Definitions: convergent evolution is the evolution of similar traits in unrelated lineages; The Red-Queen hypothesis is intended to explain two different phenomena: the advantage of sexual reproduction at the level of individuals, and the constant evolutionary arms race between competing species (Wikipedia).  From Gary: One-hundred meters, not 100 feet from forest edges, will provide interior songbirds protection from brown-headed cowbirds (Molothrus ater) and; some research has shown a minimum of 67 acres of forest block is needed for veery (Catharus fuscescens) reproduction, however most nesting occurs in forest blocks greater than 240 acres.