Predicting origins of passerines migrating through Canadian migration monitoring stations using stable-hydrogen isotope analyses of feathers: a new tool for bird conservation (original) (raw)
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The use of isotope tracers for identifying populations of migratory birds
Oecologia, 1997
To determine whether stable isotopes can be used for identifying the geographic origins of migratory bird populations, we examined the isotopic composition of hydrogen (deuterium, δD), carbon (δ 13 C), and strontium (δ 87 Sr) in tissues of a migratory passerine, the black-throated blue warbler (Dendroica caerulescens), throughout its breeding range in eastern North America. δD and δ 13 C values in feathers, which are grown in the breeding area, varied systematically along a latitudinal gradient, being highest in samples from the southern end of the species' breeding range in Georgia and lowest in southern Canada. In addition, δD decreased from east to west across the northern part of the breeding range, from New Brunswick to Michigan. δ 87 Sr ratios were highest in the Appalachian Mountains, and decreased towards the west. These patterns are consistent with geographical variation in the isotopic composition of the natural environment, i.e., with that of precipitation, plants, and soils for δD, δ 13 C, and δ 87 Sr, respectively. Preliminary analyses of the δD and δ 13 C composition of feathers collected from warblers in their Caribbean winter grounds indicate that these individuals were mostly from northern breeding populations. Furthermore, variances in isotope ratios in samples from local areas in winter tended to be larger than those in summer, suggesting that individuals from different breeding localities may mix in winter habitats. These isotope markers, therefore, have the potential for locating the breeding origins of migratory species on their winter areas, for quantifying the degree of mixing of breeding populations on migratory and wintering sites, and for documenting other aspects of the population structure migratory animals -information needed for studies of year-round ecology of these species as well as for their conservation. Combining information from several stable isotopes will help to increase the resolution for determining the geographic origins of individuals in such highly vagile populations.
Oecologia, 2004
Successful application of stable-hydrogen isotope measurements (δD f ) of feathers to track origins of migratory birds and other wildlife requires a fundamental understanding of the correlation between δD f and deuterium patterns in rainfall (δD p ) over continental scales. A strong correlation between δD p and δD f has been confirmed for birds and insects in North America, but not yet for other continents. Here, we compare δD f data from resident European birds to new δD p basemaps for Europe. Three maps, representing growing-season and mean annual δD p estimates from an elevation-explicit, detrended interpolation model and growing-season δD p estimates from simple Kriging, all indicate that strong isotope gradients occur across Europe with a general depletion occurring in a northeast direction. The feather data, representing 141 individuals of 25 avian species from 38 sites, ranged from −131 to −38‰. Regression analysis showed that strong correlations existed between both mean annual and growing-season δD p estimated by detrended interpolation and δD f of non-aquatic and noncorvid birds (r 2 =0.66 and 0.65, respectively). We also examined mean annual and growing-season δ 18 O p vs. δ 18 O f for our samples. Both oxygen regressions were similar (r 2 =0.56 and 0.57, respectively) but poorer than for deuterium. Our study reveals that δD measurements of feathers from migratory birds in Europe may be used to track their origin and movements, and so provide a powerful investigative tool for avian migration research in Europe.
Tracing diets and origins of migratory birds using stable isotope techniques
1999
Measurements of naturally occurring stable isotopes of several elements Could in foodwebs are being used increasingly to address a number of ecological questions, particularly those involving nutrient flow and foodweb structure. However, only during the last decade has the potential of this technique been realized by avian ecologists, and there exists a multitude of potential applications in this field. In this paper, the uses of stable i sotope applications to avian ecological studies are reviewed. In particular, pengbasisisiven to the use of 5 N ( N/ N) measurements to delineate trophic position in marine systems and e'C ( CJ CJ and S ( 5) measurements to establish sources ornaments in an diets. Recent applications of the measurement of deuterium isotope ratios 5D (DM) in feathers to trace origins of migratory songbirds is also presented_ When combined with DNA analyses, the stable isotope approach holds great promise for linking breeding and wintering areas of neotropical migrant birds and other migratory organisms.
Journal of Applied Ecology, 2009
Quantifying connectivity between breeding, stopover, and wintering locations is critical to the management and conservation of migratory animals. Mark-recapture approaches to establishing connectivity are limited due to marking location bias and poor recovery. Alternatively, endogenous markers like stable isotopes can augment extrinsic markers and help to overcome their limitations. 2. We used a stable hydrogen isotope ( δ D) isoscape for Europe and δ D analysis of feathers from harvested woodpigeons Columba palumbus in France, the Iberian Peninsula, and Corsica to estimate their natal origins. 3. We propagated error associated with the relationship between deuterium in feathers ( δ D f ) and mean growing-season precipitation ( δ D p ) for woodpigeons in Europe. For every δ D f value, we estimated a range of possible δ D p values and used this to map the probability of origin. 4. We estimated that ~50% of the woodpigeon harvest in France was comprised of residents or from nearby countries to the east. About 30% of the take were medium-distance migrants, and about 10% were long-distance migrants from Scandinavia, northwest Russia and the Baltic. A greater proportion of the long-distance migrants were taken in Spain. In Corsica, birds primarily originated from northern Italy to the Ukraine. 5. The proportion of northern migrants harvested decreased with latitude, suggesting a leapfrog migration pattern. Birds harvested at lower latitudes showed an inverse relationship between wing length and δ D f , which suggested that longer-distance migrants had longer wings. 6. Synthesis and applications. This is the first application of stable isotope methodology to quantify population structure and migratory connectivity for a European game species. In addition, we used statistical approaches accounting for potential geospatial assignment errors. Most of the French woodpigeons harvested are resident birds, which suggests that local management of the hunt in France may be most effective. However, southwestern France appeared to take a somewhat greater proportion of migrant woodpigeons, and thus, conservation and management of woodpigeons in France should recognize regional differences. Our approach provided a methodological template that can be applied to questions of migratory connectivity for numerous species of game and non-game migrant birds.
Ecological Applications, 2011
The recent application of stable-isotope analyses, particularly the use of stablehydrogen-isotope (dD) measurements of animal tissues, has greatly improved our ability to infer geographic origins of migratory animals. However, many individual sources of error contribute to the overall error in assignment; thus likelihood-based assignments incorporating estimates of error are now favored. In addition, globally, the nature of the underlying precipitation-based dD isoscapes is such that longitudinal resolution is often compromised. For example, in North America, amount-weighted expected mean growing-season precipitation dD is similar between the boreal forest of southwestern Canada and areas of northern Quebec/Labrador and Alaska. Thus, it can often be difficult to distinguish objectively between these areas as potential origins for broadly distributed migrants using a single isotopic measurement. We developed a Bayesian framework for assigning geographic origins to migrant birds based on combined stable-isotope analysis of feathers and models of migratory directions estimated from band recovery data. We outline our method and show an example of its application for assigning origins to a population of migrant White-throated Sparrows (Zonotrichia albicollis) sampled at a Canadian Migration Monitoring Network station at Delta Marsh, Manitoba, Canada. We show that likelihood-based assignments of geographic origins can provide improved spatial resolution when models of migration direction are combined with assignments based on dD analysis of feathers.
Oecologia, 2005
The Canadian Migration Monitoring Network consists of several fixed migration monitoring stations (MMS) that apply constant-effort protocols to track changes in the abundance of migratory birds. Such monitoring will be important for tracking long-term population trends of songbirds, especially for species breeding in remote areas such as the North American boreal forest. The geographical catchment sampled by individual MMS, however, remains largely unknown. Here, we used hydrogen isotope measurements (dD) of feathers of white-throated sparrows (Zonotrichia albicollis) moving through Delta Marsh MMS in Manitoba, Canada, to determine both wintering and breeding ground catchment areas monitored by this station. The dD of tail feathers, collected from spring and fall migrants delineated previous breeding or natal latitudes, ranging from the northern to the southern extremes of the western boreal forest. The dD values of head feathers grown on the wintering grounds and collected during spring migration revealed that individuals wintered in a broad region of the southeastern United States. The isotope data showed no relationship between estimated breeding/natal and wintering latitudes of white-throated sparrow populations. Stable isotope data provided little information on longitude. Band-encounter analyses, however, indicated a clear east-west segregation of these sparrows across Canada, supporting connectivity among breeding/natal and wintering longitudes over the entire scale of this species' range. Isotope analyses of multiple feather types representing different periods and geographic regions of the annual cycle can provide key information on migratory connectivity for species moving through dedicated MMS.
Ibis, 2019
Running head: Origins and timing of passerine migration through the Alps Understanding spatial linkages between areas used by migratory animals during the annual cycle is fundamental to their conservation. Stable isotope measurements of animal tissues can be a valuable tool in understanding spatial connectivity and migration phenology of migratory wildlife. We inferred natal origins of two migratory passerines, European Pied Flycatcher Ficedula hypoleuca and European Robin Erithacus rubecula, captured during autumn migration in the Italian Alps by combining feather δ 2 H (δ 2 H f) and ring recovery data. We used a spatially-explicit likelihood-based method to assign individuals to a precipitation δ 2 H surface calibrated to represent feather δ 2 H, together with the directional probability of origin from ring recoveries. The highest probabilities of origin for most individuals of both species were in central and northeastern Europe. Seasonal trends in δ 2 H f , which described the species' migratory phenology through the Italian Alps, were correlated with feather δ 13 C, δ 15 N and δ 34 S values, indicating strong spatial discrimination related to continental patterns for these isotopes. We demonstrate how this combined information can define catchment areas and migratory connectivity of birds intercepted in the Alps. We highlight the importance of ringing data in defining directional priors to define Bayesian-based probability surfaces using continental δ 2 H f isoscapes, and how such information can be used to inform estimates of migratory connectivity.
Establishing Winter Origins of Migrating Lesser Snow Geese Using Stable Isotopes
Avian Conservation and Ecology, 2012
Increases in Snow Goose (Chen caerulescens) populations and large-scale habitat changes in North America have contributed to the concentration of migratory waterfowl on fewer wetlands, reducing resource availability, and enhancing risks of disease transmission. Predicting wintering locations of migratory individuals is critical to guide wildlife population management and habitat restoration. We used stable carbon (δ 13 C), nitrogen (δ 15 N), and hydrogen (δ 2 H) isotope ratios in muscle tissue of wintering Snow Geese to discriminate four major wintering areas, the Playa Lake Region, Texas Gulf Coast, Louisiana Gulf Coast, and Arkansas, and infer the wintering locations of individuals collected later during the 2007 and 2008 spring migrations in the Rainwater Basin (RWB) of Nebraska. We predicted the wintering ground derivation of migrating Snow Geese using a likelihood-based approach. Our three-isotope analysis provided an efficient discrimination of the four wintering areas. The assignment model predicted that 53% [95% CI: 37-69] of our sample of Snow Geese from the RWB in 2007 had most likely originated in Louisiana, 38% [23-54] had wintered on Texas Gulf Coast, and 9% [0-20] in Arkansas; the assessment suggested that 89% [73-100] of our 2008 sample had most likely come from Texas Gulf Coast, 9% [0-27] from Louisiana Gulf Coast, and 2% [0-9] from Arkansas. Further segregation of wintering grounds and additional sampling of spring migrating Snow Geese would refine overall assignment and help explain interannual variations in migratory connectivity. The ability to distinguish origins of northbound geese can support the development of spatially-adaptive management strategies for the midcontinent Snow Goose population. Establishing migratory connectivity using isotope assignment techniques can be extended to other waterfowl species to determine critical habitat, evaluate population energy requirements, and inform waterfowl conservation and management strategies.
Combining stable isotope analyses and geolocation to reveal kittiwake migration
Marine Ecology Progress Series, 2011
Determining migratory strategies of seabirds is still a major challenge due to their relative inaccessibility. Small geolocators are improving this knowledge, but not all birds can be tracked. Stable isotope ratios in feathers can help us to understand migration, but we still have insufficient baseline knowledge for linking feather signatures to movements amongst distinct water masses. To understand the migration strategies of kittiwakes Rissa tridactyla and the link between stable isotopes in feathers and the areas in which these were grown, we tracked 6 kittiwakes from Hornøya, Norway, with light level geolocators over 1 yr. Then we analysed the stable isotopes of carbon and nitrogen in their 1st and 7th primary feathers as well as in the 1st, 3rd, 5th, 7th and 10th primaries of 12 birds found freshly dead in the same breeding colony. After breeding, all tracked birds moved east of the Svalbard Archipelago and subsequently migrated to the Labrador Sea. Thereafter, birds showed individual variation in migration strategies: 3 travelled to the NE Atlantic, whereas the others remained in the Labrador Sea until the end of the wintering period. Changes in stable isotope signatures from the 1st to the 10th primary feathers corresponded well to the sequence of movements during migration and the area in which we inferred that each feather was grown. Thus, by combining information on moult patterns and tracking data, we demonstrate that stable isotope analysis of feathers can be used to trace migratory movements of seabirds.