Tree kingfisher

Tree kingfishers, also known as wood kingfishers or Halcyoninae, are a diverse group of birds. They are the most numerous subfamily within the kingfisher family, Alcedinidae. This group contains about 72 different species organized into 11 genera. While many people associate kingfishers with water, tree kingfishers are quite different. They are compact birds with large heads and short tails. Most possess long, pointed bills used for hunting.

They belong to the order Coraciiformes, which is known for producing brightly colored birds.

The biology of these birds is shaped by their specific hunting styles. Unlike some other kingfishers, none of the tree kingfishers are specialist fish-eaters. Most species use a watch-and-wait method to find food. They sit on a perch and scan the area for movement. Once they spot prey, they dive down to capture it. Their diet mainly consists of slow-moving invertebrates or small vertebrates.

Some species, like the Vanuatu kingfisher, eat only insects and spiders. Others, such as the shovel-billed kookaburra, use their bills to dig through leaf litter for worms.

Tree kingfishers live in a wide variety of environments across the globe. They are found in warm climates throughout Africa, Asia, and Australasia. Interestingly, no members of this subfamily live in the Americas. Their history likely began in tropical Australasia, which remains a major center for their diversity. These birds are highly adaptable to different habitats. They can live in lush tropical rainforests or open woodlands. Some even thrive in arid thornbush country or dry areas of Australia and Africa.

Reproduction for tree kingfishers involves careful teamwork and specific nesting sites. Most species are monogamous, meaning they have one partner. They are also territorial and will defend their living space. They typically nest in holes located in trees. These holes might be natural cavities or old nests left by woodpeckers. Some species even excavate holes directly into termite nests.

Both parents share the responsibilities of incubating the eggs and feeding the chicks. To manage resources, they often lay eggs at one-day intervals. This ensures that if food is scarce, the older and larger nestlings receive the most nutrition.

When the chicks hatch, they are very different from their parents. They are born naked, blind, and completely helpless. One unique physical trait is that they stand on their heels rather than their toes. While most species follow a standard mating pattern, some exceptions exist. For example, three species of kookaburras use a cooperative breeding system. In this system, young birds from earlier broods help the parents raise new chicks. This social structure helps the family survive in their environment.

Scientists have worked for a long time to classify these birds correctly. The name Halcyoninae was introduced by Nicholas Aylward Vigors in 1825. Later, in 1841, Charles Lucien Bonaparte introduced the name Daceloninae. Today, Halcyoninae is recognized as the primary name for this subfamily. The kingfisher family Alcedinidae is divided into three main subfamilies. These include Halcyoninae, Alcedininae, and Cerylinae. Modern science continues to refine our understanding of these relationships.

A molecular study published in 2017 used DNA to examine their genetic connections.

The diversity within the subfamily is visible through many different body types. While most look like typical kingfishers, some have very specialized features. The Tanysiptera paradise kingfishers are known for having long tail streamers. The shovel-billed kookaburra possesses a massive, conical bill. Some insect-eating species have developed flattened, red bills to help them catch prey. These physical variations show how different species have adapted to their specific niches. From the large Stork-billed kingfisher to the small paradise kingfishers, the group shows incredible variety.