Least Bittern (Ixobrychus exilis) Science Article 6
Unlike most herons, bitterns are considered to be noncolonial nesters. Literature records of the nesting dispersion of the Least Bittern (lxobrychus exilis) support this view. Beecher (1942) reported densities ranging from 1 nest in 39.87 acres (0.06 nests per ha) to 4 nests in 1.38 acres (1.7 nests per ha) with an average density of 1 nest per 2.54 acres (1 nest per ha).
JAMES A. KUSHLAN, The AUK, vol 90