Maintaining insectivorous birds in captivity – Part 1

Being fully aware as I am of my inadequate knowledge on the nutrition, care and breeding of the white-rumped shama, I am always on the lookout for sources of information that may usefully add to what I know.

This morning, I came across an article entitled, “Maintaining insectivorous birds in captivity” by Kerry A. Muller. He holds the title of Curator of Birds, Taronga Zoological Park Trust, Sydney, NSW, Australia.

My interest was piqued as the title and the author’s job description suggested that useful information might be gleaned from the article. Unfortunately, articles in academic publications cost an arm and a leg to download and this was no different. I reluctantly paid the equivalent of S$40.00 for the online article of 7 pages without being sure that it would indeed contain useful information.

The value of such articles  is not so much that they provide information which can be applied immediately, though in this case there was an appendix to the article that contained some proven diets for insectivorous birds and which I will include in Part 2 of this post. More importantly, such articles may serve to prod the mind to contemplate on matters that would not otherwise have been given a thought to.

I would like to share some aspects of the article and my thoughts when reading it.

Kerry notes that the diet for captive insectivorous birds usually consists of a combination of insects and an artificial insectile mixture. He then observes that “Birds fed on insects alone almost invariably decline and in time die.” The question that immediately springs to mind is “Is this true” and “Why is this so?”

I think that what Kerry meant is that captive insectivorous birds that are fed only insects do not do well over extended periods because the very limited species of insects that are available to the owner of such birds are unable to fulfill all their nutritional requirements. I came to have an understanding of this many years ago when I tried to apply to my shamas what I had learnt from Robert Black’s “Avian Nutrition”.

I should say at the outset that I found the book to be extremely informative and I did learn a lot from it. However, there was one aspect that Black seems to have got wrong. He had stressed the importance of Vitamin B but he concluded that birds that are fed live insects would not require Vitamin B supplementation as this vitamin would be sufficiently supplied from the live tissues of the insects.

At that time, my birds were fed a diet comprised of pineapple beetles, fish, frogs, mealworms and crickets, all of which were captive raised. In addition, I supplemented with vitamins, minerals and also Vitamin B. They were doing alright although I felt that they were not in as good form as they could be.

What Black wrote seemed reasonable to me and I stopped supplementation of vitamins and minerals. A few months thereafter, some of my birds had fits that were caused by a deficiency of Vitamin B. How, did I know this? Well, I suspected this was so and I fed the Vitamin in liquid form to the affected bird. Within a few minutes it recovered. 

After some thought, I concluded that Black was likely to be correct only with regard to birds that have the opportunity to feed on a wide variety of free ranging insects as occurs in the wild. In captivity, the available insects and other live food just do not provide the amount of Vitamin B (and possibly other vitamins and minerals) that the bird requires and intelligent supplementation is required.

With the above in mind, I thought I could understand and agree with Kerry’s comment that captive birds that are fed only insects will invariably decline and in time die. What then should be done? I would think that we should first seek to determine what is lacking in the live food that we provide to our birds and try to improve the quality of the live food itself if we can.

Kerry mentions that captive raised insects have a very low content of calcium, phosphorus and vitamins D3, A, E and B complex. This was in line with my experience. Kerry also mentions that such insects are lower in protein and fats and especially lower in carbohydrates than might be expected.

To remedy the deficiencies, I should note that the quality of the captive raised insects may be enhanced by providing food to them that will in turn improve their quality as food for our birds. Take crickets for example. When purchased from the supplier, they normally come in a container with some newspaper. The newspaper is intended as bedding material – somewhere for the crickets to hide. It is not meant as food for the crickets although new owners of insectivorous birds will often not feed anything else to the crickets.

What I do is feed my crickets with pellets intended for chickens. This is the same food that the owner who farms the crickets feeds them. I buy the pellets from him at S$1.00 per kilo. In addition to the pellets, I feed carrots, apples, oranges and other vegetables and fruit to provide moisture and nourishment. The cost is not as extravagant as it seems since I can get 4 to 5 slightly damaged apples from the NTUC outlets at S$1.00 per bag.

I recently imported a 5 kilo bag of dry food from Wombarroo, Australia, that was especially formulated for feeding crickets. It was a trial order that is unlikely to be repeated because of the cost. Anyway, the pellets for chickens are probably a suitable substitute.

With regard to mealworms, the shop feeds them with bran but this has little food value. It’s much better to feed oats to them. A large tin of Nestum costs only S$4.00 and lasts a long time. Just as with the crickets, also provide fruits and vegetables to the mealworms.

Kerry observes that suitable commercial mixtures in the West are usually known as “Mockingbird food”. When offering such food it is usual to supplement with raw ground beef or beef heart and boiled egg yolk as well as adding insects. 

Kerry also notes that “It has been suggested by some nutritionists that the proteins and sugars that are obtained from the amino acids of insects may differ considerably from those of mammals, and that their absorption and utilization by insectivores may incorporate complex biochemical processes not yet fully understood.  However, Kerry further notes that insectivorous birds do much better in captivity than insectivorous mammals and he suspects that the problem lies more in management than in nutrition.