When Animals Tell the Truth: Honest Signalling Theory

Honest signalling Theory. Why would animals tell the truth? Is it strong moral fiber? Maybe they paid really close attention when their mother told them the story of the boy who cried wolf? Not exactly. It's actually about self preservation.

Signalling theory states that animals send out signals that benefit themselves. Honest signalling theory states when an animal tells the truth , eg: sends a signal that says 'I'm healthy' when the animal is actually healthy, it does so to avoid a possible confrontation and therefore injury. Smaller, younger or weaker animals are unable to perform the behavior, therefore the behavior must be performed by a large and healthy animal.

Animals can determine the likely winner of a confrontation without either party risking injury. An extremely large difference in size means the smaller of the two potential rivals is at a serious disadvantage, and has a high chance of being hurt. Can't mate with a female, or even hunt for food, if you're too hurt to move.

This is our second article on signalling theory. Click here for an article about dishonest signalling. 

Honest Signalling Theory Examples

barking gecko gif

Video source: Bernard DUPONT

The barking gecko

Take the barking gecko, in the gif above, for example. They will bark to potential mates or rivals trying to invade their territory. The deeper (lower frequency) the bark, the larger the size of the gecko. By barking at a rival as it approaches, the barking gecko gets to size up their opponent. Since the smaller geckos can't imitate the calls of the larger geckos due to their size, a smaller gecko hearing a much lower bark knows he better get out of town.

birds of paradise mating ritual

Video source: BBC Earth

Birds of paradise

In this gif, from the video BBC Planet Earth - Birds of Paradise mating dance, you can see a portion of the flamboyant mating rituals of one bird of paradise.

You will also find honest signalling in birds. Sick, young or feeble males are unable to waste energy on such trivial things as pretty colors. Males that are thriving, however, have the extra energy to be as fabulous as they want.

elk bellowing

Video source: dw_ross

Elk

Some ungulates even get in on the party. Elk will bellow for extended periods of time. Healthy-large males have a larger lung capacity and can roar for longer periods of time.

Predator-Prey Signals

It's not just animals that are looking to mate or fend off rivals that will send honest signals. You will also see honest signalling in the predator-prey relationship.When hunting, a predator must analyze potential prey to determine how much it will cost them, in terms of energy, time and/or risk of injury, to catch their target and eat. Animals will sometimes send out honest signals to tell predators they are too healthy so look elsewhere for your next meal.

springbok stotting

Video source: Tee La Rosa

 

Springbok

What seems to be unnecessary jumping by the springbok, a species of antelope seen in the gif above, is actually a sign to predators they are healthy called stotting (also called pronking or pronging). It's basically a giant billboard to potential predators that says 'See how healthy I am?! Don't even try to eat me cause you'll never catch this awesomeness!' I'm paraphrasing of course. Since chasing them down would cost a lot of energy and chances are less the predator would get to eat, the predator will continue looking for an easier target.

Yellow-banded poison dart frog

Aposematism, or animals using coloration to ward off predators, can also be honest signalling. Through generations of conditioning, the yellow-banded poison dart frog has taught predators that its bright colors mean its not to be trifled with. The frog secretes neurotoxins through their skin which can cause irregular heart rhythms and even heart failure!

crested anole

Photo by: schizoform

The Puerto Rican crested anole

The Puerto Rican crested anole, Anolis cristatellus, will perform push-ups as a defense mechanism to ward of predators. As mentioned before, when hunting, predators must constantly analyze their prey to determine if they will not only be successful in catching prey, but also how much is it going to cost them to eat in terms of energy spent, time and potential injuries. A. cristatellus takes this opportunity of a predator analyzing them to show off just how buff they are by performing pushups. This is called a pursuit-deterrent signal. The predator sees how swole the lizard is and realizes it will cost them too much.

Sources:

Cain III, J.W.; Krausman, P.R.; Germaine, H.L. (2004)."Antidorcas marsupialis" (PDF). Mammalian Species (753): 1–7. doi:10.1644/753.

Alcock, J. (1989). Animal behavior: An evolutionary approach. Sunderland, Mass: Sinauer Associates.

Blount JD, Speed MP, Ruxton GD, & Stephens PA (2009). Warning displays may function as honest signals of toxicity. Proceedings. Biological sciences, 276 (1658), 871-7 PMID: 19019790

Smith, E.; Bliege Bird, R; Bird, D (2002). "The Benefits of Costly Signalling: Meriam Turtle Hunters". Behavioral Ecology. 14 (1): 116–126.doi:10.1093/beheco/14.1.116

Leal, M. (1999). Honest signalling during prey–predator interactions in the lizard Anolis cristatellus. Animal Behaviour, 58(3), 521-526

http://octavia.zoology.washington.edu/handicap/honest_intro_01.html

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