Tobar Rainbow Humming Top Traditional Spinning Toy

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A phylogenetic tree unequivocally indicates that modern hummingbirds originated in South America, with the last common ancestor of all living hummingbirds living around 22 million years ago. [8] Hummingbird flight has been studied intensively from an aerodynamic perspective using wind tunnels and high-speed video cameras. Two studies of rufous or Anna's hummingbirds in a wind tunnel used particle image velocimetry techniques to investigate the lift generated on the bird's upstroke and downstroke. [143] [144] The birds produced 75% of their weight support during the downstroke and 25% during the upstroke, with the wings making a "figure 8" motion. [145] Hummingbirds generate a trail of wake vortices under each wing while hovering. [146] [147] Maxwell, James Clerk (2003). The Scientific Papers of James Clerk Maxwell. Dover Publications. ISBN 0-486-49560-4. A top may be used to demonstrate visual properties, such as by James David Forbes and James Clerk Maxwell in Maxwell's disc (see color triangle). By rapidly spinning the top, Forbes created the illusion of a single color that was a mixture of the primaries: [3]

The enlargement of the brain region responsible for visual processing indicates an enhanced ability for perception and processing of fast-moving visual stimuli encountered during rapid forward flight, insect foraging, competitive interactions, and high-speed courtship. [77] [78] A study of broad-tailed hummingbirds indicated that hummingbirds have a fourth color-sensitive visual cone (humans have three) that detects ultraviolet light and enables discrimination of non-spectral colors, possibly having a role in flower identity, courtship displays, territorial defense, and predator evasion. [79] The fourth color cone would extend the range of visible colors for hummingbirds to perceive ultraviolet light and color combinations of feathers and gorgets, colorful plants, and other objects in their environment, enabling detection of as many as five non-spectral colors, including purple, ultraviolet-red, ultraviolet-green, ultraviolet-yellow, and ultraviolet-purple. [79]In 2013, a 50-million-year-old bird fossil unearthed in Wyoming was found to be a predecessor to hummingbirds and swifts before the groups diverged. [39] Evolution [ edit ] While hovering, hummingbirds do not benefit from the heat loss by air convection during forward flight, except for air movement generated by their rapid wing-beat, possibly aiding convective heat loss from the extended feet. [104] [107] Smaller hummingbird species, such as the calliope, appear to adapt their relatively higher surface-to-volume ratio to improve convective cooling from air movement by the wings. [104] When air temperatures rise above 36°C (97°F), thermal gradients driving heat passively by convective dissipation from around the eyes, shoulders, and feet are reduced or eliminated, requiring heat dissipation mainly by evaporation and exhalation. [104] In cold climates, hummingbirds retract their feet into breast feathers to eliminate skin exposure and minimize heat dissipation. [107] Kidney function [ edit ] During torpor, to prevent dehydration, the kidney function declines, preserving needed compounds, such as glucose, water, and nutrients. [109] The circulating hormone, corticosterone, is one signal that arouses a hummingbird from torpor. [128] Wave Cyclone | Ocean Tornado | Aqua Blast | Deep Typhoon | Magma Hurricane | SS Tornado EX | SS Marine | SS Super-Marine

Maxwell took this a step further by using a circular scale around the rim with which to measure the ratios of the primaries, choosing vermilion, emerald, and ultramarine. [4] Spinning methods [ edit ] Finger twirling [ edit ]

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Although hummingbird eyes are small in diameter (5–6mm), they are accommodated in the skull by reduced skull ossification, and occupy a larger proportion of the skull compared to other birds and animals. [74] Further, hummingbird eyes have large corneas, which comprise about 50% of the total transverse eye diameter, combined with an extraordinary density of retinal ganglion cells responsible for visual processing, containing some 45,000 neurons per mm 2. [75] The enlarged cornea relative to total eye diameter serves to increase the amount of light perception by the eye when the pupil is dilated maximally, enabling nocturnal flight. [75] The northward migration of rufous hummingbirds occurs along the Pacific flyway, [172] and may be time-coordinated with flower and tree-leaf emergence in early spring, and also with availability of insects as food. [171] Arrival at breeding grounds before nectar availability from mature flowers may jeopardize breeding opportunities. [173] Feeding [ edit ] Hummingbirds feeding; video recorded at 1,500 frames per second Hummingbird visiting flowers in Copiapó, Chile: The apparent slow movement of hummingbird wings is a result of the stroboscopic effect. Ghost Rex | Ghost Pendulum | Ghost Kraken | Ghost Pirate | Ghost Whale | Ghost Condor | Captain Whisker and Johnny | Ghost Titan | Egg Wizard Hummingbirds have varied specialized characteristics to enable rapid, maneuverable flight, exceptional metabolic capacity, adaptations to high altitude, sensitive visual and communication abilities, and long-distance migration in some species. Among all birds, male hummingbirds have the widest diversity of plumage color, particularly in blues, greens, and purples. [4] Hummingbirds are the smallest mature birds, measuring 7.5–13cm (3–5in) in length. The smallest is the 5cm (2.0in) bee hummingbird, which weighs less than 2.0g (0.07oz), and the largest is the 23cm (9.1in) giant hummingbird, weighing 18–24 grams (0.63–0.85oz). Noted for long beaks, hummingbirds are specialized for feeding on flower nectar, but all species also consume small insects.