Natural environment
[edit]
Tahkuna Nature Reserve
Hiiumaa is an island in Estonia located north of Saaremaa in the Baltic Sea. It is the northernmost island in the Muhu archipelago, which includes Saaremaa and Muhu. Hiiumaa has a low relief (up to 68 m above sea level) and is mostly formed of limestone, that is exposed in cliffs around parts of the island's coast. In the north of the island there are a series of fossilized beaches preserved as uplift has occurred. The modern beaches are primarily on the northern and western coast lines. The natural environment is protected within the Tahkuna Nature Reserve and West Estonian Archipelago Biosphere Reserve.
The Hiiu Shoal (Nekmangrund) is located off the northwestern shore of Hiiumaa Island. The Soela Strait separates Hiiumaa from Saaremaa to its south, and the Muhu Strait separates it from the mainland of Estonia.
Ecology[edit]
Beach vegetation on HiiumaaThe fauna and flora of Hiiumaa are similar to the Estonian mainland. The mammal fauna includes elk, red deer, roe deer, wild boars, foxes, lynxes and martens. Wolves and bears have recently started to repopulate the island after being made locally extinct.
Minks were also reintroduced in 2000, after they were exterminated by trappers. Since the end of the 1990s the island shelters a conservation project aimed at restoring populations of European mink, an endangered species of which there is about only 1,000 individual specimens left in Europe as of 2017. This project started with removing from the island all American minks that had escaped from breeding farms, and reintroducing some European minks. The latter started breeding.
The bird species found on the island include black storks, golden eagles, cranes, avocets and swans. The forests are dominated by pine and deciduous trees, the rest of the uncultivated land is covered by swamps and dunes. The island has about 1000 species of large plants of which 50 are protected.
Geology[edit]
The exposed geology of Hiiumaa is composed of Paleozoic limestone which dips towards the South, covered by glacial sediments. In the North of the island the limestones are Ordovician and they young upwards to the Silurian in the South. These limestones formed at 30 degrees South and have since been moving North with the rest of the Estonian block. Bore holes have found Cambrian sedimentary rocks and a crystalline basement.
In the Ordovician (c. 455 million years ago) the sea floor was hit by a meteorite forming the 4 km wide Kärdla impact structure. This structure was then filled with Paleozoic sediment. It located about 4 km west-southwest of Kärdla and is barely visible in the modern geomorphology. The crater is well preserved at depth, with a clear rim, breccia and minerals and rocks formed from the heat and pressure of the impact.
The limestone is overlain by Pleistocene glacial deposits that were deposited as the ice cap retreated 11 to 12 thousand years ago. These include terminal moraines, the two most prominent being one in the South of Island running towards the North-East and another forming the Kõpu Peninsula.
Climate[edit]
Climate data for Hiiumaa (Ristna 1991–2020 normals and extremes 1922–present, western part of Hiiumaa)
Month
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Year
Record high °C (°F)
8.4(47.1)
7.1(44.8)
15.0(59.0)
21.5(70.7)
27.8(82.0)
29.4(84.9)
31.5(88.7)
31.5(88.7)
27.0(80.6)
18.6(65.5)
13.0(55.4)
9.6(49.3)
31.5(88.7)
Mean daily maximum °C (°F)
1.2(34.2)
0.3(32.5)
2.5(36.5)
7.3(45.1)
12.6(54.7)
16.9(62.4)
20.8(69.4)
20.3(68.5)
15.9(60.6)
10.3(50.5)
5.8(42.4)
3.2(37.8)
9.7(49.5)
Daily mean °C (°F)
−0.5(31.1)
−1.6(29.1)
0.3(32.5)
4.1(39.4)
9.0(48.2)
13.5(56.3)
17.5(63.5)
17.3(63.1)
13.3(55.9)
8.3(46.9)
4.2(39.6)
1.6(34.9)
7.2(45.0)
Mean daily minimum °C (°F)
−2.7(27.1)
−3.7(25.3)
−2(28)
1.1(34.0)
5.6(42.1)
10.4(50.7)
14.4(57.9)
14.2(57.6)
10.5(50.9)
5.9(42.6)
2.3(36.1)
−0.3(31.5)
4.6(40.3)
Record low °C (°F)
−28.4(−19.1)
−26.9(−16.4)
−20(−4)
−11.9(10.6)
−3.8(25.2)
−0.6(30.9)
4.6(40.3)
1.5(34.7)
−2.3(27.9)
−6.9(19.6)
−15.1(4.8)
−26.2(−15.2)
−28.4(−19.1)
Average precipitation mm (inches)
52(2.0)
42(1.7)
35(1.4)
31(1.2)
32(1.3)
50(2.0)
53(2.1)
72(2.8)
60(2.4)
72(2.8)
72(2.8)
58(2.3)
628(24.7)
Average precipitation days (≥ 1.0 mm)
11.8
9.4
8.3
6.5
5.9
6.9
6.8
9.2
9.2
12.9
13.0
14.1
114.0
Average relative humidity (%)
86
86
83
81
79
81
80
80
81
83
86
85
83
Mean monthly sunshine hours
28.2
59.3
119.4
190.9
293.1
297.6
303.2
251.0
166.2
96.1
36.3
19.0
1,864.4
Source 1: Estonian Weather Service (sun, 1971-2000)
Source 2: NOAA/NCEI (precipitation day, 1991-2020)
