Red-breasted nuthatches stage incursions into Ohio on a fairly regular biennial schedule. In recent decades, seed crops at higher latitudes have peaked in the odd-numbered years (many trees show increased production of fruit every other year--even many of our oaks, producing a similar rhythm in winter reports of red-headed woodpeckers). Good crops promote higher populations of nuthatches, and hence noticeably more birds moving south in the following autumn. These incursions usually become evident by August, when we start seeing a lot more nuthatches than the previous year. In Fall 2005, the Ohio Cardinal reported: "A marked incursion. R. Royse reported 18 Oct that all hemlock groves and some pine groves in Shawnee SF harbored this species. The 10 Sep CVNP census had 44 red-breasteds to 100 white-breasteds. The southwestern counties contributed 40 reports of this species during the period." In 2003 it was "Obeying its apparent biennial cycle, numbers were up. Multiple sightings included 10 at the CVNP 13 Sep (L. Rosche), seven at Winton Wds 21 Oct (F. Renfrow), five at Secrest Arboretum in Wayne 8 Nov (S. Snyder), and three at Findlay SP in Lorain 22 Nov (C. Rieker). And in 2001: "Early sightings can presage invasions by northern birds, as in 1995, when early Sept nuthatches were followed by higher than usual numbers of redpolls, siskins, and evening grosbeaks; appearances of nuthatches as early as 15 Aug in 1993 were followed by flushes of the same species. This year Aug sightings began on 13 Aug in Cuyahoga (S. Wright), two in Lake on 23 Aug (J. Pogacnik), and five in Cincinnati on the 29th (D. Brinkman). Later, the CVNP census counted 36 on 15 Sept, and B. Zwiebel had ~20 at Magee on 7 Oct." These regular odd-numbered-year irruptions are not ironclad certainties, of course. The fall of 2004 had more r-b nuthatches than usual too, with some good records. But overall, the biennial hypothesis usually comes through: long-term Ohio numbers from Christmas Bird Counts and from venerable journals like the Cleveland Bird Calendar seem to reflect it overall. At this point, 2007 seems to be following the pattern. Nuthatches seem to be the most susceptible to periodical irruptions, though lots of other high-latitude seed-eating birds show some regularity: siskins, redpolls, grosbeaks, even chickadees and waxwings. We'll see about the other ones later, but for now it looks good for another nuthatch incursion. Bill Whan Columbus ______________________________________________________________________ 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]