Miina Auttila

Habitat preferences of the native badger and the invasive raccoon dog in southern Finland

We compared the habitat preferences of the alien raccoon dog Nyctereutes procyonoides (Gray, 1834) and the native badger Meles meles (Linnaeus, 1758) in two areas (Ruissalo and Tuulos) in southern Finland by radio-tracking the animals during summer from 2005 to 2008. We assumed that the habitat preferences of these two medium-sized carnivores differ to some extent (ie they are able to share the resources), because they have been sympatric for more than 50 years in southern Finland and populations of both species have increased during that period. The results indicated that the habitat preferences of these species are indeed different: raccoon dogs favoured meadows, gardens and open woodlands with tall and abundant undergrowth, whereas badgers favoured both pine forests and deciduous and mixed forests with thick canopy but sparse undergrowth. However, fields were favoured by both species in one study area (Tuulos). The results show that although both species are flexible in their habitat use and share some habitat preferences, the most favoured habitats differ between the species.

Estimating habitat selection of badgers - a test between different methods

Abstract. The aim of the present paper was to compare the picture of habitat selection obtained by using 1) different home ranges and core areas and 2) different methods (compositional analysis, Jacobs index and selection ratio), in radio-tracking studies of mammals. The experimental animal was the Eurasian badger Meles meles, radio-tracked in southern Finland in 2006–2007. The total home ranges used in the study, minimum convex polygon (MCP) and 95% fixed kernel home range (K95) differed in size, MCP being larger. Therefore its habitat composition resembled more that of the landscape, and comparison between K95 and the study area revealed better habitat selection within the landscape (second order selection). The proportions of two common habitat types (fields and spruce forests) differed between the core areas used in the study. Comparison between the smallest core area (K50) and MCP revealed best habitat preferences within the home range (third order habitat selection). Comparing the distribution of individual location points in different habitats to the habitat composition of home ranges did not reveal habitat preferences of badgers. The use of compositional analysis together with Jacobs index in habitat selection studies is recommended, because the simple selection ratio was not very sensitive.

Habitat impact on raccoon dog Nyctereutes procyonoides home range size in southern Finland

Monogamous canid home range size is often negatively correlated with population density. Home range size, in turn, may be affected by the habitat. Here we examined landscape features that may affect home range size of the invasive raccoon dogNyctereutes procyonoides (Gray, 1834), an important vector of diseases and parasites in Europe. The aim was thus to reveal the habitats where population density and the risk for epizootics is highest. We radio tracked 42 raccoon dogs in three areas in southern Finland between 2001 and 2007. There was an inverse relationship between home range size and the proportions of meadows and gardens, as well as habitat richness. Also mixed forests were more common in areas where home ranges were small. The risk for epizootics, such as rabies, is thus highest in areas which constitute of a mosaic of small patches of meadows, gardens and mixed forests. The preventive measures, such as bait vaccinations, against epizootics should therefore be concentrated in these areas which are mainly in and around villages.

Estimating and Mitigating Perinatal Mortality in the Endangered Saimaa Ringed Seal (Phoca hispida saimensis) in a Changing Climate

The ringed seal (Phoca hispida) is dependent on sufficient ice and snow cover for a breeding habitat. Therefore, climate change has a negative effect on pup survival. We developed methods to estimate perinatal mortality and to mitigate the effects of mild winters on the critically endangered subspecies (P. h. saimensis). Underwater surveys were used for collecting pup carcasses and placentas. Lanugo pup mortality was 13.5% and Brucella sp. was not found in the placentas. Camera traps showed sporadic human and medium-sized carnivore activity in the breeding habitat. Although carnivore activity was most intensive at lair sites, no penetration of the lairs was observed. We developed a method to mitigate the effects of poor snow cover by piling up snowdrifts (n = 117) at potential lair sites. Seals subsequently occupied 62% of these snow drifts. We suggest that the methods developed in this study should be implemented to conserve the Saimaa ringed seal.

Segmentation of Saimaa Ringed Seals for Identification Purposes

Wildlife photo-identification is a commonly used technique to identify and track individuals of wild animal populations over time. It has various applications in behavior and population demography studies. Nowadays, mostly due to large and labor-intensive image data sets, automated photo-identification is an emerging research topic. In this paper, the first steps towards automatic individual identification of the critically endangered Saimaa ringed seal (Phoca hispida saimensis) are taken. Ringed seals have a distinctive permanent pelage pattern that is unique to each individual making the image-based identification possible. We propose a superpixel classification based method for the segmentation of ringed seal in images to eliminate the background and to simplify the identification. The proposed segmentation method is shown to achieve a high segmentation accuracy with challenging image data. Furthermore, we show that using the obtained segmented images promising identification results can be obtained even with a simple texture feature based approach. The proposed method uses general texture classification techniques and can be applied also to other animal species with a unique fur or skin pattern.

Automatic individual identification of Saimaa ringed seals

In order to monitor an animal population and to track individual animals in a non-invasive way, identification of individual animals based on certain distinctive characteristics is necessary. In this study, automatic image-based individual identification of the endangered Saimaa ringed seal ( Phoca hispida saimensis ) is considered. Ringed seals have a distinctive permanent pelage pattern that is unique to each individual. This can be used as a basis for the identification process. The authors propose a framework that starts with segmentation of the seal from the background and proceeds to various post-processing steps to make the pelage pattern more visible and the identification easier. Finally, two existing species independent individual identification methods are compared with a challenging data set of Saimaa ringed seal images. The results show that the segmentation and proposed post-processing steps increase the identification performance.