Are long‐distance migrant passerines faithful to their stopover sites?

Abstract

Long-distance migrant passerines are well known to often display high levels of philopatry to breeding and wintering grounds. One could expect that similar selective pressures and similar navigation skills would result in their being faithful to stopover sites, a pattern that has been described for several populations of migratory waders and waterfowl. In this paper, we develop the argument that passerines should suffer from higher costs and receive lower benefits from stopover site faithfulness than waterfowl and waders. Based on Alerstam's (1979) ''optimal drift strategy'' theory and other considerations, we predict that passerines should have lower stopover site fidelity than geese and waders, and that site faithfulness should decrease with increasing distance from either end of the migratory journey. We present results from a long-term study on the stopover ecology of migrant passerines in southern Portugal that support these predictions and show that, for species and populations that neither nest nor winter in this country, few individuals are faithful to the stopover site. On the other hand, populations that included individuals at (or near to) the start or the end of the migratory journey, had much higher return rates. We could not find any evidence that species linked to scarce habitats, such as wetlands, were more site faithful. Our results are in agreement with several other reports, but in apparent contrast to previous conclusions resulting from some studies involving Old World warblers. These differences are discussed and it is argued that there is no solid evidence to suggest that site fidelity should be important for passerines at stopovers far away from breeding or wintering grounds, meaning that there is a large within-individual variability in the precise migratory routes and stopover sequence used each year.

Individual variability in the migratory path and stopovers of a long-distance pelagic migrant

“…Fusani et al 2009), in addition to local wind circumstances (Guilford et al 2009). In fact, other long-distance migrants that are also very dependent on wind conditions, such as some small passerines, raptors and storks, can also present low levels of stopover fidelity (Berthold et al 2004;Catry et al 2004;Shiu et al 2006;Chevallier et al 2011).…”

“…Some species are clearly more faithful than others to their wintering sites, routes, stopovers and timings (Sutherland 1998;Catry et al 2004). Most studies carried out so far on fidelity to migratory paths and stopovers have focused on species that migrate mostly over land, such as passerines, storks, geese and raptors (Fox et al 2002;Berthold et al 2004;Catry et al 2004;Alerstam et al 2006;Vardanis et al 2011;Stanley et al 2012).…”

“…Some species are clearly more faithful than others to their wintering sites, routes, stopovers and timings (Sutherland 1998;Catry et al 2004). Most studies carried out so far on fidelity to migratory paths and stopovers have focused on species that migrate mostly over land, such as passerines, storks, geese and raptors (Fox et al 2002;Berthold et al 2004;Catry et al 2004;Alerstam et al 2006;Vardanis et al 2011;Stanley et al 2012). While some studies have analysed spatial consistency during migration in pelagic travellers (Hunter et al 2003;Phillips et al 2005;Broderick et al 2007;Guilford et al 2011), none have attempted to disentangle the fidelity to routes or paths from individual consistency in winter destinations.…”

Fuelling in front of the barrier - are there age based behavioral differences in Garden Warblers Sylvia borin?

“…Why this pattern exists we cannot explain at this stage. Stopover site fidelity seems not to be very common in songbirds, but it is interesting that it has been described several times close to the Sahara desert crossing and the crossing of the Mexican Golf (Moreau, 1972;Cantos & Telleria, 1994;Merom et al, 2000;Catry et al, 2004;Jubete et al, 2006;Somershoes et al, 2009;Vogt et al, 2012 ).…”

Many routes lead to Rome: potential causes for the multi‐route migration system of Red Knots, Calidris canutus islandica

“…Unfortunately, not much is known about the degree of philopatry or site tenacity in knots (but see Spaans et al 2009), nor about the fidelity to stopover sites in migratory birds in general. It is generally thought that geese, swans, and waders are more faithful than passerines (Catry et al 2004), simply due to their higher habitat selectivity, lower sensitivity to weather during flight (wind drift), and the fact that routes are often socially transmitted (migration in flocks, younger birds learn ''best'' routes from older, more experienced individuals).…”