340 results
Search Results
Now showing 1 - 10 of 340
- Data packageData 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 packageData from: Study "Wood stork (Mycteria americana) Southeastern US 2004–2019"(2021-10-11) Basille, Mathieu; Borkhataria, Rena R.; Bryan, A. Lawrence, Jr.; Bucklin, David N.; Picardi, Simona; Frederick, Peter C.Data collection was supported by the U.S. National Park Service, U.S. Army Corps of Engineers, U.S. Fish and Wildlife Service, and U.S. Geological Survey. ABSTRACT: The function of migration is to allow exploitation of resources whose availability is heterogeneous in space and time. Much effort has been historically directed to studying migration as a response to seasonal, predictable fluctuations in resource availability in temperate species. A deeper understanding of how different migration patterns emerge in response to different patterns of resource variation requires describing migration patterns of species inhabiting less predictable environments, especially in tropical and subtropical areas. We provide the first individual-based, quantitative description of migratory patterns in a subtropical wading bird in the southeastern United States, the wood stork (Mycteria americana). Using GPS tracking data for 64 individuals tracked between 2004 and 2017, we classified migratory behavior at the individual-year level using information theory-based model selection on nonlinear models of net squared displacement. We found that the wood stork population is partially migratory, with 59% of individuals seasonally commuting between winter ranges in Florida and summer ranges elsewhere in the population range (migrants), and 28% remaining in a single area in Florida year-round (residents). Additionally, 13% of storks act as facultative migrants, migrating in some years but not in others. Comparing the distribution of residents and migrants suggests that different migratory strategies might be associated with the use of different or differently distributed resources, possibly including food supplementation from human activities. The existence of facultative migrants shows the potential for plastic change in migratory patterns. Partial migration in wood storks may be an adaptation to high heterogeneity and unpredictability of food resources. We suggest that future research should focus on wading birds as model species for the study of partial migration as an adaptation to heterogeneous and unpredictable environments.
- Data packageData from: Trans-equatorial migration links oceanic frontal habitats across the Pacific Ocean: year-round movements and foraging activity of a small gadfly petrel(2024-01-22) Clay, Thomas A.; Brooke, MdeL.Gadfly petrels are among the widest-ranging birds and inhabit oceanic regions beyond the legislative protection of national jurisdictions (the High Seas). Detailed information on breeding phenology, at-sea distributions, and habitat requirements is crucial for understanding threats and designing conservation measures for this highly threatened group. We tracked 10 Stejneger’s petrels Pterodroma longirostris, endemic to Isla Alejandro Selkirk, Juan Fernández Islands in the southeast Pacific Ocean, with geolocator-immersion loggers over two years to examine year-round movements, phenology, habitat use, and activity patterns. Birds conducted round-trip trans-equatorial migrations of 54,725 km to the northwest Pacific Ocean between Hawaii and Japan. Across the boreal summer, birds followed the c. 1000 km northward movement of the North Pacific Transition Zone Chlorophyll Front, before their return migration which took a long detour south toward New Zealand before heading east at 40–50°S, presumably benefitting from Antarctic circumpolar winds. To our knowledge, a comparable triangular migration is unique among seabirds. During the pre-laying exodus, birds traveled southwest to the Sub-Antarctic Front, and unlike congeners, there was no evidence of sexual segregation. Foraging areas during incubation were similar to pre-laying, with trips lasting 13 d and taking birds up to 4810 km southwest of the colony. Petrels spent > 75% of their time flying during breeding and migration, yet flight activity was substantially lower during non-breeding, presumably due to flight feather molt. Birds spent 87% of their time at sea within the High Seas and their apparent preference for oceanic frontal regions demonstrates the importance of protecting these remote habitats.
- Data packageData 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 packageData 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, AndreaChoosing 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 packageData from: Study "NC Wood Stork Tracking"(2023-12-23) Schweitzer, Sara; Bryan, A. Lawrence, Jr.; Brzorad, John; Kays, RolandWe 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 packageData from: Study "Marbled Murrelets at Desolation Sound, British Columbia, Canada (1998-2001)"(2022-10-26) Cooke, Fred; Lank, David B.; Bradley, Russell W.; Parker, Nadine R.; Lougheed, Cecilia; Lougheed, Lynn W.; McFarlane Tranquila, Laura A.; Pastran, Sonya A.; Greene, Randall; Vincent, Paola; Bertram, Douglas F.The Marbled Murrelet Brachyramphus marmoratus is a threatened seabird that relies on old-growth forest for nesting. We compare marine space use between breeding and non-breeding birds, and how marine home range locations and overlap vary with respect to nesting location and breeding status. We collected very high frequency (VHF) radio-telemetry data in southern British Columbia from Clayoquot Sound (190 birds; 2000-2002) and Desolation Sound (206 birds; 1998-2001). The sites differ strongly in their oceanic exposure and surrounding terrestrial features. Kernel utilization distribution-based estimates showed that breeders and non-breeders had similar overall distributions, but breeders were more spatially aggregated. Pooled home ranges of non-breeders were larger than those of breeders, but the distributions of individual home range sizes did not differ significantly by breeding status. However, compared with non-breeders, breeding murrelets were more likely to share their home range with other breeders. Home range sizes were larger and commuting distances were longer at Desolation Sound than at Clayoquot Sound; the average home range size for individuals was 241 ± 6.7 km2 at Clayoquot Sound and 330 ± 8.8 km2 at Desolation Sound. Individuals that nested closer together were more likely to share their marine home range in Desolation Sound, but not at Clayoquot Sound. Commuting distance to a nest site was not related to home range size at either site. Our results support the hypothesis that, at a local scale, breeding murrelets congregate at specific foraging areas and are not strongly constrained by commuting distance to nesting locations. Our results also support the concept that home range size may be indicative of the overall habitat quality of an area. We quantify connectivity between terrestrial and marine habitats and highlight important historical foraging locations.
- Data packageData from: At-sea distribution of spectacled eiders: a 120-year-old mystery resolved(2016-12-19) Petersen, Margaret R.; Douglas, David C.NOTE: An updated and larger version of this dataset is available through the US Geological Survey Alaska Science Center. See https://doi.org/10.5066/P9B091HG. ABSTRACT: The at-sea distribution of the threatened Spectacled Eider (Somateria fischeri) has remained largely undocumented. We identified migration corridors, staging and molting areas, and wintering areas of adult Spectacled Eiders using implanted satellite transmitters in birds from each of the three extant breeding grounds (North Slope and Yukon-Kuskokwim Delta in Alaska and arctic Russia). Based on transmitter locations, we conducted aerial surveys to provide visual confirmation of eider flocks and to estimate numbers of birds. We identified two principal molting and staging areas off coastal Alaska (Ledyard Bay and eastern Norton Sound) and two off coastal Russia (Mechigmenskiy Bay on the eastern Chukotka Peninsula, and the area between the Indigirka and Kolyma deltas in the Republic of Sakha). We estimated that >10,000 birds molt and stage in monospecific flocks at Mechigmenskiy and Ledyard bays, and several thousand molt and stage in eastern Norton Sound. We further identified eastern Norton Sound as the principal molting and staging area for females nesting on the Yukon-Kuskokwim Delta, and Ledyard Bay and Mechigmenskiy Bay as the principal molting and staging areas for females nesting on the North Slope. Males marked at all three breeding grounds molt and stage in Mechigmenskiy Bay, Ledyard Bay, and the Indigirka-Kolyma delta region. Males from the Yukon-Kuskokwim Delta molt and stage mainly at Mechigmenskiy Bay. Equal numbers of males from the North Slope molt and stage at all three areas, and most males from arctic Russia molt and stage at the Indigirka-Kolyma delta region. Postbreeding migration corridors were offshore in the Bering, Chukchi, and Beaufort seas. In winter, eiders were in the Bering Sea south of St. Lawrence Island. Our estimates from surveys in late winter and early spring suggest that at least 333,000 birds winter in single-species flocks in the pack ice in the Bering Sea.
- Data packageData from: Behavioural flexibility in an Arctic seabird using two distinct marine habitats to survive the energetic constraints of winter(2022-11-08) Patterson, Allison; Gilchrist, H. Grant; Robertson, Gregory J.; Hedd, April; Fifield, David A.; Elliott, Kyle H.Background: Homeothermic marine animals in Polar Regions face an energetic bottleneck in winter. The challenges of short days and cold temperatures are exacerbated for flying seabirds with small body size and limited fat stores. We use biologging approaches to examine how habitat, weather, and moon illumination influence behaviour and energetics of a marine bird species, thick-billed murres (Uria lomvia). Methods: We used temperature-depth-light recorders to examine strategies murres use to survive winter in the Northwest Atlantic, where contrasting currents create two distinct marine habitats: cold (−0.1 ± 1.2 °C), shallower water along the Labrador Shelf and warmer (3.1 ± 0.3 °C), deep water in the Labrador Basin. Results: In the cold shelf water, murres used a high-energy strategy, with more flying and less diving each day, resulting in high daily energy expenditure and also high apparent energy intake; this strategy was most evident in early winter when day lengths were shortest. By contrast, murres in warmer basin water employed a low-energy strategy, with less time flying and more time diving under low light conditions (nautical twilight and night). In warmer basin water, murres increased diving at night when the moon was more illuminated, likely taking advantage of diel vertically migrating prey. In warmer basin water, murres dove more at night and foraging efficiency increased under negative North Atlantic Oscillation (calmer ocean conditions). Conclusions: The proximity of two distinct marine habitats in this region allows individuals from a single species to use dual (low-energy/high-energy) strategies to overcome winter energy bottlenecks.
- Data packageData from: Deployment details for satellite tags deployed on Antarctic blue whales during the Antarctic blue whale voyage 2013, Ver. 2(2022-11-07) Andrews-Goff, Virginia; Bell, Elanor M.; Miller, Brian S.; Wotherspoon, Simon J.; Double, Michael C.One aim of the Antarctic blue whale voyage was to attempt to deploy satellite tags on Antarctic blue whales in order to describe their movement and behaviour. This was the first time satellite tags had ever been deployed on Antarctic blue whales. Antarctic blue whale movement has been described using static location information such as that derived from the retrieval of a discovery-tagged whales, photo identification or acoustic data. These techniques however are unable to provide a continuous record of actual movements instead inferring movement from two (or more) known locations at two (or more) separate points in time. Actual movements of the whale between these points in time are not known. As such, detailed information such as large scale migratory movement between breeding and feeding grounds or even fine scale movement within a feeding ground remain poorly understood.