The islands of Micronesia are small and their occupation by man often
produces serious effects on the endemic animal life of the islands. The
vulnerability of insular bird populations is well attested by the fact
that the majority of birds, which have become extinct in the past two
hundred years, have been insular forms. Two birds in Micronesia, the
Kusaie Rail (_Aphanolimnas_) and the Kusaie Mountain Starling (_Aplonis
corvinus_), are known to be either extinct or so rare that they have not
been taken since the time of Kittlitz, who visited the island of Kusaie
in December, 1827, and January, 1828. Other birds (_Anas oustaleti_,
_Caloenas nicobarica_, _Megapodius l. lapérouse_, and _Metabolus
rugensis_) have become reduced in numbers and may be threatened with
extermination.
Nelson (1921:270-274) has described the following agencies destructive
to island life of the Pacific: fire, volcanic eruptions, tidal waves,
hurricanes, clearing of the land, introduction of domestic animals and
grazing, introduction of wild animals and birds. Mayr (1945c) also
presents a discussion of conservation problems in these islands.
Fire is a serious hazard to island life, especially to the land birds.
It destroys both food and cover, these two habitat requirements being
most essential to the birds. The firing of open lands to improve grazing
conditions was a practice which persisted in the Marianas during the
time of the Spanish. This practice has declined, but the resultant
vegetational changes and erosion have adversely affected the avifauna.
Tidal waves and hurricanes (typhoons) are occasionally of such intensity
as to flood low coral atolls. Such events are damaging to, or might even
exterminate populations of land birds (_Aplonis_, _Acrocephalus_ and
others), and prevent colonizations which might otherwise occur. Clearing
of the land for agricultural use probably has affected the avifauna,
especially on the island of Tinian where much of the island has been
placed in cultivation. The occurrence of domestic stock, especially
feral hogs and cats, has affected the birds. Hogs, apparently, have been
in the islands for a long time. The English privateer, Lord Anson,
visited Tinian in October, 1742, and noted a large number of hogs
present at that time. At Guam, in 1945, the NAMRU2 party found both hogs
and cats moving freely in all parts of the island. Stomachs of cats
examined showed that they had been feeding principally on rodents.
Introduction of wild animals and plants have not been so extensive as in
the Hawaiians or other islands. There have been at least five
importations of land birds to Micronesia as well as several mammals,
other vertebrates and invertebrates. The effect of these established
colonies on the native bird life has not been studied.
The late world war has brought changes to the population of bird life in
Micronesia. The author (1946b) has elsewhere described some of the
effects of the bombing, invasion, and occupation of small islands. Some
islands, like Peleliu, suffered severely from bombing and invasion
operations. Some islands, especially smaller ones like Kwajalein and
Ulithi, were partly or almostly entirely cleared of vegetation by
occupation forces. Other effects were caused by "recreational" shooting
of birds by garrison forces; introductions of pests in materials
unloaded; and pest control by clearing, draining, and spraying with DDT
and other insecticides to the detriment of inoffensive species.
It is obvious that a well-planned program of conservation should be
placed in operation to insure survival of the endemic avifauna of
Micronesia.