Scaling of mechanical power output during burst escape flight in the Corvidae

“The paired pectoralis muscles are capable of generating enormous force, work and power output during normal flight (Tobalske et al., 2003) and these outputs increase dramatically during vigorous wing-flapping (Tobalske and Dial, 2000; Jackson and Dial, 2011).”

“…morphology (Christiansen, 1999; Doube et al., 2012; Kilbourne and Hoffman, 2013), locomotor performance (Hoyt et al., 2000; Iriarte-Díaz, 2002; Jackson and Dial, 2011; Tobalske and Dial, 2000; Walter and Carrier, 2002) and physiology (Biewener, 1989; Hoyt and Taylor, 1981; More et al., 2010;…”

“This technique has been applied multiple times on a variety of avian taxa in different experimental conditions including flight through corridors (Dial and Biewener 1993), wind tunnels (Dial et al. 1997), and ascending up vertical shafts (Jackson and Dial 2011).”

“…understanding of mechanics and control (see companion paper, Cheng et al., 2016), herein we report on the free-flight body and wing kinematics of hummingbirds, during escape from a perceived threat in which their manoeuvring flight performance should be close to maximal (Jackson and Dial, 2011).”

“birds, helping them produce mass-specific muscle aerobic power outputs comparable to or 258 greater than larger birds [24-26].”

“Across a range of taxa, there is generally a negative relationship between body size and an organism’s ability to rapidly accelerate (i.e., burst locomotor performance; Jackson and Dial 2011), change speeds, and maneuver.”

“EMG [13,14,47–50], deltopectoral strain [51–53], and sonomicrometry [54,55] are dependent on upstroke/downstroke transition timing for interpreting pectoralis function.”

“, 2013) and maximal power of flight muscle (Ellington, 1985; Josephson et al., 2000) could significantly limit manoeuvrability.”

“, 2011), as well as in different-sized corvids during steep ascending flight (Jackson and Dial, 2011); and have previously been found in cockatiels, doves, budgerigars and zebra finches over a range of flight speeds (Ellerby and Askew, 2007; Hedrick et al.”

“For example, while smaller animals may have faster acceleration (Garland, 1984; Iriarte- Díaz, 2002; Jackson & Dial, 2011) and greater manoeuvrability (Domenici, 2000; McGuire & Dudley, 2005) than larger relatives, larger animals generally exhibit greater speed (Alerstam, Hedenstrom, & Akesson,…”

“This gave a wingbeat-averaged power normalized by pectoralis mass of 317 W/kg.”

“9 g body mass (Jackson and Dial, 2011)] are larger than our measured cliff swallow free-flight power.”

“In comparison, during take-off the pectoralis undergoes near maximal shortening in the first downstroke in pigeons (Tobalske and Biewener, 2008), mallards (Williamson et al., 2001) and passerines (corvids) (Jackson and Dial, 2011).”

“…the wing through the downstroke (Dial and Biewener 1993; Dial et al. 1997; Hedrick et al. 2003; Ellerby and Askew 2007a, 2007b), but during some modes of flight such as burst ascents (Jackson and Dial 2011) and wing-assisted incline running (Jackson et al. 2011), the force profiles can be bimodal.”

“Whether these flights were maximal is not known; however, the total power is close to the maximal power reported in other species [395 W kg−1 in magpie, 350 W kg−1 in grey jay (Jackson and Dial, 2011); 390 W kg−1 in blue breasted quail (Askew et al.”

“…of self-selected locomotion, with the aim of investigating the physiological controls and performance capabilities of stereotyped maneuvers (i.e. Clark et al., 2013; Higham et al., 2001; Iriarte-Díaz and Swartz, 2008; Jackson and Dial, 2011; Read et al., 2016; Ros et al., 2011; Socha, 2005).”

“Additionally, the mass-specific power available for flight decreases within the range of m21/6 to m21/3 (Altshuler, Dudley, Heredia, & McGuire, 2010; Ellington, 1991; Hill, 1950; Jackson & Dial, 2011; Pennycuick, 1975).”

“Although larger body sizes may confer protection, including size refuge (Urban 2007b) and influence the ability to react to attacks (Jackson and Dial 2011), larger foragers have a higher likelihood of being detected (Mech and Zollner 2002, Urban 2007a) and are also hunted by larger and more…”

“In animal flight, the work and power required to move through the air scale approximately with body mass, but the available power for flight does not increase at the same rate such that mass- specific performance declines with body size (Ellington, 1991; Hill, 1950; Jackson & Dial, 2011).”

“Compared to mammals, birds (especially neoavian birds) are generally smaller and exhibit less variance in body masses, potentially due to the demand of flight [e.g., ( 62 )].”

“…technological limitations have left our understanding incomplete ( Ellerby and Askew, 2007 ; Tobalske et al., 2003 ; Tobalske and Biewener, 2008 ; Biewener et al., 1992 ; Biewener et al., 1998 ; Jackson and Dial, 2011a ; Dial et al., 1997 ; Soman et al., 2005 ; Ingersoll and Lentink, 2018 ).”

“This style of take-off is favoured by birds that are specialised for living primarily terrestrially and fly rarely such as the European migratory quail Coturnix coturnix ( Earls, 2000 ) or employed for rapid escape take-off as was examined in corvids ( Jackson & Dial, 2011 ).”

“…have been observed only for m. pectoralis major in flying birds (e.g., Askew and Marsh, 2001; Biewener et al., 1998; Earls, 2000; Ellerby and Askew, 2007; Jackson and Dial, 2011; Spedding, 1987; Williamson et al., 2001) and for m. obliquus externus in calling frogs (Girgenrath and Marsh, 1997).”

“Body mass has been shown to be a predictor of flight performance (Corvidae et al., 2006; Hertel & Ballance, 1999; Jackson & Dial, 2011; Sievwright & MacLeod, 2012; Tobalske et al., 2003; Tobalske & Dial, 2000) because of its relationship to mechanical power output.”

“Although take-off and nearor fully vertical ascent has been well studied for several avian groups (see Tobalske and Dial, 2000; Askew andMarsh, 2001; Berg and Biewener, 2008; Jackson, 2009; Jackson and Dial, 2011) and for some insects (see Marden, 1987; Muijires et al.”

“The excitation dynamics were modelled according to Hatze [16, pp 31–32].”

“Furthermore, from the linear relationship between pectoralis mass and muscle-mass specific work (Jackson & Dial 2011), the estimated pectoralis mass of 52.7 g in this study is roughly able to create 44 J kg−1 of massspecific work, equivalent to 2.3 J.”

“Several studies have focussed on take-off performance and accelerating flight in birds (Askew et al., 2001; Berg and Biewener, 2010; Earls, 2000; Jackson and Dial, 2011; Tobalske and Dial, 2000; Tobalske et al., 2004), but far fewer studies have examined bat take-off (Altenbach, 1979; Gardiner and Nudds, 2011; Schutt…”

“Enriched flight chambers have demonstrated how animals maneuver to avoid obstacles (Warrick et al., 1998; Williams and Biewener, 2015), turn in confined spaces (Hedrick et al., 2009), and perform takeoffs and landings (Jackson and Dial, 2011; Riskin et al., 2009).”