COPING WITH INFERTILITY
by Dr Brett Gartrell BVSc (Hons)
This article covers the following areas:
Infertility is the failure of a pair of birds to produce eggs with a
viable embryo. It differs from low hatchability where eggs are laid fertile
but subsequently fail to hatch.
You can differentiate between poor fertility and poor hatchability by
doing egg post-mortems and by egg candling. These are both simple to perform
and I encourage you all to try them and use these techniques regularly.
The only place where candling is not applicable is with pigmented eggs.
CAUSES OF INFERTILITY
Gender and Behavioural Problems
Twin Yellow-tailed Black Cockatoo Embryos, Calyptorhynchus
Photo by & courtesy of Garry & Shirley Walsh, Westbrook,
- Homosexual pairs in sexually monomorphic species suggest surgical
sexing or DNA sexing of all infertile monomorphic pairs.
- Birds can go through all the actions of a heterosexual pair and can
be very strongly bonded even if homosexual.
- Incompatibility - mate selection is best left to the bird unless desperate
for a particular pair to mate. A system of a central cage with a number
of potential mates in adjacent cages has proven effective in Amazons
or colony selection.
- Check birds are not bonding with adjacent birds- if they are, separate
them - they must be away from sight and sound of their old partners.
- Mate presence or absence - may stimulate fertility by removing partner
in non-breeding season and returning at same time as nestbox placement.
- Both visual and auditory signals between mates may be necessary to
- Lack of pair bonding - signs of good bonding includes mutual preening
and feeding, strong combined territorial defence, nest box inspection
Hen Pied Elegant
(Neophema elegans)in the process of laying
Photo by & courtesy of
Mick Blake, Rockhampton, Qld
If available, setting up a video camera to watch a pairs interactions
when left alone can be very informative about the state of the pair bond.
Immaturity - be aware that each bird is not going to reach sexual maturity
right on the breed average. Some birds are late developers. Younger birds
also need more stimuli to breed. Older experienced birds will commence
breeding much more readily. Inexperience contributes to infertility. Mistakes
are made in courtship, mating and nesting. Style improves with age.
- Senescence- failure to breed due to advanced age is uncommon in aviaries
even if it is common in aviculturalists. This may change as husbandry
methods improve and the bird population ages.
- Imprinted birds - hand raised birds may be bonded to human hands,
toys, mirrors etc.
- Fostered birds may become imprinted on the wrong species.
- Improper behaviour.
- Hand raised birds may be ignorant of the correct social signals to
send or be unresponsive to courtship signals
- Neurotic and psychotic birds certainly exist, especially among Cockatoos.
These birds are best removed from a breeding program.
- Aggression - more common in certain species, e.g. Major
Mitchells. May be due to one mate becoming sexually active before
the other. Can occur in pairs that have been together for years and
bred successfully. Harsh lighting or excessively long daylight hours
in indoor enclosures can contribute to aggression. Strategies to overcome
- wing clipping the aggressive partner.
- providing escape routes/safe areas for the victim by isolating a
perch with unclimbable sheet metal.
- placing escape hatches at bottom of nest boxes.
- keeping mates separate till breeding season.
- keeping potential mates in colony situation till mature.
- re-pairing when necessary.
- Length of daylight (photoperiod) is less important for tropical species
but in birds from temperate areas increasing daylight hours can stimulate
the production of reproductive hormones and breeding behaviour.
- If long daylight hours are maintained for long periods (months) the
birds response will diminish over time.
- Temperature - extremes will cause temporary infertility.
In some species climate changes are the stimulus for breeding, especially
tropical and desert species. Some of these birds can be stimulated into
breeding by using misters during the breeding season.
- Season - the more domesticated the species the less important this
becomes. Most species will nest more than once if all other conditions
- Other birds- presence of other breeding birds is a necessary stimulus
in social and colony birds.
- Proximity of other pairs can reinforce the pair bond by stimulating
territorial defence. However, excess time spent in defence can result
in lowered fertility.
- Human and other animal interaction - if birds are stressed by human
presence then this will limit fertility. Either condition the birds
with regular interaction or isolate them.
- Limit visitors and disturbances during breeding season.
- Noisy, ill trained dogs are more hindrance than help.
- Predators such as cats, hawks, rodents and snakes must be kept out.
- An important point is that the birds proper response to invasion
should be aggression not fear. Fear may be an indicator of inadequate
- Nests - the appearance of the nestbox and nesting materials can be
a powerful stimulant to reproduction if placed at the commencement of
the breeding season. Placing a nestbox with a smaller than required
hole will sometimes encourage pair bonding through the nest hole widening
process. The placement of the box, its design and materials can also
- The relationship of the exterior perch to the nest box is important.
All perches should be firmly fixed to enhance feelings of security at
the nestbox and also for mating.
- Enclosure design - size should ideally match the birds natural territory,
too small will cause insecurity, if too large, excessive time will be
spent on territory defence. The enclosure should enhance feelings of
security especially with regard to perches, nestboxes, screens, walkways
and feeding platforms.
- Inadequate dietary calcium, sodium and energy can interfere directly
with egg laying and fertility.
- Excesses - over supplementation of zinc can cause infertility.
- Obesity - causes problems with egg passage, mating and decreases ovulation
especially in Galahs, Budgies, Amazons and Macaws. Best solution is
to withhold protein supplements in non-breeding season and allow flighted
- Variability - increasing the variety of foods fed can stimulate fertility.
- Flushing - this is the practice of increasing the energy content of
the food fed as the breeding season approaches. It aims to mimic the
natural abundance of food that is a trigger to reproduction in most
species. Can increase the number of eggs ovulated.
- Feed quality - aflatoxins (fungal by-products) in seed can lower fertility.
- Inbreeding - with increased levels of inbreeding the greater chance
there is that gene defects will be expressed. It can cause lowered semen
quality, abnormal mating behaviour, more physical defects, and more
behavioural defects. To illustrate the point, 20 lines of inbred mice
were monitored over several generations. Only one family survived to
ten generations, the other nineteen died out.
- Conformation - some species have been breed so far from the wild type
they have become physically unable to breed eg turkeys, budgies
- Hybrid eggs - have a low hatchability.
Black Cockatoo Hatching
Photo by & courtesy of
Garry & Shirley Walsh, Westbrook, Qld
- Poor condition for whatever reason.
- Overuse of medications - Doxycycline lists amongst its side effects
a lowering of male fertility.
- Use of sex steroids always lowers fertility (for example body builders
on testosterone have the nickname of "sultana nuts").
- Reproductive disorders
- Physical impairments
Talk to your avian vet - there are many
factors which contribute to infertility. Its not always the birds
fault, so take a good look at your management practices and try a few
things before writing a pair off. May we all look forward to a good breeding
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