Military officials are looking for alternatives to the traditional bearskin helmet worn by the Sovereign's Foot Guards for ceremonial occasions.
The Guards have worn bearskins since 1815
The Ministry of Defence (MoD) is seeking a suitable artificial fibre following complaints from animal rights campaigners.
The group People for the Ethical Treatment of Animals (PETA) says it is not necessary to use real skins.
But the MoD said attempts to find a alternative have so far been unsuccessful.
The foot-high bearskins are worn with the ceremonial scarlet tunics by the Grenadier, Welsh, Irish, Scots and Coldstream Guards regiments.
They were first worn in 1815 in recognition of the defeat at Waterloo of Napoleon's French Imperial Guard, who also wore bearskins.
About 2,500 are in service with the Guards, each one made from the skin of one black bear.
PETA told BBC London the use of real skins was not justified when alternatives were available.
"It takes one entire bear to make one of these caps and these bears are killed in unimaginably cruel ways," PETA's Sean Gifford said.
"Some are caught in leg traps where they'll languish for up to three days before somebody comes along and puts a bullet in their head."
But the MoD said no bears were killed specifically to make the head gear.
It said the skins are a by-product of culls which the Canadian government carries out to stop the bears becoming a danger to other wildlife.
Lieutenant Colonel Peter Dick-Peter told BBC London that fake fur does not have the same qualities as the real thing.
"It looks like a 60s Beatle wig. It just doesn't look right and if the wind blows it sticks up.
"The rain soaks into the fibre and it ends up an extremely heavy piece of sodden material on somebody's head.
"In hot electrical conditions, all the hair will stand up - a really bad hair day."
The bearskins, worn on occasions such as the Changing of the Guard at Buckingham Palace and Trooping the Colour on the Queen's official birthday, are likely to stay for now.
But the search for an acceptable alternative will continue.