Birds 
Howland 
Red-tailed Tropicbird Estimated population----- 130 
Breeding population -— -- 112 
Sample nest count results (Believed 
to be more than 95% ‘complete)-n: 56 
Ho. of empty, occupied nest 
scrapes ---- 5 
Ho.of nests with unknown contents 1 
He sts/eggs ---- 29 (52-7%)* * 
Hests/small downy young -- 15 (27-3%) 
He sts/medium downy young- 7 (12-7%) 
Hests/large young - 2 ( 7 . 3 %) 
Hests/dependent immatures - Hone 
Total: nests/young —------ 2 6 (kjk^) 
Ho.Banded 22 ( 
Ho.Returned-: 36 ( 
The majority of the Red-tailed Tropicbird nests (24) were found in 
their usual nesting area in the rocks north of the lighthouse tower; a 
surprisingly large number of nests ( 12 ) were found in the interior of the 
island in the vicinity of the dead Cordia grove. Usually no more than 
four or five nests are found in this area during perids of peak nesting. 
The larger number found on this visit is very probably a result of the 
Tmm t pitied of droughtj th§ 
Vi git 
in 
ii 
nr§§. ii f§.r Itii 
than during the last several years, enabling survey personnel to discover 
nests more easily. 
Judging from the nest count it would appear that the 1968 egg peak 
had occurred from about a month and a half to two months earlier, during 
May. The presence of a few large young (birds to about a foot in length, 
mostly downy, but with juvenal back feathers well developed) and the 
absence of dependent immatures suggests that the first egg of the season 
had been laid some 2-1/2 to 3 months earlier in April or possibly late 
March. 
Table 1 below compares tropicbird counts from our four July visits 
to Howland. 
Table 1. Comparisons of July nest counts of Red-tailed Tropicbirds on 
Howland Island in 1963 , 1962, 1966 , and 1968 . 
1963 
July 6-8 
Estimated population 
4-0 
# of nests counted 
c. 15 
% of nests/eggs 
[66/0] 
% of nests/young 
[33#] 
' 1964- 
1966 
1968 
July 22-25 
July 12-22 
July 16-18 
100 
SO 
130 
34- - 
35 
56 
53# 
57# 
53 # 
4-7# 
4-3# 
47 # 
mese oaca indicate shat this yearns July population is probably 
significantly larger than that present two years ago. Even if the 12 
nests in the interior are discounted (since the survey of the interior in 
July 1966 was not as complete) the number of nests found in the-.primary 
* Percentages are based on the number of nests with known contents. 
