Feral Rabbit Populations on Pacific Islands 
J. S. Watson 1 
In their monograph, Thompson and Worden 
(1956: 7-22) discuss the world distribution of 
the European rabbit ( Oryctolagus cuniculus L.), 
but make no mention of several colonies estab- 
lished on islands of the tropical and subtropical 
Pacific. It is worth drawing attention to these 
both to complete the picture and because of 
the light they throw on the great adaptability of 
this species. 
laysan island (25° 46' N.; 171° 49' W.): 
A low, sand and coral island about 2 mi. long by 
1 mi. wide, in the northern half of the Hawaiian 
chain. Groves of sandalwood trees, thickets of 
bushes, and fan palms formerly grew on the 
island, which supported a vast albatross rookery 
and five endemic species of land birds. The 
guano deposits of Laysan were exploited be- 
tween 1892 and 1904, and the manager of the 
works, Mr. M. Schlemmer, introduced various 
breeds of domestic rabbits, including the large 
white domestic English rabbit, to the island in 
about 1903 (Dill and Bryan, 1912; E. H. Bryan, 
1942). The island was later set aside as a bird 
sanctuary. Professor Homer R. Dill led a scien- 
tific expedition from Iowa State College to Lay- 
san in 1911. The expedition found that al- 
though the rabbits had killed many bushes and 
nearly exterminated several plant species, they 
had on the whole done less damage than might 
have been expected from their numbers. The 
extermination of the rabbits, however, was rec- 
ommended as they were likely to eat out the 
vegetation which would result in the disappear- 
ance of the insects on which a number of en- 
demic bird species were dependent (Dill and 
Bryan, 1912). To accomplish this an expedition 
1 Formerly of the Animal Ecology Division, New 
Zealand Department of Scientific and Industrial Re- 
search, Wellington, N. Z. Manuscript received January 
4, 1961. 
J. S. Watson died August 12, 1959, after complet- 
ing the first draft of this paper. Additional informa- 
tion on rabbits in the Hawaiian Islands has since been 
obtained and included in the text. — K. Wodzicki. 
of four men was sent to the island for 3 months 
in 1912-13; unfortunately, they were inade- 
quately equipped to deal with the problem and, 
although over 5,000 rabbits were shot, there 
were so many petrel burrows and other cover 
that without poison it was impossible to elimi- 
nate them in so short a time (Bailey, 1956). In 
1923 the Tanager Expedition visited Laysan; 
the island by then had been reduced to a barren 
waste of sand with a few stunted trees, only 4 of 
the 26 species of plants recorded from the island 
were found ( Christophersen and Caum, 1931); 
and there were a few hundred rabbits present. 
These were shot, the last ones being hunted out 
individually. The endemic warbler ( Acrocepha - 
lus familiaris Rothschild) had vanished; the last 
three Laysan honeyeaters ( Himatione sanguinea 
fraithii Rothschild) died during a sand storm 
while the expedition was on the island; and the 
Laysan rail ( Porzanula palmeri Frohawk) died 
out shortly afterwards (Wetmore, 1925). Exter- 
mination of the rabbits was completed and no 
sign of them was seen in 1936, when the island 
was found to be recovered in vegetation. While 
circling over Laysan in an aeroplane in 1949, 
Bailey (1956) found that the vegetation had 
staged a remarkable recovery and there were 
concentrations of black-footed albatrosses ( Di - 
omedea nigripes Forster ) and Laysan albatrosses 
(D. immutabilis Rothschild). 
lisianski ISLAND (26° N., 174° W. ): An- 
other low sand and coral island about 1V4 mi. 
long by 44 mi. wide, in the Hawaiian chain, 
some 115 mi. west of Laysan. Rabbits from Lay- 
san liberated there some time after their intro- 
duction on Laysan in 1903 had destroyed the 
vegetation by 1913, when only a few living but 
many dead rabbits were seen (Elschner, 1915). 
When the Tanager Expedition arrived in 1923 
the only signs of rabbits were their bleached and 
weathered bones, and the vegetation was start- 
ing to come back. The rabbits, having stripped 
the vegetation, had apparently died of starvation 
(Wetmore, 1925). 
591 
