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- 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: 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: Deconstructing the flight paths of hippocampal-lesioned homing pigeons as they navigate near home offers insight into spatial perception and memory without a hippocampus(2022-08-30) Gagliardo, Anna; Cioccarelli, Sara; Giunchi, Dimitri; Pollonara, Enrica; Colombo, Silvia; Casini, Giovanni; Bingman, Verner P.The aim of this study was to exploit detailed analyses of GPS-recorded tracks to better characterise the impact of hippocampal (HF) lesion on spatial memory and perception in the context of homing pigeon navigation when reliant on familiar landscape features near the home loft following repeated releases from the same three locations. As reported previously, following HF lesion, a low spatio-temporal resolution analysis revealed that homing pigeons fly less direct paths home once near the loft. We now further show that 1) HF-lesioned pigeons are less likely to display fidelity to a particular flight path home when released from the same locations multiple times, 2) intact pigeons are more likely to exploit leading-line landscape features, e.g., a road or the border of a woodlot, in developing flight-path fidelity and 3) even when flying a straight path HF-lesioned homing pigeons are more likely to display relatively rapid, oscillatory heading changes as if casting about for sensory, presumably visual information. The flight behaviour differences between the intact and HF-lesioned pigeons persisted across the four releases from the three locations, although the differences became smaller with increasing experience. Taken together, the GPS-track data offer a detailed characterisation of the effects of HF lesion on landscape-based, homing pigeon navigation, offering new insight into the role of the hippocampal formation in supporting memory-related, e.g., fidelity to a familiar route home, and perhaps perceptual-related, e.g., oscillating headings, navigational processes.
- Data packageData from: Pigeons remember visual landmarks after one release and rely upon them more if they are anosmic(2020-09-24) Gagliardo, Anna; Pollonara, Enrica; Wikelski, MartinAnosmic birds' homing ability is impaired when challenged to navigate over unfamiliar areas. Nevertheless, anosmic pigeons, Columba livia, show unimpaired navigation when released within a familiar area, suggesting that they may rely on familiar visual landmarks for navigation. However, direct evidence for the reliance on familiar visual landmarks during homing in anosmic birds has never been provided. In this study we tracked pigeons subjected singly to one training flight from each of three locations. Prior to their second release from each site, half of the birds were made anosmic while the others were not manipulated. The level of route fidelity was analysed separately for three phases of the homing process, in which familiar visual cues may have different relevance and may be used within different cognitive strategies: (1) ‘Initial decision making’; (2) ‘En route navigation’; (3) ‘Local navigation around home’. Compared to control birds, the anosmic birds flew significantly closer to previously overflown locations in the ‘En route navigation’ phase, while no difference in route fidelity emerged during phases (1) and (3). Our results showed that a single experience is sufficient for pigeons to learn release site features, and that familiar visual landmarks constitute a critical source of navigational information in olfactorily deprived birds during the homing process.
- Data packageData from: Fine-scale tracking of ambient temperature and movement reveals shuttling behavior of elephants to water(2019-09-24) Slotow, Rob; Thaker, Maria; Vanak, Abi TamimMovement strategies of animals have been well studied as a function of ecological drivers (e.g., forage selection and avoiding predation) rather than physiological requirements (e.g., thermoregulation). Thermal stress is a major concern for large mammals, especially for savanna elephants (Loxodonta africana), which have amongst the greatest challenge for heat dissipation in hot and arid environments. Therefore, elephants must make decisions about where and how fast to move to reduce thermal stress. We tracked 14 herds of elephant in Kruger National Park (KNP), South Africa, for 2 years, using GPS collars with inbuilt temperature sensors to examine the influence of temperature on movement strategies, particularly when accessing water. We first confirmed that collar-mounted temperature loggers captured hourly variation in relative ambient temperatures across the landscape, and, thus, could be used to predict elephant movement strategies at fine spatio-temporal scales. We found that elephants moved slower in more densely wooded areas, but, unexpectedly, moved faster at higher temperatures, especially in the wet season compared to the dry season. Notably, this speed of movement was highest when elephants were approaching and leaving water sources. Visits to water showed a periodic shuttling pattern, with a peak return rate of 10–30 h, wherein elephants were closest to water during the hotter times of the day, and spent longer at water sources in the dry season compared to the wet season. When elephants left water, they showed low fidelity to the same water source, and traveled farther in the dry season than in the wet season. In KNP, where water is easily accessible, and the risk of poaching is low, we found that elephants use short, high-speed bursts of movement to get to water at hotter times of day. This strategy not only provides the benefit of predation risk avoidance, but also allows them to use water to thermoregulate. We demonstrate that ambient temperature is an important predictor of movement and water use across the landscape, with elephants responding facultatively to a “landscape of thermal stress.”
- Data packageData from: Prey capture and selection throughout the breeding season in a deep-diving generalist seabird, the thick-billed murre(2019-07-18) Brisson-Curadeau, Émile; Elliott, Kyle H.Generalist seabirds forage on a variety of prey items providing the opportunity to monitor diverse aquatic fauna simultaneously. For example, the coupling of prey consumption rates and movement patterns of generalist seabirds might be used to create three‐dimensional prey distribution maps (‘preyscapes’) for multiple prey species in the same region. However, the complex interaction between generalist seabird foraging behaviour and the various prey types clouds the interpretation of such preyscapes, and the mechanisms underlying prey selection need to be understood before such an application can be realized. Central place foraging theory provides a theoretical model for understanding such selectivity by predicting that larger prey items should be 1) selected farther from the colony and 2) for chick‐feeding compared with self‐feeding, but these predictions remain untested on most seabird species. Furthermore, rarely do we know how foraging features such as handling time, capture methods or choice of foraging location varies among prey types. We used three types of animal‐borne biologgers (camera loggers, GPS and depth‐loggers) to examine how a generalist Arctic seabird, the thick‐billed murre Uria lomvia, selects and captures their prey throughout the breeding season. Murres captured small prey at all phases of a dive, including while descending and ascending, but captured large fish mostly while ascending, with considerably longer handling times. Birds captured larger prey and dove deeper during chick‐rearing. As central place foraging theory predicted, birds travelling further also brought bigger prey items for their chick. The location of a dive (distance from colony and distance to shore) best explained which prey type was the most likely to get caught in a dive, and we created a preyscape surrounding our study colony. We discuss how these findings might aid the use of generalist seabirds as bioindicators.
- Data packageData from: The price of being late: short- and long-term consequences of a delayed migration timing [delayed birds](2023-07-28) Bontekoe, Iris D.; Hilgartner, Roland; Altheimer, Sylvia; 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: The price of being late: short- and long-term consequences of a delayed migration timing [control birds](2023-07-28) Bontekoe, Iris D.; Flack, Andrea; Fiedler, WolfgangChoosing 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: Non-breeding ecology of a Neotropical-Nearctic migrant, the Common Nighthawk (Chordeiles minor): Habitat, activity patterns, molt, and migration(2023-07-27) Fariña, Nestor; Villalba, Olga; Pagano, Luis G.; Bodrati, Alejandro; Stein, Eliza; Norris, Andrea R.; Cockle, Kristina L.Long-distance migratory aerial insectivores are among the most threatened groups of birds breeding in North America, yet little is published about the two-thirds of their annual cycle that unfolds in South America. To study non-breeding ecology and migration of the Common Nighthawk (Chordeiles minor), we observed, captured, and GPS-tagged individuals at Reserva Natural Rincón de Santa María, an Important Bird Area on the Paraná River in Corrientes, Argentina, from 2017 to 2022 (237 captures, 95 individuals, 556 GPS fixes from 8 females). Common Nighthawks arrived at the reserve (late November to mid-January) partway through flight feather molt; primaries 8, 9, and 10 molted consecutively until early February, followed by body feathers. Three tagged females spent December/January to March at the reserve, May to August in Florida (USA), and October/November to December/January in the Cerrado (Brazil), and at least one traveled 1800 km while molting P8. Recapture rates across seasons were 44% for females and 25% for males. Small body size and breeding locations in Florida are consistent with the chapmani subspecies previously recorded from Argentina. Direct observations and GPS tracking (8 individuals) revealed that nighthawks roosted during the day in mature exotic pines; foraged over pines and native grasslands for 26–41 min within ~40 min after sunset, nearly always in silence; and rested for the remainder of the night in native grasslands, on roads, or on rocky platforms. Common Nighthawks should be included among the growing number of migratory species that exhibit long-distance movements between stationary sites during their long non-breeding period. Our results also suggest site fidelity to non-breeding areas, a continuous molt-migration strategy, and some nuanced migratory connectivity. Programs aiming to conserve long-distance migratory aerial insectivores should support long-term monitoring led from the Global South, especially in the Cerrado and southern South America. Please see Appendix 1 for a Spanish translation of this article.