Frequency of Breeding 
The question whether North Pacific albatrosses are annual or 
biennial nesters has been the subject of much controversy, without any 
unequivocal evidence either way. The large royal albatross of New 
Zealand is reported (Richdale, 1950:30) to be a biennial nester as 
long as the chick is successfully fledged, but if the egg is destroyed 
or the chick dies, the parents may nest again the following season. 
This species has an 1l-month nesting cycle. The wandering albatross 
(Diomedea exulans) is also of necessity a biennial nester, as its 
breeding cycle is of 13 months' duration. It was thought that the 
Laysan and black-footed albatrosses might also be biennial nesters, 
but heretofore no one had followed through two successive nesting 
seasons any marked pairs of the small albatrosses including the two 
North Pacific species. In contrast to the larger albatrosses, these 
relatively smaller species have a nesting cycle of approximately 9.5 
months, so that they should be capable of nesting in subsequent years 
even if they fed a chick to the end of the fledgling period. 
One of the chief objectives of the present studies was to 
obtain positive data on this point. To this end, a follow-up check 
was made in the 1957-58 season of 497 pairs of Laysan albatrosses 
marked the previous (1956-57) season. These included 164 pairs on a 
control plot (the post office lawn),.and 333 pairs on experimental 
plots where the eggs or chicks were destroyed at different stages in 
the breeding cycle. After eliminating from consideration data from 78 
nests which could not be used for various reasons, 419 nests were left 
for calculating nesting success. Of these 419 nests, on 18 only one 
bird could be used in the calculations, as the other pair member either 
was not marked the first season, or was not captured the second season. 
The results are thus based on 820 individual birds of known nesting 
success. 
These studies have shown conclusively that a large propor- 
tion of Laysan albatrosses nesting in any one season, whether success- 
ful or not in rearing a chick, return to nest the following year. 
Presumably the same is true of black-footed albatrosses, although no 
data are available for that species. 
The percentage of birds returning and renesting the second 
year varied from 87 to 63 percent (table 3). There is a decreasing 
tendency to renest with an increase in nesting "success" (i. e., an 
increase in the length of the portion of the breeding cycle that was 
successfully completed the previous season). Thus, birds which lost 
their eggs early in the 1956-57 incubation period showed the highest 
percentage of renesting the following season, while those which suc- 
cessfully fledged a chick in the 1956-57 season showed the lowest 
percentage of renesting. 
It appears that nest destruction would tend to increase the 
number of birds nesting the following season. 
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