A "seed junkie" is a caged bird that eats only seeds and nuts, steadfastly refusing all other foods offered. Unfortunately, such an exclusive diet guarantees ill health and a greatly shortened life expectancy for these pet birds.
Why do caged birds become so easily "hooked" on seeds (primarily sunflower and safflower) and nuts (peanuts most notably) when these foods are rarely part of their diet in the wild? The answer has two parts. The first part concerns the wide availability, popularity and relative feeding convenience (including lack of perishability) of seed/nut mixtures, most often called "parrot mixes." The second part concerns the relatively high fat content of these food items.
For years, there has been speculation that sunflower seeds contain some addictive property. Recent research at the University of California at Davis has revealed that the relatively high fat (oil) content of these foods produces an "energy rush" or "high" similar to the "sugar rushes" from consuming "junk foods" containing lots of sugar. Parrots, given the opportunity, preferentially eat these high-fat foods. When deprived of them, they exhibit profound depression and a craving for the seeds. This almost addictive quality of seeds certainly contributes to the huge number of "seed junkies" currently being kept as pet birds.
Variety is Important: Caged birds should be fed a wide variety of high-quality foodstuffs. Seeds and nuts in the diet must be restricted to maximize optimal health and prevent disease. Unfortunately, just because we offer a veritable smorgasbord every day to our pet birds, this is no guarantee that they will consume the foods. Furthermore, there is certainly no guarantee that our birds will consume food items in the proper dietary proportions. Caged birds tend to select their foods according to habit (what they are accustomed to eating), and the appearance of the foods offered. If the food item is unfamiliar, or, worse yet, perceived as threatening by the bird, it will not attempt to eat it. Birds must become familiar with a food before any experimentation is likely. Visual and tactile (touch and feel) familiarity seem to be important.
Diet changes should never be attempted with sick birds or those suffering from multiple stresses (change of environment, introduction of a new cage mate, exposure to temperature extremes, etc.) because forcing a bird to experiment with unfamiliar foods produces a fair amount of stress by itself. Many larger caged birds developed very poor eating habits (dependence on seeds) during holding and quarantine before purchase. Seeds may have been the only or predominant food offered during these periods. Birds, like people, can become easily habituated in their feeding behavior and diet. Birds must gain substantial familiarity with a given food item before they will attempt to eat it. However, it is usually not sufficient to offer what the bird prefers (seeds) along with new food items. It is unlikely that the bird will completely ignore its particular preferences in favor of the new foods.