Red-footed Booby 
(Sula sula) 
Current Status : Breeds annually. 
Prior Records : Munro (1941) reported seeing this species off Nihoa May 26- 
27; 189 !• Woodside and Kramer ( 1961 ) saw these birds on the island on March 
2, 1961 . Other records are Fisher ( 1906 ), Munter (1915); Wetmore ( 1925 ); 
Vanderbilt and $e Schauensee (l94l), Kramer ( 1961 ), Kramer and Beardsley 
( 1962 ). 
Population: This species is common over all of the island. rEtr is difficult 
to census accurately since the population varies considerably through a 24- 
hour period. Ommissions and repetitious count&g are common. 
Munter ( op. cit .) estimated 800 present on March 18, 1915* Wetmore ( op* cit . 
estimated 5000 pairs present June 11-l 6 , 1925* Ho saw one adult bird in the 
dark plumage typical of southern island populations. 
The POBSP visd rt of March 6 , 1964 estimated 2600 including one dark- 
sV Ki/6 SURVEY P#* T t 
phased bird. The t r -js p of March 24, 1965 estimated 5500 adults. The of 
September 25-24, 1964 counted 449 adults during the day. The population 
60*5 VfiYt. (&pr 
using the island at that time && probably double the day count since birds 
continue to return from feeding activity until after sunset. 
Reproduction : This species nests off the ground whenever possible. On Nihoa 
it utilizes all of the island except bare rock and cliff edges, nesting 
primarily on Chenopodium shrubs and to a lesser extent in the tops of the 
Prichardia palms. 
Fisher (op. cit«) found immature birds "especially conspicuous" between 
August 5 and 10, 1902. Munter (op>. cit .) reported birds on eggs on March 18, 
1915 • Wetmore ( 0 £. cit.) reported birds on eggs to half-grown nestlings be¬ 
tween June 11 aid 16, 1925 . Vanderbilt and Schauensee ( op. cit .) recorded 
birds in all stages of breeding between August 7 1 5 } 1940. Kramer (op. cit. ) 
observed immatures only + December 10-15, I 961 . Kramer and Beardsley (op. cit.) 
