https://www.woodlandtrust.org.uk/trees-woods-and-wildlife/animals/birds/house-martin/
House Martin (Delichon urbicum) - Woodland Trust
Find out all about the house martin, a summer visitor to the UK, from what it eats to how it breeds.
house martindelichon urbicumwoodlandtrust
https://www.rspb.org.uk/birds-and-wildlife/house-martin
House Martin Bird Facts | Delichon Urbica
The house martin is a small bird with glossy blue-black upper parts and pure white under parts. Find out more
house martinbird factsdelichon