| 1. |
- Broekman, Maarten J. E., et al.
(author)
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Evaluating expert-based habitat suitability information of terrestrial mammals with GPS-tracking data
- 2022
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In: Global Ecology and Biogeography. - : Wiley. - 1466-822X .- 1466-8238. ; 31:8, s. 1526-1541
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Journal article (peer-reviewed)abstract
- Aim: Macroecological studies that require habitat suitability data for many species often derive this information from expert opinion. However, expert-based information is inherently subjective and thus prone to errors. The increasing availability of GPS tracking data offers opportunities to evaluate and supplement expert-based information with detailed empirical evidence. Here, we compared expert-based habitat suitability information from the International Union for Conservation of Nature (IUCN) with habitat suitability information derived from GPS-tracking data of 1,498 individuals from 49 mammal species.Location: Worldwide.Time period: 1998-2021.Major taxa studied: Forty-nine terrestrial mammal species.Methods: Using GPS data, we estimated two measures of habitat suitability for each individual animal: proportional habitat use (proportion of GPS locations within a habitat type), and selection ratio (habitat use relative to its availability). For each individual we then evaluated whether the GPS-based habitat suitability measures were in agreement with the IUCN data. To that end, we calculated the probability that the ranking of empirical habitat suitability measures was in agreement with IUCN's classification into suitable, marginal and unsuitable habitat types.Results: IUCN habitat suitability data were in accordance with the GPS data (> 95% probability of agreement) for 33 out of 49 species based on proportional habitat use estimates and for 25 out of 49 species based on selection ratios. In addition, 37 and 34 species had a > 50% probability of agreement based on proportional habitat use and selection ratios, respectively.Main conclusions: We show how GPS-tracking data can be used to evaluate IUCN habitat suitability data. Our findings indicate that for the majority of species included in this study, it is appropriate to use IUCN habitat suitability data in macroecological studies. Furthermore, we show that GPS-tracking data can be used to identify and prioritize species and habitat types for re-evaluation of IUCN habitat suitability data.
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| 2. |
- Bengtsson, Daniel, et al.
(author)
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Does influenza A virus infection affect movement behaviour during stopover in its wild reservoir host?
- 2016
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In: The Royal Society. - : The Royal Society. - 2054-5703. ; 3:2
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Journal article (peer-reviewed)abstract
- The last decade has seen a surge in research on avian influenza A viruses (IAVs), in part fuelled by the emergence, spread and potential zoonotic importance of highly pathogenic virus subtypes. The mallard (Anas platyrhynchos) is the most numerous and widespread dabbling duck in the world, and one of the most important natural hosts for studying IAV transmission dynamics. In order to predict the likelihood of IAV transmission between individual ducks and to other hosts, as well as between geographical regions, it is important to understand how IAV infection affects the host. In this study, we analysed the movements of 40 mallards equipped with GPS transmitters and three-dimensional accelerometers, of which 20 were naturally infected with low pathogenic avian influenza virus (LPAIV), at a major stopover site in the Northwest European flyway. Movements differed substantially between day and night, as well as between mallards returning to the capture site and those feeding in natural habitats. However, movement patterns did not differ between LPAIV infected and uninfected birds. Hence, LPAIV infection probably does not affect mallard movements during stopover, with high possibility of virus spread along the migration route as a consequence.
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| 3. |
- Bengtsson, Daniel, et al.
(author)
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Movements, Home-Range Size and Habitat Selection of Mallards during Autumn Migration
- 2014
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In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:6
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Journal article (peer-reviewed)abstract
- The mallard (Anas platyrhynchos) is a focal species in game management, epidemiology and ornithology, but comparably little research has focused on the ecology of the migration seasons. We studied habitat use, time-budgets, home-range sizes, habitat selection, and movements based on spatial data collected with GPS devices attached to wild mallards trapped at an autumn stopover site in the Northwest European flyway. Sixteen individuals (13 males, 3 females) were followed for 15-38 days in October to December 2010. Forty-nine percent (SD = 8.4%) of the ducks' total time, and 85% of the day-time (SD = 28.3%), was spent at sheltered reefs and bays on the coast. Two ducks used ponds, rather than coast, as day-roosts instead. Mallards spent most of the night (76% of total time, SD = 15.8%) on wetlands, mainly on alvar steppe, or in various flooded areas (e.g. coastal meadows). Crop fields with maize were also selectively utilized. Movements between roosting and foraging areas mainly took place at dawn and dusk, and the home-ranges observed in our study are among the largest ever documented for mallards (mean = 6,859 ha; SD = 5,872 ha). This study provides insights into relatively unknown aspects of mallard ecology. The fact that autumn-staging migratory mallards have a well-developed diel activity pattern tightly linked to the use of specific habitats has implications for wetland management, hunting and conservation, as well as for the epidemiology of diseases shared between wildlife and domestic animals.
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| 4. |
- Bowlin, Melissa, et al.
(author)
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Grand Challenges in Migration Biology
- 2010
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In: Integrative and Comparative Biology. - : Oxford University Press (OUP). - 1540-7063 .- 1557-7023. ; 50:3, s. 261-279
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Conference paper (peer-reviewed)abstract
- Billions of animals migrate each year. To successfully reach their destination, migrants must have evolved an appropriate genetic program and suitable developmental, morphological, physiological, biomechanical, behavioral, and life-history traits. Moreover, they must interact successfully with biotic and abiotic factors in their environment. Migration therefore provides an excellent model system in which to address several of the "grand challenges" in organismal biology. Previous research on migration, however, has often focused on a single aspect of the phenomenon, largely due to methodological, geographical, or financial constraints. Integrative migration biology asks 'big questions' such as how, when, where, and why animals migrate, which can be answered by examining the process from multiple ecological and evolutionary perspectives, incorporating multifaceted knowledge from various other scientific disciplines, and using new technologies and modeling approaches, all within the context of an annual cycle. Adopting an integrative research strategy will provide a better understanding of the interactions between biological levels of organization, of what role migrants play in disease transmission, and of how to conserve migrants and the habitats upon which they depend.
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| 5. |
- Garde, Baptiste, et al.
(author)
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Fine-scale changes in speed and altitude suggest protean movements in homing pigeon flights
- 2021
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In: Royal Society Open Science. - : The Royal Society. - 2054-5703. ; 8:5
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Journal article (peer-reviewed)abstract
- The power curve provides a basis for predicting adjustments that animals make in flight speed, for example in relation to wind, distance, habitat foraging quality and objective. However, relatively few studies have examined how animals respond to the landscape below them, which could affect speed and power allocation through modifications in climb rate and perceived predation risk. We equipped homing pigeons (Columba livia) with high-frequency loggers to examine how flight speed, and hence effort, varies in relation to topography and land cover. Pigeons showed mixed evidence for an energy-saving strategy, as they minimized climb rates by starting their ascent ahead of hills, but selected rapid speeds in their ascents. Birds did not modify their speed substantially in relation to land cover, but used higher speeds during descending flight, highlighting the importance of considering the rate of change in altitude before estimating power use from speed. Finally, we document an unexpected variability in speed and altitude over fine scales; a source of substantial energetic inefficiency. We suggest this may be a form of protean behaviour adopted to reduce predation risk when flocking is not an option, and that such a strategy could be widespread.
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| 6. |
- Gauld, Jethro G., et al.
(author)
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Hotspots in the grid : Avian sensitivity and vulnerability to collision risk from energy infrastructure interactions in Europe and North Africa
- 2022
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In: Journal of Applied Ecology. - : John Wiley & Sons. - 0021-8901 .- 1365-2664. ; 59:6, s. 1496-1512
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Journal article (peer-reviewed)abstract
- Wind turbines and power lines can cause bird mortality due to collision or electrocution. The biodiversity impacts of energy infrastructure (EI) can be minimised through effective landscape-scale planning and mitigation. The identification of high-vulnerability areas is urgently needed to assess potential cumulative impacts of EI while supporting the transition to zero carbon energy. We collected GPS location data from 1,454 birds from 27 species susceptible to collision within Europe and North Africa and identified areas where tracked birds are most at risk of colliding with existing EI. Sensitivity to EI development was estimated for wind turbines and power lines by calculating the proportion of GPS flight locations at heights where birds were at risk of collision and accounting for species' specific susceptibility to collision. We mapped the maximum collision sensitivity value obtained across all species, in each 5 x 5 km grid cell, across Europe and North Africa. Vulnerability to collision was obtained by overlaying the sensitivity surfaces with density of wind turbines and transmission power lines. Results: Exposure to risk varied across the 27 species, with some species flying consistently at heights where they risk collision. For areas with sufficient tracking data within Europe and North Africa, 13.6% of the area was classified as high sensitivity to wind turbines and 9.4% was classified as high sensitivity to transmission power lines. Sensitive areas were concentrated within important migratory corridors and along coastlines. Hotspots of vulnerability to collision with wind turbines and transmission power lines (2018 data) were scattered across the study region with highest concentrations occurring in central Europe, near the strait of Gibraltar and the Bosporus in Turkey. Synthesis and applications. We identify the areas of Europe and North Africa that are most sensitive for the specific populations of birds for which sufficient GPS tracking data at high spatial resolution were available. We also map vulnerability hotspots where mitigation at existing EI should be prioritised to reduce collision risks. As tracking data availability improves our method could be applied to more species and areas to help reduce bird-EI conflicts.
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| 7. |
- Jax, Elinor, et al.
(author)
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Comparative Genomics of the Waterfowl Innate Immune System
- 2022
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In: Molecular biology and evolution. - : Oxford University Press (OUP). - 0737-4038 .- 1537-1719. ; 39:8
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Journal article (peer-reviewed)abstract
- Animal species differ considerably in their ability to fight off infections. Finding the genetic basis of these differences is not easy, as the immune response is comprised of a complex network of proteins that interact with one another to defend the body against infection. Here, we used population- and comparative genomics to study the evolutionary forces acting on the innate immune system in natural hosts of the avian influenza virus (AIV). For this purpose, we used a combination of hybrid capture, next- generation sequencing and published genomes to examine genetic diversity, divergence, and signatures of selection in 127 innate immune genes at a micro- and macroevolutionary time scale in 26 species of waterfowl. We show across multiple immune pathways (AIV-, toll-like-, and RIG-I -like receptors signalling pathways) that genes involved genes in pathogen detection (i.e., toll-like receptors) and direct pathogen inhibition (i.e., antimicrobial peptides and interferon-stimulated genes), as well as host proteins targeted by viral antagonist proteins (i.e., mitochondrial antiviral-signaling protein, [MAVS]) are more likely to be polymorphic, genetically divergent, and under positive selection than other innate immune genes. Our results demonstrate that selective forces vary across innate immune signaling signalling pathways in waterfowl, and we present candidate genes that may contribute to differences in susceptibility and resistance to infectious diseases in wild birds, and that may be manipulated by viruses. Our findings improve our understanding of the interplay between host genetics and pathogens, and offer the opportunity for new insights into pathogenesis and potential drug targets.
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| 8. |
- Jax, Elinor, et al.
(author)
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Health monitoring in birds using bio-loggers and whole blood transcriptomics
- 2021
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 11:1
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Journal article (peer-reviewed)abstract
- Monitoring and early detection of emerging infectious diseases in wild animals is of crucial global importance, yet reliable ways to measure immune status and responses are lacking for animals in the wild. Here we assess the usefulness of bio-loggers for detecting disease outbreaks in free-living birds and confirm detailed responses using leukocyte composition and large-scale transcriptomics. We simulated natural infections by viral and bacterial pathogens in captive mallards (Anas platyrhynchos), an important natural vector for avian influenza virus. We show that body temperature, heart rate and leukocyte composition change reliably during an acute phase immune response. Using genome-wide gene expression profiling of whole blood across time points we confirm that immunostimulants activate pathogen-specific gene regulatory networks. By reporting immune response related changes in physiological and behavioural traits that can be studied in free-ranging populations, we provide baseline information with importance to the global monitoring of zoonotic diseases.
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| 9. |
- Jetz, Walter, et al.
(author)
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Biological Earth observation with animal sensors
- 2022
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In: Trends in Ecology & Evolution. - : Elsevier. - 0169-5347 .- 1872-8383. ; 37:4, s. 293-298
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Journal article (peer-reviewed)abstract
- Space-based tracking technology using low-cost miniature tags is now delivering data on fine-scale animal movement at near-global scale. Linked with remotely sensed environmental data, this offers a biological lens on habitat integrity and connectivity for conservation and human health; a global network of animal sentinels of environmental change.
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| 10. |
- Kleyheeg, Erik, et al.
(author)
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A Comprehensive Model for the Quantitative Estimation of Seed Dispersal by Migratory Mallards
- 2019
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In: Frontiers in Ecology and Evolution. - : Frontiers Media S.A.. - 2296-701X. ; 7, s. 1-14
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Journal article (peer-reviewed)abstract
- Long-distance seed dispersal is an important ecosystem service provided by migratory animals. Plants inhabiting discrete habitats, like lakes and wetlands, experience dispersal limitation, and rely heavily on zoochory for their spatial population dynamics. Granivorous waterbirds may disperse viable seeds of wetland plants over long distances during migration. The limited knowledge of waterbird migration has long hampered the evaluation of the importance of waterbirds in seed dispersal, requiring key metrics such as realistic dispersal distances. Using recent GPS tracking of mallards during spring migration, we built a mechanistic seed dispersal model to estimate realistic dispersal distances. Mallards are abundant, partially migratory ducks known to consume seeds of >300 European plant species. Based on the tracking data, we informed a mallard migration simulator to obtain a probabilistic spring migration model for the mallard population wintering at Lake Constance in Southern Germany. We combined the spring migration model with seed retention curves to develop seed dispersal kernels. We also assessed the effects of pre-migratory fasting and the availability of suitable deposition habitats for aquatic and wetland plants. Our results show that mallards at Lake Constance can disperse seeds in the northeastern direction over median distances of 293 and 413 km for seeds with short and long retention times, respectively, assuming a departure immediately after foraging. Pre-migratory fasting strongly affected the dispersal potential, with only 1-7% of ingested seeds left for dispersal after fasting for 12 h. Availability of a suitable deposition habitat was generally <5% along the migratory flyway. The high probability of seed deposition in a freshwater habitat during the first stopover, after the mallards completed the first migratory flight, makes successful dispersal most likely to happen at 204-322 km from Lake Constance. We concluded that the directed long-distance dispersal of plant seeds, realized by mallards on spring migration, may contribute significantly to large scale spatial plant population dynamics, including range expansion in response to shifting temperature and rainfall patterns under global warming. Our dispersal model is the first to incorporate detailed behavior of migratory waterbirds and can be readily adjusted to include other vector species when tracking data are available.
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| 11. |
- Krishnan, Krishnamoorthy, et al.
(author)
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The role of wingbeat frequency and amplitude in flight power
- 2022
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In: Journal of the Royal Society Interface. - : The Royal Society. - 1742-5689 .- 1742-5662. ; 19:193
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Journal article (peer-reviewed)abstract
- Body-mounted accelerometers provide a new prospect for estimating power use in flying birds, as the signal varies with the two major kinematic determinants of aerodynamic power: wingbeat frequency and amplitude. Yet wingbeat frequency is sometimes used as a proxy for power output in isolation. There is, therefore, a need to understand which kinematic parameter birds vary and whether this is predicted by flight mode (e.g. accelerating, ascending/descending flight), speed or morphology. We investigate this using high-frequency acceleration data from (i) 14 species flying in the wild, (ii) two species flying in controlled conditions in a wind tunnel and (iii) a review of experimental and field studies. While wingbeat frequency and amplitude were positively correlated, R 2 values were generally low, supporting the idea that parameters can vary independently. Indeed, birds were more likely to modulate wingbeat amplitude for more energy-demanding flight modes, including climbing and take-off. Nonetheless, the striking variability, even within species and flight types, highlights the complexity of describing the kinematic relationships, which appear sensitive to both the biological and physical context. Notwithstanding this, acceleration metrics that incorporate both kinematic parameters should be more robust proxies for power than wingbeat frequency alone.
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| 12. |
- Lee, KA, et al.
(author)
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Contrasting adaptive immune defenses and blood parasite prevalence in closely related Passer sparrows
- 2006
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In: Oecologia. - : Springer Science and Business Media LLC. - 1432-1939 .- 0029-8549. ; 150:3, s. 383-392
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Journal article (peer-reviewed)abstract
- Immune system components differ in their functions and costs, and immune defense profiles are likely to vary among species with differing ecologies. We compared adaptive immune defenses in two closely related species that have contrasting inflammatory immune responses, the widespread and abundant house sparrow (Passer domesticus) and the less abundant tree sparrow (Passer montanus). We found that the house sparrow, which we have previously shown mounts weaker inflammatory responses, exhibits stronger adaptive immune defenses, including antibody responses, natural antibody titers, and specific T-cell memory, than the tree sparrow. Conversely, tree sparrows, which mount strong inflammatory responses, also mount stronger nonspecific inflammatory T-cell responses but weaker specific adaptive responses. Prevalence of avian malaria parasite infections, which are controlled by adaptive immune defenses, was higher in the geographically restricted tree sparrow than in the ubiquitous house sparrow. Together these data describe distinct immune defense profiles between two closely related species that differ greatly in numbers and distributions. We suggest that these immunological differences could affect fitness in ways that contribute to the contrasting abundances of the two species in North American and Western Europe.
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| 13. |
- Lindström, Åke, et al.
(author)
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A Puzzling Migratory Detour: Are Fueling Conditions In Alaska Driving The Movement Of Juvenile Sharp-Tailed Sandpipers?
- 2011
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In: The Condor: ornithological applications. - : Oxford University Press (OUP). - 0010-5422. ; 113:1, s. 129-139
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Journal article (peer-reviewed)abstract
- Making a detour can be advantageous to a migrating bird if fuel-deposition rates at stopover sites along the detour are considerably higher than at stopover sites along a more direct route. One example of an extensive migratory detour is that of the Sharp-tailed Sandpiper (Calidris acuminata), of which large numbers of juveniles are found during fall migration in western Alaska. These birds take a detour of 1500-3400 km from the most direct route between their natal range in northeastern Siberia and nonbreeding areas in Australia. We studied the autumnal fueling rates and fuel loads of 357 Sharp-tailed Sandpipers captured in western Alaska. In early September the birds increased in mass at a rate of only 0.5% of lean body mass day(-1). Later in September, the rate of mass increase was about 6% of lean body mass day(-1), among the highest values found among similar-sized shorebirds around the world. Some individuals more than doubled their body mass because of fuel deposition, allowing non-stop flight of between 7100 and 9800 km, presumably including a trans-oceanic flight to the southern hemisphere. Our observations indicated that predator attacks were rare in our study area, adding another potential benefit of the detour. We conclude that the most likely reason for the Alaskan detour is that it allows juvenile Sharp-tailed Sand-pipers to put on large fuel stores at exceptionally high rates.
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| 14. |
- Martin II, LB, et al.
(author)
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Investment in immune defense is linked to pace of life in house sparrows
- 2006
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In: Oecologia. - : Springer Science and Business Media LLC. - 1432-1939 .- 0029-8549. ; 147:4, s. 565-575
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Journal article (peer-reviewed)abstract
- The evidence for a relationship between life history and immune defense is equivocal, although the basic premise is intuitively appealing: animals that live short lives and reproduce early and rapidly should not waste resources on defenses they might never use. One possible reason for a lack of strong support for this hypothesis could be the inherent complexity of the vertebrate immune system. Indeed, different components of the vertebrate immune system vary in their relative costs and benefits, and therefore only some defenses may complement variation in species' life history. To address this hypothesis, we compared multiple types of immune activity between two populations of house sparrows (Passer domesticus) with distinct life histories, one from Colon, Panama, which lay small clutches over an extended breeding season (i.e., slow-living) and the other from Princeton, New Jersey, which lay larger clutches in a smaller window of time (i.e., fast-living). We expected (a) that more costly types of immune defenses would be stronger in the slow-living sparrows and (2) that the slow-living sparrows would show a greater increase in whole-body energy expenditure after immune challenge compared to their fast-living counterparts. We found that secondary antibody response to a novel antigen was more rapid and energetic investment in immune activity was greater in slow-living sparrows. However, cell-mediated immune activity was more robust in fast-living sparrows, and other measures of defense were not different between populations. These results provide partial support for a relationship between life history and immune defense in this species, but they also indicate that this relationship is not clear-cut. Further study is necessary to identify the influence of other factors, particular pathogen environment during development, on the architecture of the immune system of wild animals.
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| 15. |
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| 16. |
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| 17. |
- Sadeghayobi, Elham, et al.
(author)
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Digesta retention time in the Galapagos tortoise (Chelonoidis nigra)
- 2011
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In: Comparative Biochemistry and Physiology A. - : Elsevier BV. - 1095-6433 .- 1531-4332. ; 160:4, s. 493-497
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Journal article (peer-reviewed)abstract
- The retention time of food in the digestive tract of animals has important implications for digestive physiology. Retention time impacts digestive efficiency and among herbivores affects plant-animal interactions including herbivory and seed dispersal. Poorly studied yet iconic Galapagos tortoises are large-bodied generalist herbivores and ecosystem engineers which migrate seasonally. Potentially variable digesta retention times due to strong seasonal and attitudinal temperature gradients may influence tortoise seed dispersal abilities and rates of herbivory. We fed captive adult tortoises living in semi-natural conditions on Galapagos with inert particles and seeds from locally available fruits to determine whether seed size and ambient temperature influenced retention time. Median retention time varied from 6 to 28 days, with a mode of 12 days. Seed size had no effect on any of our measures of retention time, but ambient temperature was inversely correlated with retention times. Long retention time facilitates long distance seed dispersal by Galapagos tortoises, which may improve effectiveness. The effect of temperature, which may double from hot lowlands to cold highlands through the seasonal cycle, on tortoise digesta retention time will strongly influence seed dispersal efficiency and may influence patterns of food selection and migration in this species.
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| 18. |
- Safi, Kamran, et al.
(author)
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Flying with the wind: scale dependency of speed and direction measurements in modelling wind support in avian flight
- 2013
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In: Movement Ecology. - : Springer Science and Business Media LLC. - 2051-3933. ; 1
-
Journal article (peer-reviewed)abstract
- BackgroundUnderstanding how environmental conditions, especially wind, influence birds' flight speeds is a prerequisite for understanding many important aspects of bird flight, including optimal migration strategies, navigation, and compensation for wind drift. Recent developments in tracking technology and the increased availability of data on large-scale weather patterns have made it possible to use path annotation to link the location of animals to environmental conditions such as wind speed and direction. However, there are various measures available for describing not only wind conditions but also the bird's flight direction and ground speed, and it is unclear which is best for determining the amount of wind support (the length of the wind vector in a bird’s flight direction) and the influence of cross-winds (the length of the wind vector perpendicular to a bird’s direction) throughout a bird's journey.ResultsWe compared relationships between cross-wind, wind support and bird movements, using path annotation derived from two different global weather reanalysis datasets and three different measures of direction and speed calculation for 288 individuals of nine bird species. Wind was a strong predictor of bird ground speed, explaining 10-66% of the variance, depending on species. Models using data from different weather sources gave qualitatively similar results; however, determining flight direction and speed from successive locations, even at short (15 min intervals), was inferior to using instantaneous GPS-based measures of speed and direction. Use of successive location data significantly underestimated the birds' ground and airspeed, and also resulted in mistaken associations between cross-winds, wind support, and their interactive effects, in relation to the birds' onward flight.ConclusionsWind has strong effects on bird flight, and combining GPS technology with path annotation of weather variables allows us to quantify these effects for understanding flight behaviour. The potentially strong influence of scaling effects must be considered and implemented in developing sampling regimes and data analysis.
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| 19. |
- Shafer, Aaron B. A., et al.
(author)
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Forecasting Ecological Genomics : High-Tech Animal Instrumentation Meets High-Throughput Sequencing
- 2016
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In: PLoS biology. - : Public Library of Science (PLoS). - 1544-9173 .- 1545-7885. ; 14:1
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Journal article (peer-reviewed)abstract
- Recent advancements in animal tracking technology and high-throughput sequencing are rapidly changing the questions and scope of research in the biological sciences. The integration of genomic data with high-tech animal instrumentation comes as a natural progression of traditional work in ecological genetics, and we provide a framework for linking the separate data streams from these technologies. Such a merger will elucidate the genetic basis of adaptive behaviors like migration and hibernation and advance our understanding of fundamental ecological and evolutionary processes such as pathogen transmission, population responses to environmental change, and communication in natural populations.
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| 20. |
- Thorup, Kasper, et al.
(author)
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Resource tracking within and across continents in long-distance bird migrants
- 2017
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In: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 3:1
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Journal article (peer-reviewed)abstract
- Migratory birds track seasonal resources across and between continents. We propose a general strategy of tracking the broad seasonal abundance of resources throughout the annual cycle in the longest-distance migrating land birds as an alternative to tracking a certain climatic niche or shorter-term resource surplus occurring, for example, during spring foliation. Whether and how this is possible for complex annual spatiotemporal schedules is not known. New tracking technology enables unprecedented spatial and temporal mapping of long-distance movement of birds. We show that three Palearctic-African species track vegetation greenness throughout their annual cycle, adjusting the timing and direction of migratory movements with seasonal changes in resource availability over Europe and Africa. Common cuckoos maximize the vegetation greenness, whereas red-backed shrikes and thrush nightingales track seasonal surplus in greenness. Our results demonstrate that the longest-distance migrants move between consecutive staging areas even within the wintering region in Africa to match seasonal variation in regional climate. End-of-century climate projections indicate that optimizing greenness would be possible but that vegetation surplus might be more difficult to track in the future.
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| 21. |
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| 22. |
- van Toor, Mariëlle L., et al.
(author)
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Flexibility of Continental Navigation and Migration in European Mallards
- 2013
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In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:8
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Journal article (peer-reviewed)abstract
- The ontogeny of continent-wide navigation mechanisms of the individual organism, despite being crucial for the understanding of animal movement and migration, is still poorly understood. Several previous studies, mainly conducted on passerines, indicate that inexperienced, juvenile birds may not generally correct for displacement during fall migration. Waterbirds such as the mallard (Anas platyrhynchos, Linnaeus 1758) are more flexible in their migration behavior than most migratory songbirds, but previous experiments with waterbirds have not yet allowed clear conclusions about their navigation abilities. Here we tested whether immature mallard ducks correct for latitudinal displacement during fall migration within Europe. During two consecutive fall migration periods, we caught immature females on a stopover site in southeast Sweden, and translocated a group of them ca. 1,000 km to southern Germany. We followed the movements of the ducks via satellite GPS-tracking and observed their migration decisions during the fall and consecutive spring migration. The control animals released in Ottenby behaved as expected from banding recoveries: they continued migration during the winter and in spring returned to the population's breeding grounds in the Baltics and Northwest Russia. Contrary to the control animals, the translocated mallards did not continue migration and stayed at Lake Constance. In spring, three types of movement tactics could be observed: 61.5% of the ducks (16 of 26) stayed around Lake Constance, 27% (7 of 26) migrated in a northerly direction towards Sweden and 11.5% of the individuals (3 of 26) headed east for ca. 1,000 km and then north. We suggest that young female mallards flexibly adjust their migration tactics and develop a navigational map that allows them to return to their natal breeding area.
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| 23. |
- van Toor, Mariëlle L., et al.
(author)
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Flexibility of habitat use in novel environments : insights from a translocation experiment with lesser black-backed gulls
- 2017
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In: Royal Society Open Science. - : The Royal Society. - 2054-5703. ; 4:1, s. 1-14
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Journal article (peer-reviewed)abstract
- Being faced with unknown environments is a concomitant challenge of species' range expansions. Strategies to cope with this challenge include the adaptation to local conditions and a flexibility in resource exploitation. The gulls of the Larus argentatus-fuscus-cachinnans group form a system in which ecological flexibility might have enabled them to expand their range considerably, and to colonize urban environments. However, on a population level both flexibility and local adaptation lead to signatures of differential habitat use in different environments, and these processes are not easily distinguished. Using the lesser black-backed gull (Larus fuscus) as a system, we put both flexibility and local adaptation to a test. We compare habitat use between two spatially separated populations, and use a translocation experiment during which individuals were released into novel environment. The experiment revealed that on a population-level flexibility best explains the differences in habitat use between the two populations. We think that our results suggest that the range expansion and huge success of this species complex could be a result of its broad ecological niche and flexibility in the exploitation of resources. However, this also advises caution when using species distribution models to extrapolate habitat use across space.
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| 24. |
- van Toor, Mariëlle L., et al.
(author)
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Integrating animal movement with habitat suitability for estimating dynamic migratory connectivity
- 2018
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In: Landscape Ecology. - : Springer. - 0921-2973 .- 1572-9761. ; 33:6, s. 879-893
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Journal article (peer-reviewed)abstract
- High-resolution animal movement data are becoming increasingly available, yet having a multitude of empirical trajectories alone does not allow us to easily predict animal movement. To answer ecological and evolutionary questions at a population level, quantitative estimates of a species' potential to link patches or populations are of importance. We introduce an approach that combines movement-informed simulated trajectories with an environment-informed estimate of the trajectories' plausibility to derive connectivity. Using the example of bar-headed geese we estimated migratory connectivity at a landscape level throughout the annual cycle in their native range. We used tracking data of bar-headed geese to develop a multi-state movement model and to estimate temporally explicit habitat suitability within the species' range. We simulated migratory movements between range fragments, and calculated a measure we called route viability. The results are compared to expectations derived from published literature. Simulated migrations matched empirical trajectories in key characteristics such as stopover duration. The viability of the simulated trajectories was similar to that of the empirical trajectories. We found that, overall, the migratory connectivity was higher within the breeding than in wintering areas, corroborating previous findings for this species. We show how empirical tracking data and environmental information can be fused for meaningful predictions of animal movements throughout the year and even outside the spatial range of the available data. Beyond predicting migratory connectivity, our framework will prove useful for modelling ecological processes facilitated by animal movement, such as seed dispersal or disease ecology.
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| 25. |
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| 26. |
- Willemoes, Mikkel, et al.
(author)
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Narrow-Front Loop Migration in a Population of the Common Cuckoo Cuculus canorus, as Revealed by Satellite Telemetry.
- 2014
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In: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:1
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Journal article (peer-reviewed)abstract
- Narrow migration corridors known in diurnal, social migrants such as raptors, storks and geese are thought to be caused by topographical leading line effects in combination with learning detailed routes across generations. Here, we document narrow-front migration in a nocturnal, solitary migrant, the common cuckoo Cuculus canorus, using satellite telemetry. We tracked the migration of adult cuckoos from the breeding grounds in southern Scandinavia (n = 8), to wintering sites in south-western Central Africa (n = 6) and back to the breeding grounds (n = 3). Migration patterns were very complex; in addition to the breeding and wintering sites, six different stopover sites were identified during the 16,000 km annual route that formed a large-scale clockwise loop. Despite this complexity, individuals showed surprisingly similar migration patterns, with very little variation between routes. We compared observed tracks with simulated routes based on vector orientation (with and without effects of barriers on orientation and survival). Observed distances between routes were often significantly smaller than expected if the routes were established on the basis of an innate vector orientation programme. Average distance between individuals in eastern Sahel after having migrated more than 5,000 km for example, was merely 164 km. This implies that more sophisticated inherent guiding mechanisms, possibly involving elements of intermediate goal area navigation or more elaborate external cues, are necessary to explain the complex narrow-front migration pattern observed for the cuckoos in this study.
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