Person: Dechmann, Dina K.N.
Dechmann, Dina K.N.
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Dechmann
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Dina K.N.
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- Data packageData from: Temporal and contextual consistency of leadership in homing pigeon flocks(2014-07-31) Santos, Carlos David; Neupert, Stefanie; Lipp, Hans-Peter; Wikelski, Martin; Dechmann, Dina K.N.Organized flight of homing pigeons (Columba livia) was previously shown to rely on simple leadership rules between flock mates, yet the stability of this social structuring over time and across different contexts remains unclear. We quantified the repeatability of leadership-based flock structures within a flight and across multiple flights conducted with the same animals. We compared two contexts of flock composition: flocks of birds of the same age and flight experience; and, flocks of birds of different ages and flight experience. All flocks displayed consistent leadership-based structures over time, showing that individuals have stable roles in the navigational decisions of the flock. However, flocks of balanced age and flight experience exhibited reduced leadership stability, indicating that these factors promote flock structuring. Our study empirically demonstrates that leadership and followership are consistent behaviours in homing pigeon flocks, but such consistency is affected by the heterogeneity of individual flight experiences and/or age. Similar evidence from other species suggests leadership as an important mechanism for coordinated motion in small groups of animals with strong social bonds.
- Data packageData from: Commuting fruit bats beneficially modulate their flight in relation to wind(2014-03-18) Dechmann, Dina K.N.; Fahr, Jakob; Wikelski, MartinNOTE: An updated and larger version of this dataset is available. See https://doi.org/10.5441/001/1.k8n02jn8. ABSTRACT: When animals move, their tracks may be strongly influenced by the motion of air or water, and this may affect the speed, energetics and prospects of the journey. Flying organisms, such as bats, may thus benefit from modifying their flight in response to the wind vector. Yet, practical difficulties have so far limited the understanding of this response for free-ranging bats. We tracked nine straw-coloured fruit bats (Eidolon helvum) that flew 42.5+17.5km (mean + s.d.) to and from their roost near Accra, Ghana. Following detailed atmospheric simulations, we found that bats compensated for wind drift, as predicted under constant winds, and decreased their airspeed in response to tailwind assistance such that their groundspeed remained nearly constant. In addition, bats increased their airspeed with increasing crosswind speed. Overall, bats modulated their airspeed in relation to wind speed at different wind directions in a manner predicted by a two-dimensional optimal movement model. We conclude that sophisticated behavioural mechanisms to minimize the cost of transport under various wind conditions have evolved in bats. The bats’ response to the wind is similar to that reported for migratory birds and insects, suggesting convergent evolution of flight behaviours in volant organisms.
- Data packageData from: Greater spear nosed bats commute long distances alone, rest together, but forage apart(2023-08-22) O'Mara, M. Teague; Dechmann, Dina K.N.Animals frequently forage in groups on ephemeral resources to profit from social information and increased efficiency. Greater spear-nosed bats, Phyllostomus hastatus, develop group-specific social calls, which are hypothesized to coordinate social foraging to feed on patchily distributed balsa flowers. To test this, we tagged all members of three social groups of P. hastatus on Isla Colo n, Panama , using high-frequency GPS during a season when balsa had begun to flower. We found that bats commuted 20-30 km to foraging sites, more than double the distance reported previously. In contrast to our expectations, we found that tagged individuals did not commute together, but did join group members in small foraging patches with high densities of flowering balsas on the mainland. We hypothesized that close proximity to group members would increase foraging efficiency if social foraging were used to find flower clusters, but distance between tagged individuals did not predict foraging efficiency or energy expenditure. However, decreased distance among tagged bats positively influenced the time spent outside roosting caves and increased the duration and synchrony of resting. These results suggest that social proximity appears to be more important during resting and that factors other than increased feeding efficiency may structure social relationships of group members while foraging. It appears that, depending on the local resource landscape, these bats have an excellent map even of distant resources and may use social information only for current patch discovery. They then may no longer rely on social information during daily foraging.
- Data packageData 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.