New migration pattern described for ringed plovers: old theories fail as explanation

When finished breeding in south Sweden (study population is at Ottenby), males and females ringed plover depart to different wintering areas. But males go further south, to winter mainly on the Iberian peninsula, while females stay on average 800 km nearer to the breeding site. In birds it is usually the other way around, that males winter closer to the breeding site, often explained by the need of the territory-defending sex (usually male) that have a need to arrive early on the breeding ground and therefore stay the winter closer. In this new study, Linus Hedh and Anders Hedenström describe a new migration pattern, and add a new model that may explain the new findings. Read more at
https://authors.elsevier.com/a/1aG1j57im1nfX

New paper suggests bats save energy from flight in ground effect

In a new paper published in Current Biology, Animal Flight Lab members describe how Daubenton's bats save energy by flight near a surface, such as a water surface where these bats search for food. The saving s were of the order 30%, which is actually more than what was expected from a glider in ground effect.

Span efficiency of swifts

In a new paper by Per Henningsson and co-workers the span efficiency of swifts flying by flapping and gliding flight, respectively, are analysed. Somewhat counter to intuition the swifts were more efficient during flapping flight than during gliding flight. The reasons for this are discussed in the paper, which is published open access in Plos Biology.

New paper about Leading Edge Vortices in a moth

The first study of the flow above the wings of a freely flying insect, showing the structure of the lift boosting leading edge vortex, is published today by the Animal Flight Lab in Scientific Reports. The leading edge vortex is generally seen as a stable vortex, attached to the top surface of the wing, but this new study finds it to have a complex structure. At the inner wing the vortex has a single core, but mid wing and outwards the vortex is highly variable with multiple simultaneous cores. The highly variable flow may affect the aerodynamic control of the moth. In addition to the high complexity, the circulation of the vortex on the outer part of the wing is higher than the circulation measured in the wake behind the animal. This implies that the vortex accounts for the entire lift production at the outer wing and is in fact stronger than is necessary to generate the required lift force, which suggests a high aerodynamic cost of flight in the moths. These new findings will serve as a baseline comparison for past and future studies of the aerodynamics of insect flight based on tethered animals and mechanical flappers.

Composite image of a representative vector field, color coded by vorticity, showing the complex leading edge vortex above the wing on top of a photo of a Hummingbird hawkmoth (Macroglossum stellatarum)

Money money money

A great day for Animal Flight Lab as both Christoffer Johansson and Per Henningsson bagged research council grants for their research! This means excellent opportunities to carry out research of highest quality the coming 3-4 years. Per has just returned from a 3 year postdoc in Oxford, where he studied insect flight with Richard Bomphrey, will now get the opportunity to become established as a researcher. He will develop comparative studies of maneuvering flight between insects birds and bats, while Christoffer will aim at understanding more about the aerodynamic control of flight.

Congratulaitons!

Update from Brown about bat flight

Last Friday AFL alumni Rhea von Busse visited and gave a talk about her postdoc work at Brown University. Rye Waldman, also at Brown, also presented his work on flow visualization using dual plane light sheets and his work on the aerodynamics of compliant membranes. Rhea showed some really nice X-ray films of flying bats. These experiments nicely showed the movements of the wing skeleton during flight. Rhea also showed that bats can swim, but if they really liked it was not apparent from the footage.

Rye Waldman and Rhea von Busse.

Rye Waldman explains a wake.

New blue thing

As we are waiting to get the laser fixed a new shiny blue storing cabinet arrived. This will help us keep track of all the auxiliary equipment, such as lenses and manuals that now populate all other spaces in the control room to the wind tunnel. Here we can se it be assembled and put into place.

An intelligence test: the locking mechanism is put into function
Up to the right a female common scooter can be seen.