Ключевые слова: animal, avian, beak, bill, bird, birdsong, birdwatching, black, blackmasked, blue, blue sky, call, canary, chirp, common yellowthroat, cook county, cook county forest preserve, elm, fauna, forest, geothlypis trichas, green, illinois, isolated, leaf, leafy, leaves, no people, one, ornithology, passerine, perch, perched, profile, sing, singing, single, sit, sky, skyline, solitary, songbird, spears woods, trill, united states, warble, warbler, woodland, yellow,