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Providing a nutritionally balanced diet is crucial to any aviculturalist, to maintain a healthy flock of birds. Many questions regarding nutrition's role in the successful reproduction of wild caught parrots have yet to be explored. Following the formulation of a seed kernel/nut/dehydrated fruit/vegetable and grain mix, Hagen's Gourmet Parrot Mix, a study was conducted to estimate the potential reproductive stimulation which could result from providing food in a varied form versus only in a formulated uniform granule.
The following data was collected during the summer months (May-October 1994), at the Hagen Avicultural Research Institute (HARI). Following a simulated winter season (dry & cool, short 8 hour days) in our indoor facility, 82 pairs of parrots (refer to Table #1 for species composition) were introduced to our outdoor breeding aviary. Each flight cage (8 ft long x 30 in.wide X 4 ft high), was equipped with a wooden nest box (12x12x24 in Amazon species, 10x10x24 smaller species), plywood panels along the back side to minimize disturbance around nest boxes, natural perches, supplemental water sprinkler (on hot days), water bowls and automatic gravity feeders for the formulated diet.
Pairs were selectively divided into 2 groups to allow this comparative study. One group was maintained on the Tropican High Performance Diet, and the other group was offered an additional diet, the Gourmet Mix containing seed kernels, nuts, dehydrated fruits and vegetables, and also Tropican granules as a source of calcium and other nutrients missing in the base mix.
Every attempt was made to eliminate variables and have a control group to compare to. Selection of the pairs took into consideration previous reproduction records, laying pairs, and the housing method each pair had been subjected to during the previous winter season. Several amazon species had been split into two different winter housing: some pairs were colony housed, with three pairs per aviary, to simulate the natural flocking and mate selection; while other pairs continued to be housed individually. These variables were equally distributed between the two feeding methods, to try to eliminate any biased results.
Table 2 summarizes the summer production on the two feeding methods in this one outdoor aviary at HARI. A total of 32 pairs out of 82 (39%) laid eggs. It appears that significantly more pairs laid eggs when they were fed a bowl of the Gourmet mix versus only the Tropican. However not all the birds given this bowl actually consumed it; 11 pairs out of 42 did not (Table 5). In fact within the non-Amazona group a significant number of pairs (9 out of 11 pairs) did not really eat it whereas only two pairs of amazons out of 28 pairs given the gourmet mix did not eat it. It was the Tucumans that did not.
Colony housing half the pairs of three species of amazons did not appear to increase their fertility or the number of pairs that would breed (Table 3). Most of the pairs colony housed remained with their previous mate within the colony aviary. Two pairs out of 11 colony housed did pair bond with a different bird during the 3 months of flocking.
When comparing the reproductive success of amazon versus non-amazon species (Table 4) the infertility often associated with Amazona species is apparent. Many of the amazons laid eggs two to three weeks after being moved outside, whereas most of the non-amazon species bred later in the summer. The first 10 or so pairs to breed outside laid clear eggs with half of the pairs laying over the whole summer having infertility.
Nutritionally it is very difficult to say what individual birds were getting out of the Gourmet mix. Selection of the many different ingredients definitely occurs. A higher level of fat intake probably occurs since the mix analyses out at 13 % fat and some of the lower fat ingredients are left uneaten. Protein levels as a function of caloric content (better indicator of net protein intake per day) are low. Legumes do not make up a significant portion of the Gourmet mix and could add protein to the diet without too much supplemental fat. Dehydrated fruits and vegetables contain mostly simple carbohydrate and very little of the nutrients missing in seed kernels and nuts, such as calcium, essential amino acids and many of the vitamins.
Even more difficult to measure is the psychological stimulation that varied diets may provide. A misconception that varied diets are more natural is prevalent within aviculture. Most wild species eat only a few different types of palm nuts during the year and never eat sweet fruits such as those grown commercially for human consumption. Parrots are seed and nut predators. They kill the future offspring of a tree. So why would a nut tree produce sweet fruit to attract parrots? Fig trees do attract birds by producing edible fruits but these trees produce small seeds that are not broken open by soft bill type birds, are undigested and then get deposited elsewhere in the forest.
There is no doubt that many pet birds given sweet, moist human table foods enjoy and look forward to their human companions serving up these foods. But is this learned behaviour or natural? Branches, rawhide chew toys, bells and other non-food items which entertain captive parrots may provide the same mental stimulation as a varied diet without the labour, mess, possible source of fungus and bacteria, vermin, bugs etc.
The dryness of the food, the lower location in the cage and the shyness of certain pairs may be the reason for many of the non-amazon species not to eat from the supplemental bowl of Gourmet mix. Hot water can be added to a small portion of this mix to rehydrate the ingredients and thus increase palatability.
The high infertility within the amazons is an ongoing concern. Perhaps the male amazons need more time to come into season. Next year we will put half the male amazons outside two weeks before their mates. Hopefully this will allow them to become sexually active before the female lays her eggs.
There is also still great potential in increasing the total number of
pairs breeding with only 16 out of 82 pairs fertile (19.5%). More than
80 percent of this flock are not breeding for whatever reason. Personally
I believe that stress related to environment, experience, maturity and
many other factors besides diet are the reasons for this. Increasing the
fertility of those pairs that are at least laying eggs is the first step.
Also increasing the number of pairs of those species such as the Hahn's
Macaw which does breed well in our aviaries instead of more difficult
to breed species such as Caiques, some types of amazon, Red-mask Conures
etc.. will also help.
Mark has a Master of Agriculture from the University of Guelph and specializes in Psittacine Aviculture. His continued Research includes Nutrition, Incubation and other Psittacine Aviculture research projects.