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  • Data package
    Data from: Turbulence causes kinematic and behavioural adjustments in a flapping flier
    (2024-02-20) Lempidakis, Emmanouil; Ross, Andrew N.; Quetting, Michael; Krishnan, Krishnamoorthy; Garde, Baptiste; Wikelski, Martin; Shepard, Emily L.C.
    Turbulence is a widespread phenomenon in the natural world, but its influence on flapping fliers remains little studied. We assessed how freestream turbulence affected the kinematics, flight effort, and track properties of homing pigeons (Columba livia), using the fine-scale variations in flight height as a proxy for turbulence levels. Birds showed a small increase in their wingbeat amplitude with increasing turbulence (similar to laboratory studies), but this was accompanied by a reduction in mean wingbeat frequency, such that their flapping wing speed remained the same. Mean kinematic responses to turbulence may therefore enable birds to increase their stability without a reduction in propulsive efficiency. Nonetheless, the most marked response to turbulence was an increase in the variability of wingbeat frequency and amplitude. These stroke-to-stroke changes in kinematics provide instantaneous compensation for turbulence. They will also increase flight costs. Yet pigeons only made small adjustments to their flight altitude, likely resulting in little change in exposure to strong convective turbulence. Responses to turbulence were therefore distinct from responses to wind, with the costs of high turbulence being levied through an increase in the variability of their kinematics and airspeed. This highlights the value of investigating the variability in flight parameters in free-living animals.
  • Data package
    Data from: Coexistence of two sympatric predators in a transitional ecosystem under constraining environmental conditions: a perspective from space and habitat use
    (2023-12-11) Warret Rodrigues, Chloé; Roth, James D.
    Background: Range expansion of species, a major consequence of climate changes, may alter communities substantially due to competition between expanding and native species. Methods: We first quantified size differences between an expanding habitat generalist, the red fox (Vulpes vulpes), and a circumpolar habitat specialist, the Arctic foxes (Vulpes lagopus), at the edge of the Arctic, where climate-related changes occur rapidly, to predict the likelihood of the larger competitor escalating interference to intraguild killing. We then used satellite telemetry to evaluate competition in a heterogeneous landscape by examining space use early during the foxes' reproductive period, when resource scarcity, increased-food requirements and spatial constraints likely exacerbate the potential for interference. We used time-LoCoH to quantify space and habitat use, and Minta's index to quantify spatio-temporal interactions between neighbors. Results: Our morphometric comparison involving 236 foxes found that the potential for escalated interference between these species was high due to intermediate size difference. However, our results from 17 collared foxes suggested that expanding and native competitors may coexist when expanding species occur at low densities. Low home-range overlap between neighbors suggested territoriality and substantial exploitation competition for space. No obvious differential use of areas shared by heterospecific neighbors suggested low interference. If anything, intraspecific competition between red foxes may be stronger than interspecific competition. Red and Arctic foxes used habitat differentially, with near-exclusive use of forest patches by red foxes and marine habitats by Arctic foxes. Conclusion: Heterogeneous landscapes may relax interspecific competition between expanding and native species, allowing exclusive use of some resources. Furthermore, the scarcity of habitats favored by expanding species may emphasize intraspecific competition between newcomers over interspecific competition, thus creating the potential for self-limitation of expanding populations. Dominant expanding competitors may benefit from interference, but usually lack adaptations to abiotic conditions at their expansion front, favoring rear-edge subordinate species in exploitation competition. However, due to ongoing climate change, systems are usually not at equilibrium. A spread of habitats and resources favorable to expanding species may promote higher densities of antagonistically dominant newcomers, which may lead to extirpation of native species.
  • Data package
    Data from: The price of being late: short- and long-term consequences of a delayed migration timing [naturally-timed birds]
    (2023-07-28) Bontekoe, Iris D.; Fiedler, Wolfgang; Wikelski, Martin; Flack, Andrea
    Choosing the right migration timing is critical for migrants because conditions encountered en route influence movement costs, survival, and, in social migrants, the availability of social information. Depending on lifetime stages, individuals may migrate at different times due to diverging constraints, affecting the composition of migration groups. To examine the consequences of a delayed migration timing, we artificially delayed the migration of juvenile white storks (Ciconia ciconia) and thereby altered their physical and social environment. Using nearly continuous 1 Hz GPS trajectories, we examined their migration behaviour, ranging from sub-second level performance to global long-distance movement, in relation to two control groups. We found that delayed storks experienced suboptimal soaring conditions, but better wind support and thereby achieved higher flight speeds than control storks. Delayed storks had a lower mortality rate than the control storks and wintered closer to the breeding area. In fact, none of the delayed storks reached the traditional African wintering areas. Thus, our results show that juvenile storks can survive migrating at the ‘wrong’ time. However, this had long-term consequences on migration decisions. We suggest that, when timing their migration, storks balance not just energy and time, but also the availability of social information.
  • Data package
    Data from: Study "NC Wood Stork Tracking"
    (2023-12-23) Schweitzer, Sara; Bryan, A. Lawrence, Jr.; Brzorad, John; Kays, Roland
    We tracked two wood storks (Mycteria americana) from a breeding site in North Carolina, documenting their migrations to southern Florida. This is one of the northernmost breeding grounds for the species. Dice was tracked with a GPS/GSM/ACC tag from e-obs GmbH, and Mr Lay was tracked with a GSM-GPS tag from Microwave Telemetry Inc. Duplicates and location outliers were flagged in Movebank by manually flagging visible outliers and then using filters. First, the duplicate filter was used to flag multiple records records with matching tag ID and timestamp, with a preference to retain "eobs:status" values in the following order: A, B, C, D, blank. Second, the speed filter was run using maximum plausible speed of 50 m/s and maximum location error 100 m, using the "longest consistent track" method.
  • Data package
    Data from: Fitness, behavioral, and energetic trade-offs of different migratory strategies in a partially migratory species
    (2023-08-03) Soriano-Redondo, Andrea; Franco, Aldina M.A.; Acácio, Marta; Payo-Payo, Ana; Martins, Bruno Herlander; Moreira, Francisco; Catry, Inês
    Alternative migratory strategies can coexist within animal populations and species. Anthropogenic impacts can shift the fitness balance between these strategies leading to changes in migratory behaviors. Yet some of the mechanisms that drive such changes remain poorly understood. Here we investigate the phenotypic differences, and the energetic, behavioral, and fitness trade-offs associated with four different movement strategies (long- and short-distance migration, and regional and local residency) in a population of white storks (Ciconia ciconia) that has shifted its migratory behavior over the last decades, from fully long-distance migration towards year-round residency. To do this, we tracked 75 adult storks fitted with GPS/GSM loggers with triaxial acceleration sensors over 5 years, and estimated individual displacement, behavior, and overall dynamic body acceleration, a proxy for activity-related energy expenditure. Additionally, we monitored nesting colonies to assess individual survival and breeding success. We found that long-distance migrants travelled thousands of kilometers more throughout the year, spent more energy, and >10% less time resting compared to short-distance migrants and residents. Long-distance migrants also spent on average more energy per unit of time while foraging, and less energy per unit of time while soaring. Migratory individuals also occupied their nests later than resident ones, later occupation led to later laying date and reduced number of fledglings. However, we did not find significant differences in survival probability. Finally, we found phenotypic differences in the migratory probability, as smaller-sized individuals were more likely to migrate, and they might be incurring in higher energetic and fitness costs than larger ones. Our results shed light into the shifting migratory strategies in a partially migratory population and highlight the nuances of anthropogenic impacts on species behavior, fitness, and evolutionary dynamics.
  • Data package
    Data from: More grazing, more damage? Assessed yield loss on agricultural grassland relates non-linearly to goose grazing pressure
    (2023-11-29) Buitendijk, Nelleke H.; de Jager, Monique; Kruckenberg, Helmut; Kölzsch, Andrea; Moonen, Sander; Müskens, Gerhard J.D.M.; Nolet, Bart A.
    1. In recent decades, conflict between geese and agriculture has increased. Management practices to limit this conflict include concentrating geese in protected areas, derogation shooting or population reduction. To justify such management, we need to understand their effects on goose-related damages, which requires an understanding of how yield loss is influenced by goose abundance and species interactions. 2. We combined data from monthly goose counts and GPS-tracked geese to estimate grazing pressures by barnacle, white-fronted and greylag geese on agricultural grassland in Fryslân, the Netherlands. Using linear mixed models, we related this to damages assessed by professional inspectors. 3. Our results show a positive nonlinear relationship between yield loss and barnacle goose grazing pressure, where assessed damage increases with a decelerating rate as grazing pressure increases. For white-fronted geese, we find a negative relationship, while for greylag geese both positive and negative relationships occur. For each species, the relationship is influenced by the abundance of the other two. 4. For barnacle geese, the relationship can be explained by selection of fields offering the best balance between food intake and energy expenditure, and by grass regrowth, with highest grazing pressures occurring over a longer time period. The results for the other species are likely due to spatial and temporal differences in foraging preferences compared to barnacle geese, where larger species avoid areas with highest damages. 5. Synthesis and applications. Our results suggest that decreasing herbivore abundance may not translate directly to decreased yield loss, and management tools such as population reduction or derogation shooting should be used with care. Management aimed at concentrating geese in refuges could help to alleviate farmer–goose conflict, although further studies are required to determine if it would lead to damage reduction. We also find that not all species contribute equally to agricultural damage; care should be taken to ensure wildlife management targets the right species.
  • Data package
    Data from: Diverse foraging strategies of breeding Swinhoe's Storm-Petrel in the productive marginal sea of Northwest Pacific
    (2024-01-04) Cheng, Yachang; Zhu, Lei; Xue, Lin; Ma, Shisheng; Jia, Nan; Zang, Shaoping; Cao, Zhihai; Yuan, Jing; Liu, Yang
    Understanding the foraging behavior is essential for investigating seabird ecology and conservation, as well as monitoring the well-being of the marine environment. Breeding seabirds adopt diverse foraging strategies to maximize energy gains and cope with the intensified challenges of parenting and self-maintenance. Such trade-off may stem from the heterogeneity of food resources and the constraints of central place foraging. Nevertheless, abundant marine productivity could alleviate the energy limitation for seabirds, resulting in a consistent foraging approach. Here, we investigated the foraging strategy during the breeding season of a cryptic small-sized seabird, Swinhoe's Storm-petrel (Hydrobates monorhis), in the Yellow Sea, a productive marginal sea of the Northwest Pacific. Using GPS tracking, we evaluated habitat preference, quantified the foraging strategy, and tested if environmental conditions and individual traits influence foraging trips. We found that Swinhoe's Storm-petrels preferred nearshore areas with shallow water and engaged in primarily short foraging trips. Distinctive southeastward and southwestward strategies emerged when combining trip metrics, including foraging direction, duration, and maximum distance. The bathymetry, proximity to the coastline, and sea surface temperature differed in two foraging strategies. Foraging strategies exhibited flexibility between individuals, potentially explained by wing morphology, in which longer-winged birds are more likely to embark on longer-distance foraging trips. These findings highlight the impact of environmental factors and individual traits on seabirds' foraging decisions in productive marginal sea ecosystems. Our study also provides valuable insights into the foraging ecology of this Asian endemic Storm-petrels.
  • Data package
    Data from: Early life and acquired experiences interact in shaping migratory and flight behaviors
    (2023-11-21) Efrat, Ron; Hatzofe, Ohad; Mueller, Thomas; Sapir, Nir; Berger-Tal, Oded
    Two types of experience affect animals' behavioral proficiencies and accordingly their fitness: early-life experience–an animal’s environment during its early development, and acquired experience–the repeated practice of a specific task. Yet, how these two experience types and their interactions affect different proficiencies is still an open question. Here, we study the interactions between these two types of experience during migration, a critical and challenging period. We do so by comparing migratory proficiencies between birds with different early-life experiences, and explain these differences by testing fine-scale flight mechanisms. We used data collected by GPS transmitters during autumn migrations of 65 individuals to study the flight proficiencies of two groups of Egyptian vultures (Neophron percnopterus), a long-distance, soaring raptor. The two groups differed greatly in their early-life experience, one group being captive-bred and the other wild-hatched. Both groups improved their migratory performance with acquired experience, exhibiting shorter migration times, longer daily progress, and improved flight skills, specifically more efficient soaring-gliding behavior. The observed improvements were mostly apparent for captive-bred vultures which were the least efficient during their first migration but were able to catch up in their migratory performance already in the second migration. Thus, we show how the strong negative effects of early-life experience were offset by acquired experience. Our findings uncover how the interaction between early-life and acquired experiences may shape animals' proficiencies and shed new light on the ontogeny of animal migration, suggesting possible effects of sensitive periods of learning on the acquisition of migratory skills.
  • Data package
    Data from: Study "Milvus_milvus_Soaring_over_Adriatic_sea"
    (2023-12-11) Škrábal, Jan; Literák, Ivan; Raab, Rainer
    Background: For soaring birds, the ability to benefit from variable airflow dynamics is crucial, especially while crossing natural barriers such as vast water bodies during migration. Soaring birds also take advantage of warm rising air, so-called thermals, that allow birds to ascend passively to higher altitudes with reduced energy costs. Although it is well known that soaring migrants generally benefit from supportive winds and thermals, the potential of uplifts and other weather factors enabling soaring behavior remains unsolved. Methods: In this study, we GPS-tracked 19 Red Kites, Milvus milvus, from the Central European population that crossed the Adriatic Sea on their autumn migration. Migratory tracks were annotated with weather data (wind support, side wind, temperature difference between air and surface—proxy for thermal uplift, cloud cover, and precipitation) to assess their effect on Red Kites' decisions and soaring performance along their migration across the Adriatic Sea and land. Results: Wind support affected the timing of crossing over the Adriatic Sea. We found that temperature differences and horizontal winds positively affected soaring sea movement by providing lift support in otherwise weak thermals. Furthermore, we found that the soaring patterns of tracked raptors were affected by the strength and direction of prevailing winds. Conclusion: Thanks to modern GPS-GSM telemetry devices and available data from online databases, we explored the effect of different weather variables on the occurrence of soaring behavior and soaring patterns of migratory raptors. We revealed how wind affected the soaring pattern and that tracked birds could soar in weak thermals by utilizing horizontal winds, thus reducing energy costs of active flapping flight over vast water bodies.
  • Data package
    Data from: Where do livestock guardian dogs go? Movement patterns of free-ranging Maremma sheepdogs
    (2014-11-05) van Bommel, Linda; Johnson, Chris N.
    In many parts of the world, livestock guardian dogs (LGDs) are a relatively new and increasingly popular method for controlling the impact of wild predators on livestock. On large grazing properties in Australia, LGDs are often allowed to range freely over large areas, with minimal supervision by their owners. How they behave in this situation is mostly unknown. We fitted free-ranging Maremma sheepdogs with GPS tracking collars on three properties in Victoria, Australia; on two properties, four sheep were also fitted with GPS collars. We investigated how much time the Maremmas spent with their livestock, how far they moved outside the ranges of their stock, and tested whether they use their ranges sequentially, which is an effective way of maintaining a presence over a large area. The 95% kernel isopleth of the Maremmas ranged between 31 and 1161 ha, the 50% kernel isopleth ranged between 4 and 252 ha. Maremmas spent on average 90% of their time in sheep paddocks. Movements away from sheep occurred mostly at night, and were characterised by high-speed travel on relatively straight paths, similar to the change in activity at the edge of their range. Maremmas used different parts of their range sequentially, similar to sheep, and had a distinct early morning and late afternoon peak in activity. Our results show that while free-ranging LGDs spend the majority of their time with livestock, movements away from stock do occur. These movements could be important in allowing the dogs to maintain large territories, and could increase the effectiveness of livestock protection. Allowing LGDs to range freely can therefore be a useful management decision, but property size has to be large enough to accommodate the large areas that the dogs use.