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Willow Tits in Britain - inbreeding & partial albininism (1 Viewer)

lewis20126

lewis20126

Well-known member
As Willow Tits in Britain become isolated in small regional pockets, there seems to be an increasing occurrence of white feathers in the head, wings and tail. Friends have noticed this is West Norfolk and Yorkshire in the past year. This must be due to inbreeding. Does anyone know if anyone is collecting data on this nationally or researching this effect in isolated bird populations?

The phenomenon is well known in the isolated population of White-winged Wood Duck in Sumatra and with Edward's Pheasant in Vietnam and I'm sure there are other less exotic examples.

In respect of the Willow Tits it is possible that some transfers of birds between populations might be useful, although the species looks highly likely to become extinct within the next couple of decades anyway.


cheers, alan
 
Never seen any like this up here in Northumbs, but our Willow Tit population is reasonably healthy at least for the moment (sadly, that can't be said of Marsh Tits, which have disappeared from most of the county where they used to occur).
 
I've not seen any in the small and isolated population of Willow Tits on the chalk in North Hampshire but I would expect this to happen in the near future.

cheers, alan
 
Durham has quite a sizeable and healthy population of Willow Tits, but as County Recorder, I've not received any recent reports of abnormal plumages. There are still a good few 'habitat corridors' and linked populations so hopefully inbred populations are not an imminent threat here.

Mark
 
Can't say I have seen any such white areas on the ones that visit my garden, but I will have a closer look.

Tim
 
They are quite fragmented in Warwickshire now, this is the first Year I haven't seen one in the county but I will have to have a look at the ones coming to feeders in North Warks'.

Mike.
 
Not willow tit but I remember seeing a tree sparrow that was the last of a metapopulation of about 200 birds. It was an all sandy coloured affair, pretty much a tree sparrow in desert camouflage.
 
My local patch in Staffs has at least 2, maybe 3 pairs of breeding Willow Tits. We had one we called "Patchy" because of white feathers in its head. It stuck around for 2-3 years. We've had another one this year and its usually always in the same area. Yes they do exist
 
peterbrash said:
Not willow tit but I remember seeing a tree sparrow that was the last of a metapopulation of about 200 birds. It was an all sandy coloured affair, pretty much a tree sparrow in desert camouflage.
Click to expand...

Had a Great Tit at work like that a couple of years back.

James
 
Never seen any reports of the birds here in the North East, not 100% but i think our population is on the small side, ive only seen one and that was on the edge of a boggy Woodland on the edge of a housing estate and never seen any on our local bird club sightings page, only location nearby is Wynyard Woods, were both Marsh and Willow tits can be seen on a regular basis.

Damian.
 
I'm the recorder at Carsington Water in Derbyshire and we've a small population of around 6 or 7 pairs of Willow Tits. Can't say I've noticed any plumage anomalies but I'll certainly look at them a little more closely now.
 
lewis20126 said:
[...] there seems to be an increasing occurrence of white feathers in the head, wings and tail. Friends have noticed this is West Norfolk and Yorkshire in the past year. This must be due to inbreeding. [...]
Click to expand...
Sorry but I doubt that, Alan.
If that would be true all not migrating birds living all islands must be white since decades, they aren´t. E.g the Golden-shouldered Parrot, an endemic of the Cape York Pen. in Australia with only 2500 birds. I assume there´s inbreeding too.
If plumage changes would be connected to inbreeding what would be more easy to create white birds then? Let´s breed white Palm Cockatoo´s and sell it for good money!
lewis20126 said:
The phenomenon is well known in the isolated population of White-winged Wood Duck in Sumatra and with Edward's Pheasant in Vietnam and I'm sure there are other less exotic examples.[...] cheers, alan
Click to expand...
Well known? I must admit I didn´t care much about before your post but the only reference I found was in the"Waterfowl" article by D.A Holmes in 1977 where he mentions an observation of 5 (five!) birds with partialy albinism of the White-winged Wood Duck.
http://wildfowl.wwt.org.uk/index.php/wildfowl/article/viewFile/546/546

Long time ago I mentioned here my "thesis" that the often observated albinism in birds are constricted to English speaking countries with, for me, excuse the term, "weird" feeding behaviours and I assume that plumage modifications are based on that. It´s mostly the US, Canada and the UK where such birds are reported.

Regards,
Roman
 
lewis20126 said:
Roman.

I think you'll find albinism is a very well established expression of inbreeding in a number of non avian species. Humans are just one example :eek!:

cheers, alan
Click to expand...



Not questioning your general hypothesis Alan, only your terminology. "Partial albinism" is not a phenomenon that exists. Albinism is either complete or absent. What you are presumably referring to is leucism (although this phenomenon too is sometimes misidentified). Recommended reading, any of Hein van Grouw's papers on colour aberrations in birds.
 
GMK said:
Not questioning your general hypothesis Alan, only your terminology. "Partial albinism" is not a phenomenon that exists. Albinism is either complete or absent. What you are presumably referring to is leucism (although this phenomenon too is sometimes misidentified). Recommended reading, any of Hein van Grouw's papers on colour aberrations in birds.
Click to expand...

Guy - thanks. I'm well aware of leucism! I think ornithologists seem to have appropriated the various terms and redefined them so am using in a somewhat more colloquail sense, to mean "partially white".

wiki: "Albinism (from Latin albus, "white"; see extended etymology, also called achromia, achromasia, or achromatosis) is a congenital disorder characterized by the complete or partial absence of pigment in the skin, hair and eyes due to absence or defect of tyrosinase, a copper-containing enzyme involved in the production of melanin. It is the opposite of melanism.

Albinism results from inheritance of recessive gene alleles and is known to affect all vertebrates, including humans. While an organism with complete absence of melanin is called an albino (UK /ælˈbiːnoʊ/,[1] or US /ælˈbaɪnoʊ/)[2] an organism with only a diminished amount of melanin is described as albinoid.[3]"

I suppose whther this partial absence of pigment is uniformly distributed or in discrete patches is another question.

cheers, alan
 
lewis20126 said:
Roman.

I think you'll find albinism is a very well established expression of inbreeding in a number of non avian species. Humans are just one example :eek!:

cheers, alan
Click to expand...

eg wiki: "Certain ethnic groups and populations in isolated areas exhibit heightened susceptibility to albinism, presumably due to genetic factors. These include notably the Native American Kuna, Zuni and Hopi nations (respectively of Panama, New Mexico and Arizona); Japan, in which one particular form of albinism is unusually common; and Ukerewe Island, the population of which shows a very high incidence of albinism.[28]"

The point is that albinism results from inheritance of recessive gene alleles and as I understand it recessive traits are more likely to be expressed in young where parents are closely related. Parents are more likely to be closely related in small populations.

cheers, alan
 
lewis20126 said:
Guy - thanks. I'm well aware of leucism! I think ornithologists seem to have appropriated the various terms and redefined them so am using in a somewhat more colloquail sense, to mean "partially white".

wiki: "Albinism (from Latin albus, "white"; see extended etymology, also called achromia, achromasia, or achromatosis) is a congenital disorder characterized by the complete or partial absence of pigment in the skin, hair and eyes due to absence or defect of tyrosinase, a copper-containing enzyme involved in the production of melanin. It is the opposite of melanism.

Albinism results from inheritance of recessive gene alleles and is known to affect all vertebrates, including humans. While an organism with complete absence of melanin is called an albino (UK /ælˈbiːnoʊ/,[1] or US /ælˈbaɪnoʊ/)[2] an organism with only a diminished amount of melanin is described as albinoid.[3]"

I suppose whther this partial absence of pigment is uniformly distributed or in discrete patches is another question.

cheers, alan
Click to expand...

i am very much not an expert but as this "partial albinism" vs. "leucism" question arises so frequently i've looked into it.
My understanding is that albinism and leucism are separate pigment disorders with different underlying causes.

seems either can be complete or partial, at least in name..

here is a list of scientific publications including the words "partial" and "albinism" in the title, often together

http://www.ncbi.nlm.nih.gov/pubmed?term=(partial[Title]) AND albinism[Title]

it's not entirely sure what phenotype this refers to, whether a piebald effect or an all-over reduction (but not absence) of pigment

but leucistic is definitely not a synonym for piebald either, so maybe your willow tits are partially leucistic?........

James
 
Alan, I am sure you are aware of leucism (I was not suggesting you aren't), but I still think that these Willow Tits and many other birds that birders describe as albinos, with or without the the modifier "partial", are not true albinos. You said it yourself, albinism means a lack of pigment (in humans) in the skin, hair and eyes (i.e. not just one, but all three surface/s). In birds it means a pigment deficiency in the feathers, eyes and skin, and true albinos are rare because they suffer from chronically poor eyesight, so are susceptible to an early death through predation. It doesn't necessarily mean that the bird appears all white, but unless the Willow Tits you discuss lack pigments in the eyes, then they are not albinos.

James is entirely correct, the root causes of albinism and leucism are different. And one result of that is the latter does not affect the eyes.

Terminology may well have been mis-used, even perhaps to some extent developed through common usage, with the consequence that other birders will perfectly understand the type of bird you are describing when referring to "a partial albino", but that doesn't actually make such usage truly correct.

Anyway, I am sure that you would prefer to hear from people who have seen Willow Tits with some errant white feathers, which (for the record) I have not.
 
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