The Rufous-necked Wood-rail breeds in mangrove swamps from Mexico south to northern South America and is an utterly unexpected find so far north - as previously mentioned, it represents the first occurrence of the species in the ABA recording area.
How long is it before something similar happens in the Western Palearctic or, more specifically, Britain & Ireland? And what mega will it be...?
Likely scenarios for such an event to occur perhaps concern birders photographing/videoing of large flocks of birds such as waders, gulls, terns or seabirds. How galling would it be to film a huge feeding flock of Manx Shearwaters, only to notice a Black-capped Petrel sneak through after the event?!