Goldfinches are the last songbirds to nest each year in North America. We expect to see them for a time in late summer or early autumn, then vanish for awhile, then reappear in winter. This is predictable routine for them in many parts of their range. Unlike goldfinches, which virtually never eat insects but subsist almost entirely on a diet of seeds, purple finches and house finches seasonally alternate between diets of seeds and insects. During their insect-feeding stage, they naturally visit feeders less frequently.
Violent weather can dramatically alter the landscape.
Food and cover can be eliminated, redistributed, or obscured for hours, days, weeks, or months. Such weather can also create ideal migration conditions for those species that migrate. Both house and purple finches can be very sedentary, while goldfinches can wander widely. A September hurricane could have hastened the departure of birds that would have been moving anyway, or it could have eliminated vital habitat, forcing the birds to move. Almost everyone understands in general terms that birds' lives are governed by natural phenomena such as weather and climate, seasons, time of day, age, gender, other animals, plant community types, and individual needs including space, food, and cover.