Birds

[Heatherelk]

Which birds are the old world equivalents of hummingbirds ?
Which passerine bird nests furthest north ?

[Cetti]

Sunbirds - first answer (according to Google)

[wildwood]

Eurotrochilus inexpectus was a hummingbird like species that lived in the old world.
If you mean in the present age probably the honeysuckers and sugarbirds.

The Dunlin breeds pretty high North but this is always open for contention.
The odd Alpine Cough for one may breed even further north.

[jumbojim]

The Sunbirds (Nectariniidae),which live in Africa,are the ecological equivalent of Hummingbirds,which are related to the Swifts.They feed on nectar,and some species are symbiotic with certain plants.
The Dunlin,of course is not a Passerine,but a Scolopacid wader-my guess for the most northerly nesting passerine,would be probably the Lapland Bunting (Calcarius lapponicus),or the Snow Bunting (Plectrophenax nivalis),although this is more a high altitude species.The Lapland Bunting breeds right up into the Arctic circle,in the short Arctic summer-also maybe Shore Lark?