Sensor:
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    Data from: Flyway connectivity and exchange primarily driven by moult migration in geese [Pannonic population]
    (2019-02-06) Müskens, Gerhard J.D.M.; Szinai, Péter; Sapi, Tamas; Kölzsch, Andrea; Wikelski, Martin; Nolet, Bart A.
    Background: For the conservation and management of migratory species that strongly decrease or increase due to anthropological impacts, a clear delineation of populations and quantification of possible mixing (migratory connectivity) is crucial. Usually, population exchange in migratory species is only studied in breeding or wintering sites, but we considered the whole annual cycle in order to determine important stages and sites for population mixing in an Arctic migrant. Methods: We used 91 high resolution GPS tracks of Western Palearctic greater white-fronted geese (Anser A. albifrons) from the North Sea and Pannonic populations to extract details of where and when populations overlapped and exchange was possible. Overlap areas were calculated as dynamic Brownian bridges of stopover, nest and moulting sites. Results: Utilisation areas of the two populations overlapped only somewhat during spring and autumn migration stopovers, but much during moult. During this stage, non-breeders and failed breeders of the North Sea population intermixed with geese from the Pannonic population in the Pyasina delta on Taimyr peninsula. The timing of use of overlap areas was highly consistent between populations, making exchange possible. Two of our tracked geese switched from the North Sea population flyway to the Pannonic flyway during moult on Taimyr peninsula or early during the subsequent autumn migration. Because we could follow one of them during the next year, where it stayed in the Pannonic flyway, we suggest that the exchange was long-term or permanent. Conclusions: We have identified long-distance moult migration of failed or non-breeders as a key phenomenon creating overlap between two flyway populations of geese. This supports the notion of previously suggested population exchange and migratory connectivity, but outside of classically suggested wintering or breeding sites. Our results call for consideration of moult migration and population exchange in conservation and management of our greater white-fronted geese as well as other waterfowl populations.
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    Data from: Evaluation of micro-GPS receivers for tracking small-bodied mammals
    (2017-03-16) McMahon, Laura A.; Rachlow, Janet L.; Shipley, Lisa A.; Forbey, Jennifer S.
    GPS telemetry markedly enhances the temporal and spatial resolution of animal location data, and recent advances in micro-GPS receivers permit their deployment on small mammals. One such technological advance, snapshot technology, allows for improved battery life by reducing the time to first fix via postponing recovery of satellite ephemeris (satellite location) data and processing of locations. However, no previous work has employed snapshot technology for small, terrestrial mammals. We evaluated performance of two types of micro-GPS (< 20 g) receivers (traditional and snapshot) on a small, semi-fossorial lagomorph, the pygmy rabbit (Brachylagus idahoensis), to understand how GPS errors might influence fine-scale assessments of space use and habitat selection. During stationary tests, microtopography (i.e., burrows) and satellite geometry had the largest influence on GPS fix success rate (FSR) and location error (LE). There was no difference between FSR while animals wore the GPS collars above ground (determined via light sensors) and FSR generated during stationary, above-ground trials, suggesting that animal behavior other than burrowing did not markedly influence micro-GPS errors. In our study, traditional micro-GPS receivers demonstrated similar FSR and LE to snapshot receivers, however, snapshot receivers operated inconsistently due to battery and software failures. In contrast, the initial traditional receivers deployed on animals experienced some breakages, but a modified collar design consistently functioned as expected. If such problems were resolved, snapshot technology could reduce the tradeoff between fix interval and battery life that occurs with traditional micro-GPS receivers. Our results suggest that micro-GPS receivers are capable of addressing questions about space use and resource selection by small mammals, but that additional techniques might be needed to identify use of habitat structures (e.g., burrows, tree cavities, rock crevices) that could affect micro-GPS performance and bias study results.
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    Data from: Flexible flight response to challenging wind conditions in a commuting Antarctic seabird: do you catch the drift?
    (2016-01-14) Tarroux, Arnaud; Weimerskirch, Henri; Wang, Sheng-Hung; Bromwich, David H.; Cherel, Yves; Kato, Akiko; Ropert-Coudert, Yan; Varpe, Øystein; Yoccoz, Nigel G.; Descamps, Sébastien
    Flight is intrinsically an energetically costly way of moving and birds have developed morphological, physiological and behavioural adaptations to minimize these costs. Central-place foraging seabirds commute regularly between nesting and foraging areas, providing us with opportunities to investigate their behavioural response to environmental conditions that may affect flight, such as wind. Here we tested hypotheses on how wind conditions influence flight behaviour in situations devoid of the confounding effect that, for instance, active foraging behaviour can have on movement patterns. We studied the Antarctic petrel, Thalassoica antarctica, a seabird breeding far inland in Antarctica and commuting through vast ice-covered areas characterized by steady and strong winds as well as a strict absence of foraging opportunities. We combined the three-dimensional location data from 79 GPS tracks with atmospheric wind data over three consecutive breeding seasons (2011-2013) in order to assess individual flight responses to wind conditions. Antarctic petrels encountered generally unfavourable winds, particularly during return flights. Despite their capacity to adjust their speed and heading in order to maintain constant track direction (compensation) in the strongest winds, they generally drifted as wind strengthened. Strong winds induced low-altitude flight. Birds tended to otherwise fly relatively high, but at altitudes with more favourable winds than what they would have encountered if flying higher. Our results show that commuting Antarctic petrels: (1) can tolerate a certain amount of drift according to wind conditions and (2) might be more limited by their ability to assess drift, rather than compensate for it, at least during returning flights.
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    Data from: Foraging habitat choice of white-tailed tropicbirds revealed by fine-scale GPS tracking and remote sensing
    (2018-12-27) Santos, Carlos David; Campos, Leila F.A.S.; Efe, M.A.
    Background: The introduction of animal tracking technology has rapidly advanced our understanding of seabird foraging ecology. Tracking data is particularly powerful when combined with oceanographic information derived from satellite remote sensing, allowing insights into the functional mechanisms of marine ecosystems. While this framework has been used extensively over the last two decades, there are still vast ocean regions and many seabird species for which information is scarce, particularly in tropical oceans. Methods: In this study we tracked the movement at high GPS recording frequency of 15 White-tailed Tropicbirds (Phaethon lepturus) during chick-rearing from a colony in Fernando de Noronha (offshore of Northeast Brazil). Flight behaviours of travelling and searching for food were derived from GPS data and examined in relation to satellite-sensed oceanographic variables (sea surface temperature, turbidity and chlorophyll-a concentration). Results: White-tailed Tropicbirds showed marked preference for clear and warm sea surface waters, which are indicative of low primary productivity but are likely the best habitat for preying upon flying fish. Discussion: These findings are consistent with previous studies showing that foraging habitat choices of tropical seabirds may not be driven by primary productivity, as has been widely shown for non-tropical species.
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    Data from: First three-dimensional tracks of bat migration reveal large amounts of individual behavioral flexibility
    (2019-05-28) O'Mara, M. Teague; Wikelski, Martin; Kranstauber, Bart; Dechmann, Dina K.N.
    It is generally assumed that small migrating birds and bats explore wind conditions and then choose a flight altitude, which they then maintain. Because of their high metabolism and flight costs, bats should also minimize energy expenditure during migratory flight, but we know little of how individuals make their migratory journeys. We followed migrating common noctules (Nyctalus noctula) fitted with miniaturized barometric pressure radio transmitters by airplane to record three dimensional migratory movements. Mean airspeeds were 7.2-15.9 m/s and overall climb rates were faster than overall descent rates. While all bats migrated in the same northeasterly direction, they showed flexibility in their altitudes, distances and stopover sites both within and among individuals. This suggests that individuals make decisions to take advantage of wind, landscape, and navigational conditions or other, yet unknown factors, to optimize their nightly flights. Our results once more confirm that the flexibility and behavioral repertoire of individuals in the wild is greater than we assume.
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    Data from: As the duck flies: estimating the dispersal of low-pathogenic avian influenza viruses by migrating mallards
    (2018-11-26) van Toor, Mariëlle L.; Ottosson, Ulf; van der Meer, Tim; van Hoorn, Sita; Waldenström, Jonas
    Many pathogens rely on the mobility of their hosts for dispersal. In order to understand and predict how a disease can rapidly sweep across entire continents, illuminating the contributions of host movements to disease spread is pivotal. While elegant proposals have been made to elucidate the spread of human infectious diseases, the direct observation of long-distance dispersal events of animal pathogens is challenging. Pathogens like avian influenza A viruses, causing only short disease in their animal hosts, have proven exceptionally hard to study. Here, we integrate comprehensive data on population and disease dynamics for low-pathogenic avian influenza viruses in one of their main hosts, the mallard, with a novel movement model trained from empirical, high-resolution tracks of mallard migrations. This allowed us to simulate individual mallard migrations from a key stopover site in the Baltic Sea for the entire population and link these movements to infection simulations. Using this novel approach, we were able to estimate the dispersal of low-pathogenic avian influenza viruses by migrating mallards throughout several autumn migratory seasons and predicted areas that are at risk of importing these viruses. We found that mallards are competent vectors and on average dispersed viruses over distances of 160 km in just three hours. Surprisingly, our simulations suggest that such dispersal events are rare even throughout the entire autumn migratory season. Our approach directly combines simulated population-level movements with local infection dynamics and offers a potential converging point for movement and disease ecology.
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    Data from: Shearwaters know the direction and distance home but fail to encode intervening obstacles after free-ranging foraging trips
    (2019-10-13) Padget, Oliver; Stanley, Geoff; Willis, Jay K.; Fayet, Annette L.; Bond, Sara; Maurice, Louise; Shoji, Akiko; Dean, Ben; Kirk, Holly; Juarez-Martinez, Ignacio; Freeman, Robin; Bolton, Mark; Guilford, Tim
    While displacement experiments have been powerful for determining the sensory basis of homing navigation in birds, they have left unresolved important cognitive aspects of navigation such as what birds know about their location relative to home and the anticipated route. Here, we analyze the free-ranging Global Positioning System (GPS) tracks of a large sample (n = 707) of Manx shearwater, Puffinus puffinus, foraging trips to investigate, from a cognitive perspective, what a wild, pelagic seabird knows as it begins to home naturally. By exploiting a kind of natural experimental contrast (journeys with or without intervening obstacles) we first show that, at the start of homing, sometimes hundreds of kilometers from the colony, shearwaters are well oriented in the homeward direction, but often fail to encode intervening barriers over which they will not fly (islands or peninsulas), constrained to flying farther as a result. Second, shearwaters time their homing journeys, leaving earlier in the day when they have farther to go, and this ability to judge distance home also apparently ignores intervening obstacles. Thus, at the start of homing, shearwaters appear to be making navigational decisions using both geographic direction and distance to the goal. Since we find no decrease in orientation accuracy with trip length, duration, or tortuosity, path integration mechanisms cannot account for these findings. Instead, our results imply that a navigational mechanism used to direct natural large-scale movements in wild pelagic seabirds has map-like properties and is probably based on large-scale gradients.
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    Data from: Flexible characterization of animal movement pattern using net squared displacement and a latent state model
    (2016-11-29) Bastille-Rousseau, Guillaume; Potts, Jonathan R.; Yackulic, Charles B.; Frair, Jacqueline L.; Ellington, E. Hance; Blake, Stephen
    NOTE: An updated and larger version of this dataset is available. See https://doi.org/10.5441/001/1.6gr485fk. ABSTRACT: Background: Characterizing the movement patterns of animals is an important step in understanding their ecology. Various methods have been developed for classifying animal movement at both coarse (e.g., migratory vs. sedentary behavior) and fine (e.g., resting vs. foraging) scales. A popular approach for classifying movements at coarse resolutions involves fitting time series of net-squared displacement (NSD) to models representing different conceptualizations of coarse movement strategies (i.e., migration, nomadism, sedentarism, etc.). However, the performance of this method in classifying actual (as opposed to simulated) animal movements has been mixed. Here, we develop a more flexible method that uses the same NSD input, but relies on an underlying discrete latent state model. Using simulated data, we first assess how well patterns in the number of transitions between modes of movement and the duration of time spent in a mode classify movement strategies. We then apply our approach to elucidate variability in the movement strategies of eight giant tortoises (Chelonoidis sp.) using a multi-year (2009–2014) GPS dataset from three different Galapagos Islands. Results: With respect to patterns of time spent and the number of transitions between modes, our approach out- performed previous efforts to distinguish among migration, dispersal, and sedentary behavior. We documented marked inter-individual variation in giant tortoise movement strategies, with behaviors indicating migration, dispersal, nomadism and sedentarism, as well as hybrid behaviors such as “exploratory residence”. Conclusions: Distilling complex animal movement into discrete modes remains a fundamental challenge in movement ecology, a problem made more complex by the ever-longer duration, ever-finer resolution, and gap-ridden trajectories recorded by GPS devices. By clustering into modes, we derived information on the time spent within one mode and the number of transitions between modes which enabled finer differentiation of movement strategies over previous methods. Ultimately, the techniques developed here address limitations of previous approaches and provide greater insights with respect to characterization of movement strategies across scales by more fully utilizing long-term GPS telemetry datasets.
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    Data from: Home range use and movement patterns of non-native feral goats in a tropical island montane dry landscape
    (2015-05-11) Chynoweth, Mark W
    Advances in wildlife telemetry and remote sensing technology facilitate studies of broad-scale movements of ungulates in relation to phenological shifts in vegetation. In tropical island dry landscapes, home range use and movements of non-native feral goats (Capra hircus) are largely unknown, yet this information is important to help guide the conservation and restoration of some of the world’s most critically endangered ecosystems. We hypothesized that feral goats would respond to resource pulses in vegetation by traveling to areas of recent green-up. To address this hypothesis, we fitted six male and seven female feral goats with Global Positioning System (GPS) collars equipped with an Argos satellite upload link to examine goat movements in relation to the plant phenology using the Normalized Difference Vegetation Index (NDVI). Movement patterns of 50% of males and 40% of females suggested conditional movement between non-overlapping home ranges throughout the year. A shift in NDVI values corresponded with movement between primary and secondary ranges of goats that exhibited long-distance movement, suggesting that vegetation phenology as captured by NDVI is a good indicator of the habitat and movement patterns of feral goats in tropical island dry landscapes. In the context of conservation and restoration of tropical island landscapes, the results of our study identify how non-native feral goats use resources across a broad landscape to sustain their populations and facilitate invasion of native plant communities.
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    Data from: Forecasting spring from afar? Timing of migration and predictability of phenology along different migration routes of an avian herbivore [Barents Sea data]
    (2014-09-01) van der Jeugd, Henk; Osterbeek, Kees; Ens, Bruno J; Shamoun-Baranes, Judy; Exo, Klaus-Michael
    1. Herbivorous birds are hypothesized to migrate in spring along a seasonal gradient of plant profitability towards their breeding grounds (green wave hypothesis). For Arctic-breeding species in particular, following highly profitable food is important, so that they can replenish resources along the way and arrive in optimal body condition to start breeding early. 2. We compared the timing of migratory movements of Arctic-breeding geese on different flyways to examine whether flyways differed in the predictability of spring conditions at stopovers, and whether this was reflected in the degree to which birds were following the green wave. 3. Barnacle geese (Branta leucopsis) were tracked with solar Argos/GPS PTTs from their wintering grounds to breeding sites in Greenland (N = 7), Svalbard (N = 21) and the Barents Sea (N = 12). The numerous stopover sites of all birds were combined into a set of 16 general stopover regions. 4. The predictability of climatic conditions along the flyways was calculated as the correlation and slope between onsets of spring at consecutive stopovers. These values differed between sites, mainly because of the presence or absence of ecological barriers. Goose arrival at stopovers was more closely tied to the local onset of spring when predictability was higher and when geese attempted breeding that year. 5. All birds arrived at early stopovers after the onset of spring and arrived at the breeding grounds before the onset of spring, thus overtaking the green wave. This is in accordance with patterns expected for capital breeders: first they must come into condition; at intermediate stopovers arrival with the food quality peak is important to stay in condition and at the breeding grounds early arrival is favoured so that hatching of young can coincide with the peak of food quality. 6. Our results suggest that a chain of correlations between climatic conditions at subsequent stopovers enables geese to closely track the green wave. However, the birds’ precision of migratory timing seems uninfluenced by ecological barriers, indicating partly fixed migration schedules. These might become non-optimal due to climate warming and preclude accurate timing of long-distance migrants in the future.