Chronic egg laying occurs when a female bird lays more than the normal number of eggs or more commonly has repeated clutches of eggs, especially in the absence of a mate. Certain pet birds, such as cockatiels, lovebirds and budgerigars tend to be more prone to becoming chronic egg layers. However, any species of bird can develop this problem. Hand-raised, single pet birds, who use their owners as a mate substitute, commonly become chronic egg layers.
Chronic egg laying is caused by a failure of the bird’s hormones to “switch off” egg laying at inappropriate times. This may be due to a number of different factors. Inappropriate day length is one contributing factor to chronic egg laying. Birds are genetically programmed to lay when summer approaches and the days become longer. Pet birds that stay up late with their owners are always in an artificial state of summer. .
High fat diets, seasonal changes from cooler to warm weather and from prolonged dry spells to increased periods of rainfall can also trigger the single pet female bird to lay. These factors once again create an artificial spring/summer state when the temperature is warmer and food is abundant.(ideal conditions for raising chicks) However, one of the main contributing factors to the chronic egg laying syndrome is the single female bird that is strongly bonded with her owner.
This bird will be inadvertently stimulated by “courtship” type behaviour with the owner e.g. mutual grooming or preening, taking food from the owner’s mouth, being stroked on her back and under her wings. These types of behaviours can trigger a hormonal response which results in egg laying.
Chronic egg laying can cause metabolic exhaustion in the bird. The bird’s calcium level is depleted and hypocalcaemia (low blood calcium) may result. With the calcium at a low level, uterine muscles are unable to contract to enable the egg to be laid (egg binding). This is a serious problem which requires veterinary intervention. Other serious health problems caused by chronic egg laying include; retained eggs, egg related peritonitis, uterine prolapses, seizures and death.
There are a number of changes that an owner can institute at home in order to prevent the cycle of chronic egg laying. Make sure that the bird has a nutritionally balanced diet at all times; add extra calcium supplements during the egg laying period. Do not remove the eggs as they are laid, as this can actually encourage the bird to lay more eggs.
Leave the eggs in the cage for three weeks so the bird knows that she has a clutch. This may contribute to her “switching off” her egg laying/hormonal activity. Decrease the “day-length” time of your bird. Optimally, parrots require 12 hours of light and 12 hours of dark. Their 12 hours of sleep time should be uninterrupted – the cage should be placed in a dark, quiet room. Shorter day lengths create an artificial winter and help to stop hormonal/egg laying activity.
Discourage mating behaviour with the owner (vent rubbing, tail lifting, regurgitating food). Where practical or possible obtain a suitable mate for the female bird and allow her to go through a full breeding cycle. This only works in younger birds who have not become to mal-imprinted on their owners.
However, if these measures do not stop the chronic egg laying behaviour, veterinary intervention may be necessary. Hormone treatment can temporarily stop the egg laying. However, prolonged hormone therapy is not without side effects. In some cases a hysterectomy may be warranted.
Behavioural consultations may also help the owner to understand the reason for chronic egg laying and take steps to prevent it.