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Index of Subjects Hi Steve, Hopefully Ken's and Ian's posts answered your questions regarding large numbers of Chimney Swifts at Temperance Street and other sites. I'll put my 2 cents in as well. > They have been here for some time already in our short summer, so > if they paired off earlier and went off to find nest holes to raise > young, what are they doing roosting nightly 200 strong, 2/3 the way > through July? If one were to observe a roost such as Temperance Street or the Robie Tufts Nature Centre every evening between early May and mid-September, we would expect swift numbers to rise and fall in two separate peaks: the first in late May/early June, and the second in late July/early August, with numbers trailing off during the period in-between. Generally speaking, this is indeed what we observe at the roost sites that Swiftwatchers are monitoring, which was the basis for selecting those 6 set dates of Swift Watch ( 3 in the spring, and 3 in the "fall"). However, like Ken says, we have much to learn about Chimney Swift movements and migrations, and it is quite possible that some birds favour one site during the northward migration and another site on their way back south. As well, year-to-year differences in weather patterns would likely influence the timing of those migrations, especially for the aerial insectivores (chimney swifts, flycatchers, swallows, nighthawks, etc), whose insect prey are in turn dictated by temperature and precipitation. > Who is incubating the eggs or sheltering the young, or > don't swifts do that? Or are these all male roosts, leaving the female > swifts to do all the work back at the nest? Chimney Swifts share parenting duties, including nest construction, incubation and feeding young. Eggs hatch after ~20 days, and young stay inside their nest chimney for a further ~30 days, climbing around the on walls and learning to fly within the chimney. > If instead this means that there are actually 200 or so unmated swifts > loafing around but not breeding, that sounds like an impending population > disaster and cause for concern that the numbers are so high, not the > reverse We think most of the birds that remain at the roosts all summer are non-breeders, which are joined by failed breeders throughout the season. Although swifts are territorial (one chimney will only host one nesting pair), many chimneys serve as nest and roost sites simultaneously, and non-breeders sometimes help out with parental duties including feeding and incubating. Daytime observations at known roost sites could tell us whether those sites are being used as nest sites as well (generally, in good weather only parents will enter the chimney during the daytime). It is important (and alarming) to note that Quebec -which has conducted Chimney Swift monitoring since 1998- estimates that only 60% of breeding adults in that province actually reproduce, due to the limited number of chimneys now available for nesting. Unless rates of chimney conversion/demolition are different between provinces, it is likely that the situation is similar elsewhere in Canada [see COSEWIC report on Chimney Swifts, available on the Species at Risk Public Registry: http://www.sararegistry.gc.ca/species/speciesDetails_e.cfm?sid=951 ]. Hope that helps, Steve. Jim Wolford might have some more thoughts to add to this. Thanks for posing those questions! Ally and Swiftwatchers Allison Manthorne Maritimes Swiftwatch Coordinator /Coordonnatrice du projet Maritimes Swiftwatch Bird Studies Canada /Études d'Oiseaux Canada PO Box/ C. P. 6227 17 Waterfowl Lane/ 17 ruelle Waterfowl Sackville, NB (Nouveau-Brunswick) E4L 1G6 Phone/tel : 506-364-5196 amanthorne@birdscanada.org marswifts@birdscanada.org ------------------------------------------------------------------- > Hi Ken, Jim, other swift-watchers > As a non-clued-in person reading these regular swift reports, I'm a bit > puzzled by the numbers. > We keep getting notices of gratifyingly (?) large numbers of swifts > entering this Temperance Steet chimney and a few others, but these are > swifts that migrated in some time ago and obviously would have come to > breed. They have been here for some time already in our short summer, so > if they paired off earlier and went off to find nest holes to raise > young, what are they doing roosting nightly 200 strong, 2/3 the way > through July? Who is incubating the eggs or sheltering the young, or > don't swifts do that? Or are these all male roosts, leaving the female > swifts to do all the work back at the nest? Or have they bred > successfully already, so that some of these may be newly fledged > offspring from this year? If the last were the case, you might expect > high numbers roosting just after in-migration, then very low numbers > during breeding elsewhere, then high numbers again after this year's > offspring took wing. Is that what your numbers show, Jim or Ken? > > If instead this means that there are actually 200 or so unmated swifts > loafing around but not breeding, that sounds like an impending population > disaster and cause for concern that the numbers are so high, not the > reverse. Someone please explain. > Steve, Halifax
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