Migratory connectivity of Golden-crowned Sparrows from two wintering regions in California

Abstract

Knowledge of migratory connectivity is critical to understanding the consequences of habitat loss and climate change on migratory species. We used light-level geolocators to determine breeding locations and migratory routes of wintering Golden-crowned Sparrows (Zonotrichia atricapilla) in two regions of California, USA. Eight out of 9 birds tagged at coastal-wintering sites in Marin County went to breeding sites along the Gulf Coast of Alaska, while 7 out of 8 inland-wintering birds in Placer County migrated to interior sites in the Yukon, Northwest Territories, and British Columbia, Canada. Our estimate of the strength of migratory connectivity was relatively high (rm = 0.66). Coastal-wintering birds followed a coastal migration route while inland-wintering birds migrated inland. Coastalwintering birds migrated significantly farther than inland birds (3,624 km versus 2,442 km). Coastal birds traveled at a greater rate during spring migration (179 km/d) than did inland birds (118 km/d), but there was no statistical difference in the rate of fall migration (167 km/d and 111 km/d, respectively). Dates of arrival and departure, and duration of spring and fall migration, did not differ between groups, nor did return rates. Rates of return also did not differ between tagged and control birds. The distinct migration routes and breeding areas suggests that there may be more structuring in the migratory geography of the Golden-crowned Sparrow than in a simple panmictic population.

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“…Our findings are consistent with data from geolocator-tagged birds (Seavy et al 2012, Cormier et al 2016). These authors tagged wintering Goldencrowned Sparrows near Bolinas north of San Francisco (Marin County) and in inland central California (Placer County).…”

“…Birds we recorded in inland central California sang songs of types 2, 3, or 5. Geolocator data from Cormier et al (2016) showed most of their birds that wintered in inland central California were breeding in southern Yukon or northern inland British Columbia, where song types 3, 4, and 5 are expected. however, one of those tagged birds bred near the Gulf of Alaska, where song type 2 predominates.…”

“…Thus, assuming that wintering Golden-crowned Sparrows sing the same song they sing in their breeding range, we should be able to map the winter ranges of the dialects identified by Shizuka et al (2016) and assess the extent to which birds breeding in specific subsets of the breeding range winter in specific subsets of the winter range, the concept termed "migratory connectivity. " Furthermore, provided that connectivity between breeding and winter locations is strong, the high degree of winter site fidelity of the Golden-crowned Sparrow (Mewaldt and Farner 1957, Seavy et al 2012, Cormier et al 2016 should increase the likelihood that wintering birds' song types can be mapped into discrete geographic regions. Understanding migratory connectivity is important if conservation efforts for a migratory species are to be focused on the appropriate area.…”

Migration pattern of Gambel’s White-crowned Sparrow along the Pacific Flyway

“…Yet, this individual had three longer stopovers in Alaska before proceeding to its breeding area. A similar pattern has been observed for Golden-crowned Sparrows: individuals migrating northwards along the coast to coastal breeding sites moved faster than individuals migrating to interior breeding sites (Cormier et al 2016).…”

“…The central-north Alaska breeding birds continued on their great circle route to their breeding sites while the westerly breeding individual (ID4552) turned westwards to the coast at about 54°N. This latter individual resumed migration on a coastal route, similar to that found in closely related Golden-crowned Sparrows (Zonotrichia atricapilla) wintering in coastal regions of California and breeding in similar areas in southwestern Alaska (Seavy et al 2012;Rakhimberdiev et al 2015;Cormier et al 2016).…”