"Normal" Flyer Weight

Tips, experience & advice related to the healthy and not-so-healthy flying squirrel
Joan
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"Normal" Flyer Weight

Postby Joan » Fri Jan 12, 2007 6:53 pm

I recently wrote to Tom Risch, PhD from the Dept of Biology at Arkansas State University http://biology.astate.edu/risch.htm to inquire about size in wild flyers. Tom was a Key Note speaker at the NFSA National Conference in 2004 in Alabama and he has done extensive flyer research at the Savannah River Ecology Laboratory: http://www.uga.edu/~srel/ Tom attached a paper that has some data on weights of flyers in it. The article is titled "Reproductive and resource benefits to large female body size in a mammal with female-biased sexual size dimorphism" and is in Animal Behaviour, available online 3 January 2007, authors H. Bobby Fokidis, Thomas S. Risch and Travis C. Glenn.

Here's what Tom wrote to me:
"If you look at the graphs, there are data in grams. There are 28 grams in one ounce. Of the about 2,000 squirrels that I caught over the years, only a very few were ever over a 100 grams. So in the wild, a 3oz squirrel is huge and a 4 oz squirrels is unheard of. Females are bigger than males, which is a focus of the paper."

I'll review the paper and report back on the weight findings.
Last edited by Joan on Thu Apr 05, 2007 5:25 pm, edited 3 times in total.
"A lot of people spend time talking to the Animals, but not that many people listen. That's the real problem! ... Winnie the Pooh

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Postby Joan » Mon Mar 26, 2007 7:57 pm

OK, better late than never. I've put together a summary of this article:

Female flyers are not significantly larger or heavier than males at first reproduction, but become about 7% heavier and 22% larger than males at subsequence breedings. Litter size is influenced by both maternal body size and body mass with larger and heavier females bearing larger litters. First time breeding females were not significantly larger or heavier than males, but become so on subsequence breeding attempts, at about one year of age.
However, despite female growth continuing beyond their first reproduction, increase body size and body mass in females was positively associated with litter size, independent of female's age. A large majority of first-time breeding females produce only two offspring (64% of first-time litters), which may indicate a physiological constraint on reproduction at an early age before they have reached their full adult body size. Female flyers often breed within a few months of their own birth and prior to their first birthday.
The youngest wild female (colony bred... in Dr. Risch's research colony) gave birth at four months. The youngest female of a HOF to breed was 6 months. Mishi was one week short of one year of age when she produced her first litter. She and Chuck were about the same size then, but she is considerably larger and heavier now.
Since our furballs tend to be fatter than corresponding in age wild flyers, our females' size would be considered "unheard of" in the wild.
Last edited by Joan on Fri Mar 30, 2007 8:27 pm, edited 1 time in total.
"A lot of people spend time talking to the Animals, but not that many people listen. That's the real problem! ... Winnie the Pooh

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Vickie
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Postby Vickie » Mon Mar 26, 2007 8:05 pm

Great study--thanks for the summary, Joan. I kind of got "the giggles" though, when I read:

". . . increase body size and body mass in females was positively associated with litter size . . ."

Not unlike human females, eh?
First Barnie, and now Jimmy--Zing, went the strings of my heart!

den942
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On age...

Postby den942 » Wed Mar 28, 2007 9:40 pm

How do they know the age of these squirrels? Are they tagged so they
know without a doubt they are breeding that young? Could they be
getting younger and older females mixed up? I know I have some I
sure can't tell apart by looking at them.
In fifteen years I've never seen a female flyer give birth younger than
one year old. Also, some of my bigger females have one or two
babies quite often and my smaller youngest girl has had ten babies
in her first three litters. He first litter at age one was four babies.
She had two litters of three since. Right now she has three and two
females three times her age had one and two in their spring litters.
Pretty much the opposite of his study.
I can not say I have seen any corelation between female size and
litter size.

den942
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Re: On age...

Postby den942 » Thu Mar 29, 2007 8:07 am

All this said, I realized all mine I'm referring to are a different subspecies
than he is talking about. I sold all but a pair of the flyers I got from
Florida a few years back. So far one litter in about 5-6 years from
the Florida pair. My best breeders are from Ohio or a Michigan male
and Ohio females. The Kentucky pair I have don't appear to be doing
anything this spring but they did breed when there was 3 more of them
in the cage last year. Go figure...

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Re: On age...

Postby Joan » Mon Apr 02, 2007 10:03 am

den942 wrote:How do they know the age of these squirrels? Are they tagged so they know without a doubt they are breeding that young?


Apparently so as Dr. Risch states:
In a message dated 4/2/2007 10:48:42 A.M. Eastern Daylight Time, trisch@astate.edu writes:


Hi Joan,
They all have marks.  In a case like that one she was marked in as a pup with her littermates.
 
Tom

The HOF pup was one of Beverly's that was adopted out:

In a message dated 3/30/2007 8:35:37 P.M. Eastern Daylight Time, skwerlbaitbev@aol.com writes:


Smidgen, a pup I gave to Sheila, on Long Island, produced pups at under 6 months, if I remember correctly.  I'll e her, and ask.  I think Smidgen was barely 6 months -- might have been 5 ...
"A lot of people spend time talking to the Animals, but not that many people listen. That's the real problem! ... Winnie the Pooh

Joan
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Re: On age...

Postby Joan » Wed Apr 04, 2007 10:24 pm

Joan wrote:The HOF pup was one of Beverly's that was adopted out:

In a message dated 3/30/2007 8:35:37 P.M. Eastern Daylight Time, skwerlbaitbev@aol.com writes:


Smidgen, a pup I gave to Sheila, on Long Island, produced pups at under 6 months, if I remember correctly.  I'll e her, and ask.  I think Smidgen was barely 6 months -- might have been 5 ...


Here's more information directly from Sheila:

"Smidgen was 5 days short of 6 months old when she had the first litter : 2 males and 2 females----the afternoon of 8/31/03

(picture attached you can see that the blood on the floor of the box is still red (wet).
Image

She had tried to have them on my desk.... 1st litter:
Sebastian-----lives with BW (dad)
Froggy------ prefers to live by herself (lighter in color) (her crazy sisters are too much for her)
Boy #2------ went to a girl (Lisa) who flew from Michigan to pick up/has one from Dennis
Girl #2------- ditto above

The second litter was at 1 year 29 days------4/3/04---1 male and 4 females."
"A lot of people spend time talking to the Animals, but not that many people listen. That's the real problem! ... Winnie the Pooh


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