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GPS tags have become a common tool in ecological studies of animal behaviour and demography despite previous research indicating negative impacts on vital rates across a variety of taxa. Many researchers face tradeoffs when deciding whether they are an appropriate tool because GPS tags may impact vital rates, but they provide detailed data on movements and behaviour that often cannot be obtained in other ways. Using band recovery data, we evaluated the strength of effects induced by GPS tags on annual mortality of adult females across 13 waterfowl taxa, and examined whether taxa with a slower life-history strategy and larger body size were more resilient to GPS tag effects than their fast-lived counterparts with small body size. All species were exposed to hunting, which may interact with underlying processes affecting the impact of GPS tags on mortality, but also allowed for robust analysis of overall annual mortality. Hazard ratios, indicating the risk of death for individuals wearing GPS tags compared to those wearing only metal bands, ranged from 1.13 to 3.25 and the mean proportional difference in survival between marker types across species was 0.33. The magnitude of tag effects was surprisingly consistent across life-history tempo and body size, indicating that slower-lived species did not buffer the effect of wearing GPS tags. Our results highlight that even large, long-lived species, which are generally better at buffering their mortality against environmental adversity, are not immune to the effects GPS tags can have on survival and mortality. The results of our study emphasize the importance of testing for such effects across taxa in future research as technology advances. [ABSTRACT FROM AUTHOR]

Abstract GPS tags have become a common tool in ecological studies of animal behaviour and demography despite previous research indicating negative impacts on vital rates across a variety of taxa. Many researchers face tradeoffs when deciding whether they are an appropriate tool because GPS tags may impact vital rates, but they provide detailed data on movements and behaviour that often cannot be obtained in other ways. Using band recovery data, we evaluated the strength of effects induced by GPS tags on annual mortality of adult females across 13 waterfowl taxa, and examined whether taxa with a slower life-history strategy and larger body size were more resilient to GPS tag effects than their fast-lived counterparts with small body size. All species were exposed to hunting, which may interact with underlying processes affecting the impact of GPS tags on mortality, but also allowed for robust analysis of overall annual mortality. Hazard ratios, indicating the risk of death for individuals wearing GPS tags compared to those wearing only metal bands, ranged from 1.13 to 3.25 and the mean proportional difference in survival between marker types across species was 0.33. The magnitude of tag effects was surprisingly consistent across life-history tempo and body size, indicating that slower-lived species did not buffer the effect of wearing GPS tags. Our results highlight that even large, long-lived species, which are generally better at buffering their mortality against environmental adversity, are not immune to the effects GPS tags can have on survival and mortality. The results of our study emphasize the importance of testing for such effects across taxa in future research as technology advances.

Many birds that are territorial in the breeding season live in groups during the nonbreeding season, thereby gaining benefits such as protection from predators and increased access to resources. However, how the social connections in group life change across seasons in migratory animals is mostly unknown. We ask whether winter social connections continue during the breeding season in a migratory songbird. Golden-crowned Sparrows (Zonotrichia atricapilla) have distinct, stable winter communities that include both site and group fidelity across years: birds almost always rejoin the same social community each year after migration. If these birds have social connectivity across migration, we would expect individuals that associate in winter would also associate together on their breeding grounds. Our small-scale GPS tagging study combined with intensive social behavior data indicates that sparrows in the same tightly knit winter community migrate to highly disparate locations during summer, and therefore, social connections in winter do not continue in summer. This suggests that Golden-crowned Sparrows have entirely separate social structures across seasons and that long-term social memory allows them to reform stable groups each winter. Muchas aves que son territoriales durante la temporada reproductiva viven en grupos en temporada no reproductiva, ganando así beneficios como protección ante deprededores y mayor acceso a recursos. Sin embargo, cómo las conexiones en la vida de grupo cambia a través de las estaciones en animales migratorios es mayormente desconocido. Nos preguntamos si las conexiones sociales de invierno continúan en temporada reproductiva en un ave canora migratoria. El gorrión Zonotrichia atricapilla tiene comunidades de invierno discretas y estables que tienen fidelidad de sitio y de grupo a través de los años: las aves casi siempre se unen a la misma comunidad cada año después de la migración. Si esas aves tienen conectividad social a través de la migración, esperaríamos que individuos que se asocian en invierno también se asociarín en sitios reproductivos. Nuestro estudio de pequeña escala con marcación GPS combinado con datos de comportamiento social intensivo indica que los gorriones de la misma comunidad altamente relacionada durante el invierno migra a sitios muy diferentes durante el verano por lo que las conexiones sociales de invierno no continúan durante el verano. Esto sugiere que el gorrión Zonotrichia atricapilla tiene estructuras sociales completamente separadas a través de las estaciones y que la memoria a largo plazo le permite volver a formar grupos estables cada invierno. Palabras clave: comunidades animales,estructura social, grupos de invierno, marcas GPS, migración, redes sociales. [ABSTRACT FROM AUTHOR]

Mapping the distribution of seabirds at sea is fundamental to understanding their ecology and making informed decisions on their conservation. Until recently, estimates of at-sea distributions were generally derived from boat-based visual surveys. Increasingly however, seabird tracking is seen as an alternative but each has potential biases. To compare distributions from the two methods, we carried out simultaneous boat-based surveys and GPS tracking in the Minch, western Scotland, in June 2015. Over 8 days, boat transect surveys covered 950 km, within a study area of ~6,700 km2 centered on the Shiant Islands, one of the main breeding centers of razorbills, and guillemots in the UK. Simultaneously, we GPS-tracked chick-rearing guillemots (n = 17) and razorbills (n = 31) from the Shiants. We modeled counts per unit area from boat surveys as smooth functions of latitude and longitude, mapping estimated densities. We then used kernel density estimation to map the utilization distributions of the GPS tracked birds. These two distribution estimates corresponded well for razorbills but were lower for guillemots. Both methods revealed areas of high use around the focal colony, but over the wider region, differences emerged that were likely attributable to the influences of neighboring colonies and the presence of non-breeding birds. The magnitude of differences was linked to the relative sizes of these populations, being larger in guillemots. Whilst boat surveys were necessarily restricted to the hours of daylight, GPS data were obtained equally during day and night. For guillemots, there was little effect of calculating separate night and day distributions from GPS records, but for razorbills the daytime distribution matched boat-based distributions better. When GPS-based distribution estimates were restricted to the exact times when boat surveys were carried out, similarity with boat survey distributions decreased, probably due to reduced sample sizes. Our results support the use of tracking data for defining seabird distributions around tracked birds' home colonies, but only when nearby colonies are neither large nor numerous. Distributions of animals around isolated colonies can be determined using GPS loggers but that of animals around aggregated colonies is best suited to at-sea surveys or multi-colony tracking.

Dispersal is one of the key processes in shaping distributional ranges and community assemblages, but we know little about animal dispersal at the individual, population, or community levels, or about how dispersal correlates with the establishment and colonization of new areas. This is largely due to difficulties in studying individual movements at the relevant spatiotemporal scale, leading to a gap between the direct study of dispersal and our understanding of the build-up of larger-scale biodiversity. Recent advances in tracking technology make it possible to bridge this gap. We propose a way to link movement, dispersal, ecology, and biogeography. In particular, we offer a framework to scale-up from processes at the individual level to global patterns of biodiversity. [ABSTRACT FROM AUTHOR]