THRUSH COUNTERPARTS

      Most folks in the eastern United States are familiar with the handsome American robins and eastern bluebirds, and some parts of their life histories.  Those species of birds are in the thrush family, and have counterpart thrush relatives, namely varied thrushes and mountain bluebirds that do the same jobs as American robins and eastern bluebirds, but in the higher altitudes of western North America. 

     Though related, and nesting in the upper altitudes of western North America, the attractive varied thrushes and mountain bluebirds don't compete with each other for food and nesting sites.  The former species raises young in open, mud and grass cradles on tree limbs in the dense, dark understories of moist, mixed coniferous/deciduous forests, while the bluebirds rear offspring in abandoned tree cavities and erected bird houses in mountain meadows.  Their American robin and eastern bluebird counterparts nest the same ways, except robins now hatch young in shrubbery and young trees in the eastern, abundant suburban lawns.    

     Varied thrushes and mountain bluebirds have characteristics in common.  All ages and both genders have attractive feathering, especially the adult males.  Both species winter in lower elevations, and a few individuals of both kinds winter in the eastern United States, the thrushes in older suburban areas and the bluebirds in farmland, both human-made habitats.  

     Both types feed on invertebrates during warmer months, and berries and seeds in winter.  But they don't compete for food because they live in different habitats.  The thrushes trot over woodland floors to ingest invertebrates, as robins do.  Bluebirds catch prey by dropping on them from weed-top perches and by sweeping out from perches to catch flying insects in mid-air, as eastern bluebirds do.  American robins and eastern bluebirds don't compete for food either.  

     Males of both kinds sing beautiful songs, as all thrushes do, and both species raise two broods per summer with about four to five young in a brood.  Females of these species build the nurseries and brood the eggs.  But both parents of both kinds feed the young invertebrates.    

     Varied thrushes are up to ten inches long, close to the size of American robins.  Males have striking black and orange feathering, but their mates and young are light-brown and yellow.  Many varied thrushes winter on lawns, parks and in thickets to feast on berries, up to twenty birds in a flock.

     Mountain bluebirds are about seven inches long and have large, black eyes.  Males are blue all over, but their bellies have lighter blue.  Females and young are mostly light-gray with blue tails and flight feathers.  

     The related varied thrushes and mountain bluebirds are related to thrushes, and have counterparts in eastern North America that have the same jobs in the same habitats as they do..  And varied thrushes and mountain bluebirds don't compete with each other for food and space, just as their counterparts don't.  Spacing allows several related species the ability to thrive without competition.     

          

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