At certain times of year, we all tend to eat a bit more – whether on vacation, around holidays, or to celebrate other special occasions. For birds, however, the time of overeating is very specifically driven by biology and helps them prepare for migration: it’s hyperphagia time.

Hyperphagia Definition

(noun) A state of extreme increased appetite and nearly continual eating. Many migratory bird species enter hyperphagia several days or weeks before beginning migration in order to store excess fat to serve as energy during the journey. The fat is stored mostly along the breast and flanks, and birds may increase their body mass by as much as 30-50 percent during this time. While hyperphagia has not been extensively studied, it is believed to be triggered by the same factors that birds use to know when to migrate, including changing daylight levels and sun angles.

Birders can assist hyperphagic birds by keeping feeders filled with foods high in calories and fat such as suet, peanut butter, nuts, Nyjer, black oil sunflower seeds, and nectar. Just before migration begins, birds will visit feeders more frequently and will feed for longer periods of time. This makes it essential to keep feeders refilled so birds have the opportunity to build their fat reserves or they may not have enough energy to complete their migration successfully.

Along with increased feeding frequency, hyperphagia can be recognized by a decrease in feeder aggression. At the time birds enter this pre-migration state, breeding season has ended and hormone levels have dropped. This makes birds less territorial and more apt to share feeders and prime feeding spots, such as in nectar-rich flowerbeds or at ripened sunflower heads. Granted, some birds will always be a bit aggressive no matter what season, but it can be another clue about hyperphagia.

Pronunciation

HIGH-purr-FAY-jee-uh – Rhymes with bye-fur-hay-jee-uh (yeah, that’s not a word, but I tried…)

Also Known As

Hyperphagic (adjective)