Couldn’t help but think of the ‘X Men’. Wolferton sounds too close to Wolverine is well. O.K. I’ll stop now.
by Dave Appleton and Nick Moran
Bedazzled by colour, we surmised in our ignorance on this day that the surprising dark face of the male Golden Pheasant we saw was the result of a little bit of Lady Amherst’s Pheasant influence. A follow-on email discussion between Nick M. and Dave Appleton was illuminating. Lee Evans also emailed Yoav P. and MG to say he thought dark throats did not necessary indicate hybrid introgression.
Dave Appleton’s correspondence with Nick Moran is below (with much thanks to both). A fuller discussion with lots more photos can be found on Dave’s site.
“I’ve taken quite an interest in these birds for some years, as well as having an interest in hybrid birds in general, and all the evidence I’ve found (and I’ve looked quite hard) is pointing to them being mutants and not hybrids.
For me there are two possible hypotheses:
(1) that ‘obscurus’ birds are hybrids with Lady Amherst’s Pheasant, backcrossed with Golden Pheasant;
(2) that they are mutant but pure Golden Pheasants.
In considering these I make the following observations:
Regarding the hybrid hypothesis:
o Golden Pheasant x Lady Amherst’s Pheasant hybrids are very common in captivity and are fertile so backcrossed hybrids are possible;
o Based on my experience of hybrids I would not expect hybrids to normalise to a single type unless that was broadly intermediate between the two species and neither one species predominated in the population;
o If I was wrong about that and they did normalise to a single type then I can’t see how a population could move from being pure-looking to being these normalised hybrid types unless the second species (or a hybrid with that second species) was introduced to the population at some point;
o The Wolferton birds are reported to have changed from being pure-looking to dark-throated (although I have not been able to establish beyond doubt that they were ever pure-looking – the evidence for that is entirely anecdotal);
o There have been no records of Lady Amherst’s Pheasants or hybrids (excluding ‘obscurus’ birds) in the Wolferton area;
o The Breckland birds are also now showing some evidence of dark throats without any reported introduction of Lady Amherst’s Pheasant.
Regarding the mutant hypothesis:
o Many aviculturists describe ‘obscurus’ as a type of Golden Pheasant, not a hybrid;
o If ‘obscurus’ is indeed a mutant form and not a hybrid then I would expect it to occur in captive populations with in-breeding much more frequently than in wild populations with little in-breeding;
o The form ‘obscurus’ is common in captivity and appears to be rare in significant wild populations (I have no data from native populations but have found no references to ‘obscurus’ appearing there and most references specify that it’s a characteristic found in captivity or in feral populations);
o If a wild (or feral) population declined to the extent that gene flow was restricted and in-breeding became commonplace then I would expect mutants to occur more frequently;
o There is anecdotal (only) evidence that the Wolferton population has increasingly displayed characters of ‘obscurus’ as the population has declined;
o If ‘obscurus’ is a mutant form predominating in in-bred populations then we might expect such birds to appear in other declining populations, such as in the Brecks;
o The last 2-3 birds I’ve seen in the Brecks have had darker throats than normal (albeit not as dark as the birds at Wolferton).
So my observations reconcile far better with the mutant hypothesis than the hybrid one.
Sometimes people voice an objection that goes along the lines of “ Isn’t it too coincidental to be credible that a pure Golden Pheasant should throw up a feature of Lady Amherst’s Pheasant through mutation when the two species are known to hybridise readily in captivity?” The simple answer is no – mutant characteristics in birds are often characteristics of closely related species, presumably because both species normally have the genes for that characteristic but they are normally suppressed in one species and expressed in the other. So it’s not surprising to me that a frequent mutant form of Golden Pheasant should be one that displays a characteristic that’s typically found on a closely-related species. I suspect the objection is a significant one though in so far as it has helped to sustain the notion that these birds may be hybrids. Several high-profile birders have propagated the view that they are hybrids apparently based only on their perception that pure birds surely can’t look this different from textbook pure birds.
I think there is more to learn about these birds and some of it might surprise me. If it shows that they are hybrids after all then that would surprise me! But I always hope that by sharing my thinking on things like this it might prompt others to engage and challenge me where I might have got it wrong.
Like you I don’t really care about their tickability! I suspect that all Golden Pheasants populations are destined for BOU’s category C6, a category that seems to me to be an anomaly itself – self-sustaining populations that have failed to sustain themselves….. huh?