Sensor:Magnetometer
Magnetometer
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Magnetometer
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magnetometer
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- Data packageData from: Thermal soaring in tropicbirds suggests that diverse seabirds may use this strategy to reduce flight costs(2023-09-03) Garde, Baptiste; Fell, Adam; Krishnan, Krishnamoorthy; Jones, Carl G.; Gunner, Richard; Tatayah, Vikash; Cole, Nik C.; Lempidakis, Emmanouil; Shepard, Emily L.C.Thermal soaring can offer substantial reductions in flight cost but it is often assumed to be confined to a relatively narrow group of fliers (those with low wing loading relative to their body mass). Using high-frequency movement data, including magnetometry and GPS, we identified thermal soaring in a seabird previously thought to use only flapping flight; red-tailed tropicbirds (Phaethon rubricauda). We tracked 55 individuals breeding on Round Island, Mauritius, and examined the environmental conditions that predicted thermal soaring in 76 trips (ranging from 0.8 to 43 h, mean= 5.9 h). Tropicbirds used thermal soaring and gliding flight for 13% of their flight time on average (range 0 - 34%), in association with both commuting and prey-searching/ pursuits. The use of thermal soaring showed strong variation between trips, but birds were more likely to soar when flying with tailwinds. This enables them to reduce their flight costs without a substantial increase in trip duration, which is pertinent in the breeding season when they are constrained by time and the need to return to a central place. Birds may therefore be able to increase the amount of thermal soaring outside the breeding season. Overall, we suggest that thermal soaring may be more widespread than previously thought, given that birds without specific morphological adaptations for this behaviour can soar for extended periods, and the bio-logging approaches best-placed to detect thermal soaring (high-frequency GPS/ magnetometry) tend to be used in the breeding season, when thermal soaring may be less likely.
- Data packageData from: Study "LifeTrack White Stork Rheinland-Pfalz" (2015-2023)(2024-01-17) Fiedler, Wolfgang; Hilsendegen, Christiane; Reis, Christian; Lehmann, Jessica; Hilsendegen, Pirmin; Schmid, Heidi; Wikelski, MartinHow animals refine migratory behavior over their lifetime (i.e., the ontogeny of migration) is an enduring question with important implications for predicting the adaptive capacity of migrants in a changing world. Yet, our inability to monitor the movements of individuals from early life onward has limited our understanding of the ontogeny of migration. The exploration–refinement hypothesis posits that learning shapes the ontogeny of migration in long-lived species, resulting in greater exploratory behavior early in life followed by more rapid and direct movement during later life. We test the exploration–refinement hypothesis by examining how white storks (Ciconia ciconia) balance energy, time, and information as they develop and refine migratory behavior during the first years of life. Here, we show that young birds reduce energy expenditure during flight while also increasing information gain by exploring new places during migration. As the birds age and gain more experience, older individuals stop exploring new places and instead move more quickly and directly, resulting in greater energy expenditure during migratory flight. During spring migration, individuals innovated novel shortcuts during the transition from early life into adulthood, suggesting a reliance on spatial memory acquired through learning. These incremental refinements in migratory behavior provide support for the importance of individual learning within a lifetime in the ontogeny of long-distance migration.
- Data packageData from: Study "LifeTrack White Stork Vorarlberg" (2016-2023)(2024-01-17) Fiedler, Wolfgang; Niederer, Walter; Schönenberger, Alwin; Flack, Andrea; Wikelski, MartinHow animals refine migratory behavior over their lifetime (i.e., the ontogeny of migration) is an enduring question with important implications for predicting the adaptive capacity of migrants in a changing world. Yet, our inability to monitor the movements of individuals from early life onward has limited our understanding of the ontogeny of migration. The exploration–refinement hypothesis posits that learning shapes the ontogeny of migration in long-lived species, resulting in greater exploratory behavior early in life followed by more rapid and direct movement during later life. We test the exploration–refinement hypothesis by examining how white storks (Ciconia ciconia) balance energy, time, and information as they develop and refine migratory behavior during the first years of life. Here, we show that young birds reduce energy expenditure during flight while also increasing information gain by exploring new places during migration. As the birds age and gain more experience, older individuals stop exploring new places and instead move more quickly and directly, resulting in greater energy expenditure during migratory flight. During spring migration, individuals innovated novel shortcuts during the transition from early life into adulthood, suggesting a reliance on spatial memory acquired through learning. These incremental refinements in migratory behavior provide support for the importance of individual learning within a lifetime in the ontogeny of long-distance migration.
- Data packageData from: Study "Common Crane Lithuania GPS, 2015-2016"(2024-09-11) Dagys, Mindaugas; Žydelis, RamunasMovement is a key means by which animals cope with variable environments. As they move, animals construct individual niches composed of the environmental conditions they experience. Niche axes may vary over time and covary with one another as animals make tradeoffs between competing needs. Seasonal migration is expected to produce substantial niche variation as animals move to keep pace with major life history phases and fluctuations in environmental conditions. Here, we apply a time-ordered principal component analysis to examine dynamic niche variance and covariance across the annual cycle for four species of migratory crane: common crane (Grus grus, n = 20), demoiselle crane (Anthropoides virgo, n = 66), black-necked crane (Grus nigricollis, n = 9), and white-naped crane (Grus vipio, n = 9). We consider four key niche components known to be important to aspects of crane natural history: enhanced vegetation index (resources availability), temperature (thermoregulation), crop proportion (preferred foraging habitat), and proximity to water (predator avoidance). All species showed a primary seasonal niche “rhythm” that dominated variance in niche components across the annual cycle. Secondary rhythms were linked to major species-specific life history phases (migration, breeding, and nonbreeding) as well as seasonal environmental patterns. Furthermore, we found that cranes’ experiences of the environment emerge from time-dynamic tradeoffs among niche components. We suggest that our approach to estimating the environmental niche as a multidimensional and time-dynamical system of tradeoffs improves mechanistic understanding of organism–environment interactions.
- Data packageData from: Flight behaviour of Red Kites within their breeding area in relation to local weather variables: conclusions with regard to wind turbine collision mitigation(2024-08-05) Aschwanden, Janine; Stark, Herbert; Liechti, Felix1. Birds and bats are prone to collisions with wind turbines. To reduce the number of bat collisions, weather variables are commonly used to shut down wind turbines when a certain constellation of weather variables occurs. Such a general approach might also be interesting to mitigate raptor collisions. Studies on the relationship between flight behaviour and weather variables are needed. 2. To investigate the flight behaviour of raptors within their breeding area in relation to local weather variables, we used high resolution data of flight tracks of Red Kites collected on a wind energy test site (Germany). Birds were tracked with a Laser Range Finder (LRF) or with GPS transmitters. Weather variables were continuously registered on site. We used generalized linear mixed models to analyse the influence of weather variables and of the measurement method on different flight parameters. Furthermore, we investigated the probability of flying within a virtual rotor height range defined by three hub heights (84 m, 94 m, 140 m, diameter: 112 m). 3. The median flight altitude measured by LRF (52.5 m, 95% CI: 44.9–61.0, N=2,511) was on average 25 m higher than the corrected one resulting from GPS (27.8 m, 95% CI: 24.7–31.2, N=6,792). Flight speed also differed between methods (GPS: 29.2 km/h, 95% CI: 28.2–30.3 km/h; LRF: 25.1 km/h, 95% CI: 24.0–26.3 km/h). The effects of the weather variables were weak. Birds tended to fly less and lower during wet (humid, rainy, or foggy) than dry weather, and lower during strong than weak winds. Probabilities of flying within a height range of virtual rotors increased with decreasing hub height, and hence ground clearance. 4. Synthesis and applications: Flight behaviour was highly variable. Flights occurred during all weather conditions at different altitudes throughout the day over the entire season. Further research into the relationship between flight behaviour, weather variables, collisions, and other factors is needed as a basis for developing shutdown regimes generally suitable for raptors. The mean flight altitude and speed differed between the measurement methods. Any values resulting from studies should be interpreted in the context of the method.