You may have read, as I have, that some greens contain oxalates, therefore they should not be fed to your birds. But greens are so important to their overall diet, let’s not dismiss them if we don’t have to.

The ones we’re going to discuss do  have an effect on finch diets. Lady Gouldians can be given foods containing oxalates  in small amounts– either as part of a larger diet, or skip a few days in between.

What Are Oxalates, And Why Are They Bad?

Oxalates is the term we use to refer to oxalic acid. It’s a natural product we regularly consume, and so do our birds if they are eating leafy greens and legumes. Oxalic acid is a chemical, and its chemical formula is C2O2(OH)2. Oxalic acid chemically combines with metals in the body, mainly calcium and magnesium – making them unavailable to be absorbed. Also, oxalate crystals can be sharp and irritate various body parts – you’ll relate if you’ve ever had a kidney stone, most of which are calcium oxalate.[i]

Understanding the role of oxalic acid is important because we’re always trying to keep our birds’ calcium levels up, particularly during the breeding season.

By the way. There will always be variations in the amount of plant oxalate because of planting and growing conditions, harvesting styles, and whether you’re feeding the leaves, stems, or roots. But in general the foods we need to watch are spinach (1400 mg/cup) and maybe beet greens*, the two with the highest oxalate levels.

There are many foods that contain some level of oxalates. (Here are a few in a chart) There are also other chemicals, like phytate (available in grains) that also decrease the body’s absorption of calcium.  But calcium is controlled by hormones, and can be reabsorbed if needed – for example, during egg-laying. The chemical reaction that happens when your bird eats spinach will not leach every bit of calcium from his body. It simply takes away some of the immediately available calcium.

How to Use Them Wisely

Does this mean we should never feed spinach to our finches? I like to buy big bags of baby spinach leaves, and I usually have them around. So not feeding them to the birds means I have to go buy something different for them. Well, it turns out I don’t have to eliminate spinach from their diet, and neither do you.

When trying to offset or reduce these oxalates, it’s easy to minimize the effect by providing lots of other greens, particularly dark green vegetables. We can overcome the binding effect of oxalic acid. We won’t eliminate it, if we’re feeding any foods that contain it. Rather, offering many different foods will minimize its importance. [ii] Variety, as I have said many times, is key to a ‘good’ or even ‘GREAT’ Gouldian finch diet. Nutrition will influence the lifespan, health, and appearance of your Lady Gouldian Finches.

• I’m saying beet greens are a maybe because one source listed them at over 500 mg/cup, and another said just 171 mg/cup. This is one of our problems – the lack of correct data.

[i] Oxalicacidinfo.com, accessed 8/2/21.

[ii] Nutritional Considerations section I: Nutrition and Dietary supplementation, Debra McDonald, Phd.