Birds are classified into different groups based on certain characteristics they share. The main groups used to classify birds are:
Order
The largest grouping of birds is the order. There are around 30 different orders of birds. Some examples of orders are:
- Passeriformes – perching birds like finches, sparrows, crows
- Charadriiformes – shorebirds like gulls, plovers, sandpipers
- Accipitriformes – birds of prey like eagles, hawks, vultures
- Anseriformes – waterfowl like ducks, geese, swans
- Strigiformes – owls
- Galliformes – game birds like pheasants, grouse, turkeys
- Pelecaniformes – water birds like pelicans, cormorants, gannets
Orders are based on anatomical similarities between groups of birds. Birds in the same order evolved from a common ancestor and share traits like skeletal structure, plumage, behavior, habitat, and diet.
Family
Within orders, birds are further divided into families. Families group together birds that are closely related and share many features. Some examples of families are:
- Phasianidae – pheasants, grouse, turkeys, partridges, quail
- Fringillidae – finches
- Alcidae – auks, murres, puffins
- Laridae – gulls
- Accipitridae – hawks, eagles, kites
- Strigidae – typical owls
Birds in the same family can usually interbreed and produce fertile offspring. Ornithologists look at DNA, anatomy, behavior, and other factors to determine which birds belong to a family.
Genus
The next level down is the genus. A genus contains closely related species with a recent common ancestor. Some examples of genera are:
- Turdus – thrushes like the American robin and European blackbird
- Anas – dabbling ducks like mallards, wigeons, pintails
- Buteo – broad-winged hawks like red-tailed hawks, ferruginous hawks
- Pica – magpies
Species within a genus are very morphologically similar and in some cases nearly identical genetically. They occupy similar ecological niches.
Species
The most specific level of classification is the species. A species generally refers to birds than can reproduce with each other and produce fertile offspring. Some examples are:
- Turdus migratorius – American robin
- Anas platyrhynchos – mallard
- Buteo jamaicensis – red-tailed hawk
- Pica pica – Eurasian magpie
Species may be further divided into subspecies that have unique geographic ranges or subtle morphological differences. Species and subspecies designations are based on genetic, behavioral, geographic, and visible distinctions between populations.
Summary Classification Levels
Here is a summary of the hierarchical classification levels for birds from most broad to most specific:
Classification Level | Description | Example |
---|---|---|
Order | Large grouping based on anatomy and evolution | Passeriformes |
Family | Closely related species with shared traits | Fringillidae |
Genus | Very similar and recently diverged species | Turdus |
Species | Populations that can interbreed | Turdus migratorius |
Identifying Birds
When identifying an unknown bird, you can use its physical features and behaviors to narrow down what group it belongs to:
- Size and proportions – The relative size and proportions of the bill, wings, legs, and tail can indicate what order a bird belongs to.
- Color patterns – The plumage color and distinctive markings can distinguish between closely related species.
- Behavior – How the bird flies, forages, builds nests, and moves on the ground offers clues to its family.
- Habitat – Whether the bird is found near water, in forests, grasslands etc. constrains what groups it could belong to.
- Vocalizations – The sounds and songs are unique to certain families and species.
- Range – The geographic location where the bird is found limits the possibilities.
Field guides that illustrate key identification features provide a great resource. Apps like Merlin Bird ID can help you narrow down a bird’s species by location and answering a series of questions.
Why Classify Birds?
Classifying birds allows us to:
- Understand evolution and how different groups of birds are related.
- Study their anatomy, behavior, ecology, distribution and other traits.
- Communicate unambiguously about specific birds.
- Determine conservation needs of species.
- Explore biogeography and the ranges of species.
Having a standardized classification scheme is essential for all types of ornithological research and birdwatching. As we gain new information from genetic studies and observation, the classification system continually improves and sometimes gets reorganized.
Other Classification Considerations
Some other points about classifying birds include:
- Classification looks at evolutionary relationships, not superficial similarities in appearance or behavior.
- The genetically closest relatives are not always visually similar (for example hawks vs pelicans).
- Classification is based on shared derived traits, not ancestral traits.
- Convergence describes when distant groups evolve similar traits independently (like wings in bats and birds).
- Classification is a dynamic process and changes when new evidence becomes available.
Conclusion
Classifying birds allows us to understand how they evolved, study their biology, and distinguish between the over 10,000 living species. The main levels used to classify birds are order, family, genus, and species. Orders are the broadest groups based on anatomy and evolution. More closely related species are divided into families, genera, and species based on their shared traits and ability to interbreed. Observing field marks, behavior, habitat, and distribution can help identify unknown birds. As our knowledge expands, the classification system is refined but provides a consistent way to study and communicate about birds.