WHITE SQUIRRELS
PURPOSE

To monitor the distribution and abundance of Brevard’s resident white squirrel population
INTRODUCTION
Origins
The city of Brevard, NC hosts an established colony of white squirrels, a color morph that
currently makes up more than 20% of the native Eastern gray squirrel (Sciurus carolinensis)
population. The white squirrels are not albinos as are other well-studied white colonies (Stencel and
Ghent 1987). Brevard’s variant has pigmented eyes, a distinctive head patch, and dorsal stripe.
According to local folklore, all of today’s white squirrels are descended from a single pair
trapped from northern Florida and eventually released in Brevard in 1951 (The White Squirrel
Shoppe). The existence of white squirrels with the same distinctive pattern scattered throughout
central and northern Florida supports the Florida connection (White Squirrel Research Institute).
However, this widespread distribution casts doubt on the rest of the legend. The supposed circus
caravan wreck and an exotic oriental origin may simply be embellishments to make the story more
interesting.
Copyright © Dr. Robert R. Glesener
Since that time, the Brevard white morph has not only increased in abundance within the city, but
it also has dispersed over a wide area. Today, white squirrels with similar markings are found from
Cashiers in the west to Hendersonville in the east, a span of approximately 50 miles (White Squirrel
Research Institute). However, the disjunct nature of their distribution suggests that their dispersal
may have been assisted by trap and release by admiring humans.
Figure 1. Gray and white color morphs of the Eastern gray squirrel
(Sciurus carolinensis)
Genetics of Coat Color
There is much variation in both the white and gray morph, and little is known of their underlying
developmental genetics. However, these variants do appear to segregate as separate Mendelian units.
Mixed litters occur in which individuals are either white or gray, not intermediate. It is often
assumed that, like albinos, the white morph is recessive, but breeding experiments are sparse,
uncontrolled, and inconclusive. In fact, an analysis of the rapid increase to the current stable
dimorphism suggest that the white morph may actually be dominant (Glesener 2001a).
Biology of Gray Squirrels (Halloran 2001)
Gray squirrels, common throughout the eastern United States, are considered to be arboreal, or
tree, squirrels. They are highly adapted for climbing trees, with tough curved claws and flexible
joints giving them the ability to have headfirst descent. Powerful hindlimbs are used for leaping.
Their bushy tails are primarily for balance, but they are also used to communicate and can be held
over the body like a blanket for warmth.
These squirrels have two breeding seasons, winter and summer. However, an individual female
will rarely have two successive litters unless food is plentiful. A typical litter consists of 2 or 3 pups.
The gestation period is 42 days. The young remain in the nest for an additional 8 weeks before
following the mother on brief foraging forays in the immediate vicinity. By 10 weeks they are
Copyright © Dr. Robert R. Glesener
usually weaned. Summer litters often overwinter with the mother before dispersing. Both sexes
mature just inside one year. The average life span is 4 years, although individuals of this species can
live up to 7 or 8 years (15 years in captivity). Gray squirrels have a dominance hierarchy: females in
estrus will mate first with the dominant male, but they will pursue further matings with subordinate
males. Although these squirrels have a social dominance hierarchy, they are not territorial. Their
home ranges overlap.
Gray squirrels are active year round and are generalist omnivores. They feed heavily on nuts,
seeds, flowers, and buds of many tree species. They can also feed on bones, bird eggs, nestlings, and
frogs. Of course, in urban areas like Brevard, backyard feeders are also an important source of
nutrition, particularly in poor mast years. Soft foods are usually consumed on the spot. Nuts may
cached, i.e., buried in shallow underground holes, for latter use. They are probably relocated by
smell with many going undetected thereby serving as a means of seed dispersal for nut-bearing trees.
Eastern gray squirrels have three types of nests: winter dreys, summer dreys, and dens. Dreys are
twig and leaf nests built in tree forks at least 25 feet off the ground. They look like large, loosely
constructed bird nests. Winter dreys are more complex and better insulated than summer ones.
However, tree dens (cavities in the trunk of a tree), when available, are preferred in the winter
months.
Figure 2. Picture of a squirrel drey built in a tree fork.
Copyright © Dr. Robert R. Glesener
Figure 3. Picture of two squirrels with a tree den.
Brevard Annual Squirrel Count
In 1997, four Brevard College students and one faculty conducted the 1st Annual Brevard Squirrel
Count as part of a directed study. It was patterned after a long-term study of the albino colony in
Olney, IL (Stencel and Ghent 1987). A study area of approximately 3.0 square miles centered on
downtown Brevard was divided into 35 sectors. Each fall, teams of volunteers methodically walk
through these same Sectors on three consecutive Saturday mornings, recording all squirrels observed,
white and gray. The Count is not an actual census. It represents the percentage of white versus gray
morphs seen on the mornings of the Count, but it is an obvious underestimate of the absolute
numbers. However, we have every reason to believe that the percent white of those observed
approximates the actual percent white, and the more complete the Count, the more accurate that
estimate will be. From year to year, the abundance of squirrels has varied widely in concert with
available hard mast (Greenberg 1999, Glesener 2001b). However, the percent of the white morph has
remained remarkably constant in the 20-25% range.
Study Purpose
You will be participating in this year’s Annual Squirrel Count being conducted by Brevard
College’s White Squirrel Research Institute. This survey will help us monitor the distribution and
abundance of Brevard’s resident white squirrel population. The data from this year’s count will be
available to the public on our website at http://tornado.brevard.edu/whitesquirrel/ within a few
months. In the meantime you may wish to examine the website for results of previous counts and
other squirrel information. We do not expect to see every squirrel that resides in the study area, but
the more complete the count, the more accurate the data.
Copyright © Dr. Robert R. Glesener
FIELD PROCEDURE
1. Please arrive shortly prior to 8:00 am to receive your assignment.

Each count will be conducted in an 8:00-10:00 a.m. time range. Please bring a watch.

Unless told otherwise, report to the first floor of the Moore Science Building.

Enter the North door (Library end) and queue up at the table in the foyer area (by the rock
collection).

You will be assigned to a particular Sector and will receive a Map for that specific Sector.

If there are enough participants, you may be assigned a partner.

An identification tag and clipboard help you look more "official."

Attach the your map and the data sheet to a clipboard with the map page on top.

If you are transporting yourself, consult a city map for directions to your Sector.

Leave the building by the South door.
2. During the two hour interval of the count, you are to walk the entire area of the
Sector Map one time.

Take a moment and plan your path ahead of time.

Avoid doubling back which could result in some squirrels being counted twice.

Not visiting some areas means that some active squirrels will be missed.

Do not be afraid to visit backyards and wooded areas, but please do not climb fences or enter
other restricted areas. Ask permission when appropriate (you will be surprised in how
cooperative most folks are). Be polite.

Comply with resident’s requests.
3. After a sighting, record the location of the squirrel on the Map with a W for
white or a G for gray as soon as possible.

If you can distinguish adults and juveniles use upper case (W or G) for adults and lower case
(w or g) for juveniles. Because it is difficult to distinguish "W" from "w", so circle the w if it
is a juvenile.

If you are uncertain as to whether it is an adult or juvenile, just mark "G" or "W". While this
additional information may be useful for future studies, we are not actually distinguishing
between adults and juveniles in this count.
Copyright © Dr. Robert R. Glesener

Then write another W or G in the appropriate box down below on that same map page
indicating the time interval of the observation.

IT IS JUST AS IMPORTANT TO OBSERVE AND RECORD GRAY SQUIRRELS AS
WHITE ONES.

If you have time, record the location of nests on your map with an N.
4. Observational Tips.

Remember that tree squirrels nest in trees but forage mostly on the ground. Look carefully
on the ground near and in large trees, espeically hardwoods, and around feeders, etc.

Look carefully in areas where you observe nests

Clucking sounds may be coming from a squirrel (however, you must see the squirrel to
determine if it is white or gray).
5. If you see a squirrel on an adjacent Sector, record its approximate location off
the edges of your Map BUT DO NOT INCLUDE IT IN THE TALLY BOXES
FOR YOUR SECTOR.

If your Sector and an adjacent one are separated by a street, then the midline of the road
marks the boundary.
6. Record “Road kills” on the Map and tally boxes with WK or GK.

There is also a separate “Totals” box for road kills in the “Observations” table on the
datasheet.
7. If you note any interesting behaviors, predators (including cats, dogs, etc.) that
may effect squirrel activity in that area, etc, mark an O (for “Observation”) on
the Map

Include a complete description on the Data Sheet

DON’T LET THESE EXTRA OBSERVATIONS INTERFERE WITH THE MAIN
OBJECTIVE, I.E., COMPLETING THE COUNT.
8. When you finish your assignment, return to the command center, and tabulate
your observations.

Use the numbers from the 8 interval boxes on the map sheet to fill out the top three tables of
the data sheet.
Copyright © Dr. Robert R. Glesener

The most important numbers are those of the "Totals" column of the third table representing
the total number of white and total number of gray seen during your count.

If you did not distinguish between adult and juveniles, enter all data in the adult boxes.

Make sure you record the Sector number and fill out the rest of the requested information
including any comments, suggestions, etc., before turning it in.

Your name (and that of all partners) must appear at the bottom of the data sheet to get credit.

If you are doing a make-up count or are doing your count at a non-standard time or day, be
sure to complete the weather information at the top of the data sheet. If you are doing a
standard Saturday morning count, this will be the same for everyone.

Staple the map and data sheet together with the datasheet on top and turn in immediately.
In case of heavy rain or high winds, we may postpone the count until the following day. If there is a
question and you are coming in from some distance, try calling 883-8292 Extension 2301 sometime
around 7:15 a.m. A message regarding the status of the count should be available. If you encounter
any problems that need immediate assistance during the count or get lost, please try 883-8292
Extension 2278 or 2377.
Strip Line Transect Census
As mentioned above, the Count reliably estimates the percent of the white versus gray morphs
but underestimates the actual abundance. All squirrels will not be out during the two hours of the
Count and all squirrels out will not be observed. There are many other ways to estimate population
density. One of the simplest from a methodological point of view is the strip line transect census.
Some of you may not be able to participate in the regular count or may be seeking extra credit and
will be assigned a ~1 kilometer line transect to census. You will be given maps similar to those
referred to above with a transect line charted for you to walk. Theoretically, the line should be
straight but that is not usually possible. The important thing is that "observable distances" from any
sections of the line not double back allowing the same squirrel to be observed twice. On the
assumption that you see all squirrels located directly on the transect line and that the probability of
detection falls off as some function of the distance of the squirrel from that line, there are statistical
procedures that use the number and distances of squirrels observed to predict the actual number.

Select a time to conduct the census in consultation with your instructor. Early mornings or late
afternoons on a fair weather day are best.

On the day of the census, check out a camera with a 500 mm telephoto lens or a range finder.

Record starting time (ending time, too, when complete) and weather conditions.

Walk the transect line slowing pausing frequently to observe. Look in all directions. Count you
paces as you proceed.
Copyright © Dr. Robert R. Glesener

If see a squirrel, note its location and its color on your map using G for gray and W for white.
Try to identify a landmark to which you can refer if the squirrel moves.

Attempt to move along transect line until the squirrel is perpendicular to the transect line
(continue to look in all directions for other squirrels). Looking through the viewfinder of the
camera, focus on the squirrel. If the squirrel has moved, focus on the landmark indicating its
original position.

Read and record the perpendicular distance from the transect line to the squirrel using the meter
scale on the lens' barrel. Also record the pace number at this point.

If the distance is too close or too far to accurately measure with the lens calibration, set your
clipboard down on the line to mark your current position. Count the number of paces from the
line to the landmark. Return to the clipboard. Record the number of paces from the transect line
to the landmark. Continue with the transect.

Upon returning to the classroom, use a meter stick to measure the length of a single pace.

Use a calculator to convert paces recorded to actual distance.

Return camera, clipboard and datasheet(s) to instructor.
Figure 4. Diagram of strip line transect method.
Copyright © Dr. Robert R. Glesener
LITERATURE CITED AND OTHER REFERENCES
Buckland, S. T., D.R. Anderson, K.P. Burnham, and J.L. Laake. 1993. Distance sampling:
estimating abundance of biological populations. Chapman and Hall, London.
Glesener, Robert R. 2001a. Change in gene frequency in an urban eastern gray squirrel population.
J. Elisha Mitchell Sci. Soc. 117 (in press).
Glesener, Robert R. 2001b. Equilibrium of Brevard NC's white and gray variants of the eastern gray
squirrel. J. Elisha Mitchell Sci. Soc. 117 (in press).
Greenberg, Cathryn H. 1999. Summary: Acorn production by southern Appalachian oaks, 19931997. USDA Forest Service, Bent Creek Experimental Forest, 1577 Brevard Rd. Asheville NC.
Halloran, P. Eastern Grey Squirrels. [on-line] available
http://spot.colorado.edu/~halloran/sq_grey.html , 2001.
Stencel, J.E., and A.W. Ghent. 1987. Analyses of annual surveys of white and gray squirrels
(Sciurus carolinensis) in Olney, Illinois, 1977-1986. American Midland Naturalist 118(2):251257.
White Squirrel Research Institute, Brevard College. [on-line] available
http://tornado.brevard.edu/whitesquirrel/, 2001.
White Squirrel Shoppe, The. 2 W. Main Street, Brevard, NC 28712 [on-line] available
http://www.whitesquirrelshoppe.com, 2001.
Copyright © Dr. Robert R. Glesener
Figure 5. Study area covered in the Brevard Annual Squirrel Count.
Copyright © Dr. Robert R. Glesener
Figure 6. Sample of a sector map sheet used in the white squirrel
count.
Copyright © Dr. Robert R. Glesener
Data Sheet — White Squirrel Count
Sector:
Date: ___________________ Count (circle):
1st
2nd
3rd
Start time:
Finish time:
Temp (883-3103) _____ Sky: __________ Precip: __________ Wind: __________
Time
Tally of gray
squirrels seen
Time
Tally of white
squirrels seen
1st 15 min
A
J
2nd15min
A
J
3rd
min
A
1st 15 min
A
J
2nd15min
A
J
3rd
min
A
Kind of squirrel
15
J
15
J
Adult
4th 15 min
A
J
5th 15 min
A
J
6th 15 min
A
J
7th 15 min
A
J
8th 15 min
A
J
4th 15 min
A
J
5th 15 min
A
J
6th 15 min
A
J
7th 15 min
A
J
8th 15 min
A
J
Juvenile
Totals
Gray
White
Totals
Observations
Squirrels killed by cars
Totals
(separate from
above)
Cats, Dogs, or other predators
Nesting sites
Man made feeding site
Any observed behavior (mating, collecting food, fighting, bark marks, etc.); Please
specify where and how many squirrels were involved:
Volunteer Information:
Name:
Address:
Comments:
Copyright © Dr. Robert R. Glesener
Phone: