Thursday, April 3, 2014

Sexual Selection

 I Like Bright Feathers and I Cannot Lie

Wouldn’t it be a wonderful world if the boys were the ones who had the responsibility of wooing over a girl? Today it seems like girls are the ones who are expected to dress up, do their makeup every morning, and stay “bikini ready” just for the guys. I wish it were the other way around sometimes…It would be nice to just roll out of bed, wear my pajamas to class, and gain 20 pounds without anyone batting an eye. But wouldn’t it be even better if you did all these things ladies, and the boys just couldn’t get enough of you? This is the case in most animals, including birds. The male birds go to extreme lengths to mate with a female. They undergo selective pressures to get the chance to mate with a female[1]. Sexual selection causes the males to grow colored and ornate feathers to attract the females[1].

Dress to Impress [2]


When thinking of ornately feathered birds, the peacock comes to my mind instantly. Look at that difference between the male and the female! Who knew that boys could look so much better than their female counterparts? For this blog post, I am going to take a few steps back and shed some more light on why so many male birds are prettier than the females. Charles Darwin developed a theory that explains this occurrence [3]. He proposed that the traits that increase survival in a species are favored by natural selection. On the other hand, traits that help a male win over females are influenced by sexual selection. Sexual selection is the cause of the brilliant feathers on a male peacock, the fiery red of a cardinal, and the red or orange on the crown of a house finch.
Male and Female Peacock [4]

The Special One

So why are the males the more colorful of the 2 sexes? This is because it is the MALES job to attract the female. The female can pick and choose over whichever male bird she fancies. That must be nice… You may be asking yourself why do bright colors or long feathers seem attractive to the females. Why don’t they just choose any ole bird? This is because the females know that the most attractive bird is most likely the healthiest and will pass on the “best” genes to her future offspring[3].
Birds of Paradise [5]

Walk the Walk and Talk the Talk

Bright lengthy feathers aren’t the only things female birds are after. They want a man that can be a great singer and exhibits a specific behavior they deem attractive. An interesting example of this is in the bowerbird species. The males create elaborate bowers (structures of various sizes) and decorate them to attract the females. Each bowerbird has a specific taste, and the male’s decoration displays their “personality”. Some like the shiny beetle wings, while other male bowerbirds may choose flowers or berries. The females drop by to check out the bowers and if they are impressed, the males get to copulate with the female[6].

Follow this link for a peak into the lives of a bowerbird mating ritual!

Male Bowerbird with decorated bower [7]

You Are the Only Exception

In some instances, the female bird can be more colorful and ornate than the males of the same species. In these species the males incubate and care for the young while the females fight over territory and mates. We understand that the more competitive of the two sexes tends to be the more brightly colored[3].


In many species of birds, males go through daily routines of prepping for the females whether that is arranging their feathers or testing their vocal chords. It is interesting to see the many ways sexual selection plays out in bird species. Males spend much of their time and energy growing out beautiful feathers, singing for hours, and “dancing” in some instances. If you are a man and think your girl expects too much of you, then remember that she never made you build a bower with aluminum cans, fungi, and leaves before the first date.




  1. You discussed how in some species, such as the sandpiper bird, the female is more attractive than the males. You said this was because the females are more competative than the males of this species. Why would a select group of species have more competitive females instead of males? Why would they not select for males to be more competitive like most species?

  2. Sexual selection and natural selection are two very intriguing processes! Your discussion of how the males compete to woo the women who will end up rearing their young made me think of a group of primates. In my ecology class, we talked about Geladas. The males of this particular group have a chest area that varies in redness. The more intensely colored the patch, the more fit the male is supposed to be. Of course, this comes with a cost. The darker patches tend to result in more heat loss and energy expenditure. However, these males demonstrate great stamina regardless of the costs. Males fight among each other to maintain their role as the alpha male. Austin brings up a good point though. It is quite interesting to consider what happens when the tables are turned.

  3. I think the general rule is that whichever sex is more invested in the young is the one that gets to choose its mate. If the male is the sex that raises the child, then the female is the sex that must compete for a mate. Basically, higher parental involvement (evolutionarily) leads to lower sexual competition, and vice versa.

    Also, this courtship display is always under attack of mimicry. Certain birds will mimic either a feather pattern or a song in order to trick a female into mating with them. One example of this is the lyre bird. They are masters of mimicry, and can repeat pretty much any sound they hear. The link below will take you to a video of a lyre bird in action.

  4. I want to begin by saying I appreciate how colorful this post is. This concept was very new for me when learning about it. Of course we know humans try to look better for the opposite sex, but I never before thought about how animals do such. I especially became interested in the difference between male and female white peacocks after knowing a family friend who raises peacocks here in Georgia. Since the feathers are all white it becomes harder to distinguish male albino peacocks from female albino peacocks. Typically, the resort to waiting a while and determining via size differences.

    Here are pictures of two of the peacocks that the family raised as of 2012 that I took if anyone is interested:

  5. There are so many different ways and things that species use to attract a mate. Another example would be a lions’ mane, the larger it is the better. This is an interesting topic, and the colors and visuals you used were a great addition to your post. The various mating habits of species are all fascinating and teach us a whole new side to animals. They show us that animals too make decisions based on future advantages they will gain by doing so. It makes sense that the selector would want a mate who has the best and the healthiest genes to pass on to offspring. Like Emily said, I think it mostly depends on which sex invests more in the offspring and he/she is the one who does the choosing while the other sex races to be chosen by showing off some alluring trait.

  6. I like the way this topic was portrayed, especially with the different colors. Aside from the colors, Darwin had two reasonings for how sexual selection worked: through competition by combat or by display. You mentioned examples for display, but an example for combat would be elephant seals. These seals generally migrate to their breeding ground about two weeks early and fight off other males to get the best breeding site and attract most females. Because males mate with more than one female, this allows the species to have greater sexual dimorphism.

  7. Great post. Like Davisha said, I enjoyed the flow and colloquial tone. Its important to remember that we are writing for a blog and not a scientific journal. You started to elaborate on Hamilton-Zuk and I was wondering why you didn't into to the reasons why a female might chose one male over another. I really do think, however, that humans display their own degrees of sexual selection. It's the reason we are hairless compared to our closest animal relatives, its also a major player in why there are distinctive human races.

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