Breeding Disappointments

nesting masked lovebirdsThere are a number of reasons for infertile eggs, and in virtually all cases, the cause is not an infertile male, but usually, the management of the birds themselves. If mating is made more difficult for any reason, then the likelihood of infertile eggs will be significantly increased.

One of the defining characteristics of birds is that they all reproduce by means of eggs, which have a hard, calcareous shell. Yet just as in so many other aspects of their biology, the reproductive system of birds is effectively slimmed down, reducing its weight and thus facilitating flight.

This is most obvious in the case of the hen. Although as with mammals, there are right and left ovaries and corresponding oviducts, adult hens rely entirely on the left side of this system for breeding purposes, with the right side normally never developing.    

In the case of male birds, there is no actual penis either, although in a few groups such as waterfowl, there is a slightly swelling which aids the transference of sperm during mating. Otherwise, mating relies entirely on sperm passing directly out from the male’s cloaca through into the female’s vent, and travelling up the oviduct. 

Infertile eggs

There are a number of reasons for infertile eggs, and in virtually all cases, the cause is not an infertile male, but usually, the actual management of the birds themselves. If mating is made more difficult for any reason, then the likelihood of infertile eggs will be significantly increased.

As a result, some canary breeders like to trim the vent areas of their birds when placing them in the breeding cages. This is thought to improve the likelihood of successful mating, by removing the dense covering of plumage here which could otherwise prove to be an impediment.

It is more important however, especially in breeding cages, to ensure that the perches are fixed firmly in place. Otherwise if these are loose, the hen will have difficult in supporting herself with the cock bird balanced on top of her, causing mating to be unsuccessful.  

Another consideration is the stage at which the pair are introduced to the breeding cage, particularly in the case of budgerigars. If this is left too late, the hen will retreat to the nestbox immediately, giving her prospective partner little opportunity to mate with her.hen budgerigar in breeding condition

As a guide therefore, do not wait until the hen’s cere coloration has become deep brown (see right), but transfer her to the breeding cage at the stage when it is darkening in colour. You can also shut off the nestbox for a week or so after introducing the pair here, which should encourage successful mating. 

Only one mating is normally required to fertilise a clutch of eggs, with the sperm potentially remaining viable in the female’s reproductive tract for three weeks or so. If you are breeding birds in aviary surroundings, this create the possible problem that you cannot be sure of the parentage of chicks, because it is not uncommon for hens to mate in quick succession with more than one cock bird. As a result, a nest of chicks may not all be fathered by the same individual.

Compatibility

Lack of compatibility can also be a problem, even sometimes in budgerigars, although it is more often encountered in larger parrots which form what potentially can be a life-long pair bond. Grey parrots (Psittacus erithacus) which are incompatible are likely to just ignore each other, and often under these circumstances, instead of producing infertile eggs, the hen will not make any attempt to lay.  grey parrot compatibility

As a result, proven pairs which are known to be compatible will attract a premium price, compared with those which are simply DNA-sexed. Reaching a decision on compatibility can be difficult however, and should not be rushed, simply because larger parrots in particular are often slow to settle in new surroundings.

This process may take two or three years at least, but watching the behaviour of the parrots ought to give some clues as to whether they are agreeing well. Following each other around the aviary, plus feeding and preening together are all encouraging signs.

Should you have a doubt however, then swapping the birds round can resolve the problems : sometimes very rapidly. In one case for instance, a grey parrot hen was incubating what turned out to be fertile eggs within a fortnight of being provided with a new partner. She had steadfastly refused to have anything to do with her previous mate for five years.  

It’s always a difficult decision to take this step though, so keep thinking whether there could be something in the environment that is stopping the birds from breeding, assuming that they are receiving a good diet, including a supplement when necessary. This will allow you to focus on their surroundings.

Perhaps they are nervous and there is a lot of disturbance in their immediate vicinity, such as cats, foxes or squirrels climbing over their aviary? The position of the nestbox can be especially critical to breeding success. Although Australian parakeets will often breed in the open flight, many other parrots prefer having a nestbox located in the privacy of the shelter where it is also darker. If in doubt, it is a good idea to offer the pair a choice of nestboxes from the outset.  

Pair of ringnecksAnother problem which can arise is that the pair do not come into breeding condition simultaneously. Not all parrots for example form a lasting pair bond, as in the case of the ring-necked parrakeet (Psittacula krameri) and related psittaculids. The hen bird (with wings outstretched in this photo) is dominant outside the breeding period, to the extent that the male (with the neck collar) may be reluctant to approach her.

Under these circumstances, mating may simply not occur. Although it is advantageous, especially for the breeding of colour mutation, to be able to swap partners without difficulty, it is better not to pair a young cock with a mature hen, who may intimidate him.