They hope to fool Scottish corncrakes flying from Africa to spring breeding grounds in the highlands.
Rathlin is in the flight path of the migrating birds, which were once common here, but have all but died out.
There is still a breeding population in Scotland and the RSPB hopes some may return to the County Antrim island.
Corncrake numbers began to decline in Northern Ireland with changes to farming.
Their crek-crek call was a signal that summer was on its way.
But a move from hay to silage hit both habitat and bird numbers.
The corncrake is reluctant to break cover.
That meant silage, which is normally cut from the edge to the middle of the field, posed a big risk as birds sought shelter in the middle of the crop and fell foul of machinery.
RSPB Northern Ireland volunteers have been planting strips of nettles around the edges of fields on the island.
They grow early and will provide cover for calling males from the end of April.
If a male is heard, the farmer will be eligible for a grant to delay the harvesting of his ground.
He will also be encouraged to cut from the centre of the field to the edge, to let the birds escape into the field margins.
Gregory Woulahan, head of reserves with RSPB NI, says ten calling males on the island would be a sustainable population.
"Now that's a lot of birds to get in at any one time. But the RSPB has been leading a project in the Nene Washes in the east of England where we actually reintroduced corncrake.
"That's still to be proven if it works or not.
"And if it does work there is that potential here on Rathlin if we got the right amount of habitat for them."
Rathlin last had a calling male in 2014, but a helicopter landed in the same field and scared it off.
A handful of sightings are reported in Northern Ireland every year. The last one was at Articlave near Coleraine.
There is also a small number of the birds in some places in the Irish Republic, including the islands off the County Donegal coast.
Conservationists are planting nettles on Rathlin Island in an attempt to trick an endangered species into landing and breeding there.