available concerning the number of banded birds presently in the 
population, and the size of the population, to calculate what propor- 
tion may have come from other areas); and (3) most unemployed birds 
seem to be almost as strongly attached to a particular site as are 
breeding birds (see Kenyon et al. 1958). 
One fact was made exceptionally clear from this killing 
program: The number of unemployed albatrosses far exceeds what was 
previously thought. Original estimates were about 15 percent of the 
breeding population (Kenyon et al. 1958); it is now evident that the 
number of unemployed albatrosses exceeds the breeding population, 
perhaps by as much as 100 percent. Many of these unemployed birds 
spend only relatively short periods on the island and there is a 
steady turnover throughout the season. 
With the present lack of knowledge of albatross population 
dynamics, it is impossible to determine the status of these unemployed 
birds in the population. It seems likely that a large proportion of 
them belong to the 4-to 7-year age classes -- immature birds which 
have returned to the island but have not yet reached breeding age. 
Present evidence indicates that approximately 67 percent of the breed- 
ing population nests each year (see Ecological and Life History 
Studies -- Frequency of Breeding). This eliminates the possibility 
that the unemployed population is composed largely of older birds 
which are simply skipping a year at nesting. 
If the above suggestion is correct, and the large majority 
of unemployed birds are in the 4- to 7-year age classes, it indicates 
that the survival rate (subsequent to successful fledging) during the 
first 7 years must be very high. 
The important implications of such a high survival rate among 
subadults are that the l- to 3- -year age classes must of necessity 
(assuming a fairly constant annual increment to the population) be even 
larger than the 4- to 7-year age classes. It is these younger age 
classes, which remain at sea throughout the year, that will be contri- 
buting to the unemployed population on the islands throughout the next 
3 to 5 or more years, and thus contribute to the potential aircraft 
hazard for some years to come, regardless of the scope or intensity 
of any immediate killing programs. 
Results.--Observations subsequent to the killing program 
indicated neither a reduction in numbers of albatrosses soaring over 
the runways adjacent to the kill area (see figs. 4 and 5 and tables 
10 and 11), nor a reduction in the frequency of aircraft strikes (see 
table 4). Under favorable wind conditions, the density of soaring 
albatrosses equaled, and often exceeded, that observed before the 
kill. 
At no time did the density of soaring albatrosses over the 
portions of the runway adjacent to the kill. area drop anywhere near 
32 
