Starlings can be excluded from entering nestboxes boxes by using the correct size entrance hole, but will out-compete bluebirds for woodpecker holes and other natural nesting cavities.During the summer, bluebirds feed mainly on insects. In the winter, they depend on wild berries.
1. (Geological Science) (of sedimentary rock, etc) composed of fragments of pre-existing rock that have been transported some distance from their points of origin. 2. (Biology) biology dividing into parts: a clastic cell. 3. (Medicine) able to be dismantled for study or observation: a clastic model of the brain.
Clastic sediment grains can be round, angular, or in-between (subangular or subrounded). Breccia is a clastic sedimentary rock that by definition consists largely of angular grains of pebble size or larger. Conglomerate, another sedimentary rock, consists largely of rounded grains of pebble size or larger.