Chris,
That is interesting, but the birds in question are insectivores and mostly
eat spiders around breeding time. To me, it stands to reason that beef lard
and peanut cake do not in any way resemble spiders, nor even the usual food
provided by bird feeders. I have never encountered or even heard of peanut
cake before this study, and it is reasonably well know that fat is not
something you feed to insectivorous birds.
On Wed, Jun 2, 2010 at 9:48 AM, Chris Lloyd <> wrote:
> My understanding was that the outer layer of the exoskeleton of an
> arthropod was chitin, a protein carbohydrate compound secreted by the
> epidermis. There is very little calcium (0.1 to 0.3 - if any at all) in the
> exoskeleton or attached muscles and organs of most insects. The exception
> being the crustaceans which reinforce the chitin structures with calcium.
>
>
>
> Most growing chicks require calcium at a rate of approx. 1-1.5% by wet
> weight. My understanding is that most adults supply calcium to chicks by
> gape feeding (Passeriformes, Coraciiformes, et al) by being fed available
> calcium carbonate (e.g. bone, crustacean shells, eggshells etc.) or it comes
> in the supply of whole animals (i.e. skeleton contained) with birds such as
> fish eaters and raptors.
>
>
>
> There is probably more calcium in some bird feeder material (e.g. dog
> kibble, some seeds) that most insect if the above is correct. This by no
> means should be read as support for bird feeders in Australia – I don’t do
> it for a range of reasons not the least of which is the way it may distort
> population structures.
>
>
>
> Chris Lloyd
>
>
>
> [image: Logo v5]
>
>
>
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