Basic Feeding Needs"I planted some bird seed. A bird came up. Now I don't know what to feed it." - Steven Wright (comedian)
Due to their high metabolic rate, finches may eat up to (approximately) 30% of their body weight daily.5,7 Finches in the wild do not only eat seed; they feast on insects and/or young sprouts as well. For these wild finches, the plant material and insects that they consume provide the nutrients that they need (protein, fats, carbohydrates, vitamins, and minerals). However, many finches kept in captivity are fed only seed, which by itself is highly deficient in many nutrients required by the avian body, and too high in fat.5,7 This, unfortunately, is part of the reason why so many birds on a seed-only diet easily become sick, stressed, show other symptoms of malnutrition, and may even die. A seed-based diet needs to be substituted to create a complete, balanced, and appropriate diet for finches. This may partly be accomplished by providing the birds with an "egg-mix" on a regular basis (boiled egg crushed shell and all with added fruits and vegetables). If you opt to try switching your birds to a pelleted (formulated) diet, which is highly recommended as a replacement for seed in the diet, you must be sure to select a pellet which is formulated specifically for finches.5 Try to avoid artificial coloring in the pellets as it is unnatural. Several companies have created formulated diets, such as Harrison's. which sells an organic pelleted diet that can be used for finches (called "High Potency Mash"). Lafeber. (pictured on the right) and Kaytee. also provide quality formulated diets. Although it is more expensive than plain seed, it is also far more balanced with a higher nutritional value, and is therefore healthier. Ideally about 70% of a caged finch's diet should be formulated (uncolored pellet made specifically for finches), and the remainder should be fresh foods.5 You will need to gradually wean your birds onto a pelleted diet since it is a newly introduced food to your birds.
There are many products available on the market (many found at pet stores) that are "recommended for" or "made for" finches, which are actually better to avoid. For instance, boxes of grit can be found with a picture of a finch or canary on the front, but this does not mean that the product is good for the bird. Finches do not require grit, and grit may in fact actually cause health complications for the bird, especially if overconsumed5. Additionally, although a cuttlebone may be a good source of calcium and trace minerals, it may be unsafe to offer since it may also contain high levels of toxins (such as heavy metals) and contamination from environmental pollution.5 You should not offer charcoal as it may lead to vitamin B deficiency, nor should you provide seed bells which contain wood glue (wood glue is toxic).5 See Safe, Toxic, & Unsafe Foods or Warnings: Dangers to Avoid for a list of other items to avoid feeding your birds. Never buy a bag of seed or pellets that looks old, stale, or has webs in it. Note: it is a good idea to freeze new bags of seed for 7 days to kill any moth or beetle larva which may be present inside. Although the bugs are generally harmless, an infestation is a pain to rid yourself of.
Appropriate "treats" for finches include egg-mix, sprouted seed, and spray millet. Spray millet should only be given occasionally since finches would be more than happy to eat nothing but, and the millet is not very nutritional. Moist foods (including egg-mix, sprouts, & fresh vegetables) can be contaminated by microorganisms in as little as four hours due to their high water content,5 so these foods should be removed from the cage within approximately four hours to prevent spoilage.
A note on providing drinkable water: if collecting water from plastic or copper pipes, allow the water to run for several minutes prior to filling dishes. Flushing plastic and copper pipes will help remove any water which has accumulated toxic levels of chemicals.5 Additionally, some cities add disinfectants, algae inhibitors, and other chemicals to their tap water which may be toxic to birds; if this is the case with the city in which you reside, you should provide distilled, bottled water instead. Do not add disinfectants, medications, or vitamins to the birds' water. The routine addition of any disinfectant to the birds' water may change the normal microbial flora residing in the gastrointestinal tract; medications tend to settle out of solution and therefore may be rendered ineffective or dangerously concentrated; and vitamins added to the water oxidize (become useless) and encourage rapid bacterial proliferation (a 100 fold increase within a mere 24 hours).5,2 Water which has been contaminated with feces or food will quickly become fouled by bacteria; therefore you must not only rinse and refill the water bowl daily, but you must also thoroughly wash or disinfect the bowl regularly to remove the active bacterial biofilm.5