Posted: 07.10.21 at 16:20 by Stuart Higgins and Ellie Brown
Kingston's Bushy Park is best known for its majestic herds of Red and Fallow Deer plus a massive assortment of birds, rabbits and insects.
Now another animal can be added to the list - giant crabs!
Two massive crustaceans were spotted on paths in the park this week causing alarm among park visitors.
Now Kingston Nub News can reveal that these are Chinese mitten crabs, one of the world's 100 worst invasive species.
The creepy creatures sport distinctive furry glove-like coverings on their main claws and have carapaces that can grow as large as a dinner plate.
But experts say they are preyed upon by the herons and crows of the Royal Park, which helps keep crab populations down.
Bushy Park manager Phil Edwards told Nub News: "There have been a small number of mitten crabs in the park for a number of years but fortunately these numbers are successfully managed by herons which fed on them, keeping them at consistent low levels."
He added: "Visitors can help us manage the parks delicate ecosystem by not leaving unwanted pets into the park.”
In the past pet terrapins and even goldfish have been dumped in the park.
But the Chinese critters are particularly unwelcome as they burrow into river banks, damage fishing gear and compete with native species.
Reports show that the crabs are abundant in the park's river near the Sandy Lane entrance, before they migrate to the Thames in spring.
A fascinating article in the London Naturalist from 2008 references the little-known species and gives some more information on the crabs' impact on the parks.
The Chinese mitten crab "is an omnivorous predator, whose impact on the amphibian and fish populations of Bushy Park is as yet unknown," the article states.
"But it is believed that through predation and competition for resources, as well as its nutrient releasing and habitat altering burrowing activities which may also have an impact on plant diversity, its presence may become increasingly detrimental," it continues.
"This species spends four or five years upstream in fresh water, and must return to the saline waters of the Thames Estuary to reproduce.
"It is a measure of the ability of this species to migrate to and from the estuarine environment that it can be found so far upstream."
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Chinese mitten crabs were rare in Britain before the 1990s, when their population surged.
There are fears that the species could invade the Thames and its tributaries - but for now it seems to be kept in check thanks to the park's ecosystem.
The Natural History Museum has even got involved and is asking budding naturalists to record their crab sightings.
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