Memoranda Societatis pro Fauna et Flora Fennica

A vagrant walrus (Odobenus rosmarus) in Finland

2024-04-18T14:15:29+03:00

In July 2022, a vagrant female Atlantic walrus (Odobenus rosmarus rosmarus) was seen on the south coast of Finland. The same individual, which was called ’Stena’ in the international press, had previously been observed in the waters of several other European countries along the North and Baltic Seas. By the time the animal reached Finnish waters it was in poor condition and did not survive a rescue attempt. Post-mortem investigation revealed that the animal was malnourished and its digestive tract was almost empty, but trace amounts of DNA from bivalves and other aquatic invertebrates could be recovered. However, apart from minor age-related ailment and superficial skin wounds, the walrus showed no obvious signs of illness or injuries. Dental wear suggested that the animal was at least 20 years old. Its body and cranial measurements, including tusk length, were well above the average size for a female Atlantic walrus. Mitochondrial DNA supported its origin in the eastern Barents Sea populations. The specimen was mounted and put on display in the Natural History Museum, Helsinki. This is the first confirmed free-ranging walrus observation in the northern part of the Baltic Sea and Finland.

Adult white-tailed sea eagles (Haliaeetus albicilla) train their post-fledged young in catching prey

2024-04-18T14:49:33+03:00

This article describes two observations from the outer archipelago of SW Finland on how adult white-tailed sea eagles (Haliaeetus albicilla) actively train their post-fledged offspring to identify, catch and handle prey outside the nest. This involves synchronised and deliberate behaviour from the adults. Adult-juvenile training may be fundamental, as the food sources are shifting, the competition for abundant food items is strong, and the dependence of alternative prey is increasing.

Population structure of forest land snails (Gastropoda) in southern Finland

2024-09-28T15:30:14+03:00

Land snails have been divided into four different groups for this study: living adults, deceased adults, living juveniles and deceased juveniles. The three areas studied in southern Finland differed from each other in the quantity of land snail species and individuals present. The collected material can be inspected in many ways. The percentages of living and dead land snails, appearance frequencies of species and other results of the study are made apparent through charts and figures. Even results within a species have fascinating differences.

Occurrence of the invasive Japanese rose (Rosa rugosa) in the Åland Islands

2024-10-04T19:26:18+03:00

The Japanese rose (Rosa rugosa Thunb.) is an invasive alien species in Europe that exerts adverse ecological effects on biodiversity. In Finland, it occurs mainly along the coastline and in the archipelagos of the Baltic Sea, where it replaces native plant species and threatens rare and red-listed habitats, like sand beaches and coastal meadows. This study sums for the first time occurrences of Japanese rose stands on the seashores of the Åland Islands in SW Finland. Altogether, 57 stands of Japanese rose were found, mainly from inventories made by the authors in 2014–2020. The median size of the stands was 7 m². Although the most common habitat was stone shores, coastal meadows were also typical. The largest stand, measuring 238 m², was found on a sand beach. Knowledge of the distribution, stand sizes, and habitat types of the naturalized Japanese rose is essential for planning, eradication, and control measures. Since large areas of the archipelago are still without occurrence data, further inventories should be conducted to understand better the occurrence of the Japanese rose in the Åland Islands.

Two new Taraxacum species (Asteraceae) from Nordic countries

2024-10-06T15:24:36+03:00

Two new species of Taraxacum from Finland, Sweden and Norway are described here based on both field studies and cultivated material. Their morphology is compared with closely related species. Holotypes are deposited in H. Taraxacum (sect. Boreigena) hirsuticaule J. Räsänen has been found in northern Finland, Sweden and Norway, Taraxacum (sect. Borea) boreipix J. Räsänen only in Finland, Inari Lapland. Additional studies are required to clarify their total distributions.

Differences in the time of flowering in populations of European Golden Rod (Solidago virgaurea) on the Åland Islands, SW Finland

2024-11-18T14:35:40+02:00

In northern Åland, SW Finland, I discovered that the yearly development of the Golden Rod (Solidago virgaurea) most probably is dependent on light and partly on the effective temperature sum. The plants, growing on bare cliffs in northern Åland, start flowering about 1,5 months earlier than the plants of the interior of Åland but are much shorter. This may probably be an effect of phenotypic plasticity but may also depend on genetic factors. Plants from the cliffs will, when transplanted to the interior, flower at about the same time as on the cliffs if given enough light. If not, they will flower later and, in any way, they are very small, just like their origins. This speaks in favour of light being a key factor in the development and that the plants of the interior are poor competitors.