 The eggs hatch after about three weeks and the young are attended by both parents . Males are present around the nest for most of the day , and females most of the night . The parents exchange nest duties in the morning and in the evening . Most of the feeding of the chicks occurs during the period where they swap nesting duties . Little feeding is done in the period of the day that is between the two duty swaps and no feeding is done between midnight and 6 a.m. Chick mortality is highest in the first twenty days post hatching , with anywhere from 37 to 83 % of hatchlings surviving to three weeks of age in the Everglades . During periods of food limitations and starvation events , the American white ibis tends to exhibit sex @-@ dependent pre @-@ fledgling mortality . For many bird species that have sexually dimorphic nestlings , mortality rates are higher for larger @-@ sized male nestlings as a result of the parents ' inability to meet its greater nutritional needs . However , in the case of the American white ibis , the male nestlings actually have a lower mortality rate as compared to the females despite being on average 15 % greater in mass as compared to its female counterparts . Although current research has yet to discover the underlying factors to why the males tend to have better survival rates under such conditions , it is suspected that the parents tend to feed the larger male nestlings first because they are either perceived by the parents to have a higher chance of survival , or , being generally larger , the male nestlings simply out @-@ compete the small females for food . 
