Comparative Breeding Data -- Laysan and Lisianski 
Date of 
Survey 
Population and Breeding 
Data - Laysan 
SOOTY TERB 
Population and Breeding 
Data- Lisianski 
Relationship of Lisi- 
anski cycle to Laysan 
early 
Mar. 
1 96k 
mid 
Sept 
196 ^ 4 - 
300000-600000 prebreeding 
3000-^+000 on ground bb 
day 
50000-75000 ca. 25000 
flying imm. small # of 
unfldged yg. 
50000-100000. Most over 
head, ca.800-1000 on 
ground 
^000-5000, fledged & 
nr.fleding yg. observed 
Initiation not clearly 
different. 
Overall for bulk of birds 
similar. If relative 
pops mean anything poss. 
most Lis. birds completing 
cycle earlier. Suggests 
early 
7000-12000. 5000-10000 
•J-J *-*— C-UL, ^L. J. 
3500-1600. Some on ground 
Initiation not clearly 
Mar. 
on ground by day. Prebr. 
Bo e. 
different 
1965 
mid 
150,000. ca. 50000 yg. 
300000 ca.50000 yg., most 
Cycle seems to be 
July 
hinc e to nr.fig. yg. 
nr. flging. a few n/e 
clearly terminating 
1965 
(Bone fledged, mostly 
ca. 50000 yg. already 
earlier. iSuggests earlier 
chicks, eivdently) 
fledged. 
beginning 
1965 summ 
Lis cycle end somewhat earlier, poss. all over somewhat earlier. 
mid 
2000000, ca. 500000 n/e 
1000000, ca. 250000/e 
Lisianski cycle seems 
June 
from settling to s inc. 
95 fo e ca. 5% yg. 
to be ca. 2 weeks 
1966 
eggs 
(ca. 10,000 yg., almost 
earlier. 
all recently hatched) 
■ 
late 
100 - a few crippled imm. 
10- Bonbreeding. Sev. 
Finishing about the same 
Oct. 
and a few fledged imm w/ 
fly imm. & crip imm. 
but overall data do not 
1966 
adults 
present./ 
conflict with conclusion 
that Lis cycle somewhat 
earlier 
1966 summ. 
Lis cycle evidently somewhat earlier 
mid 
1000, ca. 200 on ground 
5000-8000 - sw. overhead 
Similar not clear which 
Mar. 
at night 
no nests found. 
might be earlier. If bords 
1967 
on ground means anything 
poss. Laysan earler. 
early 
1513000, settling to nh yg 
1700000 Most preparing 
Bot clearly different 
June 
est. 257000 eggs. 
to lay or with fr. eggs. 
1967 
Some mod & heav. inc 
e and a few small chicks 
early 
60000 sev. thou. yg. fr. 
15000 , Ig chks to flged. 
Bot clearly different 
Sept. 
3/1 to fledged. Most birds 
yg. Most birds with 
1967 
post breeding 
large chicks 
1967 summ 
- Cycles not clearly different from available data 
mid 
7500, on ground by day 
If on ground means anything 
Mar 
sfe 750O91 swirling, 1 flock 
possibly Lisianski cycle 
1968 
on ground at night.(ca.200) 
somwwhat earlier. 
some 
1965,-1966 
Overall summary - Similar, but apparently slightly earlier in seasons (±$ls & 9 possibly 
also 196^, 1968). 
