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Upstroke-based acceleration and head stabilization are the norm for the wing-propelled swimming of alcid seabirds RESEARCH ARTICLE
Anthony B. Lapsansky and Bret W. Tobalske Alcids, a family of seabirds including murres, guillemots, and puffins, exhibit the greatest mass-specific dive depths and durations of any birds or mammals. These impressive diving capabilities have motivated numerous studies on the biomechanics of alcid swimming and diving, with one objective being to compare stroke-acceleration patterns of swimming alcids to those of penguins, where upstroke and downstroke are used for horizontal acceleration. Studies of free-ranging, descending alcids have found that alcids accelerate in the direction of travel during both their upstroke and do...
Source: Journal of Experimental Biology - June 2, 2019 Category: Biology Authors: Lapsansky, A. B., Tobalske, B. W. Tags: RESEARCH ARTICLE Source Type: research

Cardiovascular responses to progressive hypoxia in ducks native to high altitude in the Andes RESEARCH ARTICLE
Sabine L. Lague, Catherine M. Ivy, Julia M. York, Beverly A. Chua, Luis Alza, Rebecca Cheek, Neal J. Dawson, Peter B. Frappell, Anthony P. Farrell, Kevin G. McCracken, Graham R. Scott, and William K. Milsom The cardiovascular system is critical for delivering O2 to tissues. Here we examine the cardiovascular responses to progressive hypoxia in four high-altitude Andean duck species compared to four related low-altitude populations in North America, tested at their native altitude. Ducks were exposed to stepwise decreases in inspired partial pressure of O2 while we monitored heart rate, O2 consumption rate, blood O2 saturat...
Source: Journal of Experimental Biology - February 9, 2020 Category: Biology Authors: Lague, S. L., Ivy, C. M., York, J. M., Chua, B. A., Alza, L., Cheek, R., Dawson, N. J., Frappell, P. B., Farrell, A. P., McCracken, K. G., Scott, G. R., Milsom, W. K. Tags: RESEARCH ARTICLE Source Type: research

Kinematics and aerodynamics of avian upstrokes during slow flight RESEARCH ARTICLE
Kristen E. Crandell and Bret W. TobalskeSlow flight is extremely energetically costly per unit time, yet highly important for takeoff and survival. However, at slow speeds it is presently thought that most birds do not produce beneficial aerodynamic forces during the entire wingbeat: instead they fold or flex their wings during upstroke, prompting the long-standing prediction that the upstroke produces trivial forces. There is increasing evidence that the upstroke contributes to force production, but the aerodynamic and kinematic mechanisms remain unknown. Here, we examine the wingbeat cycle of two species: the diamond dov...
Source: Journal of Experimental Biology - June 18, 2015 Category: Biology Authors: Crandell, K. E., Tobalske, B. W. Tags: RESEARCH ARTICLE Source Type: research

Identification of avian flapping motion from non-volant winged dinosaurs based on modal effective mass analysis
by Yaser Saffar Talori, Jing-Shan Zhao, Yun-Fei Liu, Wen-Xiu Lu, Zhi-Heng Li, Jingmai Kathleen O'Connor The origin of avian flight is one of the most controversial debates in Paleontology. This paper investigates the wing performance ofCaudipteryx, the most basal non-volant dinosaur with pennaceous feathered forelimbs by using modal effective mass theory. From a mechanical standpoint, the forced vibrations excited by hindlimb locomotion stimulate the movement of wings, creating a flapping-like motion in response. This shows that the origin of the avian flight stroke should lie in a completely natural process of active loc...
Source: PLoS Computational Biology - May 1, 2019 Category: Biology Authors: Yaser Saffar Talori Source Type: research