House Finch (Haemorhous mexicanus)
Author: Alexandra (Alex) Forsythe
Until 1940, House Finches were only found in the western portion of the United States. In 1940 illegally caged House Finches were being sold as “Hollywood Finches” by a pet store in New York. In order to escape prosecution for the illegal pet trade, the store released the birds into the wild. The birds thrived and spread across the eastern U.S. Today, they are widespread with an estimated population of up to a billion birds.
House Finches are strict vegetarians, eating seeds, buds and fruit throughout the year, and feeding the same vegetarian diet to their chicks. At feeders, they prefer thistle, sunflower and safflower.
In 1994, Cornell began conducting a survey to track a bacterial disease that affects House Finches across the country. House Finch Eye Disease is caused by a bacteria that causes a type of conjunctivitis leaving the bird listless, mostly blind and vulnerable to predators. The disease killed half of the House Finches in eastern North America, but it has decreased to 5 – 10% of the population in recent years. Several species are known to have been exposed to the disease, including Black-capped Chickadees, American Goldfinches and Wood Thrushes, but other species do not always show signs of illness after exposure. The results of the study indicate that the disease varies seasonally. There are few birds with the disease during the summer, but the number of diseased birds peaks in the spring and fall. The survey lasted 15 years, but data continues to be collected through Project FeederWatch.
In tandem with the House Finch eye disease study, Cornell also conducted the House Finch Nest Survey to determine whether nesting success changed since the disease began. An interesting observation came out of that study: ravens, crows, jays, cats and other predators take note when a human regularly observes nests. If you want to check on a nest regularly, make certain no one is watching you or else you will inadvertently lead predators to the nest and help cause the demise of the chicks.
If you see a finch with red, swollen, runny or crusty eyes, report the bird to Project FeederWatch. To help decrease the spread of avian diseases, be sure to regularly clean your feeders with bleach and rake underneath the feeders to remove old seed and droppings.