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aTaken as the between-year re-capture rate divided by the within-year re-capture rate, and by the estimated survival rate (from other studies) to give maximum likely estimates of the return rates of surviving birds (after Catry et al. 2004b). From Catry et al. (2004). Data for Pied Flycatcher are from central Spain (Veiga 1986).

aTaken as the between-year re-capture rate divided by the within-year re-capture rate, and by the estimated survival rate (from other studies) to give maximum likely estimates of the return rates of surviving birds (after Catry et al. 2004b). From Catry et al. (2004). Data for Pied Flycatcher are from central Spain (Veiga 1986).

or more times, return rates to a stopover site in Israel were 27/123 or 22%, which was not very different from the return rates of summer breeders in the same area (210/773 or 27%) (Merom et al. 2000). Among Chaffinches Fringilla coelebs migrating over the Courland Spit in the southeast Baltic, some individuals were recaught up to seven years after having been ringed there (Payevsky 1971).

For other migratory birds, notably waterfowl and shorebirds, suitable feeding areas are often localised and far apart, and it is in such species that the highest recurrence rates have been recorded. For example, some shorebirds and geese have only one or two main stopover sites on their migration routes, so inevitably almost the entire population may stop at these sites on each journey. Not surprisingly, then, many ringed birds of these species are known to have visited the same staging sites year after year on migration.9 The minimum annual return rate of adult Semi-palmated Plovers Charadrius semipalmatus to 10-15 ha of beach at Manomet in eastern North America, where the birds stayed for about three weeks each autumn, averaged 71% (Smith & Houghton 1984). This proportion was similar to the likely annual survival rate, implying that most surviving individuals returned. Another large estimate of 65% was obtained for Sanderlings Calidris alba at a stopover site in southwest Iceland (Gudmundsson & Lindstrom

9For shorebirds, see Pienkowski (1976), Evans & Townsend (1988), Harrington et al. (1988), Smith & Houghton (1984), Gudmundsson & Lindstrom (1992), Pfister et al. (1998), Wernham et al. (2002).

1992). Similarly, among Greenland White-fronted Geese Anser albifrons staging in two areas of Iceland, and seen in more than one season, 89% were re-sighted within 4 km of the capture site from spring to the following autumn, 88% from autumn to the following spring, 96% from one spring to the next, and 100% from one autumn to the next (Fox et al. 2002). In general, same-season site-fidelity (97%) was significantly greater from year to year than different-season site-fidelity (87%, Fishers exact test, n = 177, P < 0.05). But the overall rates were again so high as to imply that all (or almost all) surviving birds used the same sites in successive years. Lower estimates for geese include 40.7% (or 48.5% when adjusted for mortality) in Brent Geese Branta bernicla in the Netherlands (Ebbinge 1992), 52.4% as a mortality-adjusted estimate for Barnacle Geese B. leucopsis in Norway (Gullestrad et al. 1984), and 72% as a non-adjusted estimate for Canada Geese B. c. minima in Alaska (Gill et al. 1997). Among birds in general, however, this degree of stopover site-fidelity may well be exceptional, and despite following the same route, many migrants may stop at different places in different years, either by choice or by force of circumstance.

High fidelity to stopover sites might also be expected in soaring raptors, storks, cranes and pelicans, in which entire populations funnel each spring and autumn through narrow bottlenecks (Chapter 7). Such narrow front migration is likely to limit the number of stopover sites available, thus raising the probability that individuals use the same places on successive journeys. Many individuals may use these sites for roosting, but not necessarily for feeding.

In summary, passerines that encounter many possible stopping places on their journeys apparently show less fidelity to specific stopover sites than do some waterfowl and shorebirds for which potential stopping places are few and far between. Among many passerines, fidelity to stopover sites is much less marked than fidelity to breeding or wintering sites. Patterns of stopover site-fidelity seem to reflect the effects of landscape, habitat and food supplies, and not only features of the species themselves.

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