The birds 'territories are normally less than 190 meters in diameter because a larger area would entail the expenditure of too much energy in border patrol work, taxing the bird's strength and giving his antagonist an advantage.
但它們亦有自知之明，野心不大，領域一般保持在一百九十公尺內。因為領土太大，必須浪費精力從事巡視疆界的工作，易造成體力不支，給對方可乘之機。