Why Do Birds Open Their Wings? (5 Key Reasons + Sunning Explained)

Vultures, hawks, cormorants and storks may commonly be seen adopting what is known as the ‘horaltic pose’ – perching with their wings spread out as wide as can be, while facing their backs into the intense heat of direct sunlight.

But what is the purpose of this pose? Why do birds spread their wings wide when not in flight? Keep reading as we look into the possible reasons why birds might open their wings wide.

Birds may open their wings wide for many different reasons. These can relate to their habitat, e.g. helping to dry off wet feathers after a swim, rapidly raising their body temperature in cold weather, or as part of a routine feather-care regime, where exposure to sunlight helps kill parasites.

Soaring birds are a familiar sight, gliding on thermals with their wings spread as wide as possible to benefit from the updrafts of the thermal currents. But many birds also engage in wing-spreading behavior when they are stationary on the ground, or when they are perched in trees or on clifftops.

Some explanations may be simple, including drying off after a swim or underwater dive, and maximizing body heat by exposing a large area of feathers into the warmth of the sun’s rays.

For more insight into why birds might spread their wings when they are not flying, please continue reading.

White-backed vulture (Gyps africanus) with open wings perched on a top of a tree, Kalahari desert, Botswana

Different reasons birds open their wings

There is no sole reason that explains why birds are seen with their wings outstretched when they are not in flight, but here are some suggestions that might hold the key to this behavior.

Sunning

The first documented mention of birds ‘sunning’ themselves was recorded by John James Audobon in 1831, who noted the behavior of a great white heron with its wings in an outstretched pose, seemingly soaking up the heat from the sun’s rays. Many birds can be seen to turn their backs to face direct sunlight on the warmest days, to benefit from the intense heat.

Sunbathing can aid birds to dry off wet feathers after a swim or dive and regulate their body temperature. It can also assist preening and feather maintenance and may be engaged in for pure enjoyment and relaxation.

Grey Heron 'sunning', capturing rays on open wings

Stretching

Widespread wings can release tension after flying or sleeping. A stretch of the wings can improve circulation and help muscles to relax if a bird has been settled in one position for too long. Opening the wings wide and stretching can aid blood flow and is a common movement before a bird takes off in flight.

Corn Bunting stretching with open wings

Temperature regulation

Spreading their wings wide helps some birds to control their body temperatures, as they are able to expose as large an area as possible to the sun’s rays. This allows them to absorb as much heat as possible through their wing surfaces, which they then use as energy, enabling them to avoid using up energy resources they have taken from food.

Abdim's stork or white-bellied stork sunning

Before they land

As flying birds come into land, opening their wings as wide as they can is a common technique used to gradually slow down speed and prepare for landing. Drag from the widest surface area possible enables a bird to make a controlled descent and experience a safe landing. Owls, eagles and other raptors can be seen using this method to ensure their flight ends smoothly.

Mallard duck coming in to land on an icy lake

Intimidation

By spreading their wings wide, birds can increase their perceived size and therefore present a more intimidating appearance to drive off predators and threats to their territory. Spreading their wings wide in a show of dominance is a behavior commonly seen in geese and swans.

A pair of swans fighting

What is sunning for birds?

If you’ve observed a bird in warm weather for any length of time, the chances are you will have seen it engaging in “sunning” – resting with its wings outstretched as wide as possible, in direct sunlight. The bird may either be sitting on the ground or on a perch, or standing, as is often the case for wading birds such as flamingos.

Basking in the sun with their wings spread wide exposes a bird’s feathers to maximum amounts of sunlight and warmth. Many bird species regularly practice sunning in summer months, including cormorants, flamingos, darters, robins, larks and doves.

The benefits of sunning

Sunning brings a range of benefits to different birds, depending on species and habitat. These include the following reasons:

Drying

Birds that spend a lot of time in, on, or under water can frequently be seen adopting a pose with their wings spread wide, with their backs facing into the warmth of direct sunlight. Sunning enables the birds to speed up the natural drying process, avoiding prolonged periods with damp, cold feathers.

Cormorants can frequently be seen perched on rocks or high up in waterside trees with their wings outstretched. Swans, gannets, coots, moorhens, and pelicans can also be seen with their backs and wide wings facing into the sun as they dry off their feathers.

Double-crested cormorant (phalacrocorax auritus) drying its wings

Warmth

Birds living in cold environments may take advantage of sunnier days to maximize their own body heat. Stretching out their wings and expanding the surface area exposed to the warm solar rays allows birds to utilize heat from the sun as energy needed to regulate their body temperatures.

Cold-climate birds that use this technique include Steller’s eider and snowy owls. Turkey vultures drop their own body temperature overnight, becoming slightly hypothermic, and use a sunning posture each morning to quickly raise their temperature again.

Sunning postures early in the morning for birds like Snowy Owls, can help bring their temperature back to a normal level quicker

Feather maintenance

For some sunbathing avians, intense sunlight can offer an important benefit in boosting the health of their feathers. The exposure to heat and light plays a valuable role in ridding birds of parasites.

Sunlight is capable of quickly raising the temperature of a bird’s wings to around 70 degrees C, which is high enough to kill any lice or parasites that may be living on their skin and feathers.

Preening

Additional feather maintenance benefits can be witnessed in the effect that sunlight has on the essential preen oil generated by birds to ensure their feathers are in top condition.

Exposure to sunlight aids the spread of preen oil throughout a bird’s plumage, and causes important compounds in the oil to be converted into Vitamin D, boosting the health of birds.

For more information on preening, check out this guide.

Sanderling preening feathers

Relaxation

Birds may simply sun themselves because they enjoy it and find it relaxing. Whether they spread their wings and sit in a sunny spot on a garden path or enjoy a dust bath with outstretched wings, many birds seem to jump at the chance to pause and soak up the sun on the brightest of summer days.

Blackbirds, larks, and finches are among the birds most frequently seen sunning themselves for pleasure in backyards and on lawns.

Young female blackbird basking in the sun, in the grass

Why do birds open their wings in the rain?

Although many birds take shelter undercover when showers start, occasionally you may see birds engaging in some rather unusual wing-spreading activity as the rain falls.

Birds, particularly woodpigeons and some doves, can be seen sitting flat to the ground, stretching out first one wing out to the side of their body, and then a while later, alternating to give the other wing a turn.

The reason for this is thought to be “rainbathing”, the opposite of sunbathing, and is particularly common among rainforest birds, who take advantage of the frequent showers to assist with regular preening activities.