Black Squirrels

tim · 23rd October 2003, 10:59 PM

I used to live in a small town in Hertfordshire called Letchworth, about 35 miles north of London.
There was a thriving population of grey squirrels (tree rats) that had driven out the indigenous red species. (cries of "shame, shame" all round please).
In the last fifty years what seems to be a local mutation has taken place and a significant percentage (a guess would be 1 in 10 or 15) are now "black" - actually very dark brown. The percentage seems to be increasing, so being black must have some advantage. This may be that it is an urban environment and the black animals stand out and get fed by humans succumbing to the "aaawww" factor.
Any ideas?
And in case you don't believe me here's a picture of one of the little buggers (and no, I haven't photoshopped it...........)

davefoc · 24th October 2003, 12:28 AM

I liked your story and your picture Tim, but I have absolutely nothing to say about it, so I'm doing this in lieu of saying bump.

UnrepentantSinner · 24th October 2003, 12:35 AM

{/political correctness}

We have the same thing happen in the states, but with people.

{political correctness}

mummymonkey · 24th October 2003, 01:03 AM

Maybe black squirrels are faster runners?

Flame · 24th October 2003, 01:42 AM

Zooboard discussion

Also info here that says that the black squirrel is actually a rare version of the grey...

species maps

Brown · 24th October 2003, 04:27 AM

I am aware of a location in the United States that has a large population of black squirrels. It is not unusual for the locals to be amused when a visitor exclaims, "Hey, you have black squirrels!"

(Most squirrels in the area are grey or light brown.)

wayrad · 24th October 2003, 04:59 AM

White squirrels are also common in some places:
http://www.roadsideamerica.com/set/squirrels.html

BillHoyt · 24th October 2003, 05:03 AM

Quote:

Originally posted by Brown
I am aware of a location in the United States that has a large population of black squirrels. It is not unusual for the locals to be amused when a visitor exclaims, "Hey, you have black squirrels!"

(Most squirrels in the area are grey or light brown.)

They are becoming abundant in Connecticut. I'm noticing them in more rural areas rather than urban.

Cheers,

tonygraham · 24th October 2003, 05:33 AM

Is it possible that the darker pigmentation may have different thermal properties that confer an advantage in winter?

(By the way, I'm not sure that that's not just a wombat hanging by its feet).

BillHoyt · 24th October 2003, 05:55 AM

Quote:

Originally posted by tonygraham
Is it possible that the darker pigmentation may have different thermal properties that confer an advantage in winter?

(By the way, I'm not sure that that's not just a wombat hanging by its feet).

Possible? Absolutely. But why, then, are the greys in great abundance up here? And, if Tim is right, why are the blacks now increasing? Interesting questions.

Cheers,

arcticpenguin · 24th October 2003, 06:41 AM

Tim,

Are you sure that the blacks are the same species?

BillHoyt · 24th October 2003, 06:45 AM

Quote:

Originally posted by arcticpenguin
Tim,

Are you sure that the blacks are the same species?

A/P,

From observations on my road, I'd say "absolutely". On my dirt road, they are all black. At the far end of the connecting tar road, they are all grey. In between there is a band of distinctly dark grey squirrels. I'd say, offhand, there's gene flow.

Cheers,

Suezoled · 24th October 2003, 06:54 AM

Viable genetic mutation? Viable dominant genetic mutation??? Whoooeeee! I'm in love!

BillHoyt · 24th October 2003, 07:02 AM

Quote:

Originally posted by Suezoled
Viable genetic mutation? Viable dominant genetic mutation??? Whoooeeee! I'm in love!

Based on the "dark greys", it looks to me like incomplete dominance. Unless, of course, the black squirrels prefer to wear leather.

Cheers,

Andonyx · 24th October 2003, 08:10 AM

In Virginia, at least from 1975-1993 they had only the grey and brown kind.

But the weird thing is, simply crossing the border into Maryland would produce black squirrels in abundance.

It's just odd to me that their areas of confinement were so specific.

Ziggurat · 24th October 2003, 10:48 AM

Here's another possibility: the color doesn't need to confer any advantage at all, but it may be linked to a trait that does confer advantage.

First, for those not familiar with the term, linked traits are ones where the genes that encode them are close or adjacent to each other on the chromosome. During mixing of the chromosomes to produce genetically distinct offspring, the chromosome is spliced in a relatively small number of places compared to the number of genes, so that linked traits are generally passed down together. If fur color is linked to some other important gene, and a squirrel with black fur has a particularly useful gene for this other trait, then the propagation of that trait throughout the population will generally carry any linked traits wih it (assuming, of course, that black fur isn't a big disadvantage to offset the advantage of the other gene). So the propagation of something like black fur doesn't necessarily need to have anything to do with it being advantageous. Of course, it could be, but this alternate scenario is something to keep in mind.

mummymonkey · 24th October 2003, 10:54 AM

Quote:

Originally posted by Ziggurat
Here's another possibility: the color doesn't need to confer any advantage at all, but it may be linked to a trait that does confer advantage.

That's what I inferred.

BillHoyt · 24th October 2003, 10:55 AM

Quote:

Originally posted by Ziggurat
Here's another possibility: the color doesn't need to confer any advantage at all, but it may be linked to a trait that does confer advantage.

First, for those not familiar with the term, linked traits are ones where the genes that encode them are close or adjacent to each other on the chromosome. During mixing of the chromosomes to produce genetically distinct offspring, the chromosome is spliced in a relatively small number of places compared to the number of genes, so that linked traits are generally passed down together. If fur color is linked to some other important gene, and a squirrel with black fur has a particularly useful gene for this other trait, then the propagation of that trait throughout the population will generally carry any linked traits wih it (assuming, of course, that black fur isn't a big disadvantage to offset the advantage of the other gene). So the propagation of something like black fur doesn't necessarily need to have anything to do with it being advantageous. Of course, it could be, but this alternate scenario is something to keep in mind.

Hitchiking is certainly possible, although one needs to keep in mind that the hitchiking effect only lasts so long. The speed with which the two loci will resegregate (and therefore break down the hitchiking effect) depends on the chromosomal distance between them, but it is guaranteed to happen.

I guess there are two questions here:
o Are the numbers of black squirrels really increasing?
o If so, is the black color directly advantageous or indirectly advantageous either because of hitchiking or because of a side-effect of the advantageous gene.

Cheers,

BobM · 24th October 2003, 11:46 AM

My nieghborhood in southeastern Michigan has become dominated by black squirrels in the last decade. They are now in the majority.

zakur · 24th October 2003, 12:12 PM

Black Squirrel Squabbles

White Squirrel Wars

Can't we all just get along?!

mummymonkey · 24th October 2003, 12:17 PM

Scottish squirrels are, of course, ginger.

arcticpenguin · 24th October 2003, 12:38 PM

Quote:

Originally posted by Andonyx
In Virginia, at least from 1975-1993 they had only the grey and brown kind.

But the weird thing is, simply crossing the border into Maryland would produce black squirrels in abundance.

It's just odd to me that their areas of confinement were so specific.

Different hunting regulations?

tim · 24th October 2003, 01:12 PM

Quote:

Originally posted by mummymonkey
Scottish squirrels are, of course, ginger.

I am 53. I have only ever seen two red squirrels, and both those in the Lake District (The very northern part of England). They used to be common here (southern England) but after the introduction of the American grey squirrels were driven ever further northwards until it's almost unknown to see them south of the Scottish border. The greys are better equiped than the reds to exploit the ecological niche they previously enjoyed on different continents.
Typical bloody Yanks. After our squirrels' nuts.
It's actually yet another salutory lesson - DON'T INTRODUCE ALIEN SPECIES. Ask the Australians about rabbits!

zakur · 24th October 2003, 01:24 PM

Quote:

Originally posted by tim
Typical bloody Yanks. After our squirrels' nuts.

Boy that comment made me laugh! Considering one of the squirrel "rural legends" from around here:

Quote:

The mature male's testicles drop into the scrotum during breeding seasons starting at 18 months of age. During the non-breeding season of the year, the testicles are pulled up into the abdominal cavity. This has given rise to the common belief that the smaller red squirrels castrate fox and gray squirrels.

tim · 24th October 2003, 01:52 PM

Quote:

Originally posted by zakur
Boy that comment made me laugh! Considering one of the squirrel "rural legends" from around here:

Call yourself a skeptic? Believing rural legends? Shame on you Zakur!

BTox · 24th October 2003, 08:10 PM

I saw my first black squirrel in our neighborhood this summer. Will be interesting to see if the population increases.

American · 24th October 2003, 08:26 PM

Most squirrels are grey in MA. I knew one big hill in western mass that was renowned for a mostly isolated population of dark brown ones. Can't explain it, they're just there!

23rd October 2003, 10:59 PM	#1
tim Lasiorhinus latifrons Combat Division Join Date: Jan 2003 Location: Bedfordshire, UK Posts: 11,331	Black Squirrels I used to live in a small town in Hertfordshire called Letchworth, about 35 miles north of London. There was a thriving population of grey squirrels (tree rats) that had driven out the indigenous red species. (cries of "shame, shame" all round please). In the last fifty years what seems to be a local mutation has taken place and a significant percentage (a guess would be 1 in 10 or 15) are now "black" - actually very dark brown. The percentage seems to be increasing, so being black must have some advantage. This may be that it is an urban environment and the black animals stand out and get fed by humans succumbing to the "aaawww" factor. Any ideas? And in case you don't believe me here's a picture of one of the little buggers (and no, I haven't photoshopped it...........)
	__________________ I think we should be grateful that somehow the material in the universe came together and gave us consciousness. It was statiscally improbable. We won the lottery. We had a life. Hubbard's Law: Don't take life too seriously; you won't get out of it alive.

24th October 2003, 12:35 AM	#3
UnrepentantSinner A post by Alan Smithee Join Date: Aug 2001 Location: USAian is not a word Posts: 26,353	{/political correctness} We have the same thing happen in the states, but with people. {political correctness}
	__________________ I am an American citizen who is part of American society and briefly served in the American armed forces. I use American dollars and pay taxes that support the American government. And yes, despite the editorial decison to change American politics to the nonsensical "USA politics" subforum, I follow and comment on American politics.

24th October 2003, 01:03 AM	#4
mummymonkey Did you spill my pint? Join Date: Dec 2002 Location: Scotland Posts: 1,915	Maybe black squirrels are faster runners?
	__________________ Knees bent, arms stretched, Ra! Ra! Ra!

24th October 2003, 01:42 AM	#5
Flame Muse Join Date: May 2003 Posts: 584	Zooboard discussion Also info here that says that the black squirrel is actually a rare version of the grey... species maps
Flame Muse Join Date: May 2003 Posts: 584	__________________ 'And God said, Let us make man in our own image, but woe many came out like Spitting Image' - The Bible According to Spike Milligan

24th October 2003, 04:27 AM	#6
Brown Penultimate Amazing Join Date: Aug 2001 Location: Twin Cities, Canada Posts: 12,150	I am aware of a location in the United States that has a large population of black squirrels. It is not unusual for the locals to be amused when a visitor exclaims, "Hey, you have black squirrels!" (Most squirrels in the area are grey or light brown.)
	__________________ Klaatu: I'm impatient with stupidity. My people have learned to live without it. Mr. Harley: I'm afraid my people haven't. I am very sorry. I wish it were otherwise. -- The Day The Earth Stood Still, screenplay by Edmund H. North "Don't you get me wrong. I only want to know." -- Judas in Jesus Christ Superstar, lyrics by Tim Rice

24th October 2003, 12:28 AM	#2
davefoc Philosopher Join Date: Jun 2002 Location: orange country, california Posts: 7,255	I liked your story and your picture Tim, but I have absolutely nothing to say about it, so I'm doing this in lieu of saying bump.

24th October 2003, 04:59 AM	#7
wayrad Muse Join Date: Feb 2003 Posts: 739	White squirrels are also common in some places: http://www.roadsideamerica.com/set/squirrels.html
wayrad Muse Join Date: Feb 2003 Posts: 739	__________________ "No one knows the reason for all this, but it is probably quantum" - Terry Pratchett

24th October 2003, 05:03 AM	#8
BillHoyt Enlightening rod Join Date: Mar 2003 Location: Right behind you... Posts: 5,842	Quote: Originally posted by Brown I am aware of a location in the United States that has a large population of black squirrels. It is not unusual for the locals to be amused when a visitor exclaims, "Hey, you have black squirrels!" (Most squirrels in the area are grey or light brown.) They are becoming abundant in Connecticut. I'm noticing them in more rural areas rather than urban. Cheers,

24th October 2003, 05:33 AM	#9
tonygraham Thinker Join Date: Oct 2001 Posts: 225	Is it possible that the darker pigmentation may have different thermal properties that confer an advantage in winter? (By the way, I'm not sure that that's not just a wombat hanging by its feet).
tonygraham Thinker Join Date: Oct 2001 Posts: 225	__________________ How can you lie there and think of England, when you don't even know who's in the team? Billy Bragg Never criticise a man until you've walked a mile in his shoes. That way, you'll be a mile away and you'll have his shoes.

24th October 2003, 05:55 AM	#10
BillHoyt Enlightening rod Join Date: Mar 2003 Location: Right behind you... Posts: 5,842	Quote: Originally posted by tonygraham Is it possible that the darker pigmentation may have different thermal properties that confer an advantage in winter? (By the way, I'm not sure that that's not just a wombat hanging by its feet). Possible? Absolutely. But why, then, are the greys in great abundance up here? And, if Tim is right, why are the blacks now increasing? Interesting questions. Cheers,

24th October 2003, 06:41 AM	#11
arcticpenguin woo ban clan Join Date: Sep 2002 Posts: 5,717	Tim, Are you sure that the blacks are the same species?
	__________________ The power of accurate observation is frequently called cynicism by those who don't have it. - George Bernard Shaw

24th October 2003, 06:45 AM	#12
BillHoyt Enlightening rod Join Date: Mar 2003 Location: Right behind you... Posts: 5,842	Quote: Originally posted by arcticpenguin Tim, Are you sure that the blacks are the same species? A/P, From observations on my road, I'd say "absolutely". On my dirt road, they are all black. At the far end of the connecting tar road, they are all grey. In between there is a band of distinctly dark grey squirrels. I'd say, offhand, there's gene flow. Cheers,

24th October 2003, 06:54 AM	#13
Suezoled Mentally Interesting Join Date: Sep 2003 Posts: 4,588	Viable genetic mutation? Viable dominant genetic mutation??? Whoooeeee! I'm in love!
	__________________ "We must always fear the wicked. But there is another kind of evil that we must fear the most, and that is the indifference of good men." -priest guy from Boondock Saints "And we'll no longer memorize or rhyme/Too far along in our crime/ Stepping over what now towers to the sky/ With no connection" -Shins

24th October 2003, 07:02 AM	#14
BillHoyt Enlightening rod Join Date: Mar 2003 Location: Right behind you... Posts: 5,842	Quote: Originally posted by Suezoled Viable genetic mutation? Viable dominant genetic mutation??? Whoooeeee! I'm in love! Based on the "dark greys", it looks to me like incomplete dominance. Unless, of course, the black squirrels prefer to wear leather. Cheers,

24th October 2003, 08:10 AM	#15
Andonyx Graduate Poster Join Date: Jul 2002 Posts: 1,834	In Virginia, at least from 1975-1993 they had only the grey and brown kind. But the weird thing is, simply crossing the border into Maryland would produce black squirrels in abundance. It's just odd to me that their areas of confinement were so specific.
Andonyx Graduate Poster Join Date: Jul 2002 Posts: 1,834	__________________ Andonyx www.andonyx.com Shy Gypsy Slyly Shyly Tryst By My Crypt.

24th October 2003, 10:48 AM	#16
Ziggurat Penultimate Amazing Join Date: Jun 2003 Posts: 26,189	Here's another possibility: the color doesn't need to confer any advantage at all, but it may be linked to a trait that does confer advantage. First, for those not familiar with the term, linked traits are ones where the genes that encode them are close or adjacent to each other on the chromosome. During mixing of the chromosomes to produce genetically distinct offspring, the chromosome is spliced in a relatively small number of places compared to the number of genes, so that linked traits are generally passed down together. If fur color is linked to some other important gene, and a squirrel with black fur has a particularly useful gene for this other trait, then the propagation of that trait throughout the population will generally carry any linked traits wih it (assuming, of course, that black fur isn't a big disadvantage to offset the advantage of the other gene). So the propagation of something like black fur doesn't necessarily need to have anything to do with it being advantageous. Of course, it could be, but this alternate scenario is something to keep in mind.
	__________________ "As long as it is admitted that the law may be diverted from its true purpose -- that it may violate property instead of protecting it -- then everyone will want to participate in making the law, either to protect himself against plunder or to use it for plunder. Political questions will always be prejudicial, dominant, and all-absorbing. There will be fighting at the door of the Legislative Palace, and the struggle within will be no less furious." - Bastiat, The Law

24th October 2003, 10:54 AM	#17
mummymonkey Did you spill my pint? Join Date: Dec 2002 Location: Scotland Posts: 1,915	Quote: Originally posted by Ziggurat Here's another possibility: the color doesn't need to confer any advantage at all, but it may be linked to a trait that does confer advantage. That's what I inferred.
	__________________ Knees bent, arms stretched, Ra! Ra! Ra!

24th October 2003, 10:55 AM	#18
BillHoyt Enlightening rod Join Date: Mar 2003 Location: Right behind you... Posts: 5,842	Quote: Originally posted by Ziggurat Here's another possibility: the color doesn't need to confer any advantage at all, but it may be linked to a trait that does confer advantage. First, for those not familiar with the term, linked traits are ones where the genes that encode them are close or adjacent to each other on the chromosome. During mixing of the chromosomes to produce genetically distinct offspring, the chromosome is spliced in a relatively small number of places compared to the number of genes, so that linked traits are generally passed down together. If fur color is linked to some other important gene, and a squirrel with black fur has a particularly useful gene for this other trait, then the propagation of that trait throughout the population will generally carry any linked traits wih it (assuming, of course, that black fur isn't a big disadvantage to offset the advantage of the other gene). So the propagation of something like black fur doesn't necessarily need to have anything to do with it being advantageous. Of course, it could be, but this alternate scenario is something to keep in mind. Hitchiking is certainly possible, although one needs to keep in mind that the hitchiking effect only lasts so long. The speed with which the two loci will resegregate (and therefore break down the hitchiking effect) depends on the chromosomal distance between them, but it is guaranteed to happen. I guess there are two questions here: o Are the numbers of black squirrels really increasing? o If so, is the black color directly advantageous or indirectly advantageous either because of hitchiking or because of a side-effect of the advantageous gene. Cheers,

24th October 2003, 11:46 AM	#19
BobM Thinker Join Date: Mar 2002 Posts: 134	My nieghborhood in southeastern Michigan has become dominated by black squirrels in the last decade. They are now in the majority.
BobM Thinker Join Date: Mar 2002 Posts: 134

24th October 2003, 12:12 PM	#20
zakur Illuminator Join Date: Aug 2001 Location: Dayton, OH Posts: 3,265	Black Squirrel Squabbles White Squirrel Wars Can't we all just get along?!
	__________________ "I do not believe in the collective wisdom of individual ignorance." -Thomas Carlyle "That's the problem these days: nobody thinks of the tumors." -steinhenge

24th October 2003, 12:17 PM	#21
mummymonkey Did you spill my pint? Join Date: Dec 2002 Location: Scotland Posts: 1,915	Scottish squirrels are, of course, ginger.
	__________________ Knees bent, arms stretched, Ra! Ra! Ra!

24th October 2003, 12:38 PM	#22
arcticpenguin woo ban clan Join Date: Sep 2002 Posts: 5,717	Quote: Originally posted by Andonyx In Virginia, at least from 1975-1993 they had only the grey and brown kind. But the weird thing is, simply crossing the border into Maryland would produce black squirrels in abundance. It's just odd to me that their areas of confinement were so specific. Different hunting regulations?
	__________________ The power of accurate observation is frequently called cynicism by those who don't have it. - George Bernard Shaw

24th October 2003, 01:12 PM	#23
tim Lasiorhinus latifrons Combat Division Join Date: Jan 2003 Location: Bedfordshire, UK Posts: 11,331	Quote: Originally posted by mummymonkey Scottish squirrels are, of course, ginger. I am 53. I have only ever seen two red squirrels, and both those in the Lake District (The very northern part of England). They used to be common here (southern England) but after the introduction of the American grey squirrels were driven ever further northwards until it's almost unknown to see them south of the Scottish border. The greys are better equiped than the reds to exploit the ecological niche they previously enjoyed on different continents. Typical bloody Yanks. After our squirrels' nuts. It's actually yet another salutory lesson - DON'T INTRODUCE ALIEN SPECIES. Ask the Australians about rabbits!
	__________________ I think we should be grateful that somehow the material in the universe came together and gave us consciousness. It was statiscally improbable. We won the lottery. We had a life. Hubbard's Law: Don't take life too seriously; you won't get out of it alive.

24th October 2003, 01:24 PM	#24
zakur Illuminator Join Date: Aug 2001 Location: Dayton, OH Posts: 3,265	Quote: Originally posted by tim Typical bloody Yanks. After our squirrels' nuts. Boy that comment made me laugh! Considering one of the squirrel "rural legends" from around here: Quote: The mature male's testicles drop into the scrotum during breeding seasons starting at 18 months of age. During the non-breeding season of the year, the testicles are pulled up into the abdominal cavity. This has given rise to the common belief that the smaller red squirrels castrate fox and gray squirrels.
	__________________ "I do not believe in the collective wisdom of individual ignorance." -Thomas Carlyle "That's the problem these days: nobody thinks of the tumors." -steinhenge

24th October 2003, 01:52 PM	#25
tim Lasiorhinus latifrons Combat Division Join Date: Jan 2003 Location: Bedfordshire, UK Posts: 11,331	Quote: Originally posted by zakur Boy that comment made me laugh! Considering one of the squirrel "rural legends" from around here: Call yourself a skeptic? Believing rural legends? Shame on you Zakur!
	__________________ I think we should be grateful that somehow the material in the universe came together and gave us consciousness. It was statiscally improbable. We won the lottery. We had a life. Hubbard's Law: Don't take life too seriously; you won't get out of it alive.

24th October 2003, 08:10 PM	#26
BTox Graduate Poster Join Date: Jul 2003 Posts: 1,588	I saw my first black squirrel in our neighborhood this summer. Will be interesting to see if the population increases.
BTox Graduate Poster Join Date: Jul 2003 Posts: 1,588	__________________ "Your ignorance makes me ill... "

24th October 2003, 08:26 PM	#27
American Illuminator Join Date: Jul 2001 Location: CA Posts: 3,842	Most squirrels are grey in MA. I knew one big hill in western mass that was renowned for a mostly isolated population of dark brown ones. Can't explain it, they're just there!