have to stroke the base of the bill to initiate feeding. Feeding takes place once or twice a day, generally around midday. They are constantly brooded by the parents until they are a week old, after which time they are sheltered under the parents’ wings. They also rise up and gape at any nearby bird for food. Both parents feed the young, by shoving its beak into the chick's gullet and then regurgitating food. Initially covered with grey or white down, they grow their first feathers—scapulars—at 16–20 days. Their feet and beaks grow rapidly, outpacing the rest of their bodies. Chicks remain in the nest for 67 to 91 days until they fledge. Feeding The red-tailed tropicbird is mostly a , diving anywhere from an above-water height of , to a depth of about , although this may change seasonally. When diving, it remains briefly submerged—one study on Christmas Island came up with an average time of 26.6 seconds—generally swallowing its prey before surfacing. The red-tailed tropicbird sometimes catches flying fish in the air. During incubation, foraging trips are relatively long, with an average excursion taking about 153 hours. These trips are to very productive areas. After the chicks hatch, on the other hand, the parents adopt a strategy where one takes long trips (these averaging about 57 hours) for self feeding, and the other takes short trips (about three hours long) to feed the chicks. The bimodality of the length of foraging trips is likely to be because it is the optimal balance of self-feeding and provisioning for chicks. On Christmas Island, birds generally forage far out to sea in the early morning and closer to shore in the afternoon. Squid and flying fish make up a large portion of this bird's diet, along with some crustaceans, depending on location. Fieldwork in the Mozambique Channel revealed the diet of birds there to be mostly fish by mass but equal numbers of fish and squid caught. Fish recorded include the mirrorwing flyingfish (Hirundichthys speculiger) and spotfin flyingfish (Cheilopogon furcatus) and several other unidentified species of the flying fish family Exocoetidae, the pompano dolphinfish (Coryphaena equiselis) and common dolphinfish (C. hippurus), needleflish including the houndfish (Tylosurus crocodilus), and unidentified members of Hemiramphidae, Scombridae, and Carangidae. The purpleback flying squid (Sthenoteuthis oualaniensis) was by far the most common cephalopod eaten, followed by the common blanket octopus (Tremoctopus violaceus). A field study in