104 
PACIFIC SCIENCE, Vol. Ill, April, 1949 
Expedition in 1922, graciously permitted me 
to use their unpublished estimates of the bird 
populations on Midway. 
Since 1900 the populations of birds on Mid- 
way have been subjected to several periods of 
serious disturbance. Shortly after the turn of 
the century the atoll was twice visited by com- 
mercial plume hunters; it is likely that the island 
was ravaged by these hunters at least once more 
between 1910 and 1920. From 1920 to the late 
1930’s the breeding birds were not disturbed 
to any great extent. With the appearance of war 
in Europe and the threat of war in the Pacific, 
the islands of Midway became the site of great 
activity, which included vast construction proj- 
ects, the stationing of thousands of men on the 
small islands, and, finally, the inadvertent intro- 
duction of the rat. 
To discuss these major man-made disturb- 
ances or catastrophes in chronological order, the 
effects of the plume hunters must be considered 
first. We do not know how great the total num- 
bers of each species were at the time of the 
slaughter or what proportion of the total popu- 
lation was killed. Accounts such as those of 
Bryan (1906, 1910), Butcher (1905, 1907), 
and Henshaw ( 1911 ) indicate that hundreds of 
thousands of birds were killed in these forays 
on Midway, Laysan, Marcus, and Lisianski 
islands. On Laysan more than 300,000 birds 
were killed between May, 1909, and the fall of 
the same year. Over half a million were slaugh- 
tered on Lisianski. Exact figures are not known 
for the number killed on Midway, but several 
descriptions would lead one to believe that per- 
haps another half million birds were taken. On 
Marcus Island the feather hunters in 6 years 
practically eliminated a colony of albatrosses 
numbering at least one million birds. Although 
the Laysan and Black-footed Albatrosses were 
the species most desired, additional species 
known to have been taken in considerable num- 
bers on Midway were: Frigate, Red-tailed Tropic 
Bird, Bonin Island Petrel, Christmas Island 
Shearwater, Wedge-tailed Shearwater, Red- 
footed Booby, Blue- faced Booby, Fairy Tern, 
Sooty Tern, Gray-backed Tern, Noddy and Ha- 
waiian Tern, and a number of migratory species 
including the Golden Plover, Bristle-thighed 
Curlew, and the Ruddy Turnstone. On Laysan 
three other species were collected — the Laysan 
Teal, Rail, and Finch. 
The effect on the populations of birds cannot 
be reckoned solely on the basis of the number 
of adults killed for their plumage. Continued 
depredations during any one season probably 
resulted in the loss of both parents of many 
young birds. This in turn led to the death of the 
young and in many instances practically elim- 
inated the annual increment. Where the hunting 
lasted one year only those birds which had been 
at sea and had not been breeding at the time of 
the hunting were left to perpetuate the species. 
In some seabirds the number of non-breeding 
birds in any one season seems to be quite suf- 
ficient to form a nucleus for a colony the next 
year. On islands such as Marcus, where the 
plume hunters were undisturbed for several 
years, many species almost disappeared, for each 
year the breeding birds were killed and the 
increment was lost. Resident species, where 
present, suffered the most from continuous 
hunting. 
Aside from natural epidemics, such as that 
reported by Bartsch (1922) as affecting the 
Sooty Terns, there was little disturbance of the 
nesting grounds between 1910 and the late 
1930’s, when the war-caused activities started. 
The effects of the war cgn best be discussed in 
three groups: (1) effects of construction for 
war; (2) effects of daily use of the breeding 
grounds during the war; (3) the after-effects 
of the war, such as the continuing adverse pres- 
sure by rats on the bird populations. 
The main period of construction for war 
lasted more than 18 months on Midway. Thus 
it covered at least once the breeding season of 
every species on the island. Moreover, with the 
exception of the area around the Cable Com- 
pound, which had tall ironwood ( Casuarina ) 
trees, and a few small isolated areas of Scaevola, 
almost the entire surface of the two main islands 
