 Although the American white ibis is predominantly monogamous and both sexes provide parental care to their young , the male often flies off to engage in extra pair copulation with other nesting females after mating with its primary female partner . These extra @-@ pair copulations are usually done after the within @-@ pair copulations , and make up about 45 % of all total matings , although only about 15 % of all extra @-@ pair copulations are successful . By not restricting the number of females it copulates with , the male is able to increase its reproductive success considerably . Although females are receptive towards extra @-@ pair copulations , male mate @-@ guarding greatly reduces the rate of successful female involvement in attempted extra @-@ pair copulations by other males . 
