The idea of sexual dimorphism has been found in animals all across the world, even people, but there are almost no animals that have as much of a dramatic dichotomy between males and females as birds do.
More often than not, male birds are adorned with bright, flashy colors and are considerably larger than their female counterparts. This is due to the fact that males are the ones who try and impress the females of their species, with the brightest colors often being considered desirable traits.
On the other hand, there is the female bird who commonly is the sole caretaker of young birds. With more muted colors that match the common environments, female birds are more suited to protecting and caring for young, compared to their bright partners. There are very few birds that have such a distinct display of this as the cardinals do.
Sexual Dimorphism Found in Cardinals
The term “sexual dimorphism” defines the clear, distinct differences that male and female animals of the same species have between each other. One of the most common, everyday examples of this is when you see male and female people. Humans exhibit sexual dimorphism, although not many people refer to it in this manner.
As a part of biology, it comes as no surprise that there are other animals that exhibit this trait as well, with birds being one of the most flashy animals to do so. Let’s look at cardinals as an example. The difference and side-by-side comparison of the cardinal is a great way to see how sexual dimorphism creates considerable difference between males and females of a species.
In cardinals specifically, the differences go beyond just the coloration of the bird. In addition to it, there is also the behavior of the bird to consider, with male birds often being more territorial and aggressive and females preferring to stay at the nest to care for her young. Males and females also have different singing abilities and reasons for making their calls.
The Coloration of Cardinals
The most obvious difference between the male vs. female cardinal is the colors. Generally speaking, the male cardinal is known for his bright red feathers with a sharp black “mask” that wraps around the beak and comes to a point past the cardinal’s eyes. By comparison, the female cardinal sports a sandy, tawny brown color that occasionally has patches of brown-red feathers around the wings, crest, and tail, while also having a much more faded “mask” around the eyes.
Male cardinals are born the same color as female cardinals, but their red feathers will quickly grow in once their brown juvenile feathers are molted and discarded. This means that it can be easy to confuse juvenile male cardinals from their female counterparts. Thankfully, cardinals age relatively quickly, meaning that you won’t have to worry about this for quite some time.
Female cardinals are born entirely tawny, though they may have some faded black around their beak and eyes. As they mature, they will have a small amount of rust-colored feathers come in around their wings, tail, and at the tips of the crest. This is usually the most red that a female cardinal develops, and the vividness of this red can range from barely discernible to a rust-like color. Some females may have this color speckled, while others may have it more prominently and solidly featured.
When Do Male Cardinals Get Their Bright Colors?
Because male cardinals and female cardinals are born the same color, much in the same way that very young children have not developed their secondary sex characteristics, they can be hard to tell apart if you are not constantly watching their behavior. When born, cardinals have a grey hue to them and as they develop their first set of feathers, this will shift into a more tan color.
As these birds reach the age of being considered juveniles, which happens after about 12 months, the molting process will begin. This process can be compared to a lizard or snake shedding its skin, as the feathers of the cardinal begin to shift in color again and grow in length. During this period, the black masks around their beaks will develop as well as the red coloration.
Male cardinals will develop their fully red colors while the females will develop tinges and fringes of red of the locations that were specified earlier. This process can take a few months as the last of the feathers change color, but after the age of one year, you will have a much easier time discerning between male and female cardinals.
The Size of Cardinals
Another aspect of sexual dimorphism between animals is the size. Typically, males are larger than their female counterparts. There are quite a few theories out there on why this is the way that most animals have evolved, but the general consensus is that the larger size of the male can be more appealing to the female birds and the male is also more aggressive, meaning that having a more intimidating stature than other birds can help it.
With cardinals, the size difference is really only noticeable if you are able to physically measure the bird. In fact, the smallest male cardinals and the largest female cardinals share some overlap in size ranges, meaning that they have the potential to be nearly the same size, even if the male cardinal is traditionally larger by a matter of tenths of inches.
On average, male cardinals are known to stand between 8.7 and 9.25 inches long, from the crest on its head to its tail feathers. This measures to be between 22 and 23 centimeters. The female cardinals tend to measure very slightly smaller, coming in between 8.2 and 8.5 inches, which is the equivalent range of 21 and 21.5 centimeters.
The Behavior of Cardinals
Next, you will want to consider the behavioral differences that cardinals display. There aren’t many differences between how male and female cardinals act, though there have been a few noted differences that you may be able to spot. These generally focus on males being more aggressive and protective birds and the females being more patient and more focused on protecting any nests or children that she may have.
These behaviors can be most evident when male and female cardinals pair and care for their young. Male cardinals take on a protective role, helping to gather materials for nests, bringing food for the female, and defending the nest if danger approaches them. The female cardinal, on the other hand, is the one who physically builds the nest, incubates the eggs, and raises their young.
Aside from these behaviors, there is one other area where you will be able to more easily see a difference between male and female birds, and this is the songs that both of these birds have been known to sing.
The Sounds of Cardinals
Both male and female cardinals are considered songbirds, and as part of this, both of them have been recorded with their different songs. It is heavily believed that male and female cardinals exhibit different reasons and motivations for their songs, meaning that sexual dimorphism can play a role in conversation between birds as well as in their appearances.
It is believed that male cardinals are more likely to sing as a way to communicate aggression and territorialism to any potentially intruding animals. They have also been recorded making vocalizations as they attack any intruding birds, further supporting the theory that they sing as a form of aggression. In female cardinals, singing is thought to be more passive communication that is directed at her mate.
One of the most prominent beliefs is that when female cardinals vocalize, they are asking favors of the male bird, such as asking for it to hunt. It is also believed that female cardinals’ songs tend to be more intricate and elaborate than those of the male cardinals, although this can be somewhat difficult to prove.
There are quite a few ways that male and female cardinals are different from each other, with the most prominent areas of sexual dimorphism being in the coloration of their feathers.
With male cardinals boasting their vivid red feathers and female cardinals being able to blend into their nests more easily to care for her young, cardinals make the most out of their differences when they work together to raise young, with male cardinals bringing materials and food and female cardinals building the nest and incubating eggs.