This morning I heard a strange humming/ mechanical sound coming from an area of greenery/ bushes at the edge of the neighborhood. Upon inspection I found this metal object the size of my palm. No brand or electrical inputs/ connectors upon quick look. The sound was very loud up close. The pitch was quite high, but not as high as regular cat/wildlife deterrents. What is this? Location EU, Netherlands.
Edit: Thanks all for the answers! Curious to know for how long it will keep making noise.