Comparative Breeding Data - Laysan and Lisianski 
Date of Population and Breeding 
Population and Breeding 
Data--Lisianski 
Relationship of Lisi- 
RED-FOOTED 
BOOBY 
early 
100 - Rest building 
60*, some with fr.eggs 
Initiation apparently 
March 
but not certainly 
1913 
earlier on Lis ianski 
April(Lay) 
80 - e & sy 
40 , 2 n/e 
Cycle evidently initiated 
May (Lis) 
earlier on Laysan but 
1923 
disturbed conditions may 
may this untypical 
mid 
100 - sev. n/e , 1 full- 
50 , Resting 
Data insufficient to 
Feb. 
grown immature 
point out any difference 
1963 
mid- 
700- 250-300 n, 10-20 <fo 
500 - 250 n., 50-60 io 
Initiation somewhat 
Mar. 
with eggs, some building 
with eggs, no yg. 
earlier on Lisianski 
1964 
500 
if data trustworthy 
mid 
500 - not incl. 200 fly 
17 v lg. yg., ca. 1/4 
Very similar, termination 
Sept. 
imm., 1 dep yg. seen 
of pop. fly imm. 
somewhat later on 
1964 
Lisianski ? Rot clear 
that differenfce in 
termination significant 
196 ^i- summary - Initiation of cycle on Lisianski somewhat earlier but not clear that 
mid- 
3000 - ca. 200 n/e, many 
750 
- Many n complete 
Population and nest data 
Mar. 
on empt. n. Ro yg. seen 
but 
only a few eggs laid 
suggest later initiation 
1965 
(slightly) on Lisianski 
but dates of first eggs 
not certainly different. 
Bulk of laying not 
certainly different 
mid- 
1000 * ca. 500 n/ 1/2 gr. 
500 
- ca. 200 yg. from 
Rot clear that cycle 
July 
to nearly fledged yg. 
1/2 
gr. to fully feath. 
significantly different 
1965 
juveniles. 
evidence that bulk of nesting birds had a significantly different cycle 
mid- 
June 
1966 
late 
Oct. 
1966 
1500 - fr. e to nr.flg.yg 
ca. 100 n/e, 300 /yg. 
a flged. imm pres. 
2500 - a few nr.flg.yg. 
present. Ca. 7$ of pop. 
subad. & flying imm. 
2000 - est. 50“60 n/e 
and 65“85 n/yg present- 
SRCR : 56 : kl $ / e, 59 $ 
/ yg- 
2500 - ca. 15 v Ig. yg 
and unfig. imm. Do n/e 
Very small nesting est.??? 
for Lis. Data suggests 
later initiation of cycle 
on Lisianski 
Lg. yg suggest later 
termination, initiation 
of Lisianski cycle but 
different very slight. 
1966 summary - Initiation of cycle on Lisianski perhaps slightly later as was termination. 
Overall cycles apparently quite similar, not more than and perhaps not even more than 
a week appart for the bulk of the nesting birds. 
late 
Mar. 
1967 
early. 
June 
1967 
early 
Sept.. 
1967 
150+ - Rests built but 
no e. seen 
1500 - est,200-250 n. 
SNCR:172: 52/0 / e, 11$ 
nak.yg, 30 $ sdy, 7 $ 
mdy, 1 $ Idy, 
2000 - ca. 30 Idy, 80 
dep.,non fly, imm, 200 
filying imme 
170“^ 21$ of completed 
nests contained eggs. 
3000, e to Idy, most n 
with e or sy. SRCR: 5 l 6 
46 $ /e, 17$ rhyg, 14 $ 
sdy, 23$ mdy or Idy. 
2000 , ca. Ik Idy, 400 
dep. imm,, 3 $ [= 60 
indepeny imm. ] 
Data poor but suggest 
slightly earlier initiation 
on Lisianski 
Confirms ca. week or so 
earlier initiation on 
Lisianski for bulk of 
breeders. 
Data suggests rqther 
similar termination for 
all but majority of breeder; 
on Laysan possibly having 
ealier termination. 
1967 Summary - Slightly earlier initiation of cycle on Lisianski but not clear that terminatio 
much diiferent. 
