A strange white flash caught my eye the other day as I was walking through my local park. It was tucked between the green oak leaves and almost went unnoticed. After gazing closer, I could tell that I was looking at an albino squirrel. Fortunately I had my camera on me, so I used the other trees as cover and cautiously approached. I was able to get a couple of pictures of him munching on a nut, but as I emerged from behind the nearest tree the shy little guy scurried up the trunk and far away from me.
This encounter was memorable and caused me to start thinking about albinism in squirrels and other animals. After some research I turned up several resources about albinism in general, and even websites dedicated to white squirrels. What I learned is quite fascinating!
What is Albinism?
Why does it occur?
Most of the occurrences of albinism result from both parents passing down a damaged recessive version of a gene known as "TYR". Because the trait is recessive, a parent can be a carrier of the gene without showing any physical signs. If both parents are passive carriers of the gene, their child has a 25% chance of being born a true albino in accordance with Mendelian inheritance.How does inheritance work?
Chart showing the probability of albinism propagation from two parents carrying the damaged TYR gene.
What are the consequences of albinism?
An organism with albinism faces many disadvantages due to their condition. A lack of pigment strips away the naturally evolved camouflage and makes the animal easier for predators to spot in most environments. They are also more vulnerable to damage from the sun develop related cancers. Albino animals commonly have decreased sensory ability in their vision and hearing, tend to be less viable, and live shorter lives. These disadvantages coupled with the recessive properties of the condition makes true albinos somewhat rare in natural populations.How rare are albinos?
Though the frequency of albinism is variable by species, in mammals it is estimated that true albino births account for about 0.0001% of all births, or about 1 in 10,000. The recessive TYR gene responsible for albinism is estimated to be present in approximately 1 out of every 700 mammals. These numbers can be even higher in some bird and fish species. Domesticated animals such as rats, rabbits, and ferrets are sometimes intentionally bred to be albino for aesthetic or scientific purposes, but they mostly exist in confined environments. Squirrels are one of the few species where albino populations have naturally been successful in the wild.Oh yeah, ALBINO SQUIRRELS!
Based on a survey of white squirrel sightings conducted by Untamed Science, their occurrence seems to be clustered in several urban areas around the United States. The majority of white squirrel spottings (80%) are not actually true albino squirrels, rather 'white morph' squirrels that have developed a white coat but still have dark eyes. Both cases tend to be in the Eastern Grey Squirrel species. The study also has a map showing the locations of reported white squirrel and albino squirrel populations in the United States.
If you live in an urban environment in the US, there might be an albino squirrel living near you! Keep your senses alert when you are walking through your favorite parks and look for that distinctive lack of color. Squirrels that are completely black exist naturally as well, so see if you can find the two cohabiting the same grove for ultimate contrast! What animals with albinism have you seen in nature? Thanks for reading my post, I hope you enjoyed it!
