they are 3 to 5 days old, when they can thermoregulate their body temperature. They grow their first feathers—scapulars—at 13–15 days, followed by primaries at 24–27 days, tail feathers at 30–35 days and are fully feathered by 55 days. They are attended by the parents more between the 30th and 60th days; a behavior possibly related to the greater food requirements of the chicks during those days. Semi-digested food is regurgitated and then fed to younger birds, with older birds being fed solid food. The parents can be seen at normal rates with the chicks up to about the 70th day, after which the attendance by the parents falls rapidly. Chicks receive no care after fledging, with only about one out of seven chicks receiving food after the 80th day, and almost no chicks are visited after about 90 days. After fledging, the chicks will leave the nest, with few remaining after about 100 days. Feeding Although it is a poor swimmer, the red-billed tropicbird feeds on fish and squid. The fish are usually small, between about , although some caught are up to . The aquatic prey is mostly caught by diving into the water from the air, although flying fish, the preferred fish of this species, are sometimes caught while in the air. Fish species eaten include Pacific thread herring (Opisthonema libertate), sharpchin flying fish (Fodiator acutus), flying fish of the genus Hirundichthys, sailfin flying fish (Parexocoetus brachypterus), ornamented flying fish (Cypselurus callopterus), bigwing halfbeak (Oxyporhamphus micropterus), longfin halfbeak (Hemiramphus saltator), tropical two-wing flying fish (Exocoetus volitans), redlip blenny (Ophioblennius atlanticus), squirrelfish (Holocentrus adscensionis), mackerel scad (Decapterus macarellus), shortjaw leatherjacket (Oligoplites refulgens), and mackerels (Scomber spp.). Squid eaten include the glass squid (Hyaloteuthis pelagica). As they grow, the chicks are fed increasingly larger quantities of fish and squid by their parents, generally partly digested and regurgitated. Most fish that the chicks are fed are below in length, although some fish fed to larger chicks can be up to in length. This species of tropicbird usually forages alone. It usually dives into waters away from the coastline, diving from the air, at heights up to . It will usually hover over the water before diving. Sometimes, this bird follows predators that feed near the surface, such as dolphins or tuna. The red-billed tropicbird will feed on the fish driven either to or above the surface by the aforementioned predators.