EMDERBURT 
DRAFT 2 
birds 
total population ox breeding and non-breeding birds must be between 3*000 and 
4,000 
The Blue-faced Booby population on Enderbury is composed of a number of 
subunits. The population can be divided into copulatiors of 
adult birds which are nesting, have nested in the past or are about to nest 
a pa pulatin n-of subadult and non-breeding birds; and 
adult 
birds which breed on other islands. In>mdit: 
Si, at cj 
;ain 
mes 
op-the 
a considerable priori ion of 
population cconsists err if 
‘ds. 
The subadult and non-breeding component* of the population . »«■ 
VK0v^ 
in one or several large no ootaag clubs -while t^^esMent birds roost, for 
the most part, singly or in pairs ^ \y \\£^ 
The location of the clubs are fairly constant although all club yites 
may not be utilized firach night and individual birds may roost in different 
clubs on different nights. M ooting LL.d’T?— i. ni sab " 
The clubs are primarily composed of young birds/ifroni Enderbury T -yeuHg 
or 
other islands and only about 25 percent of the birds 
are breeding adults. The size of the clubs varies from month to month and only 
a fraction f the irds found ip. clubs are on the island given night. 
¥e estimate that about 2000 jio 2500 birds roost in the clubs in a period of 
. 
a year 
A nnual Cycle: The infrequent trips to the island and the long period between 
trips make it impossible to define the annual cycle accurately. In most years there 
is probably some egg laying throughout the year. In February 1964 there ere 
/ 
no nests or young present. 
Table 
_____ presents the flue-meed Booby nest counts for all seven 
P0BSP visits. B^^ntSy large numbers of eggs are first laid in late March 
wife egg laying reachisg.-s-. peak in June. Kodcira - fce numbers of eggs, are still 
being laid in October but there is relatively little breeding in mid-finter 
