Terrain shapes and bedrock
COUNTRYAAH, Tonga encompasses about 170 islands, most in two rows in
the north-north-south-west, parallel to the Tongagraven
further east. The islands form the peaks of volcanoes and
are higher in the western line due to repeated volcanism.
Four of them are active and several have a hard lava
surface, e.g. Late 518 m and the highest island, Kao 1,031 m
above sea level. Others formed by more explosive eruptions
consist of ash and pumice, which are more easily eroded by
The islands of the eastern line are low and covered by
coral lime, which also protects against degradation, e.g.
the largest island, Tongatapu, which is an elevated atoll.
Tonga has a hot and humid climate; humidity is increasing
north. The average temperature in December – January is 27 °C and in June – July 16–21 °C. The average annual rainfall
varies between 1,600 mm and 2,200 mm, but is on the
northernmost islands 2,570 mm. These can also be affected by
typhoons between December and April.
Plant-and animal life
The tropical rainforest that originally covered large
parts of the islands is now largely decomposed and replaced
with cultivations of mainly coconut. Of the almost 500
species of vascular plants, of which just over 100 are
ferns, about 25 are endemic. There are representatives for
eg. families elaeocarpusväxter, karakanötsväxter and spoon
shrub plants (Cunonia'ceae).
Especially on the low islands are coral reefs with rich
wildlife. The species of palolomask of interest for its
special reproduction is found on shallow water. The land
fauna is poor. There are no frogs or freshwater fish. Of
reptiles, there are geckos, hams and figs. There are also
snakes (fijiboor, Candoia [-dɔ in ʹa]),
but these are probably introduced by man.
Of birds, 39 species breed (of which 15 land birds), and
another 13 species are seen regularly. Among the species are
two species of tropical birds, red-footed sole, three
species of dove terns, fetus, four species of pigeons and
two species of parrots, of which only bluish-crowned lori (Viʹni
austraʹlis) is native. In addition to the mammals
introduced there are only Polynesian rats (Raʹttus
eʹxulans) and the fly dog Pteʹropus tongaʹnus.
Tonga has three designated national parks.
Tonga is located on the eastern edge of the
Indo-Australian plate, which is pushed up by the Pacific
plate. This one moves down the eastern side of Tonga,
forming one of the Pacific's deepest pits, the Tonga pit
(about 10,800 m deep). The islands are peaks of volcanoes,
the highest islands are those in the west due to repeated
volcanism. At its peak, the island of Kao reaches the
Ha'apai group, with 1031 m asl. In the east there are rows
of low coral islands. The largest island, Tongatapu, is also
a coral island.
Read more about Plant and Wildlife at Tonga.
The islands have a tropical, maritime climate with annual
mean temperatures ranging from 23 ° C in the south to 27 ° C
in the north. Precipitation increases from south (1500 mm)
to north (2700 mm); most rainfall in January-March during
the southern movement of the equatorial rain belt, at least
in May-September when the southeast passage dominates.
Plant and wildlife at Tonga
Lush tropical rainforest covers those areas that are not
The only land mammals are the introduced black and brown
rats, both a major threat to the bird fauna. Fossil finds
show that at least 20 terrestrial birds, a number of
reptiles and a bat species have disappeared since the
20 terrestrial birds, including two native (endemic)
species: Tonga whistles and Tonga furnace, the latter live
on Niuafo'ou and hatch the eggs using volcanic heat. Many
seabirds, including large colonies of the Soters and well
The reptiles include 20 species: 9 geckos, 9 hams, a boa
and an iguana. The latter, Fijiiguan, also lives on Fiji and
is believed to have reached the islands by sea from America.
Amphibians do not occur.