|During the many years that I traveled
through the jungles of Central and South America, there
was never an egg under incubation back home on the farm.
We at Voren’s Aviaries never “counted our chickens”
before they hatched. Due to the fact that I was near a
jungle somewhere in the world about half the time, there
was never anyone to tackle the responsibility who wasn’t
already overburdened by my absence. As my collection
grew near my goals and I began to curtail my travels, I
became very involved with incubation.
Well over 8,000
psittacine eggs have passed through my various
incubation procedures during the last four years. The
numbers of birds that we have hatched successfully
staggers most people (over 1,500 this year alone). I
myself am more staggered by those that don’t hatch.
Infertility can be depressing, but what really hurts are
the babies that die in the shell sometime after the
second week of incubation.
Due to my success as an aviculturist, I am called on
by many professional breeders for advice. Being in this
position allows me to see that everyone who incubates
large quantities of eggs has similar problems. Although
it is impossible to help people solve problems that I
have not been able to solve myself, this communication
allows me to question them freely and stockpile
facts–facts that at some point lead to answers.
The first fact that becomes glaringly apparent is
that the first 10 days to two weeks of incubation is the
critical period. Correct procedures during this initial
time will almost always result in a successful hatch.
Without exception, anyone incubating a reasonable
quantity of eggs who claims a success rate of over 85
percent is not pulling the eggs as they are laid. They
are either allowing the hen to keep the eggs until the
entire clutch is laid, or they are leaving them with her
for two weeks of natural incubation. Those who allow the
hen to sit for two weeks have success rates well into
the 90-percent range. Once this critical two-week period
is over, the egg can be successfully brought to term
with a wide variety of temperatures and humidities.
Under natural conditions, the most important factor
in successful incubation is heat. As long as the egg
gets enough of it and is not permitted to lose too much
of it for too long a time, everything will be fine. This
is true even though the actual temperature of the egg
fluctuates drastically when the hen is off the nest.
Hens that “sit tight” (those that rarely leave the nest)
do not have a noticeably higher hatch rate than those
that leave the nest at regular intervals. From this,
it’s safe to assume that eggs have evolved to be less
sensitive to temperature drops than to other more
One thing that a bird cannot do no matter how hard it
may try is overheat an egg. This, of course, is possible
in an incubator. Overheating is one of the things that
an egg is very sensitive to and can result in eventual
death. Temperatures that have been used successfully
range from 98.7 to 100 degrees Fahrenheit. At Voren’s
aviaries, we have settled on 99.3 degrees Fahrenheit.
Of course, the best temperature for you to use will
depend on many different factors. The most important of
these factors is humidity.
It has been long assumed that 50-percent humidity is
required for successful hatching. This is not
necessarily the case. Humidities ranging between 38 and
52 percent have been used by different professionals
under different circumstances. All have proven
successful in the situations used. An egg should undergo
a specific percentage of weight loss during the
incubation period. This weight loss is achieved by the
evaporation of water through the pores of the shell.
Since increasing the incubation temperature can
shorten the time period in which it takes a chick to
hatch, there is less time for the required water loss to
take place. If using these higher temperatures, the
lower humidities should be used to allow sufficient
water loss during the shortened time period. Conversely,
if lower temperatures are used, the chick will take
longer to hatch, and higher humidities should be used in
order to keep too much evaporation from taking place..
I have experimented with different humidities and
found that under the same environmental circumstances,
large eggs do better at lower humidities (38 to 45
percent), and smaller eggs do better at the higher range
(46 to 52 percent). In fact, it is now standard
procedure for me to incubate all macaw and Amazon eggs
at between 38 and 42 percent humidity. Conure eggs at
these humidity levels experience too much water loss and
die, or hatch in a dehydrated state. For conures, we use
a humidity level of 48 to 52 percent. I believe this is
a function of eggshell calcification differences rather
than a difference in the amount of water held in large
eggs versus small eggs. In my aviaries, the larger birds
generally produce eggs that are harder and
thicker-shelled than the conures’. Logic tells one that
an egg with a thicker and denser shell would require a
lower humidity level in order to incur the same water
loss as a thinner or less dense-shelled egg.
Differences in diets and individual metabolisms are
the major reasons that there are so many different
reports as to the ideal humidity to use in a specific
case. One must not lose sight of the fact that a bird
can sit on an egg under almost any reasonable humidity
and hatch it regardless of how marginally over or under
calcified it might be. This tells me there are major
flaws in our basic incubation philosophies.
The next most important aspect of incubation is
turning the eggs.
of times per day that a parrot egg should be turned in
the incubator is still a subject of
debate. Poultry research supports the theory that eggs
should be turned between 12 and 24 times a day. However,
some people, myself included, think that between four
and eight times per day is sufficient.
Under my incubation conditions, I noticed a marked
difference in development when the incubator was set to
turn the eggs only six times a day instead of 12 times.
The eggs developed more evenly. That is to say that the
veins that grow out from the embryo covered a larger
area and reached around to the “underside” of the egg
much earlier in the incubation process than those turned
every two hours.
no difference in incubation time, but hatchability was
Vibration is probably the most unconsidered variable
that is responsible for mortality in the shell. It also
explains why under “exactly” the same conditions, two
different people can have completely different results
using the same model incubator.
Minor differences in mounting positions, as well as
the age and type of fan motors used, can have a great
effect on the amount of vibration that is transferred
from your incubator to your eggs. Eggs in their natural
state are incubated in a vibration-free environment. It
stands to reason that even the slightest bit of
vibration can affect the development of those tiny veins
in a negative way. The question is, how much can they
stand before vibration proves lethal?
The first sign that hatching is around the corner is
when you see the egg “draw down.” This is when the air
space in the egg enlarges. It will change from its
normal round appearance to elliptical. One side of this
now-elliptical air cell will extend down one side of the
inside of the shell. The other side remains up near the
top of the egg where it has always been–hence, the
elliptical appearance. At this point, many aviculturists
move the eggs into a hatcher. Others prefer to wait
until the first “pip mark” appears on the egg.
The “hatcher” is an incubator with high humidity and
no turning mechanism. The high humidity is to make it
easier for the chick to hatch. Since the incubation
process is complete, the high humidity (the higher the
better) does not interfere with evaporation but does
make it less likely for the internal membrane to stick
to the hatching chick. Chicks that get stuck to the
membrane must be assisted out of the shell, or they will
die trying to get out. Normal time lapse between major
draw down and hatching is usually about three days.
Knowing when to enter into an egg and when to stay
out is an art in itself. Many chicks have been saved by
timely assistance, but anyone attempting this must
remember that it is always a gamble. Hatch assist is
something that you can consider if you have a chick that
has come to term but for some reason does not hatch.
One should wait at least for an internal pip before
even beginning to monitor an egg for possible need of
assistance. An internal pip is when you can see the
chick moving in the area of the air cell. This happens
just prior to the chick attempting to break through the
shell wall. Once broken through, the pip mark is called
an external pip. If an external pip is not forthcoming,
then there may be a need for assistance.
You also may have a problem if a chick externally
pips one pip and then stops. Stopping to rest after the
first pip is normal. If, however, two days pass and no
further attempt has been made to continue the hatching
process (more pip marks), then help might be necessary.
With either of these two problems (just internal pip or
just one external pip), you would proceed in the same
Chip a small hole in the shell so you can see inside.
There are some dental tools that are perfect for this
work. You should make the hole where the pip mark is or
where the pip mark should be. To determine where a pip
mark should ideally be, estimate about 3/4 the distance
down from the center of the top of the egg (the fat end)
to where the expanded air cell ends along the side of
the egg. If there is no pip mark, you will have to make
a tiny hole. A small nail spun between the thumb and
forefinger makes a perfect drill for this procedure.
Once you have drilled a hole or located the
pre-existing pip mark, begin to chip away tiny pieces of
shell until you can see what is going on inside.
Sometimes a chick will pip and get stuck to an overly
dry internal membrane. If this happens, the chick will
not be able to rotate and pip in enough spots to
facilitate hatching. A sure sign of this problem is when
you notice upon candling that there are no veins left on
the inside of the shell. The feet appear to be moving
freely, and the chick keeps pipping at the same spot. In
the case of no pip mark other than internal, the problem
could still be an overly dry membrane. It might also be
a problem of the head being poorly positioned and unable
to make an effective strike on the shell.
Remember to keep the hole as small as possible. The
membrane will usually be white in appearance. Paint the
membrane with water using a tiny paint brush. This will
make the membrane transparent and clearly show any veins
that might still be carrying blood.
If the chick has not come through the membrane and
you are convinced that it is overdue, then make a tear
in the membrane to free the chick’s beak and nostrils.
Be careful not to break any blood vessels in the
membrane. Only work in spots that are free of vessels.
This allows the chick to breath and eliminates
suffocation as a possible cause of death.
You should now cover all but the smallest air hole
with a small piece of tape. At this point, you have the
choice of allowing nature to take its course or going in
to complete hatching if you feel that there are no more
live veins in the membrane, and the yolk has been
completely absorbed. If the hole allows you to see that
the membrane is completely devoid of veins and the chick
has internally pipped and its only obstacle is a dry
membrane, you might wish to take off the top of the
shell and let the chick lift its head out of the torn
membrane. When removing the shell and membrane from
around the head, work from the nares back to the crown,
if there are any hidden blood vessels they’ll be in the
area of the crown. If no viable vessels are noticed as
you proceed, then lift the shell and membrane off the
bird’s crown down to the upper neck. If the chick is
ready to come out, you will get what I call the “jack in
the box” effect; that is, the chick’s head will pop
straight up out of the fetal position. If the chick does
not pop its head up and tries to return to the fetal
position, even if you coax the head upward, it’s best to
tape the bird in with paper tape (I use Micropore by 3M
with great success) and try again in six hours. If the
bird does pop its head up, at that point you can look
down to see if there is any yolk that has not been
absorbed. If none exists, the chick on the half shell
should be placed in a small tissue basket back into the
hatcher so it can crawl out when it is ready. This is
when the last few veins at the navel have dried.
Pulling a chick out of the half shell too early can
cause it to bleed to death. If, however, you can see
some yolk sac, you should place the chick’s head back
into the “fetal” position, place the top of the shell
back on the egg, and tape it together. Place the egg
back into the hatcher to allow the chick to finish
absorbing the yolk. A chick in this situation will have
to be released from the shell at the proper time.
Remember, always proceed with great caution. Good
luck, and may all your eggs be fertile.