House finch

House finches nest on buildings, in wreaths and in hanging plants. Males' red colour comes from pigments in their food, and females prefer the reddest males.

House finches were released on Long Island in the 1940s after being sold illegally as cage birds, and spread across the East. An eye disease, mycoplasmal conjunctivitis, has swept through their populations, and scientists study it as a model of how diseases spread in wildlife.

Nest — A cup of grass on a ledge, wreath or hanging plant
Eggs — Usually four or five
Incubation — About 13 to 14 days
Chicks — Fed by both parents
Flight — At about 12 to 19 days
Lifespan — Several years

• Finches with crusty, swollen eyes have conjunctivitis; feeders should be cleaned with a dilute bleach solution and dried to slow its spread.
• A nest in a porch wreath lasts about a month.

• Red finches are cardinals. House finches are much smaller with no crest.

• Purple finch
• American goldfinch
• House sparrow