German emergency services called out to attend to nighttime disturbances are increasingly finding themselves confronted with copulating hedgehogs.

People are calling 110 (the German emergency number) to complain about noises they typically put down to neighbours having unacceptably loud sex or to injured animals crying out for help. The spread of the hashtag #igelsex (hedgehog sex) on social media reveals the disturbances sometimes have a less predictable source.

Recently police in Augsburg were called to a primary school one night after suspicious noises were heard in the playground and a security light was activated. Only after the caretaker had been dragged out of bed and several police officers had inspected the site were the culprits found to be a pair of hedgehogs busily mating.

“The suspicious noises were soon pinned on a hedgehog couple in the midst of a mating ritual,” a superintendent wrote in his report, entitled “Prickly intruders”, adding that the hedgehogs were not disturbed.

The incident was not an isolated one. Police are frequently called out in the summer months to similar complaints, according to the news magazine Der Spiegel. It reports that hedgehogs are among the loudest nocturnal animals, competing with cicadas, frogs and the caridean snapping shrimp.

Hedgehogs are capable of making a range of sounds from a quiet snuffling to hissing, snarling, purring, whistling, clicking and even loud screaming, which is what sometimes gets them mistaken for excited or distressed humans.

According to a hedgehog expert at the veterinary faculty of the Ludwig Maximilian University in Munich, “hedgehogs snarl loudly during the hours-long mating ritual and the males make the most noise”. To non-experts their noises are often indistinguishable from human ones.

The hedgehog mating ritual is a lengthy affair, known in German as Igelkarussell, or hedgehog carrousel, and takes place over an area of around 40 sq metres. Their most active period is between April and the beginning of September.

Emergency services personnel have taken advice from hedgehog experts who urge them to avoid disturbing the animals, not least because urban hedgehog populations have dropped dramatically in recent years and are under threat. Torchlight scares the animals and often breaks up the coupling, but quiet observation will not usually disturb them.

The incidents have become fairly regular fodder for the local and national press. In Erlangen in 2016 a man reported a loud snuffling noise coming from under the stairs leading to his house, which turned out to be coming from a hedgehog couple.

In Kamenz near Dresden in 2014, a man heard loud noises coming from a charity clothes collection bin. Thinking a cat or a dog was in trouble, he called the police, who in turn called the fire brigade, who opened the bin with a hydraulic spreader to find a hedgehog couple hidden inside.

A police report from Düsseldorf in 2003 said a callout to “loud knocking noises in a garden” led to inspectors finding “two hedgehogs who were having fun and in a few weeks will have offspring”.