The House Finch is said to be a pretty common bird at backyard bird feeders, but I didn’t seen many at first. Later, perhaps as they became more comfortable with my feeders, they began to show up more regularly.
Adults have a long, square-tipped brown tail and are a brown or dull-brown color across the back with some shading into deep gray on the wing feathers. Breast and belly feathers may be streaked; the flanks usually are.
In most cases, adult males’ heads, necks and shoulders are reddish. This color sometimes extends to the belly and down the back, between the wings.
Male coloration varies in intensity with the seasons and is derived from the berries and fruits in its diet. The red of a male House Finch comes from pigments contained in its food during molt. So the more pigment in the food, the redder the male.
Females prefer to mate with the reddest male they can find, perhaps raising the chances they get a capable mate who can do his part in feeding the nestlings.
I found a 3D print pattern for a Soda Bottle Bird Feeder on Thingiverse that I was able to print on my Creality Ender-3 3D printer. It has a larger perch than some of the other patterns. It seems to work pretty well with the exception of some of the larger black oil sunflower seeds tend to clog up the narrow part of the bottle. The smaller millet flows easily enough. Every now and then I just shake the unit a bit to keep the seeds flowing.