The misnamed House Finch is a poster bird for what can be done on a vegetarian diet. They even raise their chicks with little or zero insect protein. When cowbirds and similar parasites lay their eggs in House Finch nests, they may hatch alright, and the finch mothers may feed the con chicks, but those chicks starve on the vegetarian diet, while the finch’s own chicks thrive. This bird, in the words of the Cornell Bird Lab authors,
… is a bird of remarkable records. From a few California individuals released from a pet store in New York City in 1939, and through natural expansion of its western range, in just a few decades this species came to occupy one of the widest ecological ranges of any extant bird. Originally a bird of hot deserts and dry open habitats of the southwest, it now occurs in nearly all types of landscapes and climates in North America, from edges of northern taiga to ocean coasts to metropolitan areas.Badyaev, A. V., V. Belloni, and G. E. Hill (2020). House Finch (Haemorhous mexicanus), version 1.0. In Birds of the World (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.houfin.01
Its prowess is on full display in our park, where flocks of a hundred or more swarm from shrub to ground and back, gleaning the seeds of weeds and other herbivorous edibles. These are not migrants from the north. They nest nearby and very probably nest in shrubs and trees in the park, although I have not seen their nests yet. Most of the birds in the video are youngsters in their first year. Apart from a few early blooming males who already have their red on, they all wear a greyish brown cloak similar to mature females. In a few months about half will show the red/pink/orange/yellow chest, face, and crown of the males. Then they’re ready to mate and make more amazing finches. Strength in numbers!