Male vs Female Cottonmouth Snakes: Key Differences Explained

Cottonmouth snakes – also known as water moccasins – are venomous pit vipers that are native to the southeastern region of the United States. They are semi-aquatic and live in and around slow-moving lakes, streams, and rivers. Although some cottonmouths have crossband markings on them, most are dark-colored – almost black. However, they get their name from the white color on the inside of their mouth, which can be seen when they open their mouth wide and expose their fangs. Cottonmouths are solitary snakes; males and females only interact for the purpose of mating. But how do we tell the two apart?  

Join us as we discover everything you need to know about male vs female cottonmouth snakes!

Comparing Male vs Female Cottonmouth Snakes

The 4 Key Differences Between Male and Female Cottonmouth Snakes

The key differences between male and female cottonmouths are size, diet, mating ritual, scales, and shape of the head.

Let’s examine these differences in detail below.

Male vs Female Cottonmouth: Size

Most cottonmouth snakes are between 2 and 4 feet long. However, they exhibit sexual dimorphism – and in this case, the males are larger than the females. The average weight of female cottonmouth snakes is less than 1 pound, while on average males weigh no more than 3 pounds. However, the largest males can sometimes exceed 6 feet long and weigh up to 10 pounds.

Male vs Female Cottonmouth: Head

One fascinating difference between male and female cottonmouths is the size of their heads and how that affects the size of the prey they eat. Cottonmouths are characterized by their large, spade-shaped head. However, studies have shown that males have significantly larger heads than females – this includes width, height, jaw length, and head surface area. These same studies have also found that male cottonmouths have much longer quadrate bones.

The quadrate bone is part of the upper jaw joint, and the length of this affects the size of the gape of the snake’s mouth. This is because the longer quadrate bone allows the lower jaw to be opened further. In turn, this directly affects the size of the prey that they can consume. This is because the longer quadrate bone and larger gape mean that bulkier prey can fit through the oral cavity because they can manipulate the prey better. These studies showed that the males with their larger heads could consume much larger prey than females and in greater quantities.

Although cottonmouths consume a wide variety of prey – including birds, mammals, fish, reptiles, and amphibians – fish make up a significantly large proportion of their diet. However, research suggests that although both consume other prey as well,  males strongly favor fish while females consume more reptiles. This slightly different diet means that male and female cottonmouths are not competing as much for the same food.

Male vs Female Cottonmouth: Scales

Another difference between male and female cottonmouths is the number of ventral and subcaudal scales. Ventral scales are the large scales on the underside of the body all the way from the neck to the anal scale, while subcaudal scales are the large scales on the underside of the tail (after the anal scale). Female cottonmouths have between 128 and 144 ventral scales and between 36 and 50 subcaudal scales. However, male cottonmouths have between 130 and 145 ventral scales and between 36 and 50 subcaudal scales. Despite this, we really don’t recommend you get close enough to count them!

Male vs Female Cottonmouth: Mating Ritual

Female and male cottonmouth snakes also mature at different ages – 2 years old for males and 3 years old for females. Upon sexual maturity, cottonmouths are then able to begin reproducing, but first, they need to find a mate which involves undertaking a mating ritual. The roles of the males and females are very different during this ritual, with the male role being described as a “combat dance”. The combat dance usually involves two or three males competing for the attention of the female.

Mating usually occurs in April and May, and to start with, one male cottonmouth will move back and forth either on land or in the water while waving his tail around. This is to lure any female in the area towards him, and at this point, there can be several males in the area looking for the opportunity to breed with the female. The males then begin their combat dance which involves them raising their bodies up off the ground while swaying and entwining their bodies. They then literally thrash against each other, forcing each other to the ground or into the water in a vicious battle for dominance. This battle of wills can last anywhere between ten minutes to several hours. However, eventually, the weaker snakes will slither away, leaving the strongest, most dominant male to mate with the female.

These combat rituals are an important part of sexual selection, but it isn’t intended to be a fight to the death. Instead, it is a clear and decisive way of making sure that only the strongest and healthiest males get the chance to mate with the females and contribute to the continuation of the species.

The photo featured at the top of this post is © Psychotic Nature/Shutterstock.com