AVIAN HEALTH WITH DR BOB
AUTHOR AND IMAGES DR BOB DONELEY BVSc FANZCVS (Avian Health)WINTER IS UPON US and, for the most part, our birds have lost
interest in breeding for the time being. This is our ‘make and mend’
time, when we take stock of the last breeding season, look at our
successes and failures, and learn our lessons from both. It is the
time when we start to plan for the next breeding season, only a
few months away, and get a lot of repairs and maintenance done.
As we start our planning, it is wise to go back to basic
principles—why do birds breed? Keeping those principles in mind
helps us focus on what we need to do for a successful year.
WHY DO BIRDS BREED?
Most of our parrots are seasonal breeders. Some, however,
notably Budgerigars and Cockatiels (both arid zone birds), are
opportunistic, breeding whenever conditions appear suitable. So
what triggers seasonal (and opportunistic) birds to breed?
Basically, it revolves around the evolutionary concept of
continuing generations. In other words, birds will breed when they
instinctively feel their offspring have the best chance of survival.
Day Length
The fi rst trigger is increasing day length and warmer days. The
Winter Solstice is 21 June—the longest night and shortest day of
the year. Every day after the solstice is a longer period of light
and, with that, come warmer days. These changes are perceived
through the bird’s eyes and skin and begin a hormonal cascade
that starts the bird’s process towards the coming breeding season:
- The prenuptial (or pre-breeding) moult occurs. Although this
is most obvious in softbills such as wrens, even parrots will
undergo a heavy moult in late winter to early spring as they
discard worn and tattered plumage and replace it with new
stronger and brighter feathers. - Calcium is stored in the bones of females, forming a reservoir
for egg shell production. - The gonads (ovary and testicles) begin to enlarge and start
to secrete some of the sex hormones that not only prepare
the body for reproduction but also direct the bird’s behaviour
towards courtship and nest selection and preparation.
Rainfall & Plant Growth
The next triggers revolve around the availability of food. Rainfall
comes fi rst. This is a powerful trigger for opportunistic breeders
such as Budgerigars and Cockatiels. The rain brings forward the
growth of food plants which begin to fl ower, germinate and grow
fruit. There is an abundance of high-energy foods which are needed
to sustain not only the parents but also their chicks in the nest.
Finding a Suitable Mate & Nesting
Next comes the availability of a suitable mate. We don’t really
understand what parrots fi nd attractive in other parrots but we do
know that in other species it is all about fi nding a virile partner, a
good provider and a good parent.
Many parrots are monogamous, choosing a mate for life, but
others may change their partners every season. Once a pair has
bonded, the courtship behaviours begin. The male feeds the
female, prepares the nest site, and defends their breeding territory
against all comers. As he does this, more hormonal cascades are
beginning, further heightening his desire to breed. It is obvious
that the female feels the same way, as she starts to become
‘clucky’ and her reproductive tract develops even more.
So the surges and urges are there—all they need is a place to
do the deed. In the wild, a pair of birds may return to the same
nest hollow year after year. In some cases they rarely move too
far away. The nest site has to be prepared—cleaned out, wood
chips chewed to form a suitable substrate, and potential predators
chased away.Mating & Chicks
All of these triggers begin to synchronise and the result is that
courtship gives way to mating, and egg-laying. Behaviours change
again as one or both birds begin to incubate the eggs and then
rear the chicks. Once the chicks are fl edged, and if the season
permits, the whole process can begin again. A second clutch can
be laid, incubated and reared.
It becomes obvious as you read this that there is a complex
interaction of events and triggers that lead to success in breeding.
If anything is amiss in this interaction, there may be a fl ow-on
effect that disrupts the whole breeding season, resulting in few
or no chicks. It is our job, as aviculturists, to try to ensure that
nothing does go wrong. And now is the time to do that—the
middle of the breeding season is too late!WHAT DO I NEED TO DO?
Review these factors, and make sure you have done what you can
to ensure their readiness:- Photoperiod and temperature
- Rainfall
- Diet
- A suitable mate
- A suitable nest site and
- Catering for territorial behaviour.
Photoperiod & Temperature
For most Australians, little can be done to control day length and
temperature. However, facilities where birds are housed indoors
can make use of artifi cial light, which has the same effect as
natural sunlight. I have seen aviaries where outdoor lighting on
a timer is used to control the birds’ photoperiod and stimulate
reproductive activity. This may be something to consider, but care
must be taken not to overdo things by overworking the birds,
rather than just replicating the lighting patterns in the birds’
natural environment.Rainfall
If you are fortunate to live on the coast, rainfall may not be a
big problem for you. For those of us who live further inland,
prolonged dry spells are the norm and may have signifi cant impact
on a breeding season’s success. Consider installing a sprinkler
system to replicate natural rainfall. A misting system just above a
perch is usually greatly appreciated by the birds and is also useful
in the hot summer months to bring down aviary temperatures.
This can be run on a timer system for 30–60 minutes every day or
two. Take care, however, that it doesn’t leave the aviary fl oor a
boggy mess that grows harmful pathogens and harbours parasites.Diet
The winter months are the time to reduce both the quantity
and quality of the food on offer to your birds—in other words,
an austerity diet. Feeding a base, low-fat diet of pellets and
vegetables in quantities that ensure none is left over after 24
hours, is suffi cient to maintain the birds’ health and weight but
not stimulate reproductive activity. As the days start to lengthen
and warm up, adding seed, nuts and fruit will increase the energy
content of the diet which, in turn, stimulates reproductive activity.
This is known as ‘fl ushing’ and it can be a powerful tool forWinter is ‘Make and Mend’ Time