As I was going through stacks of papers to file in anticipation of returning to my beloved island paradise, I heard a loud cry from below Mom's condo. It was not an unfamiliar one to my ears so I knew it wasn't one of her neighbors. I looked down from the lanai and there on the deck below was the source of the racket... a peacock strutting his stuff. Note I said "his" since a peacock is male... the female is a peahen, and the species is known as peafowl. Of course I immediately grabbed my HD video camera to capture some footage. Although it would be an unlikely subject for my "Munching and Mating in the Macrocystis" cable TV show, it could have value as a common example of sexual dimorphism.
Now that term does not refer to a species which has gender confusion. In fact, sexual dimorphism is quite the opposite. It refers to species which have distinct physical differences between the male and female. You know, like long hair on women and short hair on men. Oh, wait... that went out in the 60s! Well, there are other differences, but if I mention them in this column I might get censored. I think I'll choose a non-human example, say the well-developed comb on roosters vs hens.
Species with pronounced sexual dimorphism often have quite different roles for the males vs. the females. In humans males tended to be more muscular and stronger because in olden days they went out to hunt the wooly mammoths, bison or other fare for dinner. Women tended to be less well developed (at least in that respect) and did some seed gathering, food processing and child care. However, if you've perused body building magazines at your local bookstand, you may have noticed that some women have been... ah, working out with the weights.
By the time I got down the stairs, the peacock was displaying his incredible array of tail feathers and calling frequently. Of course even a marine biologist like myself could tell it was peafowl mating season. Unfortunately for the birds at Pelican Cove, all are male and there were no replies from the fairer sex (at least of that species!). I felt great empathy with these poor male birds, for my calls go unheeded as well.
Now in their native Asian habitats, the peacock might have better luck attracting one of the much duller colored peahens. He might also have better luck attracting a hungry predator with his shrieks and colorfully displayed tail. This is one of the risks associated with being a male in many species. Genetically it is often less disastrous to lose a male than a female, since one male can mate with several females (and peacocks are polygamous) while the loss of a female destroys the chance for her offspring from any male. Of course humans rarely risk drawing the attention of predators... only competitors (which could be almost as deadly). The peahen avoids such conspicuous displays and is a muted brown or gray in color. This serves her very well when tending the nest and chicks as it doesn't draw the attention of predators.
Peacocks apparently are a symbol of eternal life in some Christian thought. The beautiful eyes on their tail represent the "all-seeing" church (shudder... isn't Big Brother enough?) with the additional characteristics of holiness and sanctity. Spiritually these ornate birds are associated with resurrection and immortality. Perhaps that is why they often visit my mother. However in some other cultures these birds are symbols of pride or vanity, something not associated with Mom!
I have to reacclimate to writing about marine critters since I'll once again be diving the kelp forests soon. An interesting example of sexual dimorphism can be found in our dive park. The giant kelpfish exhibits an interesting role reversal. Females only visit the nest to mate and lay their eggs in it. Then it's off to shop with the rest of the gals. The males are tasked with defending it. You guessed it... the males tend to be duller in color and usually green or brown while the ladies may be a number of other, more beautiful (and obvious) colors such as red, yellow and lime green.
Peacocks have an association with Catalina history. Some of my island readers undoubtedly remember the peacocks at the Bird Park prior to 1966. By the time I got here three years later, most of the other exotic birds had been relocated to the Los Angeles Zoo, but the peacocks were let loose. In my early years I remember Packy Offield and I hiking the fencelines out at Middle Ranch. The peacocks used the fence posts to scratch their itches and we gathered a number of tail feathers (actually "coverts") that adorned my old apartment at Toyon Bay for many years.
Now as far as mate selection, billions of people including myself and Charles Darwin have assumed that the female selects her mate based on the tail display. If true, evolution would favor the development of more elaborate and colorful tail feathers. It just makes sense. However, at least one study of free ranging peafowl suggests the females don't seem to be swayed by the display. I find that disturbing. I'm not one to primp, but on the few occasions when an actual date is imminent, I have showered, shaved and chosen my best clothes to impress the lady. It may have worked briefly... but only until they saw my empty wallet!
© 2011 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 29, 10:00 AM weekdays and on Charter Communications Cable channel 33 at 7:30 PM on Tuesdays in the Riverside/Norco area. Please help me climb out of self-imposed poverty... buy my DVD's (see this link). Yes, take Dr. Bill home with you... we'll both be glad you did!
To return to the list of ALL of Dr. Bill's "Dive Dry" newspaper columns, click here.
Peacock beside Mom's car, head of peacock with crest; peacock displaying tail feathers and view from rear.
This document maintained by
Dr. Bill Bushing.
Material and images © 2011 Star Thrower Educational Multimedia