News

Congratulations and warm wishes to our students Inbal and Yuval!

05 May 2020

To Inbal for the birth of her son, Nuri, and to Yuval for the birth of his son, Aviv!  

Congratulations and warm wishes to the head of our lab Nir Sapir

05 May 2020

For his promotion to Associate Professor!

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New publications

Feather moult and bird appearance are correlated with global warming over the last 200 years

11 May 2020

Kiat, Y., Vortman, Y., and N. Sapir. (2019) Feather moult and bird appearance are correlated with global warming over the last 200 years. Nature Communications 10 (2540). doi: https://doi.org/10.1038/s41467-019-10452-1 ABSTRACT...

Causes and consequences of facultative sea crossing in a soaring migrant

11 May 2020

Becciu, P., Rotics, S., Horvitz, N., Kaatz, M., Fiedler, W., Zurell, D., Flack, A., Jeltsch, F., Wikelski, M., Nathan, R., and N. Sapir. 2020. Causes and consequences of facultative sea...

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Backward flight in hummingbirds employs unique kinematic adjustments and entails low metabolic cost

Sapir, N. and Dudley, R. 2012. Backward flight in hummingbirds employs unique kinematic adjustments and entails low metabolic cost. Journal of Experimental Biology 215:3603-3611.

 

ABSTRACT

Backward flight is a frequently used transient flight behavior among members of the species-rich hummingbird family (Trochilidae) when retreating from flowers, and is known from a variety of other avian and hexapod taxa, but the biomechanics of this intriguing locomotor mode have not been described. We measured rates of oxygen uptake (Graphic) and flight kinematics of Anna's hummingbirds, Calypte anna (Lesson), within a wind tunnel using mask respirometry and high-speed videography, respectively, during backward, forward and hovering flight. We unexpectedly found that Graphic in sustained backward flight is similar to that in forward flight at equivalent airspeed, and is about 20% lower than hovering  Graphic. For a bird that was measured throughout a range of backward airspeeds up to a speed of 4.5 m s−1, the power curve resembled that of forward flight at equivalent airspeeds. Backward flight was facilitated by steep body angles coupled with substantial head flexion, and was also characterized by a higher wingbeat frequency, a flat stroke plane angle relative to horizontal, a high stroke plane angle relative to the longitudinal body axis, a high ratio of maximum:minimum wing positional angle, and a high upstroke:downstroke duration ratio. Because of the convergent evolution of hummingbird and some hexapod flight styles, flying insects may employ similar kinematics while engaged in backward flight, for example during station keeping or load lifting. We propose that backward flight behavior in retreat from flowers, together with other anatomical, physiological, morphological and behavioral adaptations, enables hummingbirds to maintain strictly aerial nectarivory.

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.