No Kissing Bae, No Touching Bae
Courtship rituals by the bowerbirds
Rape is a defiance of autonomy.
It can happen to either sex. Surprisingly, it can also happen to birds, but the word rape does not apply to aves. The term is forced copulation.
Among bowerbirds, one species is known for its tendency to pounce on female birds when they land on its well-prepared stage. The tooth-billed bowerbird does not build a bower but has taken the name from the other birds known for these ornamental courtship settings.
First, it sets the stage by cleaning it, getting rid of all that it deems ‘dirty’. Once it is ready, it calls the girls. It does this through a series of mimics, although its mimicry does not match that of the lyrebird.
Once a lady gets into its space, it doesn’t spare the chance to pounce on it. You could call it bird rape. And if you do, you should ask yourself what that means about birds' choice of mates. If you did, then you’re on the right track, because birds select who they mate with.
And if they don’t like you, then:
No kissing bae
No touching bae
The bowerbirds are good examples of this unique feature in the ever-fascinating field of evolution.
But first, the wrongful interpretation.
The wrongful Zahavian interpretation
I will never cease to mention how persuasive this idea was to me in the first place. I read the entire book in my final year in medical school when my classmates were preparing for their final exams. It took that much control over me.
Yet, it turned out to be false.
Zahavi’s handicap principle states that animals display honest signals to convey their genetic quality to potential mates. Classical examples are the peacock tail feathers and the antlers of deer.
These ornamental features are expensive to produce and maintain. Only the strongest and the ones with the highest qualities can contain such costs, such handicaps.
They are handicaps since they contrast with the adaptive tenets of Natural Selection. A long tail by the peacock or the male argus pheasant has little to do with flight. As is the case with the long-tailed African widow and the feathers of the club-winged manakin. They don’t display adaptive features.
However, they are honest because you cannot fake them. You cannot fake an ability to wield a large, convoluted antler on your head or showcase the eyes on your tail feathers. These were touted to be signals.
But this interpretation falls short. If the handicap should indeed be an honest signal, it should not stop at the supposed costs. If an antler is the honest signal, the growth should progress to the point where a deer will have an extensive arborization to counteract so much of their activity or movement and still survive in the wild. The extremes of ornamental features should be the highlight of sexual creatures. It isn’t.
An example I like to use is of a competent swimmer trying to rescue someone who is drowning. You cannot fake swimming — it’s either you know it or not. It’s an honest signal. Furthermore, you could know how to swim but not how to rescue someone from drowning. This makes the rescuing even harder.
Those who can successfully save the drowning people should convey honest and expensive signals. It is expensive since it is costly to risk being drowned by the very person you’re out to save.
Very convincing. Yes?
But this theory fails when you consider that it should evolve other swimmers who take even greater tests. Say, choosing to save the person only when a shark’s fin is within sight. That should really convey great cost. But that is not the case.
So the Zahavian handicap principle falls short given such explanations. The same explanation, as seductive as it may be, doesn’t accurately explain the use of bowers in courtship.
As for the bowerbirds, they are known for creating interesting bowers. The Vogelkop bowerbird can select ornaments of only a particular colour to prepare its bower.
The flame bowerbird will create a curved bower to set the stage for the female to view his dance.
Usually, male bowerbirds are known for their aggression. As we have already discussed, the tooth-billed bowerbird is notorious for aggressively attacking females to copulate.
Therefore, the Zahavian principle would have argued that a male who is strong enough to maintain their bower and protect it from other male competitors conveyed honest signals to the female. They would therefore attract the female to the biggest or the most elaborate bowers.
Extremely convincing. Yes?
I was equally convinced and even mentioned it in my book. I added extra nuggets of interpretation from my theory, but didn’t notice the distinct differences that I now know.
Firstly, because of the flaw we have already discussed. Secondly, the truth lies in the bird we discussed earlier — the aggressive tooth-billed bowerbird.
Sexual autonomy of bowerbirds
The alternative theory is that of mate selection.
It goes thus:
Female bowerbirds became selective of the less aggressive male counterparts.
This begins to make sense when analyzing the bowers. Their bowers are not just beautifully decorated — they are well-designed to protect the female.
The structures position the female in case the male tries to pounce on them, like the aggressive tooth-billed bower bird. This aggressive species does not create bowers; it only creates a stage. The name was a misnomer.
The other bower birds have to create a bower. The Vogelkop bowerbird, for instance, creates a hut, cleaned and structured to have the male inside with the female at the entrance. It then performs its intricate dance to, hopefully, an entranced female.
While inside, the male can decide to force copulation, but the entrance is engineered such that the female can fly away if the male is combative.
The workers tested their theory by actively falling one half of the bower bird’s structure. The female moved to the other one. The male continued its dance without the female flying off. She felt secure behind the bower.
Once they are convinced by the dance showcased by the males, they would turn and position themselves, inviting the copulation to happen. Consent has been given.
Nothing forced. Plus, a show to top it all.
This security is a feature of mate selection. The females who selected such mates were the ones who had successful copulations.
Aggressive, forced copulations could injure the females. They would risk not successfully laying and defending their clutch.
Bowers were a safe bet that the male would not force their way. Or as Patoraking would sing:
No other gyal make me act well
Females make the men act with decorum. It is a strong testament to sexual autonomy in birds. It is also a feature that shows how mate choice has a powerful role in evolution.
It begs the question — why does the tooth-billed bowerbird preserve its aggressive strategy?
An easy way to sidestep this concern is by defending that the bird is not strictly a bowerbird. The other is to show how the behavioural change of some of the birds was a speciation event.
This could lead to the evolution of a new group of birds with females who would only allow copulation to happen with the males who were gentle to them or didn’t force their way. This could have been the speciation event leading to bowerbirds.
That there are very many groups of bowerbirds displaying this protective feature is a testament to the successful reproduction of various species of bowerbirds. The tooth-billed outlier is primitive, and on a lighter note, exists to give us a clue as to the origins of bowerbird behaviour. They are a living testament to the bridge in the Afrobeat, which has their males singing:
If you no gimme I no go take
Only your love I appreciate
If you no gimme I no go take
Baby girl let’s relate
But she sings say
What I’m trying to say is…
Sexual autonomy is a feature of mate choice that speaks volumes about the importance of organismal roles in evolution.
Organisms choose. They determine the long-term outcomes. In the theory of Organismal Selection, the role of an organism in determining its fate is highly stressed. Bowerbird behaviour mounts strong evidence in favour of organismal choice. Most importantly, sexual autonomy.
And if the birds can do it, so can we.
This song inspired some of the lines used in this article. Source — YouTube