The purpose of this page is to offer a glimpse into the nutritional aspects of correctly raising an orphan infant eastern gray squirrel (Sciurus carolinensis)
Squirrel Sanctuary cooperating rehabilitators are soundly versed in tree and ground squirrel diet and nutrition .This knowledge is based on education,scientific facts regarding studies , professional documentation , networking with respected squirrel specific rehabilitators, and first hand experiences in successfully raising thousands of orphaned infants in the metro NY area over the last 9 years.
This page and the following article will not lead you through a step by step method on how to raise an infant squirrel. Our hope is that you will read the article and get a feeling of the extent of knowledge and information that a professional wildlife rehabilitator ( squirrel specific )needs in order to correctly care for an infant squirrel. A supplemental feeding chart with specific milk amounts and schedule are recommended and available at no cost to licensed wildlife rehabilitators .
A growing concern is that there are websites now that advise and put out harmful , non -sanctioned recipes such as scalded milk diet , cows milk / karo syrup/ nut ball recipes and low 25% percentage weight diets. These homemade concoctions and schedules are not part of any professional recommended diet protocol for infant squirrels. First hand accounts of what an improper diet can do to a growing infant are shocking and ultimately end in starvation and death. See photos: http://www.squirrel-rehab.org/pictures/improperdiet.html If you cannot find help for your squirrel and need care instructions for infant squirrels contact http://www.squirreltales.org This website offers very good step by step instructions and has been peer reviewed .
If you have found an orphan we recommend that you first contact a professional licensed wildlife rehabilitator in your state that specializes in squirrel rehabilitation. In New York State ,the Department of Environmental Conservation has a list of licensed rehabilitators in your area. Otherwise a local veterinarian ,animal shelter, zoo, police precinct, nature ,wildlife or ecology center may be of assistance .If you have found an orphaned squirrel in the metro NY area and have had no luck reaching a local rehabilitator, email info@squirrelsanctuary.org or call Sanctuary at 516 333- 6840 .
The following article was published nationally in the Spring/Summer 2002 issue of the professional wildlife publication "Wildlife Rehab Today" and also in the Spring issue of New York State's Wildlife Rehab Councils' Newsletter "Release"
FOOD FOR THOUGHT
In wildlife rehabilitation, no other topic sparks heated discussions such as diet and nutrition. In general, rehabilitators have definite preferences for the formulas they use. Providing good nutrition to a young growing squirrel is vital to the success of its rehabilitation. Because of the intangibles that can come into play, formula and its applications will confront even the most seasoned rehabilitator.
There are numerous commercial milk replacers on the market so how does one go about deciding which is the best? Just because a product smells “yummy” does not necessarily make that the best choice nor should price be the deciding factor. The objective of the substitute formula is to closely match the nutritional components and energy content of the mother's milk as determined by past studies. Although these studies are a good reference point, interpretation of them should be viewed as a “guestimate” of what may actually exist in nature. “The composition of milks differs markedly between the early or colostrum stage and the stage of established lactation” (Ling et al, 1961, p.231).” The stage of lactation was not known for any of the eight females milked for this study, nor was it reported by either Jenness and Sloan (1970) or Ben Shaul (1962) for their milk samples. Therefore these analyses should be used only as a guide in formulating a milk substitute for pre weaned gray squirrels. (Charles M. Nixon and W. J. Harper)
Not only is the proper concentration (thickness-thinness) of the formula important, but also the feeding frequency. The basal energy requirement (BER) aka the basal metabolic rate (BMR ) is the amount of calories that an animal needs to maintain itself at rest during 24 hours. Infant mammals require 2-4 times the BER (Evans, 1987)
More food for thought....
According to one well known study, it was noted that gray squirrels in the wild nurse on schedule rather than on demand. As the young infants grow the nursing mother must leave her offspring for extended periods so she herself can eat and replenish her energy . Because of the small volume of milk available per feeding and the often-disrupted feeding schedule, the young require a milk particularly high in fat, known for its satiety.(Nixon,Harper)
To figure out the minimum amount of kcals a squirrel would need you would follow this mathematical sentence: 70 x ( weight ) .75 x 2 =amount of kcals needed in 24 hours. The weight of the animal must be converted first to Kgs before raising it to the .75 power. (Basic Wildlife Rehabilitation 1 AB IWRC)
INTRODUCTION OF FORMULA
By slowly introducing new formula we allow the squirrel’s digestive system to adjust to the new milk replacement. This procedure can also be used when switching from one formula to another.
CONSERVATIVE (For neonates and debilitated juvenile squirrels)
First 24 hours Isotonic rehydration fluid LRS or Normosol
2-3 feedings 4 parts water 1 part 33/40 or Esbilac™
2-3 feedings 3 parts water 1 part 33/40 or Esbilac
2-3 feedings 2 parts water 1 part 33/40 or Esbilac
Monitor digestion. If stool is normal for 48 hours, pinch in 1/8 part MM 1/8 part water, observe for 48 hours, if stool is normal go to 1 part 33/40, 1/4 part MM 2/14 parts water, then full strength: 1 part 33/40, .5 part MM,2 1/4 parts water .
NOTE: Do not add MM for neonates
LESS CONSERVATIVE
First 24hours Isotonic Rehydration Fluid LRS or Normosol
2-3 feedings 4 parts water 1 part 33/40, .5part MM
2-3 feedings 3 parts water 1 part 33/40, .5part MM
2-3 feedings 2.5 parts water 1 part 33/40, .5 part MM
FINALLY 2.1/4 parts water 1 part 33/40, .5 part MM
FULL STRENGTH FORMULA
NOTE : MM stands for Multi-milk™. 33/40 is a Pet-Ag product similar to Esbilac
By slowly introducing new formula we are allowing the squirrel’s digestive system to adjust to the new milk replacement. This procedure can be used when switching from one formula to another.
.
FEEDING AMOUNT
The amount of ccs per feeding is calculated by using a percentage of the squirrel’s weight in grams. Begin with 5% and when the young squirrel’s eyes open and is eating solids you can bump it up to 7%.But this is a general guideline. Observe the squirrel and see how it responds.
5%-7% is the amount that the stomach will hold comfortably. Take the squirrel’s weight in grams, divide by 2,then divide by 10 .That number will be the amount of cc to feed per feeding. For example if a squirrel weighs 40 grams, divide in 2=20,then divide by 10=2.
Results in 2 cc’s per feeding.
FEEDING FREQUENCY
Take into account how many kilocalories one cc of formula provides and how many kcals the animal needs per 24hrs.The concentration of the formula will yield different kcals values so you need to know what your animal is receiving. This will give you a rough estimate how many times a day a squirrel needs to be fed .You should also factor in the animal’s health and digestion. Monitor the stool carefully. As the squirrel grows and starts to eat solids, some of the kcals will be supplied by the solid food and the frequency of feeding gets reduced, yet the ccs per feeding get increased according to weight. But don’t rely on numbers alone as some squirrels respond differently to any feeding schedule. Use your judgment and talk to other rehabilitators. Tiny neonates can be fed @ Q2hrs . Infants @ 3-3.5 hours, eye open young juveniles Q 4 hours,older juveniles Q 5 hrs. Pre weaned BID -once in AM, once in early PM and SID-Am only. If you space the feedings too close you are not allowing the squirrel time to digest and metabolize the food. Digestive disturbances can occur with feedings that are spaced too close together. Eating also requires the squirrel to expend energy. Resting allows the squirrel to metabolize and convert the food into usable energy.
FORMULA PREPARATION
All commercial milk substitutes once opened either powder or liquid should be kept refrigerated All dry premeasured powders can be mixed together with water until smooth.33/40 and multi milk seem to mix best in cold water. Depending on your water quality regular tap water or bottled water is fine. Depending on the amount of formula you are making, a hand held whisk, blender or eggbeater will work well. Heat only the portion you will use for each feeding and refrigerate the rest for up to 24 hours.If you are making large quantities you can pour into empty ice cube trays ,date, label and freeze and use as needed. Make fresh formula daily preferably at the end of the day allowing it to settle overnight. The formula should be warmed prior to feeding. You can warm either in a microwave, or on a coffee cup warmer or heat a cup of water in a mug and warm it in that. Check the temperature of the formula by testing a drop or so on the inside of your wrist. Never feed cold formula-it will cause digestive problems! Stir the formula once making sure it is smooth and without any tiny solid formula clumps which will clog the nipple, forcing you to start all over. Unopened containers can be stored in the freezer for up to 6 months beyond the expiration date. Opened products can be kept in their original containers or airtight containers and stored in the freezer for 6 months. Dry powders can be blended together and stored in the freezer in an airtight container for 6 months ( Debbie Marcum, Rehab of NA Mammals Feeding and Nutrition )
WEIGH
Because you will adjust the amount of formula as the squirrel grows it is important to weigh the squirrel. Neonates should be weighed daily. Because they are so tiny and metabolize quickly they can dehydrate overnight and lose water weight. Weigh infants every 2-3 days during the first 4 weeks and once eyes open twice weekly .Use an accurate gram scale ( Ohaus brand-model LS2000 ) and weigh squirrel at the same time, preferably in the morning before feeding.
FEEDING UTENSILS
Nothing is as good as natural mother’s teat but we try to replicate as close as possible. For tiny neonates a 21g3/4 butterfly catheter clipped short can be attached to a one cc syringe. Experience at Squirrel Sanctuary has demonstrated that the use of a small Catac brand nipple attached to a one cc syringe also works well and is generally preferred because it is soft and pliable. Some rehabilitators use no attachment at all but we have found the potential for oral bruising because the plastic itself is too hard. Whatever method you choose it sometimes takes a tiny squirrel 24- 48 hours to get with “the program". Infants at @ 90 grams can safely be fed with a 3cc syringe with catac brand nipple attached. When squirrel reaches @150 grams a 5cc syringe could be used.The Basik brand syringe is preferred by us over other brands because of its consistency in expelling the formula and its longevity. It outlasts many other common brands.
ELIMINATION
Until the eyes open it is necessary to stimulate the squirrel to facilitate proper elimination. It is also physiologically necessary to prevent uremia and possible renal shutdown. (Strong and Speer ,Physiology for Rehabilitators, pg 48 )Neonates should be stimulated prior to feeding as it prompts the sucking reflex and adds consistency to the routine. Once eyes open it is not necessary to stimulate however, you can continue as it helps maintain sanitation. In addition you can closely monitor the squirrel’s digestive state.
You may notice that as the squirrel matures they will urinate/defecate in one area of the cage.
DEVELOPMENT
1ST WEEK—Pink, blind, deaf, bean shaped, ears flat to skull, unable to thermoregulate, umbilical cord remnant still visible, sleeps constantly, weight gain 2-5 grams. Twitch , stretch and yawn.
Approaching 2nd week-fuzz develops around the nose, a slight graying pigmentation on top of head but the belly and inside of legs remain pink Umbilicus falls off
2ND WEEK—What we refer to as the fuzzy stage .Slight fur is seen on the back, outer legs and head. Ears flaps are opening but still cannot hear
3RD WEEK—Ear canals are now open, responds to sound. Bottom incisors have erupted.
4TH WEEK-Slits of their eyes twitch as if responding to light. Slits also darken and widen. Light silver fur on top of their tail but the underside is still mostly bare.
5TH WEEK—Fully furred. Have both sets of incisors, eyes open but do not focus well for several days, can curl tail over their head) Fur on tail is thicker and longer. Begins to nibble on solid foods. Weight gain of 10 /15 grams a week.
6-7 WEEKS---Still nursing but eating more solids, rapid growth stage, forms social bonds with cage mates, sleeps less with more active periods.
8-10 WEEKS-- still nursing but beginning to wean. In the wild they begin to venture outside their nest and explore. Looks like miniature squirrel.Very playful and active within their group.
10-12 WEEKS—Weaned in nature, able to crack hard nuts, motor skills well developed.May still remain close to mother and siblings for a few weeks although can function independently.
Feeding Position
Since the swallowing reflex is not fully developed until 3-4 weeks of age a sitting position helps facilitate the gravity flow of formula to the stomach.(Evans,1987) Eye open young juveniles can be fed in a sternally recumbent position ( on their stomach ) Neonates will adapt to a consistent routine and nurse on a schedule.
WEANING
The process of weaning is one that happens gradually over several weeks . In the wild ,young gray squirrels nurse off the mother for @10 weeks. They are not fully independent until at least 12 weeks. OFFER DIETARY STAPLE AS SOON AS EYES OPEN . In rehab young squirrels will begin to nibble on solids right around the same times their eyes open however many of them just pulverize the food rather than actually eat it. This is why it is still important to continue to weigh and note weight gain or loss. Dietary staple should be high quality rodent chow or high quality monkey chow. Supplemental foods would be seasonal vegetables, fruits and nuts (limited). Peanuts and sunflower seeds are considered off limits ! Both contain amino acids that prevent proper Ca/PH absorption. Solid food should be kept in a bowl or dish and picked up at the end of each day .Do not scatter the food around the cage. This method can become unsanitary as the food could easily become mixed in with feces and urine. Don’t forget to include fresh limbs preferably with buds, leaves and gnawing items such as a small sterilized bone or stone. Some rehabilitators use deer antlers.
A juvenile beginning to
wean is approximately 8-10 weeks old. He still may desire to nurse several times
a day however he will be eating more solid food. Don’t cut back on the formula
just because solids are being eaten. Also there is no need to add vitamin
supplements to formula. This potentially could create an unbalanced diet.
As long
as the squirrel desires to nurse, offer formula along with the solid food…a
squirrel will let you know when it is ready to stop nursing.
A pre- set time limit
on weaning should not be imposed, but should occur naturally. Some squirrels wean
at @10 weeks some @12.
Once the squirrel wants one feeding a day that is the
signal that complete weaning is near.
IMPORTANT FACTORS TO CONSIDER
1. Consistency of routine
2. Formula
3. Feeding schedule
4. Stomach capacity
5. Stimulation
6. Ambient and housing temperature
7. Sanitation
Closing thoughts
What specific formula
and feeding schedules or combinations thereof that work best may vary from year
to year ,litter to litter and even individual to individual.
As products are
developed and improved so are the protocols. Talk and network with other
rehabilitators, and talk to product representatives.
Keep an open mind and up to
date with changing methods and techniques. You will be surprised how much you
can learn just by comparing notes. The information that we gather and disseminate
can only benefit the animals under our care.
Author's note : A feeding chart guideline( frequency and amount )and comparative milk analysis of commercial milk replacers are available to licensed rehabilitators only. Email Ms. Bellens-Picon at info@squirrelsanctuary.org
The article was written for licensed rehabilitators to use as a guide in conjunction with the schedule and feeding chart-available by request.
Barbara Bellens-Picon
This article was published in WILDLIFE REHAB TODAY- Spring/Summer 2002
and Nyswrc RELEASE Spring 2002 Issue
References
Casey,Allan,Casey,Shirley. Squirrel Rehabilitation Workshop .Co: Wildagain Wildlfe Rehabilitation,Inc. 2000 Manual
Casey,Allan,Casey,Shirley. “Kcalculator”Ewildagain.org: http://ewildagain.org/html/calculator.html 2/02/02
Gurnell,John. The Natural History of Squirrels. NY: Facts on File.1985
Harper,W.J.,Nixon,Charles. Composition of Gray Squirrel Milk.Ohio: Ohio Journal of Science 72 (1):3 1972
Jenness, R., R. Sloan. The composition of milk of various species:
a review. Dairy Science Abstracts 32(10): 599-612. 1970
Marcum,Debbie. Rehabilitation of North American Wild Mammals Feeding and Nutrition. CA: Self published,1997
Ling, E.,. Kon, and J. Porter. The composition of milk and the nutritive value of its components. Pp. 195-
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