News

Welcome aboard to our new student Eran Altschuler

25 October 2018

We welcome our new M.Sc. student Eran Altschuler!

Congratulations and warm wishes to our students Inbal and Yosef

27 January 2018

To Inbal for the birth of her daughter, and to Yosef for the birth of his son. We wish them and their families joy and happiness

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New publications

Contrasting aspects of tailswinds and asymmetrical response to crosswinds in soaring migrants

21 February 2018

Becciu, P., Panuccio, M., Catoni, C., Dell'Omo, G., and Sapir, N. 2018. Behavioral Ecology and Sociobiology 72(28). https://doi.org/10.1007/s00265-018-2447-0  

Hovering hummingbird wing aerodynamics during the annual cycle. II. Implications of wing feather moult

21 February 2018

Achache Y, Sapir N, Elimelech Y. 2018. Hovering hummingbird wing aerodynamics during the annual cycle. II. Implications of wing feather moult. Royal Society Open Science 5: 171766. http://dx.doi.org/10.1098/rsos.171766  

Moving in the Anthropocene: Global reductions in terrestrial mammalian movements

24 January 2018

Science 359 (6374): 466-469 http://science.sciencemag.org/content/359/6374/466  

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Into turbulent air: size-dependent effects of von Kármán vortex...

Ortega-Jimenez, V. M., Sapir, N. (equal contribution of the first two authors), Wolf, M., Variano, E. A. and Dudley, R. (2014) Into turbulent air: size-dependent effects of von Kármán vortex streets on hummingbird flight kinematics and energetics. Proceedings of the Royal Society of London B 281: 20140180.

 

ABSTRACT

Animal fliers frequently move through a variety of perturbed flows during their daily aerial routines. However, the extent to which these perturbations influence flight control and energetic expenditure is essentially unknown. Here, we evaluate the kinematic and metabolic consequences of flight within variably sized vortex shedding flows using five Anna's hummingbirds feeding from an artificial flower in steady control flow and within vortex wakes produced behind vertical cylinders. Tests were conducted at three horizontal airspeeds (3, 6 and 9 m s−1) and using three different wake-generating cylinders (with diameters equal to 38, 77 and 173% of birds' wing length). Only minimal effects on wing and body kinematics were demonstrated for flight behind the smallest cylinder, whereas flight behind the medium-sized cylinder resulted in significant increases in the variances of wingbeat frequency, and variances of body orientation, especially at higher airspeeds. Metabolic rate was, however, unchanged relative to that of unperturbed flight. Hummingbirds flying within the vortex street behind the largest cylinder exhibited highest increases in variances of wingbeat frequency, and of body roll, pitch and yaw amplitudes at all measured airspeeds. Impressively, metabolic rate under this last condition increased by up to 25% compared with control flights. Cylinder wakes sufficiently large to interact with both wings can thus strongly affect stability in flight, eliciting compensatory kinematic changes with a consequent increase in flight metabolic costs. Our findings suggest that vortical flows frequently encountered by aerial taxa in diverse environments may impose substantial energetic costs.

About us

We are a group of scientists devoted to the study of animal flight, including animal movement ecology, behavior, physiology and biomechanics. We study wild animals in the field and in the lab using a diversity of research approaches. We welcome applications for M.Sc. and Ph.D. studies and post-doctoral work in our group at the Department of Evolutionary and Environmental Biology at the University of Haifa.