Can you guess who can live in here (a), here (b) or even in here (c)?
It is one of the cutest animals we have here in Finland, the one and only Siberian flying squirrel!
Siberian flying squirrel (Pteromys volans) is a species belonging to the family Sciuridae and genus Pteromys. It is a nocturnal arboreal mammal that lives in coniferous forests. Within European Union borders, it can only be found in Finland and in Estonia.
In Finland, the species distribution covers the country from the southern coast to North Ostrabothnia. However, the population is centred around Southern Finland. There are also notable changes in the size and distribution of the species populations among different years and places.
Flying squirrels prefer old, spruce -dominated (Picea abies) forests with enough deciduous trees growing in them. However, they can live in younger forests and even in urban landscapes if there are enough food and nest holes or boxes available. The species usually nest in tree cavities made by the great-spotted woodpeckers (Dendrocopos major) or in twig nests made by the red squirrel (Sciurus vulgaris). Sometimes the nest can be found also in birdhouses or even in buildings. Flying squirrel has several nests within its home-range, which it uses for breeding and roosting and as storages. The squirrel likes to feed on leaves of aspen (Populus tremula), alder (Alnus spp.) and birch (Betula spp.) during summer. In winter it feeds on catkins of birch and alder and on spruce and pine sprouts.
This species lives up to its name. The flying squirrel has a distinctive feature of a furry glide membrane a.k.a. patagium, which is a flap of skin that stretches between the front and rear legs of the animal. By spreading this membrane the squirrel can glide from tree to tree. If the conditions are right, the flying squirrel can glide even up to 80 meters. But these kind of long glides require the conditions to be just right, e.g. the jumping tree must be tall enough. Usually the glides are around 30-40 meters, and ” treeless gaps” wider than this are considered to be dispersal barriers for the species. Flying squirrels are also very good climber and they only rarely land on the ground.
The breeding season of the flying squirrels is during spring. The squirrels mate during March and April and the cubs (usually 2-5 babies) are born 5 weeks later. The mother nurse the cubs approximately 42–45 days. The young leave the nest for good usually around August in order to find their own territories. The size of a female flying squirrel’s territory is about 10 ha whereas the size of a male flying squirrel’s territory can be even 50 ha.
The flying squirrel has been classified as a vulnerable species in the 2019 Red List as the number of individuals has reduced significantly (approximately 23 % during the last decade). The main reason for this is intense forest management activities. Because of this the amount of old-growth forests, nesting trees and the amounts of decaying wood have reduced significantly. Also the compositions of tree species have changed. In a more and more fragmented landscape it is hence extremely important to protect the remaining old-growth forests. It is also extremely important to protect and create new dispersal corridors for the species so that young individuals can find new home forests in which to flourish. This is because, the smaller and isolated the local populations gets, the more susceptible the populations is e.g. to predation, diseases or just random stochastic factors.
Luckily, measures have been taken to ensure that these beautiful animals inhabit our forests also in the future. The flying squirrel has been listed in the EU Habitats Directive Annex II and in the EU Habitats Directive Annex IV. It is also listed as a Priority species in the EU Habitats Directive, Appendix II and as a Threatened species in the Nature Conservation Decree 14.2.1997/160, Appendix 4 19.6.2013/471. These kinds of Administrative statuses and legislation gives the flying squirrel some level of protection, although the declining population estimates tells us that this still is not enough. Nonetheless, based on this legislation, it is illegal to destroy or impair known flying squirrel nestings, resting trees and sites. Hence, before e.g. any bigger development or construction plans can be implemented, it is required that you make sure no flying squirrel nesting sites get destroyed. This should also be the case in forest management also, but to be honest, with forestry, I am not that convinced that the flying squirrels are always well taken care of.
So how do you know, if there are flying squirrels living in your backyard forests? As the species is nocturnal and quite inconspicuous, it is somewhat difficult to get to see the animal itself. That is where the poop steps in. You can find out where the flying squirrel lives by tracking its poop under trees. The poop is orange and it is the same shape and size as rice grains. You can usually find them on the base of the big trees (aspen and spruce) where they have their nests or where they eat and rest. The best time for surveying this poop is during the spring from March to June. This is the time when snow has started to melt but there isn’t yet any fresh plants and flowers growing in the forest floor.
And in the end, you might ask why I tell you all this. Well, for the past few weeks my job has been to search for this poop 🙂
– K –
Some sources: (Sorry, these are in Finnish).
Luonnonsuojelulaki 20.12.1996/1096 (https://www.finlex.fi/fi/laki/ajantasa/1996/19961096)
Nieminen, M. & Ahola, A. (2017) Euroopan unionin luontodirektiivin liitteen IV lajien (pl. lepakot) esittelyt. Suomen ympäristö 1/2017. Ympäristöministeriö, 282 s.