Baby Bird Glossary

Common Words About Baby Birds

Northern Mockingbird Fledgling
Photo © Renee/Flickr/CC by 2.0

All parents know that babies have a glossary all their own, and baby birds are no different. By understanding these basic terms related to baby wild birds, it is easier to identify them and to care for them appropriately when you find a baby bird or a nesting family in your backyard.

  • 01 of 10


    Altricial Baby Birds
    Photo © OakleyOriginals/Flickr/CC by 2.0

    Altricial birds are baby birds that hatch nearly naked and blind, requiring extensive parental care to mature. Most songbirds, hummingbirds and woodpeckers are altricial and are very weak and vulnerable when they first hatch. These birds develop feathers and independence rapidly and will be ready to leave the nest in 2-3 weeks, depending on the species, though they may remain in family groups for several additional weeks.

  • 02 of 10
    Blackbird Eggs in the Nest
    Photo © NottsExMiner/Flickr/CC by-SA 2.0

    A brood can mean either a set of related eggs that are laid and hatched together, or the act of incubating those eggs until they hatch. All siblings are part of the same brood. Mated pairs of birds may raise more than one brood in a season if climate, food and health conditions are adequate. If more than one brood is raised by the same mated pair, they are considered separate broods even though the siblings are a genetic match. Brood sizes can also vary considerably among different bird species.

  • 03 of 10

    Brood Patch

    American Robin Showing Brood Patch
    Photo © VSPYCC/Flickr/CC by 2.0

    A brood patch is a bare patch of skin on a nesting bird’s chest, abdomen or sides. This skin has more blood vessels and can more easily transfer the parent’s body heat to the eggs they are incubating. This patch is difficult to see unless the birds are captured for banding or surrendered for rehabilitation, when trained experts can examine the bird's mating readiness. The brood patch will fill in after the breeding season ends. Both male and female birds may develop brood patches depending on how the genders divide incubation duties.

  • 04 of 10

    Fecal Sac

    Blue Tit With Fecal Sac
    Photo © hedera.baltica/Flickr/CC by-SA 2.0

    A fecal sac is an excreted gelatinous sac that contains a hatchling’s feces and wastes. Very young birds may excrete fecal sacs to help keep the nest clean and minimize odors that could attract predators and endanger the nest. Parent birds will dispose of the sacs, often removing them from the area, even flying great distances to discard sacs. In some cases, adult birds may eat fecal sacs to dispose of them.

    Continue to 5 of 10 below.
  • 05 of 10
    Northern Mockingbird Fledgling
    Photo © Renee/Flickr/CC by 2.0

    A fledgling is a young bird that has developed preliminary flight feathers and is ready to leave the nest. Full adult plumage may not be developed, but the bird is independent enough to begin flying. These birds may be out of the nest for several days before they can fly strongly, but their parents will still feed and protect them. They are not abandoned and should not be interfered with as they explore.

  • 06 of 10


    Baby Birds in the Nest
    Photo © Shelby Bell/Flickr/CC by 2.0

    A hatchling is a very young bird, usually just hours or one or two days old. This is a more generic term that can apply to any recently hatched bird, regardless of species or nesting type. Hatchlings require intense parental care and are unable to survive without assistance and protection. The term hatchling is usually only applied to altricial birds such as songbirds.

  • 07 of 10


    Mute Swan on the Nest
    Photo © Smabs Sputzer/Flickr/CC by 2.0

    Incubation is the act of using body heat to keep eggs at an optimum temperature for healthy development and hatching. Parent birds may share incubation duties, or the female bird may do most of the incubating. Adults will turn the eggs or may leave the nest for short periods to help with temperature regulation for the healthiest eggs. Brooding is another term for incubation.

  • 08 of 10


    Great Egret Nestlings
    Photo © Andy Morffew/Flickr/CC by 2.0

    A nestling is a young bird, typically covered with soft down, that has not yet developed its flight feathers and is not ready to leave the nest. Nestlings typically require moderate to intensive parental care and protection, but they can be left alone for extended periods while adult birds are foraging. This is a general term that can apply to any baby bird still in the nest, but not after they leave the nest.

    Continue to 9 of 10 below.
  • 09 of 10


    Photo © Garry Knight/Flickr/CC by 2.0

    Precocial baby birds are birds that hatch with open eyes and a covering of down. These birds have a higher degree of independence and can leave the nest within hours or just a few days, though they still require moderate parental care and guidance. Ducks, geese, swans, plovers, grouse, quail and chickens are all examples of precocial birds.

  • 10 of 10


    Subadult Bald Eagle
    Photo © Andy Morffew/Flickr/CC by 2.0

    The term subadult describes birds that are nearing maturity but are not yet sexually mature and lack some fully adult characteristics, such as distinct plumage. Subadult species usually take several years to reach full maturity and will molt through several plumage variations as they age. Eagles have several subadult stages, as do other raptors, gulls and skuas.