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Browsing by Subject "bats"

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  • Valanne, Valeria (2023)
    Urbanisation is rapidly increasing, along with the use of artificial lighting, which poses a growing threat to wildlife, especially nocturnal fauna. Bats are nocturnal mammals that prey on light-sensitive insects, making them particularly vulnerable to the effects of artificial light sources. Responses to artificial lights vary among bat species, with some being strongly repelled while others appear to benefit from them. However, little attention has been given to the impact of light pollution on bats in northerly latitudes, where bright summer nights may influence the effects of artificial light on these animals. In my thesis I compared the presence of bats in artificially illuminated and unilluminated areas in urban parks in Southern Finland. To see the effect of bright nights in the early summer I collected acoustic data during two time periods: bright early summer (June), and dark late summer (August). My aim was to determine if different bat species respond differently to artificial light, if lamp type affects their response, and how natural light influences their activity patterns. I found that northern bats (E. nilssonii) were drawn to street lights in both early and late summer, and they seemed to prefer HPS (high-pressure sodium) lamps to LED (light emitting diode) lamps. Conversely, more light shy bats from the genus Myotis strictly avoided street lamps at all times. The strongest effect of natural light on bats was observed on their activity patterns: the timing of peak activity shifted considerably along with changes in natural light conditions. My results indicate possible changes in the responses of nocturnal wildlife to the changes in spectral composition of illumination along with increasing popularity of LEDs. The significant differences in the responses of different bat taxa to illumination highlight the importance of conservation of dark spaces and times.