Comparative Breeding Bata - Laysan and Lisianski 
Bate of 
Survey 
Population and Breeding 
Bata --Laysan 
Population and Breeding 
Bata Lisianski 
Pelationship of Lisi¬ 
anski cycle to Laysan 
early 
Mar.^ 
1964 
3500-4000 - est.1200- 
1500 n, most w/e, a few 
/rhy. One 2/3 gr.yg seen 
1750 ca. 450 nests, ca 
80 $ with eggs 
Suggests that initiation 
of cycle somewhat 
earlier on Laysan 
mid 
Sept. 
1964 
2000 - Mostly yg. 3/4 to 
nr. fig. and imm. , a few 
yg. l/2 grown or less 
No eggs or nestlings 
Bata not good enough 
to show any difference 
1964 summary - Initiation of laying 
evidently somewhat earlier on 
Laysan 
early 
Mar. 
1965 
il-000-5000 ca. 500 n/e 
2000-3000 ca.3 00-400 nests 
ca. 75 $/e ? mostly fresh 
Bata insufficient to show 
any difference 
mid 
July 
1965 
3500, ca. 1500 n, from 
rhy to nr. fig. yg. 
1200 - fa. 400 nest with 
rhyg to nr.fig. yg.1 
No clear difference 
indicated. 
1965 summary - Not c lear that cycle 
s different 
mid 
June 
1966 
5000, hi e [to fly imm] 
ests 1000 n; 10 $ / e 
most with s to mdy 
2750 - Est 300 n, ca. 25 $ 
w/ e, 75$ with rhyg to 
l/2 grown yg. 
Bata poor, cycle overall 
similar. Just possibly 
slightly later initiation 
for bulk of Lisianski 
population if data to be 
trusted. 
late 
Oct. 
1500 - most n/ nr.fig yg 
or flged yg. No e of dy 
1500 - 324 nr.fldged or 
fledged cted, no e or dy 
Not clear that any 
difference in cycles 
1966 summary - Not clear that cycles 
laying on Lisianski 
different, possibily slightly later initiation of 
mid- 
March 
1967 
2000 - on emp n or w/e 
Many amles displaying 
1000 - ca. 200 act. n, 
SNCN: 60 : 33 % v/e 
Not clear that any 
difference in initiation 
of cycle 
early 
June 
1967 
8000 , SNCN: 1177 : 39 $ 
w/e, 17 $ rhyg, 37$ 
sdy, 6 $ m to Idy. Ct. 
ca. 90 $ complete 
early 
Sept, 
1967 
3000, vs. 500 lg. yg, 
w./at least some down. 
1 sdy, no e 
2000 - Eggs to Idy, most Suggests both that 
n -with e or sy. SNCN: 473 : initiation 
50$ e, 6 $ rhyg, 20$ sdy, earlier and termination 
25 $ mdy or Idy. later on Lisianski, 
Initiation less clear, 
poss. later. 
1000 , sdy to de. imm. most Suggests poxsxhiy ho 
ly 1 dep. yg & dep. imm. clear difference 
1 sdy and 11 mdy or Idy 
1967 summary - Not clear that cycles different - data conflicts some. Slight poss. of 
earlier initiation of laying on Lisianski but numerical proportion may not be significant 
for population as a whole. 
late 
Mar. 
1968 
1500 - SNCN: 175 : 69/0 w/e 
31 io empty but actibe 
1000 - Fr. to v.sli.inc. 
eggs. SNCN: 36: 3 6$ w/e 
and 64 $ empty. 
Possibly very slightly 
earlier initiation of 
laying on Laysan 
late 
2286 ^ Ct. of 1142 n, a few 
more than 210- 105 n 
Not clear that any real 
Mar. 
more may have been present 
. cted around shoreline. 
difference. 
1969 
SNCN: 80 : 60$ e, 40 $ empty 
SNCN: 46 : 70 $ e, 30 $ emot 
• 
later initiation of laying in some years (1964, with initiation of laying possibly 
slightly later in some years ( 1964,1966 ?, 1968). 
