John H. Robinson, Our Domestic Birds: Elementary Lessons in Aviculture
“ But not all birds of Tumbler stock are good and persistent performers, and often birds that do not perform prefer liberty for a longer period to the food that is waiting for them in the loft. Birds have sometimes been compelled to remain in the air for a long time. As a result of this treatment of poor Tumblers a type of Tumbler has been produced which will perform more or less when ascending or descending, but which, having risen to a [Pg 249] high elevation, will remain for hours circling over its home and perhaps occasionally flying away and returning. ”
