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if ff /# . ” 
A y. 
ENDERBUF.Y 
/ DRAFT 2 
BIRDS 
? 
..I (/ ■ v" (l C ..> 
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■ 
Red-tad.led Tropicbird; ( Phaethon rubricauda ) 
Current Status: Common nesting species. _ „ v „ „ v 
3T~ 3Tvx \ojVe (V\a ,ciU viaM vv 0 W) V«kccV ovOl V«SrWcL 
^e=evA mA'gy^ €?v^. V$\<2^ s's>Vo,w.cJ^ . 
Prior Rscorc:^ ^';hen G. C. Munro md A. a*. Donag^ho visited the island in 
July 1933 both recorded this species. (Bormgfeho, 1952 ; Mugbo, IS 193,8). 
Between them they banded 50 birds .and Ilunro estimated the population at n up 
to a few hundred birds. 11 an 1939 James E.A. Kinney banded 200 birds between 
OJ-j V 3 
April 2 and 1-lay 15 and to rr -j^s the - oad— s -i L.P. Schultz vl gj . 
- « 
isiun(T''P uT& collected one da^b rh,. u'js bird 
■ - - 1 mm | tirinwiiiiBpipg^^^ppJ^ a . 
Population: The largest "pdpulltion ro cgrt tert by. trie r’OBSR wan...1000,-.birds in 
1 • • - ■ ■ / a’-.... 
e k July JlguJ J. r i et -i ^ i t r -imriigyb'- 1964 } The population size 
fluctuates with the stage of the breeding cycle and is highest during the summer 
/ 
months and lowest during the winter when 7 ' only two to five percent of the total 
f 
, • / 
population Is present. From lay through June,when the largest numbers of nests 
have been found, flocks of tropicbi/ds display over the island. In November 
when almost all nests contain young the. number of birds seen Is only a fraction 
Ov\<A \o W '« »^ 
of the number actually using, the island j >±TtFe most of-the bhTft at sea * 
Hi The number of, -r r ^ l aiof whictp 
the 
<L V V-,.f -r~ 
f.vw \W3-¥> 1%^. 
Island b u- t -d o■aaobis unknown since it was impossible to determine their 
number during our short stays on the Island. . e estimate that 500 to 750 
i 
pairs nesiwon the Island. 
Annua l Cycle : P0BSP visits have been made during only five months of the year 
but data collected during these periods indicate an annual nesting cycle. 
~.j tr- 
0 
If we consider the incubation period, about 43 days, and the fledging period 
. r 
qJj about 86 days, it is possible to interpolate the annual cycle from the relatively 
- - / , . - .W ■■■-.■ : • . : ' - • 
inf requen t visits. 
The estimated number of nests Is given in table 
These numbers 
are based on'surveys of the entire island bus a number of nests were certainly 
overlooked s 4nc r o p 1 c We. believe that our 
counts have generally represented from 50-75% of the breeding population 
