Bird Sunning

Why Do Birds Sunbathe?

Titmouse Sunning
Many birds take advantage of sunny days - but why?. Photo © Kathy Vespaziani/Flickr/Used With Permission

Bird sunning behavior can be captivating to watch, but why exactly do birds sun themselves? There are many reasons birds engage in this unexpected behavior.

What Is Sunning

Bird sunning is the act of spreading out in full sunshine to expose plumage and skin to direct sunlight. Hundreds of bird species engage in sunning, and some of the most common birds to see sunning include doves, pigeons, vultures, cormorants, darters, anhingas and sparrows.

When sunning, birds orient themselves to expose the maximum amount of their plumage to the sun. Different birds will sun in different ways, but common sunning postures include:

  • Standing with the back to the sun
  • Fluffing feathers on the head and back to expose skin
  • Stretching, spreading or drooping wings
  • Spreading the tail
  • Raising wings to expose underparts or flanks

During one sunning session a bird may keep the same position or it may change positions to expose different parts of its body to the sun. Because the point of sunning is to capture the most sunlight, birds frequently sun in open, unobstructed areas such as dust baths, mulch beds or open decks where there are no shadows. Any patch of warm sunlight, however, might attract a sunning bird.

Why Birds Sun

There are several theories about bird sunning behavior, and in fact birds often sun for different reasons. In cold weather or early in the day, birds sun themselves for warmth by taking advantage of solar radiation.

This allows them to maintain their body temperature without expending as much energy from food, and it can increase their chances of survival in cold climates or when food is scarce.

Many birds are observed sunning even on the hottest days, however, and it is believed that sunning can fulfill purposes other than just temperature regulation.

Sunning can help birds convert compounds in their preening oil – secreted from a gland at the base of the tail – into vitamin D, which is essential for good health. If the birds have been in a bird bath or swimming, sunning can help their feathers dry more quickly so they can fly easier, without being weighed down by excess water. It is even believed that some birds sun themselves for pure enjoyment and relaxation, much the same way humans will sunbathe.

The most important reason for sunning, however, is to maintain feather health. Sunning can dislodge feather parasites because the excess heat will encourage insects to move to other places in a bird's plumage. This will give the bird easier access to get rid of those parasites when preening, and birds are frequently seen preening immediately after sunning. It is essential to get rid of these parasites – the tiny insects that infect feathers can cause problems for a bird's flight, insulation and appearance, all of which can impact its survival.

Helping Birds Sun

Birders who observe sunning birds in their backyard can help the birds with this behavior and give themselves the opportunity to enjoy unique bird actions. To help birds sun…

  • Take note of favored sunning spots at different times of day. Many times, birds will return to the best sunning spots repeatedly. Also note which species use which different sunning spots.
     
  • Prune vegetation away from sunning spots to ensure there are no shadows or other disruptions to the sun in those locations as the days change. Do not remove so much shelter, however, that the birds may feel unnecessarily exposed and vulnerable. Start with just a small bit of pruning and allow the birds to get used to each change before pruning more vegetation.
     
  • Take steps to protect birds from cats and other predators near sunning areas, since birds are more somnolent and less wary while sunning and can be more susceptible to attacks.
     
  • Provide fresh, clean water for birds to take advantage of after sunning to help cool their bodies. A bird bath will also give the birds other ways to keep clean and maintain their feathers.

The first time a birder sees a sunning bird they may mistakenly believe the bird to be injured, sick or even dead.

With careful observation, however, it is soon clear that sunning birds are actually just trying to keep as healthy as possible by fighting feather parasites and taking advantage of solar radiation.