Into rude air: hummingbird flight performance in variable aerial environments

Abstract

One contribution of 17 to a theme issue 'Moving in a moving medium: new perspectives on flight'. Hummingbirds are well known for their ability to sustain hovering flight, but many other remarkable features of manoeuvrability characterize the more than 330 species of trochilid. Most research on hummingbird flight has been focused on either forward flight or hovering in otherwise nonperturbed air. In nature, however, hummingbirds fly through and must compensate for substantial environmental perturbation, including heavy rain, unpredictable updraughts and turbulent eddies. Here, we review recent studies on hummingbirds flying within challenging aerial environments, and discuss both the direct and indirect effects of unsteady environmental flows such as rain and von Kármán vortex streets. Both perturbation intensity and the spatio-temporal scale of disturbance (expressed with respect to characteristic body size) will influence mechanical responses of volant taxa. Most features of hummingbird manoeuvrability remain undescribed, as do evolutionary patterns of flight-related adaptation within the lineage. Trochilid flight performance under natural conditions far exceeds that of microair vehicles at similar scales, and the group as a whole presents many research opportunities for understanding aerial manoeuvrability.This article is part of the themed issue 'Moving in a moving medium: new perspectives on flight'.

Foraging in an unsteady world: bumblebee flight performance in field-realistic turbulence

“…While we have a relatively strong understanding of how mean flows affect the locomotion and ecology of flying animals, we know comparatively little about how turbulence impacts animal flight performance [16]. Recently, a number of wind tunnel studies have helped elucidate the effects of variable, but structured flows such as von Kármán vortex trails that form behind cylinders, on flight in both hummingbirds [13,17] and insects [18][19][20]. While such flows may be locally dominant (e.g.…”

Moving in a moving medium: new perspectives on flight

“…Yet despite the ubiquity of turbulent features, our understanding of how turbulence affects flight performance remains limited. Recent advances in this area are reviewed in this issue by Ortega-Jimenez et al [15] particularly in relation to hummingbird flight. These authors also consider how the susceptibility to turbulent features and the ability to respond to them are likely to vary with flight speed and body size.…”

Avoiding topsy-turvy: how Anna's hummingbirds (Calypte anna) fly through upward gusts

“…Turbulence can limit maximum forward flight speed in orchid bees (Combes and Dudley, 2009), and other insects flying within turbulent flows exhibit increased variance in body translation and rotation (Ravi et al, 2013;Ortega-Jimenez et al, 2013). Hummingbirds flying either in von Kármán vortex streets (Ortega-Jimenez et al, 2014) or in homogeneous free-stream turbulence (Ravi et al, 2015) compensate via highly variable wing and body kinematics, and intermittently fan the tail to effect stability. Flying in sustained turbulence is also known to increase the energetic costs of flight, especially at higher flight speeds (Bowlin and Wikelski, 2008).…”

“…1D,E) that was nominally uniform along the crosswise axis of the arena. The flow field produced by the air knife was quantified with particle image velocimetry (PIV) using an identical setup previously described by Ortega-Jimenez et al (2014). Along the long axis of the arena ('position',Fig.…”