Here, the word “adaptive” invokes the process of natural selection that has fine-tuned each species to use its environment in a different way. Scientists apply the term “adaptive radiation” to groups in which one ancestor species has rapidly evolved into many descendant species, each with its own specialized way of life. Hawaii Amakihi by Frank Salmon/Macaulay Library. Among the most spectacular extremes of bird evolution, these explosions of avian diversity are worth understanding, celebrating, and conserving.Įvolution goes into overdrive to fill unoccupied niches Yet however perplexing, a deeper look at adaptive radiations reveals that these birds are wondrous examples of the power of evolution to create new forms. The process that creates these many different forms stemming from the same original bird is called “adaptive radiation,” and it has confounded past generations of seasoned naturalists and expert ornithologists. Yet despite their different shapes, sizes, and colors, these three birds are all in the same family-close descendants of the same avian ancestor. For example, on the Galápagos Islands one bird species might look like a warbler, another like a grosbeak, and a third like no other bird on the planet.
Normally, bird identification begins by mentally assessing similarities to other familiar birds: Is it a finch, tanager, wren, or sparrow? Experience allows for an educated guess and turning right to the relevant section of a field guide where the unknown bird’s likely family is illustrated.īut there are places in the world where even very closely related birds look incredibly different from one another.
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