Crested Call Genetics
Faith Valley Waterfowl
              Crested Ducks Genetics
                  By Patty Pickard

The Crested genotype, Cr’/cr, is a very interesting and fun gene to work with.
You must understand that it is a lethal gene though, so you will have a
percentage of ducklings that will develop all the way up to hatching day and
then die in the shell. This gene is called the “lethal gene” because the crest is
formed through a hole in the top of the duckling’s skull.

Below are two photos of a crested call duckling.  The first photo shows the
duckling as it is still drying off in the hatcher tray; you are clearly able to see the
duckling’s large crest-hole.  The second photo shows the same call duckling
one day later; you can see how the crest fluffed up and completely covered the
bald, swollen area on the skull of the duckling.
If a duckling receives the crested gene from both parent birds, that duckling will
not survive and will die before hatching. A double dose of the crested gene will
cause the duckling’s brain to develop improperly and outside of the skull.  Here
are two photos of an unhatched call duckling with the double dose of the crested
gene. This duckling died in the shell because it received a crested gene from
both of its parents and its brain developed outside of its skull.
If you desire to work on a crested duck program, but do not want to encounter
the lethal gene death percentage, you can get around it by not using all crested
parent birds.  You will end up with the same amount of crested offspring whether
you use all crested parent birds or if you mate a crested to a non-crested parent
bird.

If you breed two ducks together that each have the crested gene, you will get:
25% of the ducklings that are dead in the shell
50% of the ducklings that carry the gene, but might or might not have a crest   
25% of the ducklings that don’t have the crested gene

If you breed a crested parent duck to a non-crested gene carrier, you will get:
50% of the ducklings that carry the gene, but might or might not show the crest   
50% of the ducklings that do not have the crested gene

It is interesting to note that in both breeding program options, you will get 50% of
the offspring that have the crested gene. The best crests will be produced from
the first breeding option however.  Breeding a crested duck to a crested duck
seems to produce larger and more desirable crests.  Breeding a crested duck to
a non-crested duck does produce 50% of the offspring with the crested gene;
however the crests tend to be smaller in size.  
These crested grey calls came out of a crested to crested mating. Notice how
large the crests are.
This crested grey call came out of a
crested to non-crested mating.  Notice
how small her crest is.
An interesting side note about the lethal gene is that it is found in some chicken
breeds as well. The Japanese bantam chicken also has the short leg lethal gene.  
If the chick gets the short leg gene from both parents it will die in shell.  The
Araucana chicken also has the tufted lethal gene, if the chick gets a double dose it
will die in the shell.  The hatch percentages are all the same percentages as those
of crested offspring.  

These hatch percentages can easily be illustrated by looking at the Punnett
Square. The Punnett Square is a very easy tool to use in determining the outcome
of your breeding program.  For this illustration we will use the crested gene Cr’/cr.
We put the male’s genes on the top of the square and the female’s genes on the
side of the square and then combine the genes out into the 4 “offspring” boxes.  
We fill in our first offspring box by looking at our first male gene at the top and our
first female gene at the side.  Cr’ and  Cr’, which makes our first offspring Cr’/Cr’.
We then fill in the second offspring box by using our second male gene and our
first female gene; Cr' and cr which will give us the offspring Cr'/cr. We do the
second row the same way, to get complete our Punnett square.
  Cr'
cr
Cr'
Cr'/Cr'
 
cr
   
  Cr'
cr
Cr'
Cr'/Cr'
Cr'/cr
cr
   
  Cr'
cr
Cr'
Cr'/Cr'
Cr'/cr
cr
Cr'/cr
cr/cr
Now that we have filled in our Punnett Square, we can predict our offspring.
We will get and average of:
  Cr'
cr
Cr'
Cr'/Cr'
Cr'/cr
cr
Cr'/cr
cr/cr
* 1 out of 4 ducklings or 25% with the Cr’/Cr’
gene.  This is the lethal gene combination- both
parent birds gave the crested gene to this
duckling and it died in the shell.
  Cr'
cr
Cr'
Cr'/Cr'
Cr'/cr
cr
Cr'/cr
cr/cr
* 2 out of 4 ducklings or 50% with the Cr’/cr
gene.  These ducklings received one crested
gene and one non-crested gene from their
parent birds.  These ducklings are carriers of the
crested gene and may develop a crest or may
just carry the crested gene.  Not all ducklings
with the crested gene will have a crest.
  Cr'
cr
Cr'
Cr'/Cr'
Cr'/cr
cr
Cr'/cr
cr/cr
* 1 out of 4 ducklings or 25% with the cr/cr gene.
 These ducklings received one non-crested
gene from both parents, so these ducklings do
not have the crested gene; they will not have a
crest  and will not be able to pass the crested
gene to any of their offspring.
Using the Punnett Diagram, you are able to predict the percentage of the out
come of any mating, provided that the breeder knows the genes and
background of the birds. The crested duck program is an exciting and
challenging breeding program to undertake. Always remember to toe punch or
mark your ducklings from this type of a breeding program because a duckling
that does not have a crest does not necessarily mean that duckling does not
carry the crested gene. If the bird has superior type and all other desirable
traits, it could certainly be used for your crested mating the following year.