The webcam was placed in a neighbour's garden to capture the animals' behaviour in the night-time, but instead filmed a man climbing over the fence and running from the scene after trying to break into his neighbour's house.
The burglar carried out the crime at around 3.35am at a property in Herne Hill, South London, but unbeknown to the thief, he could be watched through Simon's live streaming on his wildlife website.
The 51-year-old wildlife expert was quoted on BBC News, saying:
"Anyone can view animals doing the strangest of things – but this is taking it one stage further."
The video has been sent to the police, who, according to Simon's Twitter, are "delighted' with the footage.
It's also believed the burglar was disturbed during the break-in, so thankfully nothing was stolen.
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