Rohan Ibarra, 11, of Afton, concentrates on his work as he builds a bluebird box at David Crockett Birthplace Park Saturday morning. The Afton youth was one of several youngsters who took part in a workshop showing how to build the species-specific birdhouses. Parts for the bluebird boxes had been cut in advance from repurposed lumber the park had on hand. Park Ranger Joe Nowotarski and Campground Host Robert Hankins guided the workshop, aided by Hankins’s son, Wyatt Hankins. Nowotarski told participants that bluebirds are native to East Tennessee but are in habitat competition with non-native house sparrows. The bluebird boxes, which lack perching rods and have relatively small entrance holes, are designed to be useful to bluebirds but not house sparrows, the latter favoring boxes with perching rods.