“What’s the cause of infertility in parrots?”
By Tony Silva
Infertility is the vane of the breeder. There is nothing more disheartening than discarding a clutch of eggs because they are infertile. This problem of infertile eggs affects all species but is most common in macaws, amazons, and Eclectus Eclectus roratus parrots. Indeed on a daily basis, I receive messages from breeders across the globe describing the frustration they feel at the number of infertile Eclectus eggs they discard. No one has a secret elixir that can guarantee success. Rather it is often changing husbandry principles, improving diet, dealing with subclinical health issues and treating these, or providing the birds new mates because they are incompatible that leads to success.
Let me address each issue separately:
Parrots have evolved to fly, explore, and to interact. Very few species are solitary. Kakapo Strigops habroptilus live as isolated individuals, but virtually all other species live in pairs or more commonly in groups. In all groups, mates are carefully selected—they are just not found by coincidence. As an example male Kakapo employ a unique display to attract females, who may find the display attractive and permit mating or reject the advances. This is how a solitary bird finds and then selects a male. Allowing a pair to select their mates is often the key to success. A male that a female does not find attractive may be rejected.
As an example, I have a Scarlet Macaw Ara macao who had 5 potential partners, each one selected by the breeder and offered in succession. She never produced fertile eggs with these. When I purchased her, I offered her three available males at once.
She picked one almost immediately; she climbed the perch, they opened their wings, screamed, and began to preen. Seventeen days later she produced a fertile egg—the first out of 67! Infertility is often as a result of two incompatible birds living peacefully but not amorously together.
Parrots are active. In a cage, sedentary life is often the norm. The birds become bored. By adding enrichment, toys, providing a larger aviary that meets their biological needs (parrots that are arboreal do well in a suspended enclosure while terrestrial species may be stressed when they’re unable to forage on the ground) and offering a surrounding that is conducive to breeding, one can turn a pair of birds that are indifferent to each other into a bonded pair that mates and reproduces successfully. In conures and caiques (Pionites), for example, providing enrichment strengthens the pair bond, and having others of their kind that they can see and hear has a cascading effect: pairs that may be apart and indifferent to each other will suddenly bond well in order to challenge the other pairs. Part of the act of maintaining the pair bond is mating.
We have found that in Galahs if we do not provide many fresh branches and fill the nest with wood to the entrance, infertility is a problem. By providing both the wood and fresh leafed branches, the male and female must work together at making the nest accessible. They must evacuate the clutter, which must first be chewed, and finally, they must make their nest of leaves. This activity brings a pair of birds into direct contact for quite some time, heightening sexual activity.
Wild parrots do not find a readily suitable nest where the hen can lay. In the wild, they must not only find a cavity where they can bring forth their young but must prepare it to make it suitable. By adding wood chunks to the nest—nature does not provide sawdust or shavings for them to lay on!—the pair are forced to spend many hours making the nest suitable; they must chew the cavity to enlarge it. This darkness has been found to induce gonadal development. Almost two decades ago I had pairs of Blue and Gold Macaws Ara ararauna endoscoped during the breeding season. Three pairs were offered a standard nest with shavings and three pairs were offered nests filled with wood. The pairs offered shavings in their nest displayed poor gonadal activity, while the pairs that were forced to spend time in the dark nest preparing it had gonads that were engorged. Fertility was almost a third higher in the latter group than in the former group.
In some species (amazons, for example) males appear to stimulate each other by both visual and vocal contact. Once actual breeding approaches, the pairs should be visually blocked but still allowed vocal contact. In a group that is notorious for laying clear eggs, this has helped produce far more fecund eggs than simply keeping one pair per aviary away from each other.
In Eclectus, the female is dominant. She is fed by and mates with multiple males. This contact with multiple males prevents her from terrorizing a particular male. In groups that have been poorly productive, it is possible to construct a tunnel that gives access to multiple cages, each containing
a nest and box. The females tend to take up residence in these cages while the males freely travel in the tunnel to visit, feed and mate with the various receptive hens. This mode of housing can make a collection of Eclecus become productive. Also, in this species the dominant female, when imprinted, often becomes even more aggressive. To prevent these problems, pairs should be formed from a young age, allowing them to mature together. The male then understands the specific behavior of the female, losing to a degree his fear of her.
When colony breeding Eclectus using the above cages, make sure that all the birds are of the same subspecies, as Eclectus hybrids should not be produced.
Having a basic understanding of the biology of the parrots that you are attempting to breed is key to success. It can mean the difference between fertility and infertility in the clutch.
In aviculture, it is common for the breeder to try to manage all birds in the collection using the same diet. This simplifies the daily care. Unfortunately, not all parrots are the same. The Galah Eolophus roseicapillus has evolved to feed on low-fat grass seeds while the large macaws have a beak that developed to crush hard palm seeds, which are fatty. The two species cannot be fed the same.
Feed a Galah a diet high in fat and the birds will become obese, this affecting fertility. In contrast, fertility can also be affected when a macaw is fed a diet low in fat. Providing the proper diet is key to success.
This means having a basic diet of a good seed mix or pellets, but varying this to meet the biological needs of the species; as an example, a seed diet with virtually no sunflower or safflower seeds would be provided to the Galahs while a diet with a higher component of these seeds would be acceptable for macaws. Pellets are also available in higher and lower fat content types and these could replace seeds for most species. Adding vegetables, fruits, nuts, whole grain bread, and greens, amongst a lost list of items, to provide the individual requirements of the species is important to balance out a diet.
When a pair has produced in the past but suddenly starts laying clear eggs, or the eggs contain fine bubbles, or the pair is compatible and paired from a group but lays only clear eggs, I would look for disease. Culturing from a swab taken from the mouth and another from the cloaca can often reveal pathogens that affect fertility. In such cases, the culture and sensitivity will identify the best drug to use. We invariably culture birds that produce clear eggs and in 37% of the cases have found a pathogen that when treated resulted in the pair producing viable eggs.
If two birds are incompatible, they will not breed successfully. Sitting on opposite perches, feeding independently of each other, forcing the other bird to move away when one bird moves across the cage and outward aggression will rarely produce fertile eggs. With such birds, offering them new mates is the best course of action and will eliminate years of eggs being tossed in the trash bin because they are infertile.
As can be seen from the above, many factors can contribute to failure. Identifying and correcting these is always a challenge, but when this obstacle is overcome, the gratification that the breeder receives is part of what makes aviculture so fascinating.
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