Article Figures & Tables
Figures
- Fig. 1.
Effect of approach speed on the probability of crashing (C) or not crashing (NC) through all three turning angles (45, 90 and 135 deg). Faster approach speeds (Vapp) resulted in more crashes at all angles (except 45 deg, where no crashes were observed). Vapp significantly decreased the tighter the turn became (F2,2061=104.73, P<0.001). Boxes represent the median with hinges representing the 1st and 3rd quartiles. Whiskers represent the 95% confidence interval (CI) and circles represent outliers. Sample sizes are shown in parentheses under each plot.
- Fig. 2.
Relationship between average turning speed and turning angle. Turning speed (Vturn) decreased significantly as angle increased. A Tukey HSD post hoc test suggested all turning angles were significantly different from each other. Boxes represent the median with hinges representing the 1st and 3rd quartiles. Whiskers represent the 95% CI and circles represent outliers.
- Fig. 3.
Velocity data for all quolls running around all turns (N=1580). See Fig. 6 for racetrack diagram. (A) The relationship between turning radius (rturn) and forward velocity through the 135, 90 and 45 deg turns (Vturn). The solid lines represent the relationship between turning radius and horizontal velocity predicted by the friction limit model, with static coefficients of friction between 1 and 4. (B) The relationship between turning rate, represented as angular velocity (ωturn) of the horizontal speed vector with forward velocity through the turn. The solid lines represent the relationship between turning radius and horizontal velocity predicted by the friction limit model, with static coefficients of friction of between 1 and 4.
- Fig. 4.
The negative log–log correlation between turning rate (angular velocity, ωturn) and turning radius (rturn) and the interaction of turning speed (Vturn). Vturn is represented in colour, ranging continuously from blue (slowest speeds) to red (fastest speeds). Quolls turned at a faster rate through tighter turns, but at a slower rate through wider turns. Additionally, quolls running at faster turning speeds turned at larger radii than those running at slow turning speeds, but this is associated with reduced turning rates. Turning speed is slightly more limited by turning rate (ωturn, F1,115=2078, P<0.001) than it is by turning radius (rturn, F1,115=1746, P<0.001); however, both significantly influenced speed. Therefore, it is the turning rate, the turning radius and the interaction between the two (ωturn*rturn, F1,115=1498, P<0.001) that determines the speed at which quolls turn.
- Fig. 5.
Diagram of a lateral view of a northern quoll (Dasyurus hallucatus). Morphological variables were measured using digital calipers (±0.01 mm): HL, head length (from nuchal crest to tip of snout); HW, head width; BL, body length (from nuchal crest to base of tail); TL, tail length; TW, tail width; FL, hindfoot length (heel to claw base); HLL, hindlimb length (tibia–fibula); and FLL, forelimb length (radius–ulna).
- Fig. 6.
Experimental racetrack setup for testing the manoeuvrability of northern quolls. The racetrack consisted of two mobile ‘wings’ made from pine (length 3.4 m, height 1.23 m, width 0.4 m), hinged at the centre with one of three removable angle structures, at 45, 90 and 135 deg, to allow for three turning angles. The width of the wings was tapered at the centre point of the runway (the radius of the given turning circle) to a distance of 0.15 m.
Article navigation
Related articles
Cited by...
More in this TOC section
Similar articles
Other journals from The Company of Biologists
Predicting the Future: Species Survival in a Changing World
Read our new special issue exploring the significant role of experimental biology in assessing and predicting the susceptibility or resilience of species to future, human-induced environmental change.
Big Biology Podcast - Hollie Putnam and coral bleaching
Catch the next JEB-sponsored episode of the Big Biology Podcast where Art and Marty talk to Hollie Putnam about the causes of coral bleaching and the basic biology of corals in the hope of selectively breeding corals that can better tolerate future ocean conditions.
Read Hollie's Review on the subject, which is featured in our current special issue.
Stark trade-offs and elegant solutions in arthropod visual systems
Many elegant eye specializations that evolved in response to visual challenges continue to be discovered. A new Review by Meece et al. summarises exciting solutions evolved by insects and other arthropods in response to specific visual challenges.
Head bobbing gives pigeons a sense of perspective
Pigeons might look goofy with their head-bobbing walk, but it turns out that the ungainly head manoeuvre allows the birds to judge distance.