Nature of Kuusisto Bishop's Castle Ruins
Taking care of Nature
The island of Kuusisto has changed remarkably from the times when Bishop Magnus I ˢᵗ lived in the new Bishop’s Castle at the tip of the island towards the end of 1290s. In those times, the castle was still located on its own island, which, as a result of land uplift, practically grew together with the main island.
Later on, the same happened to Fiskarinsalmi Strait located to the southwest of the castle, which used to separate the current Lyhtyholma area from the main island. Lake Kuusistonjärvi, a glo-flad separated from the sea on the main island of Kuusisto, was formed as a result of land uplift.
Wetlands, seashore meadows and reeds now replace the straits, creating an excellent habitat for large numbers of birds. Fiskarinsuntti Bay, a shallow and fertile bay left over from the old strait, offers a sheltered nesting site for various waterbirds.
Kuusistonlahti Bay and the connected Piikkiönlahti Bay with their shorelines are areas protected under the Birds Directive of the EU and, are thus part of the Natura2000 network. In addition to its vast variety of nesting birds, the area is also well-known as an important resting place for migratory birds. In spring and autumn, thousands of waterbirds and waders can be spotted throughout the entire protected area.
Tips for birdwatchers by the castle ruins
The reeds and bushes at the tip of Kuusisto Island are home to various sylvids and acrocephalid warblers. In the open seashore meadows, you may spot a meadow pipit and a western yellow wagtail in flight. Birds such as the red-backed shrike, common rosefinch and whinchat thrive amongst the meadows’ junipers. The same species can be spotted in the wetland reeds surrounding the Kuusistonjärvi Lake.
If waterbirds and waders are of interest to you, you should head along the path towards the birdwatching tower located on the southern shore of the island. The path starts from the opposite side of the road from the parking area. In the tower, you can watch the birdlife of Fiskarinsuntti Bay and its seashore meadows. Birds swimming close to the shore include the great crested greb, Eurasian coot or common coot, gadwall, Eurasian teal or common teal, common goldeneye and tufted duck. The meadows’ damp parts and shore sediment offer a perfect environment for various waders, such as the common redshank and common snipe. During the migration season, you may also spot a ruff, more common in the mires of Lapland. Slightly further away, at the bottom of Fiskarsuntti Bay, there is another birdwatching tower even closer to the shoreline and reeds. You can access the tower by turning onto Lyhdyntie Road approximately 1.5 km before the castle ruins.
During the migration season, a bird enthusiast should climb to the top of Kappelinmäki Hill which offers fantastic views towards the south and west. Migratory birds often fly along Kuusistonlahti Bay on their journey, and various birds stop and rest in the shallow waters of Fiskarinsuntti Bay. And so, you can also observe migratory birds from the birdwatching towers, and spot birds such as the broad-billed sandpiper, spotted redshank, northern shoveler and grey heron in the immediate vicinity. You should also keep your eyes peeled in case you spot a bird of prey, such as a western marsh harrier flying in the sky.
Birds’ nocturnal singing is a common sound near Kuusisto Manor, and the place is popular amongst night-time birdwatchers. On an evening stroll by the castle ruins, you may hear the buzzing song of a common grasshopper warbler and a river warbler, or the evening serenade of a thrush nightingale. You can hear the squeal of a water rail from the reeds, and the ticking song of a great reed warbler.
Nature trail offers a glimpse into the diversity of a herb-rich forest
The nature trail of Kappelinmäki is a circular route protected by the trees of the herb-rich hill. You can take a detour into history and visit the ruins of the Bishop’s Castle and, climb to the rocky top of Kallionmäki Hill and admire the spectacularly beautiful view over the archipelago.
Kappelinmäki Hill is mostly covered by an old, herb-rich spruce forest, which casts its shadow on the path running along the hill towards the shore. As the path gets closer to the shore, the forest landscape turns suddenly more open: in recent years, autumnal storms have knocked down a remarkable amount of trees on the steep northern slope, and there are various fallen tree trunks on both sides of the path. They have been left in the forest to turn into valuable decaying wood, which various insects, mosses, lichens and fungi depend on.
The herb-rich qualities of the hill’s vegetation are particularly obvious in the storm-torn area: revealed by the fallen spruce trees, plants such as guelder-rose, honeysuckle and mountain current spread their green leaves towards the sun in the spring. Towards the end of the summer, bushes paint the forest landscape orange and red with their berries. As the path approaches Kuusisto Manor, spruce trees give way to deciduous trees, and the visitor arrives in the cultural grove of Kappelinmäki Hill, a nationally valuable cultural landscape. In spring, the grove is covered in a spectacular mix of wildflowers, when plants such as liverwort or liverleaf, wood anemone, yellow anemone, Gagea, cowslip and Corydalis colour the forest floor.
Cultural landscape shows traces of a human touch
On the path leading from the parking area to the nature trail, old stone foundations catch your eye. Among them grows an old unkempt meadow. Its most valuable plants find their current habitat in the rocky patches of the dry meadow and in the shade of the old foundations. Noteworthy flora still grows in the meadow, such as field garlic and dropwort or fern-leaf dropwort, which are archaeophytes and provide evidence of Iron Age settlement. Archaeophytes refer to species introduced to new regions by people before the year 1600. Diverse insect species thrive in the patches of meadow and dry meadow, and even some rare species have been spotted in the area.
Having escaped to nature from the manor garden, some decorative plants also hide in the shade of this herb-rich forest of cultural importance: the common columbine, dame’s rocket, and elecampane, also called horse-heal or elfdock, have slowly spread among the natural flora.
The stone walls of Kuusisto Castle, the manor garden and the spruce forests of Kappelinmäki Hill are busy with winged creatures at night. On their hunting sprees, bats use sound waves and echoes, a technique called echolocation, when looking for insects to eat. Various common bat species in Finland flutter in the vicinity of the ruins: northern bats, brown long-eared bats, Daubenton's bats, whiskered bats and Brandt's bats. Rarer species such as Nathusius' pipistrelle and the common noctule have also been spotted in Kuusisto. In winter, these species migrate towards warmer regions in the south, and they may have been spotted on their migration route. In other words, they cannot, with certainty, be regarded as permanent residents of the island.
The best time to observe bats is in August and September, when darkness falls early but the nights are still warm. These creatures with leathery wings are active throughout the summer, and if you manage to stay up until the darkest moments of the summer night, you can observe bats from the turn of May and June.
Flying low in the night, hiding during the day
Northern bats can be spotted hunting in the manor garden and above the castle ruins, whereas the spruce forest of Kappelinmäki Hill is a popular hunting area for whiskered bats and Brandt's bats. They hunt in the open patches of the forest and like to fly along the nature trail. It may be difficult to spot a tiny bat against the dark forest, but a lucky hiker may feel a breeze on his or her cheek, as a bat darts by very close on its hunting spree. Daubenton’s bats typically hunt low down above the waterline but stay close to the forests along the shore. In the style of other common bats (Vespertilionidae), they may also hunt along the forest paths. The open path between the stone walls and the dense grove of alder trees surrounding the castle ruins is also a good place for spotting bats.
You are lucky if you spot a brown long-eared bat, as this bat species tends to fly high up in the canopies of the large oak trees. Sometimes it may descend from the heights and buzz like a humming bird above the garden lawn. There is an old herb-rich forest with broadleaved deciduous trees and a linden alley by Kuusisto Manor, offering even brown long-eared bats trees suitable for hunting. If you have sharp eyes, you may spot the large ears of a brown long-eared bat in flight.
In daytime, bats digest their prey in their hiding places and gather strength for the following night’s flights. A good hiding place can be found in the hollow of a tree, a cave, a bats’ nest, an attic or a gap in the wall of an old building. Usually, bats leave their nest to hunt every night, but if the weather is too cold or windy, they may miss a hunting spree. In such cases, there are not many insects about, either.
Nursing in maternity colonies
In early summer, female bats gather in maternity colonies to give birth. Bats are very loyal to a single location, and the same bats gather in the same colonies year after year. A colony may be established in the hollow of a tree, a bird house, an abandoned building or even an attic. Our most common bat species, the northern bat, is particularly keen on breeding in buildings. Bats usually have one pup at a time, and the offspring is nursed at a maternity colony. Soon after giving birth, mother bats have to leave the nest and hunt for food at night in order to produce milk to feed their young. Mother bats do not stay away from their offspring for long but return continuously to feed their pups and keep them warm.
The pups learn to fly at the age of a few weeks, and a bit later, they start hunting with their mothers. Young bats become independent two months after their birth, and thereafter, the maternity colony tends to disintegrate.