Can anyone explain this rooster's comb to me?

This is Hapsburg, a cockerel who had a difficult hatch and to this day remains a little weird. One of the ways he's weird is his comb. All eleven of his siblings and half-siblings have identifiable combs, but he has this monstrosity on his head:







I've read the article on this site about comb genetics, the separate alleles for rose comb and pea comb, but that doesn't answer the question of how I got an Indominus Rex for a rooster. What could have made him develop this?

In case it helps, these are his parents, an Easter egger and a Silkie/Mille Fleur cross, who also produced a single-comb bird.

Wow, that almost looks like a buttercup comb. It probably is just a weird and rare genetic condition. Was the father of your rooster a mix of a pure silkie and a pure Milli Fleur?

Hapsburg? after the inbred royal family? Heh.

He has rose and duplex comb(the three spikes in rear and probably involved in the 'split' look in front) possibly pea. It does look odd but is in the normal range of how this combination can look in a mix/crossbreed.

The raised part you see from the side view(last pic of him with head turned away) often shows up in a rose comb bred to a single comb in a different breed that doesn't have rose comb in their ancestry/line. Example, sebright bred to a.. leghorn or...

p.s. presence of a crest can have an influence on comb shape/appearance. He has a small crest but it still has some effect on the comb.

elizabethjg, the father is a mix of a pure Silkie and a hatchery-quality Booted Bantam (I just say Mille Fleur since it's basically a non-bearded d'uccle).

Thank you, Kev! (And yes, Hapsburg because he hatched with an underbite. Which he somehow grew out of...) Two more questions: how does duplex work, and am I correct in describing his father's comb as walnut?

Not sure what you mean exactly by work... Duplex is semi dominant but also extremely variable in expression due to unknown(?) reasons. One bird can show the barest, minimum hint of duplex yet another show it pretty strongly. Duplex essentially twins the comb, much easier to notice it on single comb.. without modifiers they can literally have two identical single combs right next to each other. Butter cup combs are this however they are also bred to have a distinctive appearance..

On a single comb bird, a bird mixed for duplex often has either extra points in the rear of comb, the beginning of a split is also pretty common- sort of like a Y shape. Common in Polish crosses/mixes.

Hard to be totally sure on the father's comb as there is a grey area where walnut and rose can overlap. His comb is more typical of a smooth(no spikes) rose comb without pea involved but a few true walnuts can have that sort of look.

One big tell for presence of pea is reduced wattles, but this has to be on a beardless bird as beard also reduces wattles... the father appears nonbearded? his wattles seem to hint at lack of pea however his wattles are also small.. hard to tell if that is due to pea or are naturally small...

Just about the only way to tell for sure is breeding him to a single combed hen(preferably also non-crested), any pea combed offspring would be proof he is really walnut combed.

That is pretty much what I meant by how does duplex work, thank you! Not that it was especially relevant to Hapsburg, but this is all super interesting to me. Usually when I try to look this stuff up it's either way beyond me or on an elementary level, repeating the same stuff I already know. Your answers are perfect.

I had assumed that Jared's (Hapsburg's father) Silkie mother was a walnut because I read Silkies have walnut combs. She and Jared's father had eight offspring, four of which had single combs, four of which had combs like Jared's, so I concluded she had (P, p) (R, r) going by what I learned from this site. I realize now that probability-wise and from what you've said, it makes more sense to conclude that she just plain didn't have a walnut comb and was (p, p) (R, r), giving me 50% single combed offspring, and leaving Jared with the same genotype. Is that all fair reasoning?

Regarding beards and wattles, about half of the eight, including Jared, had appeared to be non-bearded, so either their one gene for a beard was expressing itself very weakly or his mother was not so pure as I thought. Jared's non-bearded father had small wattles but he wasn't fully grown before I lost him. (Yeah, he started early.)

Sorry for all the rambling, I just like knowing details about what I have in my flock, even if I'm not going to breed certain individuals (i.e. Hapsburg's mother). I really appreciate your answers.

Yes you really are getting it. Excellent deduction on comb genotype, I agree P probably is not present. I was personally thinking his wattles looked 'normal'(no P) and had the look on some p+ bantams but was being overly careful because honest mistakes can sometimes really confuse someone trying to learn genetics.. I'm very impressed you figured out the silkie did not have P..

Isn't genetics so interesting once you learn and understand enough of it? Makes it fun to figure out the genotypes in your birds... like an added benefit of having chickens.

Now to silkie combs..... the whole hobby is bad with naming. Multiple names for same genotype, multiple genotypes given the same name, etc...

In my experience, quite a lot silkies are rose, not walnut- even in high quality showbred stock. Possibly the majority. Pea is present and does float around but seems to be on the side of uncommon than common. I do assume many/most silkies are modified rose instead of true walnut..

I see. Good to know!

This certainly explains why I got as many single combed birds as I did from Jared and three different hens, none of which actually had single combs. Thank you so much.