Otajärvi is one of Finland's best bird lakes, thanks to its exceptionally rich and diverse breeding bird population. The lake is a unique combination of a lush bird wetland and a rugged, traditional lake landscape. The southern and eastern parts of the lake are mostly barren and rocky. In contrast, the almost overgrown northern part features dense reed beds and clusters of bulrush. The area is an excellent destination for day trips, both during bird migration seasons and in summer.
- Accessible viewing platform for birdwatching.
- Suitable as an excursion destination for the whole family.
- Area 5.4 km²
Otajärvi ranks among the best bird lakes in Finland in terms of the number of species and pairs of waterfowl. The most abundant waterfowl species in the lake are the Common Goldeneye (Bucephala clangula), Eurasian Teal (Anas crecca) and Red-necked Grebe (Podiceps grisegena). The Whooper Swan (Cygnus cygnus) breeds at Otajärvi, and since 1997, the Greylag Goose (Anser anser) has also nested here. Due to the lake's unique characteristics, Black-throated Loon (Gavia arctica) can be seen diving in the rugged southern part of the lake.
Several rare waterbird species in Finland, such as the Western Marsh Harrier (Circus aeruginosus) and Water Rail (Rallus aquaticus), breed at Otajärvi. Night callers like the Spotted Crake (Porzana porzana) and Eurasian Bittern (Botaurus stellaris) are part of the lake's soundscape, along with Little Gulls (Hydrocoloeus minutus), Common Cranes (Grus grus) and Red-necked Grebes (Podiceps grisegena). One of the most recent breeding bird arrivals, the Bearded Reedling (Panurus biarmicus), has been nesting at Otajärvi since the early 1990s. The surrounding forests also host valuable bird species such as the Lesser Spotted Woodpecker (Dendrocopos minor) and Long-tailed Tit (Aegithalos caudatus). Additionally, birds of prey like the Eurasian Hobby (Falco subbuteo), Common Buzzard (Buteo buteo) and Osprey (Pandion haliaetus) are commonly observed hunting in the area.
In addition to its diverse birdlife, Otajärvi also features habitats protected under the EU Habitats Directive. The lake represents a naturally eutrophic lake type, with habitats like forest swamp along its shores. The southern part of the lake contains an area that is part of the Old-Growth Forest Conservation Programme.
In the lush northern part of Otajärvi, a trial project has involved cutting and removing aquatic moss to improve water quality. This moss removal, conducted as a first-aid measure for the lake's condition, also provides valuable insights into the effects of such management methods, which can be applied elsewhere. The moss was cut during the years 1999, 2001, and 2002, covering approximately 1.5 hectares.
Historically, the surroundings of Otajärvi included shore grazing meadows, which have since disappeared as reeds and willows took over. Efforts are underway to restore open shore meadows through mowing and grazing. On Iso-Kaskinen, the largest island in the lake, the natural state of the shores has been restored by dismantling old buildings.
