Inbreeding in canaries, explained
When you pair two related canaries, their chicks are inbred. The inbreeding coefficient puts a number on it: a percentage you can compare between pairings before you put them together. Here is what it means and how breeders use it.
What the percentage means
Every chick gets one copy of each gene from its father and one from its mother. If the father and mother share an ancestor, both copies may come from that same ancestor. The inbreeding coefficient is the chance that this happens for any given gene.
A chick of brother × sister is 25% inbred: for about a quarter of its genes, both copies come from the same grandparent. A chick of two unrelated birds is 0%.
The figures for common pairings
| Pairing | Chicks’ inbreeding |
|---|---|
| Father × daughter, or mother × son | 25% |
| Brother × sister | 25% |
| Half brother × half sister | 12.5% |
| Grandfather × granddaughter | 12.5% |
| Uncle × niece, or aunt × nephew | 12.5% |
| First cousins | 6.25% |
| A first cousin × the chick of a first cousin | 3.13% |
| Second cousins | 1.56% |
When the parents themselves come from inbred lines, the real figure is higher: Canora counts that too.
Why breeders inbreed, and what it costs
Pairing related birds (line breeding) fixes what a family does well: a song, a type, a colour. That is how most strong lines were built.
The cost is that hidden weaknesses are fixed too. As inbreeding rises over the generations, breeders usually see it first in fertility: more clear eggs, chicks that die in the shell, weaker young. This is called inbreeding depression, and it builds up slowly, one generation after another.
Rules of thumb many breeders use
Use close pairings (25%) only now and then, with strong, healthy birds, and on purpose.
Keep most pairings low, and watch the average of the line year after year rather than a single pairing.
When fertility or hatching drops, bring in an outcross: a good bird from another line, unrelated to yours.
Record the pedigree as far back as you can. The figure is only as good as the records: with only parents recorded, two cousins look unrelated.
How Canora helps
Canora works out the chicks’ inbreeding when you create a pair, from every ancestor in your records (Wright’s formula, the method geneticists use), and shows where it comes from: which ancestors the cock and hen share and how much each adds.
Each bird shows its own inbreeding, your named lines show their average inbreeding year by year with a warning when it keeps rising, and the pairing analysis leaves out close relatives unless you ask for them.
Common questions
Canora says 0%, but I know they are related. Why?
The ancestors they share are not in your records. Add grandparents and great-grandparents (you can import them from a spreadsheet or a photo of a pedigree) and the figure updates.
Is 12.5% too much?
It is the level of half siblings. Breeders use it from time to time to fix a line, with healthy birds. What matters more is not to repeat it generation after generation without an outcross.
Why does another program give a different figure?
Many programs only look back a fixed number of generations. Canora uses every generation you have recorded, so with deep pedigrees its figure is usually a little higher, and closer to the truth.
Know the inbreeding before you pair
Canora is free for canary breeders: pedigrees, pairs and clutches, with the inbreeding of every pairing worked out for you.