Cold blooded animals like reptiles are not usually associated with being faithful. To put it in a humanise way, reptiles flirt around with no fix sexual partner throughout its life. However, this particular reptile specie will change your life, my life (just joking) and perhaps our views on cold blooded animals.
In reptiles, and lizards in particular, monogamy is rarely reported. However, this lizard(shown above) is almost the only one that is monogamy. Monogamy is where a single male and a single female form an exclusive association and cooperate in breeding activity (Wickler and Seibt, 1983).
The reptile that is so “faithful” is Tiliqua rugosa, commonly known as Shingleback blue- tongued skink. It is found throughout the drier parts of Southern Anstralia, from approximately Bathurst in New South Wales all the way to the coast of Western Australia. (Loch, T. 2000) Shingleback skinks are among the largest of the Australian skinks. Mature adults typically weigh about 600 to 900 grams and have snout-vent lengths (SVLs) of 16 to 18 inches (VItt and Pianka, 1994).
Enough of the reptile, lets go into the sweetest part of the animal. It is best known for monogamy.
There are several reason why animals choose to be monogamy :
1) Males stay with their female partner to provide paternal care and help to raise young to ensure a higher reproduction rate.
2) Males had to guard their female partner from rivalry to ensure their own paternity.
3) Females adopt monogamy when they are advantaged by accompanying males.
However, these 3 most common reasons/functions of monogamy cannot explain why Shingleback choose to form loyal pairs for up to 20 years (FYI, their average lifespan is 15 years in the wild thus it is effectively “married” for life). So why did Shingleback choose to remain loyal when the apparent functions of monogamy are not applicable to them? Some scientists used the costs VS benefits theory to explain. They explain that it might cost more to break a relationship then to remain with the same partner throughout its life. Thus, in the case of Shingleback, the benefits of staying loyal outweigh the cost of looking for a partner every mating session. Well, i believe that some things cannot be explained using science especially in the field of relationship.
The whole duration of courtship take an amazingly long period of time (well, at least in animals). An inseparable courtship stage ensues for 6-8 weeks. In other words, the couple will stay side by side for more than 2 months before they began their mating ritual. This prolong period of courtship is seldom observed in reptiles. After the copulation, pairs then usually separated for 10 months, after which they seek out the identical partner the following years. Astonishingly, some pairs have been found together for 10 consecutive years (Vitt and Pianka. 1994). A study done by University of Michigan Museum of Zoology illustrate long-term individual recognition by this specie and also shows that these reptiles are monogamous more often than not (Loch, T.2000).
In the video shown below, we would observe the courtship behaviour exhibited by the Shingleback. I was shocked when i heard that the couple will remain side by side for up to 2 months. The courtship is so “human like” in the way when gentle touching(or licking) is the way of courtship (compared to other reptiles). Towards the last part of the video, the humane side of them shows again. The male would stay with the female after it was dead. It was indeed surprising for a reptile to do that!
Maybe, one day, we should redefine some of our definition or labeling of our cold blooded friends.
References and citation
Special thanks to Dr Ellen for her images.
Loch, T. 2000. “Trachydosaurus rugosus” (On-line), Animal Diversity Web. http://animaldiversity.ummz.umich.edu/site/accounts/information/Trachydosaurus_rugosus.html. (Accessed March 30, 2010)
Wickler, W., Seibt, U., 1983. Monogamy: an ambiguous concept.
In: Bateson, P. (Ed.), Mate Choice. Cambridge University Press, Cambridge, pp. 33–50.
Vitt, L., R. Pianka. 1994. Lizard Ecology. NJ: Princeton University Press.
Tarvin, C. C. (8th February, 2010). It Isn’t Just Once a Year: Romantic Courtship in the Animal Kingdom. Retrieved 30 March, 2010, from http://buquad.com/2010/02/08/some-tips-for-valentines-day-from-the-animal-kingdom/
Images and Video
Images from Dr. Ellen K. Rudolph (with permission)
http://www.drellenrudolph.com/featureanimals/shinglebacklizard.html (Accessed March 30, 2010)
“BBC’s Life in Cold Blood documentary series.” YouTube Channel, 23 February 2009. URL: http://www.youtube.com/watch?v=aPZiAiUYS8o&feature=player_embedded (accessed on 30 March 2010).