I know someone that swears that snakes can count and I have to agree with him. His house has one of those underground water meters out on his lawn. Somehow the meter reader didn’t fully close the lid after taking a reading. A momma garter snake moved in and gave birth to a dozen baby snakes. My friend was out on his lawn and saw the mama snake scurrying out of the semi closed lid. He opened the lid in her absence and found the dozen or so snakes.
Though this was the perfect place for snakes to live, he thought it would be better if he relocated them to a place that they would not be disturbed. He built a box similar in size and dug a hole in the ground to bury it. He placed some leaves and dirt in the box.
When the mother snake returned to feed her youngsters he gently removed all of them and relocated them to the new box. They seemed to settle in nicely, but after a short while the mother snake was out of the box making a bee line for the water meter which was now closed. She frantically slithered around and over the now closed lid. She was very upset, so my friend returned to the water meter and opened it back up and there inside he realized that he had missed one baby snake. He gently picked it up and took it to the new box along with its mother.
That mother snake knew exactly how many babies she had. This is how we know that snakes can count.