 Morton, that is, in general, the trill interval varied from short (c. 50 ms; rapid trills) in open grasslands to long (1–200 ms; slow whistles) in woodlands and forests.This ecological dimension was explored further by Handford and students in the highly diverse habitats of northwestern Argentina.They showed that the ecological ordering of dialect variation over a huge geographical space () and across a dramatic sweep of structurally distinct habitats (puna scrub, grassland, desert scrub, thorn woodland, and drought-deciduous forest (see Figure) was largely consistent with the previously established picture.