Dr Mac's - Why Organic

Clearly it is cheaper and easier to source conventional ingredients but our environment is already polluted by synthetic contaminants, many of which will not break down in our lifetime and will persist in the soils and waterways for many years to come.  Low concentrations of pesticides in foods may not have any significant impact on the health of birds, but most of these pesticides are fat-soluble and may accumulate in the body of birds to toxic levels.  Alternatively, individual pesticides may not be harmful but in combination with other pesticides, they may have an additive or synergistic effect and unexpectedly become toxic.

We are all familiar with the detrimental impact of pesticides such as DDT on the thinning of eggshells of birds.  The use of these chemicals has been banned in many countries but residues still persist in soils and many farmers still have old stores of these chemicals that they continue to use.  Pesticides can have subtle effects on health and reproduction but we rarely acknowledge the impact on behavioural attributes.  These include:

• Reduction in courtship behaviour (including reluctance of females to take food from males)
• Changes in activity patterns of males
• ↓ levels of nest defence
• Alterations in incubation behaviour
• ↓ parental attentiveness resulting in ↑ embryonic mortality
• ↓ time feeding young
• Fewer sorties to feed young
• ↑ time away from nests

In addition, pesticides can impact on a number of physiological traits including:

• ↓ production of androgen in males
• ↓ production of oestrogen and progesterone in females
• ↓ production of thyroxine (a catalytic hormone released by the thyroid gland)
• Hyperparathyroidism (results in calcium deficiencies)
• Changes to metabolism of steroid hormones