ENDERBUHY 
BIRDS 
DRAFT 
Red-tailed Tropicbird ( phaethon rubricauda) 
Current Status: Common nesting species 
Prior Records : Two hundred re re banded in 1939 by Kinney and Donaghho 
(1952) describes some of the nesting habitat observed in July 
193^ when he and Munro banded >0 adults. Schultz collected one adult in 
1939* 
Population :The population varies with the stage of the breeding cycle and 
is highest during the summer months. and lowest C;urin , the winfe er 
During seven FOBS? visits the largest population recorded has been 
1000 and the lowest 20. 
During the incubation period one adult is present at all times but after 
the chick is a few days old the adults return to the island only to bring 
food. The actual number of birds .present 
Because 01 this close approximation 01 tl 
reproductive cycle it is likely that birds return to the island only to 
i 
nest. The number of potential nesters which return to the island 
but do not nest is unknown and would be impossible to determine from the 
e 
short visits made. There are however at least 500 nesting pairs using the island 
and there might be as many as pairs using the island including ail 
unsuccessful breeders. 
Annual Cycle : P0BSP visits have been made during only 4 months of the year but 
iae^e these 
tk«e©-v=b«44-ift—the data indicate a regular cycle of nesting. If we use 
the incubation period , 43 days, and the average fledging time, 86 days it 
the 
is possible to interpolate tm annual cycle from the relative infrequent 
visits 
The nest counts given in table __ are based on surveys of the entire 
CX- -pa-cTe^- u. C.CM. pin 5G, 
island with afcborranc ^ s -^tf^ for the percentage of nests fawwK. Since 
