Hummingbirds are known for their ability to hover in midair and fly backwards, their rapid wing-flapping, and their fast heart rates. Another interesting behavior that hummingbirds exhibit is ruffling their feathers. This refers to when a hummingbird fluffs up its plumage and causes its feathers to stand out from its body. Ruffling feathers is a common behavior seen in many bird species, but why do hummingbirds do it? Here are some of the main reasons hummingbirds ruffle their feathers:
Thermoregulation
One of the most important functions of ruffling feathers is for thermoregulation. Hummingbirds have very high metabolisms and can be prone to losing body heat quickly. Ruffling their feathers creates air pockets that provide better insulation. This helps hummingbirds retain more body heat when it is cold outside or when they are resting. The fluffed feathers essentially create a warmer jacket for the hummingbird.
During cool temperatures or in higher elevations, hummingbirds may ruffle their feathers constantly to maintain their body temperature. The smaller the hummingbird, the more susceptible they are to heat loss. A ruffed up hummingbird may be responding to a drop in the ambient temperature in order to prevent its own temperature from falling to unsafe levels. Ruffling is a way to conserve their vital heat energy.
Waterproofing
In addition to insulation, ruffled feathers provide water resistance. The fluffed up feathers cause water to bead and run off the surface of the plumage. This protects the hummingbird’s skin from getting wet. It is important for hummingbirds to stay dry because having wet plumage can cause life-threatening hypothermia.
When humid or rainy conditions occur, hummingbirds will ruffle up to create a barrier against moisture. The air pockets between the feathers provide more water resistance than smooth feathers would. This adaptation allows hummingbirds to endure rain showers or damp mornings covered in dew.
Displaying Aggression
Hummingbirds can be quite territorial, especially when it comes to food sources. One bird may ruffle its feathers when another hummingbird approaches to signal its aggression and willingness to fight. The feathers make the hummingbird appear larger and more intimidating to try and ward off the intruding bird. This posturing is often seen around feeders as the resident hummingbird tries to claim that food source for itself.
Dominant or adult males may also ruffle feathers to display dominance and intimidate less dominant birds when competing for territory or mates. By puffing up, the male hummingbird establishes itself as the alpha and deters rivals. Younger males and females are more likely to respond submissively when confronted with a ruffled dominant male.
Showing Interest in Mates
Ruffling can also be associated with courtship. When a male is interested in a female, he may stand taller, expand his feathers, and show off his vibrant gorget to catch her attention. The male is signaling his fitness to try and impress the female. This behavior is most prominent during the breeding season but may be seen to a lesser degree year-round as the birds interact.
Females may also fluff their feathers some when responding to a displaying male. However, the behavior is generally more subtle than males. Ruffling feathers allows both sexes to communicate their readiness and interest in pairing up for mating.
Shaking Off Water
Hummingbirds will fluff and shake their feathers when emerging from water. Bathing helps keep their plumage in good condition. When they are done bathing, ruffling and shaking helps to remove excess water more quickly so the bird does not get chilled. The motion also helps settle the feathers back into place neatly.
Young hummingbirds may be seen ruffling and shaking off water more frequently after bathing until they get the hang of the routine. Keeping their feathers orderly and water-free is an important part of hummingbird hygiene and health.
Preening
Ruffling feathers often occurs in conjunction with preening. Preening is how birds straighten, clean, and maintain their plumage. To preen, a hummingbird will slide its beak along each feather from base to tip to smooth it into place and remove any dirt or parasites.
The ruffling motion helps loosen feathers and make them more available for preening. The added airflow also makes it easier to remove debris from between feathers. Preening after ruffling helps hummingbirds keep their feathers in top condition which is critical for thermoregulation and flight.
Molting
Hummingbirds undergo a complete molt of their feathers at least once per year. Molting is the process of shedding old feathers as new ones grow in to replace them. During the molting period, hummingbirds may appear more ruffled as their plumage becomes disheveled with new pinfeathers emerging.
The same hormones that control molting also trigger more frequent ruffling behaviors. In addition to helping old feathers detach, ruffling may stimulate proper development of the new ones. The stimulation keeps the feather follicles active and promotes the uptake of nutrients needed for growth.
Stretching and Exercising
Ruffling feathers is often paired with stretching. As hummingbirds wake up or perch after a period of rest, they will extend their wings and legs and ruffle their feathers to get the blood flowing. Stretching and exercising prepares their muscles and body for flight. The ruffle extends through the entire body like a shiver.
Fledglings learning to fly will also repeatedly stretch and ruffle as they build up flight muscles. The same motion may be seen if a hummingbird needs to extend its wings after being confined in a small space for a time. The ruffling exercise loosens up the feathers to allow maximum mobility.
When are Hummingbirds Most Likely to Ruffle Feathers?
Hummingbirds ruffle their feathers in many different contexts but there are some situations when it is most likely to occur:
Cold Temperatures
As mentioned, ruffling is very common on cold days or in cold environments to generate warmth. Hummingbirds are more likely to fluff up their plumage during inclement weather or the night when their bodies are most vulnerable to chilling.
Early Morning
Hummingbirds frequently ruffle upon first waking up in the morning. The cold of the night combined with sitting still often leads to heat loss. Ruffling helps warm them back up to prepare for the day. Stretching and preening are also common morning behaviors paired with ruffling.
Rainy or Humid Weather
The waterproofing provided by ruffled feathers makes this behavior more common on wet or damp days. Hummingbirds will stand taller and fluff out their plumage to protect against saturation whenever moisture is high in the air or precipitation occurs.
Interactions with Other Birds
Ruffling prominently occurs during encounters with conspecifics in aggressive, territorial, courtship, or mating contexts. The added display draws attention and communicates appropriate signals to other birds.
Feeders
Due to the territoriality and competition over food sources, ruffling is widespread around feeders as dominant birds try to stand their ground. New arrivals or intruders will be met with threat displays, including feather ruffling, by the birds that have claimed that space.
Nesting
Male hummingbirds may ruffle when displaying to females or defending a nesting territory. Females may fluff slightly on the nest when settling down over eggs or young. Ruffling here helps maintain insulation for the developing offspring.
Molting
Ruffling will become more prevalent during the molting season as new pinfeathers grow in. The hormones related to shedding old feathers and producing new ones also spark an uptick in ruffling motions.
Bathing
Ruffling invariably follows bathing as the feathers need to be resettled and excess moisture shaken off. Bathing frequency will influence how often post-wash ruffling is seen.
Do All Hummingbirds Ruffle Their Feathers?
Ruffling feathers is an action seen in all hummingbird species. However, some types of hummingbirds are more likely to ruffle up than others:
Ruby-Throated Hummingbird
The ruby-throated hummingbird is one of the most common backyard hummingbirds. Males have a bright red gorget while females are white-throated. Ruby-throats are very territorial and likely to ruffle when defending feeding grounds or interacting with intruders. They readily fluff up to retain heat in cool weather.
Rufous Hummingbird
Male rufous hummingbirds have vivid orange plumage on their backs and flanks. Their feathers can really stand out when ruffled. Rufous hummingbirds breed farther north than other species so they endure more cold. Ruffling helps maintain their warmth in chilly temperatures during migration and winter.
Allen’s Hummingbird
The male Allen’s hummingbird has a red-orange throat and flanks. This smaller species readily ruffles up to enhance its display when competing with other males for territory and females. Ruffling accents the bright color patches to catch the attention of competitors or potential mates.
Anna’s Hummingbird
Anna’s hummingbirds are common along the Pacific coast. The rose-pink male gorget is visible when fluffed out during behaviors like courtship displays. Anna’s hummingbirds will readily ruffle feathers in aggressive interactions or to increase insulation in cold.
Black-chinned Hummingbird
Found across much of the American west, male black-chinned hummingbirds have a dark, pencil-thin purple gorget that stands out against white neck plumage when ruffled. This species uses ruffling displays to signal territory ownership around food sources or to court females.
Calliope Hummingbird
One of the smallest species found only in western North America, the calliope hummingbird has colorful streaks of magenta and white that become more pronounced when ruffled. Puffing up helps calliopes maintain warmth with their tiny bodies and assert dominance despite their petite size.
Broad-tailed Hummingbird
Broad-tailed hummingbirds are common in the Rocky Mountains where it is cooler. Males perform dramatic dive displays during courtship with an exaggerated ruffling at the end. Broad-tails depend on ruffling to help regulate temperature in their cold, high-altitude range.
Costa’s Hummingbird
The male Costa’s hummingbird has vibrant purple throat feathers used for display. Ruffling allows the male Costa’s to accentuate this signature gorget when defending territory or courting potential mates through showy displays.
How Do They Ruffle?
Ruffling happens through a specialized muscle structure and feather positioning:
Muscle Control
Birds have pterylae muscles underneath their skin that attach to the base of feather follicles. Contracting these muscles causes the attached feathers to stand upright away from the body. This creates the ruffled appearance.
The pterylae muscles reflexively contract in response to certain stimuli like cold, shaking, threats, or courtship. Hummingbirds control ruffling actively with precision to direct feathers in key areas like the gorget or back.
Feather Structure
The feathers on a hummingbird’s body have downy, flexible bases and stiff ends that allow them to lock into an upright posture when ruffled. The wings and tail feature specialized feathers that are controlled by additional muscles and tendons to enable specialized flight capabilities.
The contour feathers are edged with interlocking barbules and barbicels that zip the feather vane together. When a hummingbird ruffles, these attachments loosen to let the feathers separate and stand away from the body. This creates airspace for insulation or displays.
Body Movement
In addition to actively fluffing their feathers, hummingbirds may sway, bob, or fan their tails during displays. Females are drawn to the erratic motions. The total body movement during ruffling enhances both communication and heat generation for the bird.
Why Is Ruffling Important?
While it may seem like just an odd behavior, ruffling serves many crucial functions for hummingbirds:
Thermoregulation
Fluffing feathers enables hummingbirds to retain body heat in cold conditions. This is critical for their survival in cold environments or at night when they are vulnerable to hypothermia. Ruffling may occur almost continuously when it is cold.
Insulate Eggs
Ruffling provides insulation for hummingbird eggs during incubation. The female fluffs her feathers when sitting to help the eggs stay warm and properly develop as the embryos grow.
Feather Maintenance
Ruffling loosens feathers and allows air contact so birds can properly preen and keep their plumage in good condition. Proper feather maintenance improves flight and insulation.
Water Resistance
The waterproofing offered by ruffled feathers allows hummingbirds to withstand rain and dampness. This helps them avoid dangerous chilling from wet plumage.
Communication
Hummingbirds ruffle during courtship and aggressive displays to convey key information to other birds like fitness, dominance, territory ownership, or mating interest. The visual signal is an important social cue.
Stimulate Molting
The hormones linked to ruffling help initiate molting each season and get new feather growth underway. Ruffling is needed to transition old, worn plumage for fresh feathers.
Exercise
Ruffling extends through the body, stretching muscles, and warming the birds up for flight. The activity energizes and loosens them up for the extreme exertion required for hovering and darting motions.
Conclusion
Ruffling feathers serves hummingbirds well by allowing them to keep warm, dry, and in good flying condition. The displays also facilitate essential communication with other birds for territory needs, courtship, and mating. While ruffling may seem like mindless fluffing, it is actually a carefully controlled process that is vital to the hummingbird’s health and reproductive success. Pay attention next time you see a hummingbird ruffle up – it is employing a complex behavior that is an important adaptation for its survival!