Infrequent extra pair paternity despite demonstrable extra-pair matings Do males exert higher level control of fertilization? Zebra finches: 16% extra pair copulations, but only 2% fathered by extra-pair males Reed bunting: 55% of chicks fathered by extra-pair males What accounts for the variation in illegitimate offspring in different species? Answer: we dont know don Does extra-pair paternity increase a males reproductive success? Seems obvious that males benefit from extra-pair copulations, right? The cuckholder only benefits at the expernse of the cuckolded Maybe benefits are washed away by loss of paternity in his own nest?