Sessions

In the past few decades, renewable energy sources have been increasing in popularity, with the goal of protecting the environment. Despite their importance, they may have negative effects on living organisms. This phenomenon is called the green-green dilemma. The negative effects of solar panels are barely known, however, due to the nature of smooth surfaces, they might cause sensory problems for certain animal taxa. From previous behavioral research, we know that echolocating bats perceive large, horizontal smooth surfaces as water and attempt to drink from them. The angle of solar panels is often close to being horizontal, therefore they may cause issues for wild bat populations. The aim of our study is to explore opportunities for mitigating these sensory issues, with the help of field behavioral experiments. Similar methods have been used to investigate the use of patterns sensed by echolocation, our research aims to explore the effect of visual patterns on water recognition.

The experiments took place at ELTE Füvészkert in the summer of 2025 and 2026 on 21 survey evenings. We placed 2x1 meter black plastic plates on the surface of a lake. We investigated three different stimuli, rotating between these between survey evenings: plain black plate (n=8), plate with 15 mm wide black stripes (n=6), plate with 15 mm wide white stripes (n=7). The plain black plate serves as a control, as from previous experiments we know that bats attempt drinking off these. The black and white stripes were placed on the plates in a grid pattern, using insulation tape. Because these tapes are slightly elevated from the surface, they can be sensed with echolocation, so the black tapes serve as a second control. The effects of the visible white stripes are compared to these two control stimuli.

To record the experiments, we used two night vision cameras and illuminated the plates using infrared light. The experiments lasted 1 hour per survey evening. We recorded the echolocation calls of the passing bats using an Audiomoth device. The data from the sound recordings are used to identify the bat species recorded in our experiment. The most common species recorded during the survey evenings was the Kuhl’s pipistrelle.

We analyzed the behavior of the bats based on the video recordings. We determined the ratio of drinking attempts compared to all passing bats. Based on our findings, the relative ratio of drinking was highest on the “plain black plate” stimulus. The relative ratio of drinking was significantly lower in the case of the “white stripes” stimulus. The white stripes successfully lower the frequency of drinking attempts, therefore suggesting the role of vision in recognizing water surfaces in bats. Our results contribute to designing solar panels with efficient methods for mitigating sensory problems.