juvenile mortality. The data are as follows: 
a) Total eggs laid 164 
b) Total young (March) 119 
c) Mortality through March 27% 
c=100- (b-100) 
( a ) 
d) Young remaining, 9 July 76 
e) Number of young which had already left 23 
(based on data from officers’ club 
study plot) 
e=0.3'd 
f) Estimated number of young successfully 
fledged 99 
f=d+e 
g) Mortality rate, laying to fledging 40% 
g=100- (e 100 ) , 
) 
Mortality in areas where much construction work was going on 
was undoubtedly higher than that in the residential area. On the other 
hand, mortality was probably lower in some of the more remote, less 
disturbed, areas. For the island as a whole, it is estimated that the 
mortality rate was somewhat higher than 40 percent, perhaps 50 percent. 
Laysan albatross juvenile mortality on Eastern Island.-- 
In the central triangle of Eastern Island, all Laysan albatross nests 
were counted on 17 January. In early June, all chicks in this area 
were banded, and subsequently a careful search was made for dead 
banded chicks. These data permit the derivation of a mortality figure 
for a representative area on Eastern Island as follows: 
a) Total nests counted, 17 January 2,676 
b) Total chicks counted (and banded), June 2,100 
c) Number banded chicks found dead on area 54 
d) Number banded chicks found dead elsewhere 
on island 3 
e) Total number found dead 57 
f) Maximum number. successfully fledged 2,043 
f=b-e 
g) Mortality, egg to fledging 24% 
g=100-(£° 100) 
( a ) 
h) Minimum mortality, early June to fledging 3% 
h=100-(£-°100) 
( b ) 
The preceding mortality figures, for both species on both 
islands, do not take into consideration the apparently high mortality 
of young birds immediately after they leave the island. Many young 
birds, either dead or so water-soaked and bedraggled that they could — 
16 
