larger portion of the population requires adequate voles to survive the long, cold winter Ohio nights. To the south, it’s not as cold, nights are shorter (allowing longer daylight hunting periods), and most importantly as shown in this year, there is reduced or absent deep snow cover. And that can be the deciding factor retaining or pushing many, perhaps most winter red-tails out of the state. This is particularly true for immatures and unmated, inexperienced young adults, the so-called “floaters.” These birds have not bred and have no mates. They are not attached to any particular winter territory. All of these birds, immatures and unmated young adult floaters, are free to wonder around the winter landscape looking for good vole habitat. That’s exactly why so many are seen at all the usual spots in winter, such as Killdeer Plains, where voles abound. Likewise when seen sitting on fence posts and utility poles along larger grassed highway margins. Lots of voles are easily captured at these sites. But, in winters like this, where deep (>3 inches) snow persists for longer than a week or so, and when nights are particularly cold, winter resident immatures and floaters quickly get in trouble. The voles run safely in their sub-snow runways, utterly unseen by any hawk perched above. Immature red-tails are particularly inexpert in capturing larger prey, a factor we falconers know first hand. After a year of chasing cottontail rabbits, they become expert in taking these larger animals. But a new immature red-tail sitting out on an Ohio Interstate looking for snow-obscured voles gets hungry in a few days and must then start chasing what few larger animals it can find. Most learn quickly that this won’t keep them fed, and two things can happen. A good number become migratory once again and start drift-hunting on the way south, looking for some non-snow vole habitats somewhere to the south. Sadly, a good number simply starve to death. Once adequate fat reserves have been depleted by a week or so of the very cold weather we had in late December and early January, the now-weak hawk can persist only by metabolizing muscle. That’s a metabolic cascade that in a few days ends in death. Falconers are familiar with all of this, and take exquisite pains to keep their birds from ever approaching this lethal weight-loss precipice. Wild winter red-tails have no such nurses or hunting mentors, causing the large winter die-off of these young birds. I would add parenthetically that the birding community could contribute markedly to a quantitative understanding of this phenomenon, if they were to be diligent in tallying both adults (with red tails) and immature (with non-redtails). Sadly, only total numbers of these hawks are commonlyrecorded, presuming that a hawk is just a hawk. That’s not so this winter. The adult red-tails I study in my area of northern Ohio (Erie and Sandusky Counties) have not declined this winter. They can handle anything nature offers here. But yes, most of the immatures hanging around the Sandusky Bay habitats (Resthaven Wildlife Area, Pickerel Creek Wildlife Area, Willow Point Wildlife Area, Blue Heron Reserve, many others) are depleted. The deep, persisting snow and cold have killed them off, or moved them (probably only a few) way to the south. Biologically (Do birders do biology? Sorry for asking that contentious question—just for prompting in this particular matter.) it would be so wonderful to have adult to immature red-tailed hawk ratios in autumn migrations and winter residencies, compared to those in the spring migrations. The helpful statistical analysis that such data would provide is too detailed to describe here. But a few years of such tallies would allow a very accurate understanding of the age structure dynamics of red-tails in Ohio. From these birder-provided data, we could begin to quantitatively understand what ratio, or even pure numbers, of red-tails die each winter. Simply compare autumn and spring migration adult to immature ratios. Right now, these numbers are meager, if non-existent. And the same thing should happen with bald eagles. The ratio of adults to immatures is markedly changing as the population expands and adapts to new habitats and prey. But mere specimen counts lend no information to answer these biological questions. Expert birders could provide helpful information if they’d start listing both immatures and adults of raptor species for which this can be so easily determined. Just how difficult is it to see a red or brown tail, or a white or black head? –John Blakeman +++UP Rare Bird Report for January 15, 2009 The month of December was mild, and many bodies of water remained open, allowing a number of lingering waterbirds including ducks and grebes to be recorded later than usual this season. It has been a decent winter for over-wintering hawks in the UP. More Cooper's, Sharp-shinned and Red-tailed Hawks than typical have been reported in recent weeks, mostly concentrated along Lake Michigan and the eastern Soo area. Northern Goshawks have been regularly seen, and there have been 3 Red-shouldered Hawk sightings in January! Surprising, Rough-legged Hawk sightings are average, if not a little low this winter. Multiple species of of white-winged and dark-mantled gulls were observed in December, but as expected, the number of gulls wintering in the UP drop rapidly in January. It has been an excellent season for Northern Hawk Owls with 7 birds reported this winter so far. Snowy Owl numbers, while not has high as last winter are present in decent counts. However, Great Gray Owls remain scarce for yet another winter. While the numbers of Black-capped Chickadees are very good this winter, numbers of Boreal Chickadees have not corresponded. Red-breasted Nuthatches are present in very low numbers. Bohemian Waxwing may be the only irruptive passerine that is regularly being seen this winter with flocks reported across the peninsula. As expected over-wintering sparrows are rare, though 2 reports of January Fox Sparrows from Lake Michigan is notable, but decent counts of Snow Buntings have been made in the eastern and southern UP. Finally there is a real lack of winter finches in the UP this season. Pine Grosbeaks are scarce, Purple Finches absent, Pine Siskins seen primarily as accessory's to moderate-sized goldfinch flocks present, and there have barely been any reports of Redpolls. There have been several sightings of Evening Grosbeaks from rural village locations- small towns with feeders seem to be the preferred site for this species. Red Crossbills have been reported in low numbers north of Marquette and in the west unit of the Hiawatha National Forest, and there have been a few reports of White-winged Crossbills in the upper Keweenaw. I have posted photos of the Yellow-billed Loon and one of the Audubon's Warblers in the 2009 photo gallery at www.upbirder.org Highlights *YELLOW-BILLED LOON* "AUDUBON'S" YELLOW-RUMPED WARBLER** Cackling Goose Ruddy Duck Spruce Grouse Golden Eagle Iceland Gull Thayer's Gull Lesser Black-backed Gull Snowy Owl Northern Hawk Owl Black-backed Woodpecker Boreal Chickadee VARIED THRUSH Bohemian Waxwing Palm Warbler ROSE-BREASTED GROSBEAK unidentified ORIOLE SPECIES *Exotics* *Eurasian Siskin* ______________________________________________________________________ Ohio-birds mailing list, a service of the Ohio Ornithological Society. Our thanks to Miami University for hosting this mailing list. Additional discussions can be found in our forums, at www.ohiobirds.org/forum/. You can join or leave the list, or change your options, at: http://listserv.muohio.edu/scripts/wa.exe?LIST=OHIO-BIRDS Send questions or comments about the list to: [log in to unmask]