Wingbeats and flight stability
The highest recorded wingbeats for wild hummingbirds during hovering is 88 per second, as measured for the purple-throated woodstar (Calliphlox mitchellii) weighing 3.2 g. The number of beats per second increases above "normal" while hovering during courtship displays (up to 90 beats per second for the calliope hummingbird, Stellula calliope), a wingbeat rate 40% higher than its typical hovering rate.

During turbulent airflow conditions created experimentally in a wind tunnel, hummingbirds exhibit stable head positions and orientation when they hover at a feeder. When wind gusts from the side, hummingbirds compensate by increasing wing-stroke amplitude and stroke plane angle, and by varying these parameters asymmetrically between the wings and from one stroke to the next. They also vary the orientation and enlarge the collective surface area of their tail feathers into the shape of a fan. While hovering, the visual system of a hummingbird is able to separate apparent motion caused by the movement of the hummingbird itself from motions caused by external sources, such as an approaching predator. In natural settings full of highly complex background motion, hummingbirds are able to precisely hover in place by rapid coordination of vision with body position.

Vision
During evolution, hummingbirds have adapted to the navigational needs of visual processing while in rapid flight or hovering by development of an exceptionally dense array of retinal neurons allowing for increased spatial resolution in the lateral and frontal visual fields. Morphological studies showed that neuronal hypertrophy, relatively the largest in any bird, exists in a brain region called the pretectal nucleus lentiformis mesencephali (or nucleus of the optic tract in mammals) responsible for refining dynamic visual processing while hovering and during rapid flight. The enlargement of this brain region responsible for visual processing indicates an enhanced ability for perception and processing of fast-moving visual stimuli which hummingbirds encounter during rapid forward flight, insect foraging, competitive interactions, and high-speed courtship. 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 courtship displays, territorial defense, and predator evasion. 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.

Hummingbirds are highly sensitive to stimuli in their visual fields, responding to even minimal motion in any direction by reorienting themselves in midflight. Their visual sensitivity allows them to precisely hover in place while in complex and dynamic natural environments, functions enabled by the lentiform nucleus which is tuned to fast-pattern velocities, enabling highly tuned control and collision avoidance during forward flight.

Metabolism
With the exception of insects, hummingbirds while in flight have the highest metabolism of all animals – a necessity to support the rapid beating of their wings during hovering and fast forward flight. Their heart rate can reach as high as 1,260 beats per minute, a rate once measured in a blue-throated hummingbird, with a breathing rate of 250 breaths per minute, even at rest. During flight, oxygen consumption per gram of muscle tissue in a hummingbird is about 10 times higher than that measured in elite human athletes.

Hummingbirds are rare among vertebrates in their ability to rapidly make use of ingested sugars to fuel energetically expensive hovering flight, powering up to 100% of their metabolic needs with the sugars they drink (in comparison, human athletes max out at around 30%). Hummingbirds can use newly ingested sugars to fuel hovering flight within 30–45 minutes of consumption. These data suggest that hummingbirds are able to oxidize sugar in flight muscles at rates high enough to satisfy their extreme metabolic demands. A 2017 review indicated that hummingbirds have in their flight muscles a mechanism for "direct oxidation" of sugars into maximal ATP yield to support their high metabolic rate for hovering, foraging at altitude, and migrating.

By relying on newly ingested sugars to fuel flight, hummingbirds can reserve their limited fat stores to sustain their overnight fasting or to power migratory flights. Studies of hummingbird metabolism address how a migrating ruby-throated hummingbird can cross 800 km (500 mi) of the Gulf of Mexico on a nonstop flight. This hummingbird, like other long-distance migrating birds, stores fat as a fuel reserve augmenting its weight by as much as 100%, then enabling metabolic fuel for flying over open water.

Heat Dissipation
The high metabolic rate of hummingbirds – especially during rapid forward flight and hovering – produces increased body heat that requires specialized mechanisms of thermoregulation for heat dissipation, which becomes an even greater challenge in hot, humid climates. Hummingbirds dissipate heat partially by evaporation through exhaled air, and from body structures with thin or no feather covering, such as around the eyes, shoulders, under the wings (patagia), and feet.

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. 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. 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. In cold climates, hummingbirds retract their feet into breast feathers to eliminate skin exposure and minimize heat dissipation.

Kidney function
The dynamic range of metabolic rates in hummingbirds requires a parallel dynamic range in kidney function. During a day of nectar consumption with a corresponding high water intake that may total five times the body weight per day, hummingbird kidneys process water via glomerular filtration rates (GFR) in amounts proportional to water consumption, thereby avoiding overhydration. During brief periods of water deprivation, however, such as in nighttime torpor, GFR drops to zero, preserving body water.

Hummingbird kidneys also have a unique ability to control the levels of electrolytes after consuming nectars with high amounts of sodium and chloride or none, indicating that kidney and glomerular structures must be highly specialized for variations in nectar mineral quality. Morphological studies on Anna's hummingbird kidneys showed adaptations of high capillary density in close proximity to nephrons, allowing for precise regulation of water and electrolytes.

Song and vocal learning
Consisting of chirps, squeaks, whistles and buzzes, hummingbird songs originate from at least seven specialized nuclei in the forebrain. In a genetic expression study, it was shown that these nuclei enable vocal learning (ability to acquire vocalizations through imitation), a rare trait known to occur in only two other groups of birds (parrots and songbirds) and a few groups of mammals (including humans, whales and dolphins and bats). Within the past 66 million years, only hummingbirds, parrots and songbirds out of 23 bird orders may have independently evolved seven similar forebrain structures for singing and vocal learning, indicating that evolution of these structures is under strong epigenetic constraints possibly derived from a common ancestor.

The blue-throated hummingbird’s song differs from typical oscine songs in its wide frequency range, extending from 1.8 kHz to approximately 30 kHz. It also produces ultrasonic vocalizations which do not function in communication. As blue-throated hummingbirds often alternate singing with catching small flying insects, it is possible the ultrasonic clicks produced during singing disrupt insect flight patterns, making insects more vulnerable to predation.

The avian vocal organ, the syrinx, plays an important role in understanding hummingbird song production. What makes the hummingbird's syrinx different from other birds in the Apodiformes order is the presence of internal muscle structure, accessory cartilages, and a large tympanum that serves as an attachment point for external muscles, all of which are adaptations thought to be responsible for the hummingbird's increased ability in pitch control and large frequency range.

TOrpor
The metabolism of hummingbirds can slow at night or at any time when food is not readily available: the birds enter a hibernatory, deep-sleep state (known as torpor) to prevent energy reserves from falling to a critical level. During nighttime torpor, body temperature falls from 40 to 18 °C, with heart and breathing rates both slowed dramatically (heart rate to roughly 50 to 180 beats per minute from its daytime rate of higher than 1000).

During torpor, to prevent dehydration, the GFR (Glomerular Filtration Rate) ceases, preserving needed compounds such as glucose, water, and nutrients. Further, body mass declines throughout nocturnal torpor at a rate of 0.04 g per hour, amounting to about 10% of weight loss each night. The circulating hormone, corticosterone, is one signal that arouses a hummingbird from torpor.

Use and duration of torpor vary among hummingbird species and are affected by whether a dominant bird defends territory, with nonterritorial subordinate birds having longer periods of torpor. The hummingbirds of the Andes in South America are known for entering exceptionally deep torpor and dropping their body temperature.

Lifespan
Hummingbirds have unusually long lifespans for organisms with such rapid metabolisms. Though many die during their first year of life, especially in the vulnerable period between hatching and fledging, those that survive may occasionally live a decade or more. Among the better-known North American species, the average lifespan is probably 3 to 5 years. For comparison, the smaller shrews, among the smallest of all mammals, seldom live longer than 2 years. The longest recorded lifespan in the wild relates to a female broad-tailed hummingbird that was banded (ringed) as an adult at least one year old, then recaptured 11 years later, making her at least 12 years old. Other longevity records for banded hummingbirds include an estimated minimum age of 10 years 1 month for a female black-chinned hummingbird similar in size to the broad-tailed hummingbird, and at least 11 years 2 months for a much larger buff-bellied hummingbird. Due to their small size they are occasionally prey of spiders and insects, particularly praying mantises.