Identifying possible causes and improving management to minimise
its effect on disease.
By Dr Colin Walker BSc, BVSc, MRCVS,
MACVSc (Avian health)
Birds are exposed to many organisms
throughout their life that have the potential to cause severe and
sometimes even fatal disease, and yet often the birds do not even
become sick. Why is this? Healthy happy birds have a natural disease
resistance that prevents these organisms causing disease. Much
of the clinical disease seen in birds is described by avian vets
as being stress-induced or stress related and so what does your
vet mean when he says your bird has become stressed? Essentially,
he means any physical or psychological factor that decreases the
bird's ability to resist disease. Birds under stress become what
is termed "immunosupressed".
This means that their immune system is less able to mount an immune
response and so the birds have become more vulnerable to disease.
Obviously we all want our birds to live long and happy lives and
so what are some of the common causes of stress and how can we
Stress and the new pet bird
The acquisition of a new bird is always exciting. However, for
the new bird, there are always many inherent and often unavoidable
stresses associated with transport and rehousing. This is particularly
so with young birds because often this time is also associated
with weaning. Not only are they separated from their parents
but there is also a possible change of diet. A bird in a new
cage must find where the food and water are, and, if weaned
into a cage with other birds, must find its own space and territory.
Having the cage ready and correctly set up will help to settle
the new bird more quickly and avoid any unnecessary stress. Considerable
thought should be put into cage size, design and placement. For
many birds, the cage represents their own space or territory
and acts as their refuge if they feel threatened. It is therefore
important that the cage promotes this sense of security. Remember
the old zoo cages that used to house animals such as tigers,
which were all wire? They are no longer used in zoos and yet
are commonly used to house pet birds. A skittish bird sitting
in a cage with four wire walls and a wire roof must feel very
exposed and vulnerable. It is good if a solid roof or one or
two solid walls can be fitted, even if this simply means tying
on some cardboard sections with string. Placing the perches high
in the cage promotes security and of course the perches should
always be of uneven diameter and have a variable surface to avoid
later foot problems. Natural branches are best. Many commercially
available cages have a removable wire floor for ease of cleaning.
Many birds do not like these. Often removing these and covering
the floor with washed dry river sand to a depth of 1 - 2 cm (available
from garden supply outlets) provides a surface that birds enjoy
walking and lying on as well as exploring. Changed regularly,
this provides an hygienic floor. The sand absorbs the moisture
from the droppings and when the cage is cleaned the sand and
dropping mixture make a good garden dressing.
Birds, when introduced to a new home, cannot intuitively sense
that you mean them no harm. Sudden movements, bright colours
and loud noises are all intimidating.
Speaking in a steady voice in a lower tone also helps.
Cage placement is important. Initially the cage should not be
placed in a major thoroughfare of the house. Remember, everything
is new and potentially frightening. Unfamiliar activity interferes
with normal rest and feeding and does little to promote a feeling
of security. Adjustment to other pets in the household, such
as dogs, will take time. It is doubtful whether birds ever become
accustomed to a cat. Often for the first few days placing the
cage in a quieter part of the house is a good idea until the
birds familiarises itself with its new cage and starts to eat
properly. Once the bird settles into its cage and starts to recognise
and know its new owner, it can then be a good idea to move the
cage to a busier area. This is particularly so for intelligent
birds such as parrots, which quickly become bored. Placing the
cage in front of a window or even outside can help to prevent
any cage boredom with a more established pet. It is however important
to remember that the sight of any natural predator such as magpies,
raptors and cats, will not only cause significant stress but
may lead to physical injury due to the bird panicking and flying
around the cage.
The temperature and humidity of the area in which the cage is
placed are also important. Ideally the temperature for most birds
should be in the range 20°C to 25°C and the humidity
about 60%. Birds can, of course, cope with much higher and lower
levels of both, however, a significant change in either value
over 24 hours, e.g. cold nights and hot days, has been shown
to be a significant stress. Draughts (which are essentially cold
currents of air through warmer air) should be avoided.
Because most time spent in the air by birds is involved in horizontal
rather than vertical flight, it is better if the pet bird's cage
is a rectangle lying on its side rather than its end. This will
make the cage much more usable for the bird. It should go without
saying that the cage needs to be big enough for the species kept.
It is unfortunate that many larger cockatoos are kept in cages
that are too small for them to even fully extend their wings,
let alone fly. Cages that are 2 foot by 2 foot by 3 foot are
not uncommon. This is analogous to keeping a budgie in a cage
6 inches square. A cage of this size for a cockatoo should only
be viewed as temporary housing or as a transport cage. If it
is the only cage that is available, then the bird needs to spend
a significant amount of time out of the cage for its long-term
Cage birds prefer clean, dry conditions. Dampness encourages
bacterial proliferation and speeds the development of worm
and coccidial eggs. Accumulated droppings, particularly around
food and water trays, expose the birds to a higher level of
germs generally and also noxious gases, such as ammonia. It
is common sense to keep the cage clean and feed and water the
birds in an hygienic manner.
The ingestion of a full and balanced diet is something that both
bird fanciers and avian vets have realised is vital, particularly
over the last 10 to 20 years. This is particularly so in certain
species. For example, it would not be an exaggeration to state
that probably more than 90% of disease seen in lorikeets relates
to a poor diet. This is even seen in free-flying lorikeets,
where people offer wild birds saucers of sugar, bread and water.
These birds develop a dependence on these easily available
foods rather than forage for themselves. Being low in protein
and lacking many micronutrients, these birds become immunosuppressed
and significantly more vulnerable to disease. In many cases,
when a disease outbreak occurs in an aviary, the owner of such
birds must not only, along with his vet, figure out what the
dissease problem is but then ask himself what made it come
in the first place, Often, an improvement in diet will help
in preventing a recurrence of the problem and avoid the need
for medication in the future. The closer the aviculturist can
mimic the diet of wild birds of that species then the better.
Often keeping in mind that many birds such as galahs, pigeons
and many parrots, are essentially foragers taking a wide variety
of foods, and simply increasing the variety offered to them
does much to improve the situation.
Parasites and Stress
A parasite is essentially any organism that lives off another
organism. In order to survive, parasites must drain energy
from their host. Many, in doing this, also physically damage
the host animal. Parasites therefore cause significant stress
to the host animal. It is common to see parasitic disease occurring
simultaneously with stress related disease. A common example
being the double barrelled problem of round worm infection
and chlamydial disease seen often in Neophemas. It is not possible
to provide effective treatment for the chlamydia until the
round worm infection has been cleared and the stress associated
with this drain on the birds system removed.
In free-flying wild birds, parasites are much less of a problem
than in caged birds because of the decreased level of contact
between individuals and the lower level of exposure to droppings
because of the wider area over which the animals roam. With the
higher stocking densities associated with captivity, exposure
to parasites dramatically increases. Without ongoing hygiene
and an adequate control program, parasite numbers can build up
to levels that cause disease and deaths in their own right. Lower
parasite burdens generally weaken birds and predispose them to
other diseases. The control of parasites is a significant concern
and will be covered in a later article. Suffice to say now, the
major parasites are worms, coccidia, lice and mites and that
there are a range of safe and effective medications available.
Your avian vet is well equipped to advise you on what parasites
are particularly relevant to your species and which medications
are best to use.
It is not only important that the correct number of birds for
the available cage space be kept but also that species that
are compatible are kept together. As a general rule pre-pubertal
young birds require less space than adults and yet over crowding
is a common cause of stress induced disease flare-ups in youngsters.
In most species, once the birds go through puberty they require
larger areas within an aviary. Parrots in particular are very
territorial and overcrowding can lead to aggression, fighting
and injuries. There cannot only be competition for cage space
but also for access to food bowls, the better (ie higher) perches
and nesting sites.
Birds, particularly young birds, gain security from a predictable
daily routine and a familiar environment. Many people not familiar
with birds, when they see them simply sitting in a cage, regard
a bird's IQ as perhaps not much higher than that of a goldfish,
when in fact anyone who has kept a bird for a period of time
realises that nothing could be further from the truth. Many
birds have an IQ similar, if not higher, than that of a dog.
It goes without saying that they not only recognise other species
of birds but also individual birds of their own and other species.
They can also recognise different humans. Some parrots can
recognise more than 60 individual voice commands. something
that is way beyond most dogs. In fact, one of my client's parrots
can whistle the entire Burke's Backyard theme, "Give me
a home among the gum trees.................”, quite impressive.
With this level of intelligence demonstrated, it is easy to
understand how loneliness and boredom can become problems in
many pet birds. Satisfying a bird's psychological needs does
much to avoid stress.
Much has been written on bird behaviour and training. Correctly
interpreting your bird's behaviour will not only increase your
level of enjoyment of him but also help to make him feel more
secure and less stressed in the captive situation. This is particularly
so with parrots and other social birds where interactions with
humans need to be a substitute for those with other members of
the flock in the wild. Most parrots form fairly strong pair bonds
within the flock that they travel in. Captive pet birds are deprived
of this sort of relationship and yet it is part of their instinct
to develop this type of bond. As a result, many transfer this
behaviour usually to their primary carer. Being an intelligent
animal, parrots easily become lonely. The primary carer not only
represents company but is also associated with the giving of
food. As a result it is only natural that a relationship starts
to develop between the primary carer and pet bird, which mimics
that of a wild pair of birds. It is important to recognise this "I
want to be your friend" behaviour for what it is. Parrots
develop a mutual trust and bond through mutual preening. Too
many people are frightened by a parrots biting beak. A parrot
that lets you stroke or scratch him around the head is displaying
trust in you. Let him know that you trust him by letting him
groom your hand. As an extension of this, stroking around the
base of the beak or the side of the tongue itself is a very strong
bonding behaviour. Suddenly jerking your hand away when a friendly
parrot moves his head towards you gives him a very confused message.
Rather than reinforcing friendly behaviour, this may to him mimic
the behaviour of a subordinate bird and trigger an aggressive
response. Once you have established a relationship with your
parrot, it will no more bite you than would your pet dog. The
trust and antics displayed by birds ranging from the family pet
budgerigar up to the largest parrots are some of the true pleasures
that bird ownership can bring.