The male House Sparrow has a black bill in the breeding season and in summer (1st & 2nd photo).
In winter the male's bill is lighter in color (4th photo).
Young males have a yellowish bill.
Females have a yellowish bill all year round (1st, 3rd & 5th photo).

1st, 2nd & 3rd photo: Engiri Lodge, Queen Elizabeth National Park, Uganda, 6 September 2025
4th & 5th photo: Entebbe, Uganda, 28 January 2025