While a different species, the British Trust for Ornithology has done some fascinating work on Common Cuckoo migration. Individuals were already moving south in the first half of June (a month earlier than anticipated). Take a look at the link below.
http://www.bto.org/science/migration/tracking-studies/cuckoo-tracking Certainly there are different life history traits, but I expect that Black-billed and Yellow-billed Cuckoos in North America will shatter conventional wisdom of what they do here. The speed at which cuckoos fledge is astonishing and I would not be at all surprised if many do not linger very long in any location. But I'll be the first to admit that I haven't a clue what cuckoos do, why they do it or when they do it! As technology develops I expect we will see more and more individuals of a variety of species (perhaps particularly first-year males?) move throughout the "breeding season". Perhaps these "summer" "breeding season" nocturnal flights and vocalizations are a way that that fairly low-density species with ephemeral habitat/food encounter each other and good habitat (either for that year or for a following year)? Perhaps this is another reason why Sora, Virginia Rail are recorded with fairly high regularity as calling flyovers in summer in areas where they are otherwise generally uncommon (i.e. Tompkins County, NY). They breed in habitats that change from year to year so a bit of wanderlust could be advantageous for the following breeding season. I think cuckoos face similar ephemeral challenges, but based on food availability. Fascinating stuff. Chris Wood eBird & Neotropical Birds Project Leader Cornell Lab of Ornithology, Ithaca, New York http://ebird.org http://neotropical.birds.cornell.edu On Thu, Jun 7, 2012 at 5:57 AM, Bill Evans <[email protected]> wrote: > There’s a delightful old paper by Gerald Thayer describing "the mid-summer, > mid-night, mid-sky gyrations of the Black-billed Cuckoo, as noted by my > father and me for three consecutive seasons in the southwestern corner of > New Hampshire": > > ”Several years before we discovered the nocturnal-flight phenomenon, we > began to be puzzled by the extreme frequency of Cuckoo calls on summer > nights. ***They uttered both the cow-row notes and the rolling guttural > call; but the guttural was much the commoner of the two, except on dark, > foggy nights, when the case was usually reversed. ***The birds were often so > far up as to be only faintly audible when directly overhead, with no > obstructions interposed; and this on a still night would seem to mean an > elevation of at least a hundred and fifty yards. They sometimes flew lower, > however, and on cloudy nights often moved about barely above the tree-tops.” > “On the evening of July 11-a pitch-dark evening with a thundershower > lowering,-they were remarkably noisy, both sitting in trees and flying high > in air. The seated ones, of which I heard only two, made the Cowcow notes, > while all the flying ones made the liquid gurgle. I heard this note overhead > between thirty and forty times in the course of about three hours, during > half of which time I was afoot on the road.” > > -- Thayer, G. H. 1903. The Mystery of the Black-billed Cuckoo. Bird Lore > 5:143-145. > > In a big nocturnal flight I heard moving up the St. Croix River (MN/WI) in > late May of 1985, I estimated a rate of passage of Black-billed Cuckoos in > the range of 100 per hour for at least a few hours in the middle of the > night. This was not a call total but a rate of vocal birds estimated by > following multiple calls from apparently the same individual, and it was > clear that these birds were migrants heading northbound. In 1988-1990 I > began recording nocturnal flight calls each fall migration period in early > July around Ithaca, NY and was surprised that in each season the highest > rate of BBCU calling was in July through early August. There seemed to be a > lot of variability in the number of calls I recorded between proximal > nights, which could be a function of weather/wind and microphone pickup > dynamics or that the birds tended to prefer some nights over others. In the > big passerine push from mid –August through mid-September across central NY, > BBCU flight calls are less common than one might expect. Using a Sennheiser > shotgun mic back in those days, my rates of BBCU nocturnal flight call > detection in the latter half of August were in the 1-2 per hour range > (averaged over whole night). In the first half of September rates dropped to > the range of one call every four hours. Whereas in July through early August > it was common to record sustained rate through the night of 4-5 per hour. > But as I mentioned there was a lot of variability from night to night. > > I haven’t recorded much in June in central NY, but my impression has been > that the breeding ground flight calling, the “mid-summer, mid-night, > mid-sky, gyrations”, is a phenomenon that increases in July. > > Bill E > > -- > NFC-L List Info: > Welcome and Basics > Rules and Information > Subscribe, Configuration and Leave > Archives: > The Mail Archive > Surfbirds > BirdingOnThe.Net > Please submit your observations to eBird! > -- -- Cayugabirds-L List Info: http://www.NortheastBirding.com/CayugabirdsWELCOME http://www.NortheastBirding.com/CayugabirdsRULES http://www.NortheastBirding.com/CayugabirdsSubscribeConfigurationLeave.htm ARCHIVES: 1) http://www.mail-archive.com/[email protected]/maillist.html 2) http://www.surfbirds.com/birdingmail/Group/Cayugabirds 3) http://birdingonthe.net/mailinglists/CAYU.html Please submit your observations to eBird: http://ebird.org/content/ebird/ --
