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-   -   Leucism vs albinism - a pedant's guide! (https://www.birdforum.net/showthread.php?t=25860)

Nightranger Tuesday 9th November 2004 09:58

Leucism vs albinism - a pedant's guide!
 
Hi all,

I was doing a bit of reading last night and found that the term "partial albino" has gone into print. I thought I would look up the precise definitions to see if the term has any meaning. There is no precise definition for leucism but it is the difference in the two traits that is interesting. Albinism is a complete lack of the cells that produce pigments whereas these cells are 'switched off' or faulty in the leucistic state. Now the difficulty comes in deciding that abnormal white patches on a a bird are caused by the lack of pigment producing cells in those areas or because they are faulty. In some cases, white or patchy birds moult into normal adult plumage and this infers that leucism is the state. However, the local may have a single wing feather that is always white and this would infer that there were no cells to rpoduce pigments on a localised basis. Given that the feather never attained normal colouration, it would probably be true to refer to the bird as an albino even though it was normal in all other respects. However, the bird that I use in my avatar (a meadow pipit, we think) has no feather pigmentation yet there is colouration in the bill, eyes and legs. It is difficult to decide if the pigment cells are switched off or absent in this case so again, it is probably OK to refer to this bird as an albino. Nevertheless, many people do not consider a bird to be albino unless it completely lacks pigmentation. In conclusion, the term "partial albino is mostly useful because it is almost impossible to determine which state is the actual cause without detailed examination of the bird. I am not sure this helps really but I found that it is not as straightforward as I first thought.

Ian

very boring banned member Tuesday 9th November 2004 11:33

Thanks. More info: Katy Penland once threw light on abnormal colourings:
http://www.birdforum.net/showpost.ph...1&postcount=11

KnockerNorton Tuesday 9th November 2004 12:00

I find it pays not to be too pedantic, as it really depends on who you are talking to. If you say 'partial albino' then people know what you mean - a bird with white patches. If you say 'albino' people think of a pure white bird with pink eyes (no pigment anywhere), and if you say 'leucistic' then most people think of a pale, washed out bird where the colouring is diluted. Scientifically, a bird with white patches is, in fact, leucistic. Just as leucistic as a washed out bird. Albino refers only to things which have two recessive genes and, therefore, no pigment anywhere. As such, you cannot be 'partial albino' as you do not have both recessive genes. As leucism is a spectrum between white and normal, any odd white feathers are leucistic. This could be genetic, or indeed possibly from infection/trauma. Leucism is kind of the opposite of melanism.

Your pipit seems to be leucistic.

Benjismum Tuesday 9th November 2004 12:46

OMG - I think I'll stick to 'white' or 'partly white'! ;)

Nightranger Tuesday 9th November 2004 13:06

Quote:

Originally Posted by Offord
I find it pays not to be too pedantic,

I agree, I have no objection to anyone using a term that has come into common usage whether it has a scientific definition or not. I was once pulled up for this in the office and if everyone knows what is meant by a partial albino as opposed to a leucistic bird then I am happy with that. The reference in print I found was in Liz Laidler's book on otters and I wondered if anyone had come across any other examples in print. As you rightly say, some of the effects of leucism are not always genetic so it has a bit of a vague definition (it seems). I have taken to using the equally inaccurate term of "genetic bird" when it involves plumage differences from the norm. It is an artifical term but it allows me to talk about 'farmyard specials' as well as natural varieties.

Ian

alcedo.atthis Tuesday 9th November 2004 18:15

"I wondered if anyone had come across any other examples in print."


Ian, certain bird books refer to albinism, and leucism, but not all.
Interestingly, I wrote to a few scientists who specialise in albinism in humans in America. Strangely, they had not heard the term "Leucistic" or "Leucism" and did not know the meaning or the source of the word(s).

I was sent a 4 page explanation of how albinism comes about and the mechanics of what causes it.

A couple of links to add to the complexity of definition, depending what you think:-
http://www.umd.umich.edu/dept/rouge_river/mywa.html
http://www.umd.umich.edu/dept/rouge_river/fall99.html
http://www.caller2.com/autoconv/news...local1265.html
http://listserv.arizona.edu/cgi-bin/...=0&F=&S=&P=778

Regards

Malky

very boring banned member Wednesday 10th November 2004 06:54

Quote:

Originally Posted by Ian Peters
I have no objection to anyone using a term that has come into common usage whether it has a scientific definition or not.

Like
twitcher = birdwatcher
America = USA
species = any split that adds lifelist
;)

Rasmus Boegh Wednesday 10th November 2004 09:59

oops :eek!: Sorry, managed to delete the original post by mistake. Here's another that should say more or less the same:

Well, the real border seems to be between "ordinary birders" and scientists. I am lucky enough to know many top scientists and in these circles there seem to be little doubt that the term "albino" only is used if there is a complete lack of pigmentation, incl soft parts. Leucism describes the various forms where there is a lack of pigmentation, but not complete. Do note that this lack can be complete in areas and still be considered leucistic, as long as other areas do have pigmentation to some extent. Hence, "partial albino" is not used at all. This also concurs with the ideas taught in the biology in university. Furthermore, see "A New Dictionary of Birds", edited by A. Landsborough Thomson, "The Cambridge Encyclopedia of Ornithology", edited by Michael Brooke and Tim Birkhead, or the link in post #2 which includes a brief writedown of an article in the LA Audubon newsletter written by Charles T. Collins... who can't exactly be called a novice!. However, this is where "ordinary birders" differ, I think in part because the term leucistic only entered the scene fairly recently in these circles. Previously, when not knowing the term leucistic, it would be logical to use the wellknown albino in a modified way; i.e. "partial albino". However, then "leucistic" enter the scene and the confusion appears to be total. I am well aware that language and meaning of specific words change over time, however, I am rather convinced that this is nothing but a case of lack of knowledge... among others, I see no indications of this change in the meaning for the words albino/leucistic in the scientific circles...

Still, as I have said before, I doubt it is that important for most people. I assume we all know what is meant if someone calls a bird "leucistic", "partially albino" or just "with white patches"...

Roger S. Wednesday 27th July 2005 14:32

Hi thanks for input,

I only had a short view from 15 ft away in my garden but it was definitely all white ,it looked a bright white , pink bill and buff legs.

Cameras is ready but has not returned with the other starlings.

If I cut through all the technical stuff would I be right in saying that its a starling with lacks the right amount of pigments.

Many thanks
Roger

Steve Lister Wednesday 27th July 2005 14:50

The last contribution does not seem to tie in with the rest of the thread Roger.

Steve

Roger S. Wednesday 27th July 2005 16:40

Your right Steve, very sorry.
I posted a question on the bird Id forum and this was a link to it. I made a mistake and replied to the link instead of my own question.

MY apologies

Roger.

Steve Lister Wednesday 27th July 2005 17:14

No worries.

Steve

admmoon Tuesday 25th August 2009 15:08

Leucism explained
 
Here is a good explanation of the difference between leucism and albinism.

http://veterinaryherpetologist.blogspot.com/

He used to have other posts, but apparently the server crashed and he had to set up a new site. His first post is one on leucism.

Rasmus Boegh Wednesday 26th August 2009 07:12

Quote:

Originally Posted by admmoon (Post 1566908)
Here is a good explanation of the difference between leucism and albinism.

http://veterinaryherpetologist.blogspot.com/

He used to have other posts, but apparently the server crashed and he had to set up a new site. His first post is one on leucism.

Above is about the vetenarian (and herpetological?) definition, i.e. of no direct relevance for their use in birding, where the above description is partially correct – partially incorrect (cf. definitions in specific ornithological references in earlier posts of this thread). Secondly, this thread is 4+ years old. Many things have happened since then. For birding the most significant is perhaps the article by J. N. Davis in Birding 39(5) dealing with color abnormalities in birds and terms used to describe them.

Just noticed this was your first post; Welcome!

fugl Wednesday 26th August 2009 15:16

It seems to me that all birders need be concerned with in regard to these conditions is reasonably accurate description of the affected feathers/soft parts. I don't know why the non-"expert"--who by definition is unlikely to have much of a handle on the underlying causation--should have to worry about getting the technical vocabulary right. What's wrong with "Brewer's Blackbird with white patches in wings & tail & pink bill" (for example)?

admmoon Friday 4th September 2009 04:41

Loose definiton of leucism is inexcusable
 
[quote=Rasmus Boegh;1567482]Above is about the vetenarian (and herpetological?) definition, i.e. of no direct relevance for their use in birding, where the above description is partially correct – partially incorrect (cf. definitions in specific ornithological references in earlier posts of this thread). Secondly, this thread is 4+ years old. Many things have happened since then. For birding the most significant is perhaps the article by J. N. Davis in Birding 39(5) dealing with color abnormalities in birds and terms used to describe them.



I must disagree. One of the problems with literature out there is there are too many people who do not use the correct definitions and that leads to confusion. The scientific and medical fields do have a standard set of definitions for a reason. When laymen begin to throw words around in the improper context, generating erroneous definitions, it leads to a large amount of confusion.

Moreover, when scientists that do not have a firm grasp on the pathogenesis of any conditions start using definitions to include a number of different pathologic conditions it leads to confusion in the academic world as well. Imagine the confusion if people started calling piebaldism vitilligo. Or leucism albinism (they do come from the same root and do mean the same thing - white). The result is confusion and a breakdown in communication. At present in the literature, including mammology, ornithology and herpetology, the technical definitions of leucism are not used correctly and not associated with the actual cause of any pigmentary condition. The result is that anything with white on it is being called leucism as long as it is not totally white with red eyes. There are forms of albinism where the defect is in a different part of the melanin cascade that produces blue eyed albinos in many species, but I have actually seen texts call this form of albinism leucism. That is inexcusable for anyone with a scientific background to do.

A good example is several texts and (of course websites) refer to "partial albinos." Where the pigment is reduced but not absent. This condition is known as hypomelanism and is a genetic defect where the melanophores produce reduced amounts of pigment. It is not leucism and not synonymous with leucism.

Secondly, if you have not been keeping up with phylogenetics Aves is not considered a class anymore but is placed under Reptilia under Archosauria. Therefore the herpetologic definitions have been applied. In fact they have been more or less accepted by paleontology for years and the rest of the biological sciences are just now catching up.

Lastly, I e-mailed the owner of http://veterinaryherpetologist.blogspot.com/ and asked him about bird pigments and leucism. He posted a reply on his blog earlier today that some might find interesting.

Sorry, I hope this does not sound terse, but I have been a biologist for a number of years and have noticed a real terminology problem in the sciences, especially in areas like these. The more general sciences like mammology, herpetology and ornithology have largely remained ignorant and failed to keep up with the more hard nosed, clinical sciences like medicine, biomedicine, molecular biology, biophysics, biochemistry, physiology, cellular mechanics and cellular biology. I could go on with that list, but I will not. I just think that if you consider the fact that of all the peer reviewed literature that is published in scientific fields each year, a conservative estimate is that, about 60% is junk and gets by not having being reviewed by those with real expertise in the field. Also, books that have not been peer reviewed are often riddled with falsehoods, and most articles that appear in hobby magazines are loaded with opinions that have no scientific data to back them up. So I get a bit edgy when I see a definition used that is archaic or downright incorrect, because it makes communication that much harder. So forgive my terseness, but it is so exasperating to have a defined term used with 14 different definitions that are not correct.

Rasmus Boegh Friday 4th September 2009 11:20

Quote:

Originally Posted by admmoon (Post 1576347)
I must disagree. One of the problems with literature out there is there are too many people who do not use the correct definitions and that leads to confusion. The scientific and medical fields do have a standard set of definitions for a reason. When laymen begin to throw words around in the improper context, generating erroneous definitions, it leads to a large amount of confusion.

From above it appears you're suggesting that scientists working with birds (probably the single field in biology with most scientists, at least when disregarding human biology) are laymen? Check the previous ornithological references and please do explain why these should be regarded as layman, but your references (at present, actually based entirely on an entry by a semi-anonymous blogger just labelled "Dr. Walden") dealing with other fields are not? I have never, and will never, claim to know what is the correct use in e.g. herpetopathology (which appears to be the primary focal point of the previously mentioned blog), but likewise find it puzzling why people that clearly have little, if any, involvement in ornithology try to explain what is the correct definition in... ornithology! I can see the blogger now warns about the Cornell Lab of Ornithology under the headline "Be Careful of Hobbyist and Birding Book Terms". Evidently, he is not familiar with the Cornell Lab of Ornithology. Until the blogger provides a reference that supports his opinion on the use of these terms in ornithology, it remains just that; an opinion by a single person with little or no actual involvement in ornithology.

Quote:

Originally Posted by admmoon (Post 1576347)
Secondly, if you have not been keeping up with phylogenetics Aves is not considered a class anymore but is placed under Reptilia under Archosauria. Therefore the herpetologic definitions have been applied. In fact they have been more or less accepted by paleontology for years and the rest of the biological sciences are just now catching up.

I *never* said anything about the phylogeny of Aves (which I deal with on an every day basis) in this thread, and why you suddenly bring this up is somewhat puzzling. But regardless - the above is only partially correct. From a purely phylogenetic point of view, you are entirely right when saying that Aves is potentially problematic - certainly, but this isn't news and has been known for decades. But, even when strictly limiting it to phylogenetics, there are several solutions to this, and only one of them involves removing Aves as a class. Others involve splitting up other groups. Regardless, strictly speaking this isn't necessary to keep Aves. Today all animals are classified using the Linnaean System (which certainly has its flaws), and no-where did Linnaeus (or, more recently, ICZN) require for taxa to be monophyletic. The Linnean System does not necessarily equal cladistics. This is true both at higher and lower levels - even species (see e.g. Funk & Omland, 2003: Annual Review of Ecology, Evolution, and Systematics 34). Furthermore, if used as described in the above quote, it can actually be argued that Aves is a senior synonym of Reptilia (it was coined ~10 years before), and in any case what generally has been placed under Archosauria are birds, crocodiles, dinosaus, and alike. Not Reptilia in its entirety (contra above quote - unless what actually was meant was, in logical order [highest to lowest], Reptilia, Archosauria, Aves), which would result in further phylogenetic problems unless defining the combined clade as broadly as Sauropsida. Anyhow, if you search through recent literature, you will notice that few authorities working with extant birds treat Aves as anything but a class, even if people working with reptiles and especially paleontology generally dislike this.

As a final comment from me on this matter, I can only recommend you read the previously mentioned article (Davis, 2007 - see comment #14). In addition to a number of recommendation for accurately describing plumage abnormalities in ornithology, it also provides a brief history of the often confusing and conflicting use of these terms. Here it is worth mentioning that the use of the terms "albinism" and "leucism" for describing abnormalities in birds actually predates knowledge of most of the processes described in the previously mentioned blog. So, while the blog may well be correct in the use of these terms in herpetopathology, it matches neither the original nor the current use in ornithology.

cheersm8 Friday 4th September 2009 11:31

I keep my life simple, pink eyes = albino, normal eyes = leucistic
I haven't gone into all the science bumf about it, but I do know that albinism is always genetic, but leucism can be both a genetic thing and also a health and diet thing.


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