The first thing to know is that squirrels are predominantly herbivores, so vegetation makes up a large part of their natural diet. But, that doesn't mean that they never eat animal protein. They need quality protein in their diet to maintain their muscles and hair growth. In the wild, they will eat bugs and worms and even raid bird's nests to eat either the eggs or young hatchlings
Squirrels have unique dietary needs in that they also need a regular source of quality calcium to stay healthy. The reason is that their incisors teeth grow continuously throughout their life at a rate of ¼ to 3/8th inch per month. This tooth growth requires 20 to 40 mg. Of quality calcium per day just to maintain this growth. Pregnant or lactating females require twice that amount. There are high calcium vegetation such as Kale that can help provide calcium, but eating bird's eggs and baby birds can also supplement their calcium needs.
Unfortunately, vegetation and nestling birds and eggs are only available for a short time every year, so squirrels are vulnerable to low blood calcium most of the year. If humans don't help them out with this need, a squirrel's body will pull calcium from their bones and they end up dying of a painful condition called Metabolic Bone Disease. When their bones become depleted of calcium they become lame and usually fall out of the trees and shatter their brittle, calcium depleted bones.
Sunlight is also needed to help squirrels synthesize Vitamin D. Vitamin D also plays a key role in the absorption of Calcium, so 20 minutes of direct sunlight per day is imperative for squirrels that are kept in the house, or, a suitable full spectrum light will help with this need. There was an excellent article that appeared on SquirrelRefuge.org that explains Metabolic Bone Disease and the importance of feeding foods that have the correct Calcium to Phosphorus Ratio. It also has a list of common foods fed to squirrels along with their Calcium to Phosphorus Ratio
At SquirrelNutrition.com we have spent the last 11 years learning and testing foods and Natural substances that can be used to keep squirrels healthy and to treat various conditions that are common to squirrels. We also provide recipes and food lists that are available on request by using one of our handy request forms! We answer all squirrel questions and help to teach people how to care for orphaned babies all the way up to elderly squirrels like our girl Lucky.
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