Australians celebrating Halloween this week are being warned that placing common decorations in gardens could cause serious damage. Cheap fake spider webs made from artificial fibers are having a terrifying effect on the country’s wildlife.

According to experts from the University of Sydney, native birds, bats, lizards and possums are all at risk. The experts have urged residents who want to celebrate the event to look for alternative decorations as decorations made from natural materials are less likely to cause damage.

Biology lecturer and researcher Dr Catherine Price issued a warning on Monday saying animals could become trapped while collecting food or nesting material. “Research shows that about 30 percent of bird nests may contain man-made material, posing a risk to the nestlings,” she said.

In recent years, internet posts showing images of animals caught in the web have gone viral, but this year Yahoo News has gathered evidence showing they are also a problem in Australia.

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Which Australian animals are captured in Halloween decorations?

The American practice of decorating front yards to celebrate the ancient pagan tradition has soared in popularity in Australia over the past five years, and rescue group WIRES has responded to several calls since.

Already this year, a yellow-throated honeyeater in the western Sydney suburb of Dulwich Hill was reported to have strands of spider web wrapped around its wings. Unfortunately, it disappeared before rescuers arrived and whether it survived is unknown.

Last year a magpie’s leg became entangled in a web in the north of the city. In the eastern suburbs, an unidentified brown and white bird got stuck and dangled “for a while.”

Professor Dieter Hochuli from the University of Sydney said fake webs behave like real ones, but they don’t feed spiders and serve no real purpose.

“They seem like an unnecessary way to cause damage. There is a chance that you will trap a bunch of unsuspecting and harmless animals in your polyester decoration, which could also eventually be turned into nests,” he said.

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