nielotne

Nielotne is a Polish term used to describe animals that have lost the ability to fly. In biology, it refers to species or populations that cannot take off, either permanently or in adulthood. Among birds, flightlessness is a well-documented trait that has evolved independently in multiple lineages, often as an adaptation to specific ecological conditions.

The best-known flightless birds are the ratites, which include the ostrich (Struthio camelus), emu (Dromaius novaehollandiae), cassowaries (Casowaries spp.), rheas (Rhea spp.), and kiwis (Apteryx spp.). Penguins are another prominent group of flightless birds; their wings have become flippers adapted for swimming. Other examples include the kakapo (Strigops habroptilus) and the takahe (Porphyrio hochstetteri). Some steamer ducks (Tachyeres spp.) also exhibit reduced or lost flight in certain populations. Flightlessness often correlates with a reliance on ground-dwelling or aquatic lifestyles and, in many cases, island habitats with few predators.

Evolutionary and anatomical factors play a key role. Flightlessness tends to arise when the energetic costs of maintaining flight exceed the ecological benefits, such as in predator-free islands or open habitats with abundant ground-based resources. Common anatomical changes include a reduced or absent keel on the sternum, smaller pectoral muscles, shortened wing bones, and sometimes denser skeletal structure or adaptations for terrestrial locomotion or swimming.

Conservation concerns are significant for many nielotne species. Numerous flightless birds have become endangered or extinct due to habitat loss, hunting, and especially the introduction of non-native predators. The phenomenon also appears in insects and other groups, where wing reduction or loss can occur in certain populations under specific ecological pressures.