Light-level geolocators reveal strong migratory connectivity and within-winter movements for a coastal California Swainson's Thrush (<i>Catharus ustulatus</i>) population

Cormier, Renée L.; Humple, Diana L.; Gardali, Thomas; Seavy, Nathaniel E.

doi:10.1525/auk.2013.12228

Cited by 46 publications

(55 citation statements)

References 14 publications

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“…These results exactly match the description of 'weak (diffuse) connectivity' [1]. Accordingly, the Mantel correlation coefficient, a measure for the strength of migratory connectivity, was about 20% lower for the Montagu's harrier compared with the California Swainson's thrush Catharus ustulatus, a species for which strong connectivity was reported [39]. Species differ remarkably in the strength of migratory connectivity.…”

Section: (C) Migratory Performance and Stopoverssupporting

confidence: 78%

Migratory connectivity and population-specific migration routes in a long-distance migratory bird

et al. 2014

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Knowledge about migratory connectivity, the degree to which individuals from the same breeding site migrate to the same wintering site, is essential to understand processes affecting populations of migrants throughout the annual cycle. Here, we study the migration system of a long-distance migratory bird, the Montagu's harrier Circus pygargus, by tracking individuals from different breeding populations throughout northern Europe. We identified three main migration routes towards wintering areas in subSaharan Africa. Wintering areas and migration routes of different breeding populations overlapped, a pattern best described by 'weak (diffuse) connectivity'. Migratory performance, i.e. timing, duration, distance and speed of migration, was surprisingly similar for the three routes despite differences in habitat characteristics. This study provides, to our knowledge, a first comprehensive overview of the migration system of a Palaearctic-African long-distance migrant. We emphasize the importance of spatial scale (e.g. distances between breeding populations) in defining patterns of connectivity and suggest that knowledge about fundamental aspects determining distribution patterns, such as the among-individual variation in mean migration directions, is required to ultimately understand migratory connectivity. Furthermore, we stress that for conservation purposes it is pivotal to consider wintering areas as well as migration routes and in particular stopover sites.

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Section: (C) Migratory Performance and Stopoverssupporting

confidence: 78%

Migratory connectivity and population-specific migration routes in a long-distance migratory bird

et al. 2014

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“…Despite the two individuals (one from each wintering location) that migrated to the opposing breeding regions, these results suggest that Golden- crowned Sparrows exhibit relatively strong migratory connectivity. Although only a few studies have used this method to quantitatively measure migratory connectivity for passerines, the ability of researchers to compare among and within species should increase with the increased use of geolocators [9,19,24].…”

Section: Discussionmentioning

confidence: 99%

“…To date, a number of geolocator studies have reported no statistical difference in return rates between tagged and control birds [12,24,39,40], but see [39,41,42]. Negative effects to breeding have been found in some studies, including greater fledgling mortality the year after tagging [43], later egg laying and lower nest success [41], although this was not the case for all species [42].…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2016

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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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“…For migratory birds breeding in North America and wintering in the Neotropics or South America, we generally lack the kind of detail on migratory connectivity between breeding, stopover and wintering sites to effectively manage and conserve species (Webster et al 2002). Recently, a number of approaches have been taken to improve our ability to track small migratory species ranging from endogenous markers such as genetics and stable isotope profiles to ever more miniaturized transmitters and geolocators (Boulet et al 2006, Hobson and Norris 2008, Stutchbury et al 2009, Chabot et al 2012, Fraser et al 2012, Cormier et al 2013, Fraser et al 2013. The use of naturally occurring stable isotope values in feathers and the modeling of origins of birds to isotopic patterns across landscape or ''isoscapes'' has especially improved our ability in this regard (Hobson and Wassenaar 2008).…”

Section: Introductionmentioning

confidence: 99%

A multi‐isotope (δ²H, δ¹³C, δ¹⁵N) approach to establishing migratory connectivity of Barn Swallow (Hirundo rustica)

García-Pérez

Hobson

2014

Ecosphere

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Establishing geographic links between different stages of the annual cycle of migratory species is fundamental to evaluating factors limiting their populations. Stable isotope measurements (δ13C, δ15N, and δ2H) of feathers combined with a knowledge of how these isotopes are structured spatially in foodwebs can be used to establish molt origins and migratory connectivity. Here, we investigated patterns of migratory connectivity between North American breeding grounds and South American wintering grounds of stable (n = 3) and declining (n = 9) populations of Barn Swallow (Hirundo rustica) in North America using a probabilistic assignment to multi‐isotope feather clusters derived for 488 winter‐grown feathers collected during the breeding season (2009 to 2012). Our study did not find evidence for differential degree of migratory connectivity between increasing/stable and declining populations of Barn Swallows but found a longitudinal structure in breeding and wintering ground origins of populations. Probable wintering areas for northern and western breeding birds corresponded with western regions of South America, while birds breeding in southern and eastern North America tended to occupy areas in north‐eastern South America. Possible factors contributing to the differential population trends between stable or increasing and declining breeding populations could be related to habitat quality of the different wintering areas, changes in climate, and the cost of long‐distance migration. The use of a multi‐isotope approach and the combination of prior information on geographic distribution of vegetation types, based on δ13C measurements, effectively constrained geographic origins of swallows and our approach can be applied to defining migratory connectivity for other species.

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Light-level geolocators reveal strong migratory connectivity and within-winter movements for a coastal California Swainson's Thrush (Catharus ustulatus) population

Cited by 46 publications

References 14 publications

Migratory connectivity and population-specific migration routes in a long-distance migratory bird

Migratory connectivity and population-specific migration routes in a long-distance migratory bird

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

A multi‐isotope (δ²H, δ¹³C, δ¹⁵N) approach to establishing migratory connectivity of Barn Swallow (Hirundo rustica)

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Light-level geolocators reveal strong migratory connectivity and within-winter movements for a coastal California Swainson's Thrush (Catharus ustulatus) population

Cited by 46 publications

References 14 publications

Migratory connectivity and population-specific migration routes in a long-distance migratory bird

Migratory connectivity and population-specific migration routes in a long-distance migratory bird

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

A multi‐isotope (δ2H, δ13C, δ15N) approach to establishing migratory connectivity of Barn Swallow (Hirundo rustica)

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A multi‐isotope (δ²H, δ¹³C, δ¹⁵N) approach to establishing migratory connectivity of Barn Swallow (Hirundo rustica)