About 100 guys who get a kick out of peering through binoculars gathered up their best gear early Saturday in Stiffkey, England -- a parish along North Norfolk -- and flocked to the nearby salt marsh to get a gander at a rare bird who hadn't graced their area in 40 years.

The beast in question ... a little something called the Rufous Bush Chat, otherwise known as the Rufous-tailed scrub robin. It usually breeds in Mediterranean areas, and can even be found in areas around Africa ... but is rarely seen in northern Europe. Last time it was spotted in Britain was in 1980, out in the shire county of Devon ... this according to the BBC.

As for how it ended up in the U.K. ... local bird experts reportedly suggested it was seeking a more tropical climate, but somehow got turned around on its journey and landed there.

Now, Rufous here might not be much to look at from a first glance ... but the rarity of its presence was more than enough to get all these fellas together for a closer look. Ecologist Mike Hoit -- who was on the scene snapping shots -- tells us that while it may appear a lot of the guys out there were unsafely clustered together, the gathering was much more socially distanced than photos might suggest. And besides, they're outdoors ... which helps some.