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How Lovebirds Maneuver Rapidly Using Super-Fast Head Saccades and Image Feature Stabilization.

Kress D, van Bokhorst E, Lentink D - PLoS ONE (2015)

Bottom Line: High-speed flight recordings revealed that rapidly turning lovebirds perform a remarkable stereotypical gaze behavior with peak saccadic head turns up to 2700 degrees per second, as fast as insects, enabled by fast neck muscles.Similarly, before landing, the lovebirds stabilize the center of the perch in their visual midline.Similar gaze behaviors have been reported for visually navigating humans.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, Stanford University, Stanford, California, United States of America.

ABSTRACT
Diurnal flying animals such as birds depend primarily on vision to coordinate their flight path during goal-directed flight tasks. To extract the spatial structure of the surrounding environment, birds are thought to use retinal image motion (optical flow) that is primarily induced by motion of their head. It is unclear what gaze behaviors birds perform to support visuomotor control during rapid maneuvering flight in which they continuously switch between flight modes. To analyze this, we measured the gaze behavior of rapidly turning lovebirds in a goal-directed task: take-off and fly away from a perch, turn on a dime, and fly back and land on the same perch. High-speed flight recordings revealed that rapidly turning lovebirds perform a remarkable stereotypical gaze behavior with peak saccadic head turns up to 2700 degrees per second, as fast as insects, enabled by fast neck muscles. In between saccades, gaze orientation is held constant. By comparing saccade and wingbeat phase, we find that these super-fast saccades are coordinated with the downstroke when the lateral visual field is occluded by the wings. Lovebirds thus maximize visual perception by overlying behaviors that impair vision, which helps coordinate maneuvers. Before the turn, lovebirds keep a high contrast edge in their visual midline. Similarly, before landing, the lovebirds stabilize the center of the perch in their visual midline. The perch on which the birds land swings, like a branch in the wind, and we find that retinal size of the perch is the most parsimonious visual cue to initiate landing. Our observations show that rapidly maneuvering birds use precisely timed stereotypic gaze behaviors consisting of rapid head turns and frontal feature stabilization, which facilitates optical flow based flight control. Similar gaze behaviors have been reported for visually navigating humans. This finding can inspire more effective vision-based autopilots for drones.

No MeSH data available.


Related in: MedlinePlus

Low variation of retinal size and relative expansion velocity (RREV) of the approached perch suggests these cues matter for controlled landings on a swinging perch.We defined the tail pitch as the behavioral indicator for landing initiation (time = 0 ms). Negative time values represent the time before and positive time values the time after the downward pitch of the tail feathers. Shaded areas ranging from -30 ms to 0 ms mark the minimal time period of visuomotor delay during which visual flight control is unlikely. Absolute horizontal flight speed (A) has less variation across flights than relative horizontal flight speed (B) with respect to the moving perch. (C) The most parsimonious landing parameters are indicated by a minimum in the coefficient of variation (c.v.) across flights and birds. The retinal size (orange) and RREV (green) for the approached perch varied less that the parameter tau and the retinal expansion. Tail pitch timing was extracted individually from high-speed flight videos. n = 16, N = 5 birds.
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pone.0129287.g007: Low variation of retinal size and relative expansion velocity (RREV) of the approached perch suggests these cues matter for controlled landings on a swinging perch.We defined the tail pitch as the behavioral indicator for landing initiation (time = 0 ms). Negative time values represent the time before and positive time values the time after the downward pitch of the tail feathers. Shaded areas ranging from -30 ms to 0 ms mark the minimal time period of visuomotor delay during which visual flight control is unlikely. Absolute horizontal flight speed (A) has less variation across flights than relative horizontal flight speed (B) with respect to the moving perch. (C) The most parsimonious landing parameters are indicated by a minimum in the coefficient of variation (c.v.) across flights and birds. The retinal size (orange) and RREV (green) for the approached perch varied less that the parameter tau and the retinal expansion. Tail pitch timing was extracted individually from high-speed flight videos. n = 16, N = 5 birds.

Mentions: To give insight into how an actual recorded U-turn flight looks, we will illustrate one example first (Fig 2, S1 Movie) before presenting quantitative results across birds (Figs 3 to 7). In a typical recorded flight, the lovebird took off from the perch, flew more than halfway into the arena, performed a rapid turning maneuver ‘on a dime’ in which it oriented itself back to the perch, flew back to the perch and landed on it (Fig 2A).


How Lovebirds Maneuver Rapidly Using Super-Fast Head Saccades and Image Feature Stabilization.

Kress D, van Bokhorst E, Lentink D - PLoS ONE (2015)

Low variation of retinal size and relative expansion velocity (RREV) of the approached perch suggests these cues matter for controlled landings on a swinging perch.We defined the tail pitch as the behavioral indicator for landing initiation (time = 0 ms). Negative time values represent the time before and positive time values the time after the downward pitch of the tail feathers. Shaded areas ranging from -30 ms to 0 ms mark the minimal time period of visuomotor delay during which visual flight control is unlikely. Absolute horizontal flight speed (A) has less variation across flights than relative horizontal flight speed (B) with respect to the moving perch. (C) The most parsimonious landing parameters are indicated by a minimum in the coefficient of variation (c.v.) across flights and birds. The retinal size (orange) and RREV (green) for the approached perch varied less that the parameter tau and the retinal expansion. Tail pitch timing was extracted individually from high-speed flight videos. n = 16, N = 5 birds.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4481315&req=5

pone.0129287.g007: Low variation of retinal size and relative expansion velocity (RREV) of the approached perch suggests these cues matter for controlled landings on a swinging perch.We defined the tail pitch as the behavioral indicator for landing initiation (time = 0 ms). Negative time values represent the time before and positive time values the time after the downward pitch of the tail feathers. Shaded areas ranging from -30 ms to 0 ms mark the minimal time period of visuomotor delay during which visual flight control is unlikely. Absolute horizontal flight speed (A) has less variation across flights than relative horizontal flight speed (B) with respect to the moving perch. (C) The most parsimonious landing parameters are indicated by a minimum in the coefficient of variation (c.v.) across flights and birds. The retinal size (orange) and RREV (green) for the approached perch varied less that the parameter tau and the retinal expansion. Tail pitch timing was extracted individually from high-speed flight videos. n = 16, N = 5 birds.
Mentions: To give insight into how an actual recorded U-turn flight looks, we will illustrate one example first (Fig 2, S1 Movie) before presenting quantitative results across birds (Figs 3 to 7). In a typical recorded flight, the lovebird took off from the perch, flew more than halfway into the arena, performed a rapid turning maneuver ‘on a dime’ in which it oriented itself back to the perch, flew back to the perch and landed on it (Fig 2A).

Bottom Line: High-speed flight recordings revealed that rapidly turning lovebirds perform a remarkable stereotypical gaze behavior with peak saccadic head turns up to 2700 degrees per second, as fast as insects, enabled by fast neck muscles.Similarly, before landing, the lovebirds stabilize the center of the perch in their visual midline.Similar gaze behaviors have been reported for visually navigating humans.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, Stanford University, Stanford, California, United States of America.

ABSTRACT
Diurnal flying animals such as birds depend primarily on vision to coordinate their flight path during goal-directed flight tasks. To extract the spatial structure of the surrounding environment, birds are thought to use retinal image motion (optical flow) that is primarily induced by motion of their head. It is unclear what gaze behaviors birds perform to support visuomotor control during rapid maneuvering flight in which they continuously switch between flight modes. To analyze this, we measured the gaze behavior of rapidly turning lovebirds in a goal-directed task: take-off and fly away from a perch, turn on a dime, and fly back and land on the same perch. High-speed flight recordings revealed that rapidly turning lovebirds perform a remarkable stereotypical gaze behavior with peak saccadic head turns up to 2700 degrees per second, as fast as insects, enabled by fast neck muscles. In between saccades, gaze orientation is held constant. By comparing saccade and wingbeat phase, we find that these super-fast saccades are coordinated with the downstroke when the lateral visual field is occluded by the wings. Lovebirds thus maximize visual perception by overlying behaviors that impair vision, which helps coordinate maneuvers. Before the turn, lovebirds keep a high contrast edge in their visual midline. Similarly, before landing, the lovebirds stabilize the center of the perch in their visual midline. The perch on which the birds land swings, like a branch in the wind, and we find that retinal size of the perch is the most parsimonious visual cue to initiate landing. Our observations show that rapidly maneuvering birds use precisely timed stereotypic gaze behaviors consisting of rapid head turns and frontal feature stabilization, which facilitates optical flow based flight control. Similar gaze behaviors have been reported for visually navigating humans. This finding can inspire more effective vision-based autopilots for drones.

No MeSH data available.


Related in: MedlinePlus