Comparative Breeding Data - Laysan and 
Lisianski 
Date of 
Survey 
Population and Breeding 
Data-Laysan 
Population and Breeding 
Dat a-Lisianski 
Relationship of Lisi¬ 
anski cycle to Laysan 
BROWN BOOBY 
early 
March 
1965 
10 No nests 
30 1 nest/w eggs 
Earlier? 
mid 
July 
1965 
]250] ca.6 n /hi e or rhy 
est [50] yg. present 
100 nearly full grown 
young, est.20 yg 
Earlier? Evidently 
completing cycle 
sooner. 
1965 summary -- Data poor but consistent -with earlier cycle on 
Lisianski 
mid- 
June 
1966 
80 Fresh e to nearly 
full gr. yg. 5 n/e counted, 
est. 20 yg. present 
90 Eggs to small yg. 
est. 15 nests. SNcn:ll 
27 fo eggs, 73 fo sy. 
Initiation earlier on 
: Laysan - not clear that 
termination would be 
different. 
mid-late 
Oct. 
1966 
100 Most with Ig. dep. 
yg. 1 n/e seen 
200 1 n/e, one a runt 
Not clear that termination 
different.1 
1966 summary -- Initiation of cycle apparently earlier on Laysan but not clear that H 
termination of cycle -was markedly different on two islands. 
early 
June 
1967 
50 5 n ? // e & l/mdy 
75 E to medium yg. 
ca. 50 io e 50 °!o yg. 
SNCN:l 8 : 56 /o e, 28 / 0 
sy, 17 °lo mdy 
Not clear that cycles I 
any different 1 
early 
Sept. 
1967 
20 k n/ Idy, 3 dep imm. 
^-0 E to dep. imm. 
mostly Idy & imm. 
Ct. of 5 n : & e & 4 - Idy 
2 dep. imm seen. 
Cycle seems basically 1 
similar for bulk of 1 
population but termination 1 
of Lisianski cycle later H 
if 1 e nest viable. I 
1967 summary — Cycles very similar bat termination of Lisianski cycle possibley later 
\ 
Overall conclusion vis a vis Laysan - Similar but initiation of a^feLng s&rifermay be 
earlier in some years (1965)? later in others (1966). 
