Animals are Homosexual ?!?

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Dolphins

Animals are homosexual? You must be kidding!!!

This is probably the reaction that most people will give when they hear this statement. Homosexuality itself is a topic that can be rather taboo. Even considering homosexuality in animals, would thus probably stir much controversy.

The strong Darwinist concept of animals teaches that animals only have sex to procreate. However, interestingly homosexuality that has no reproductive purpose is actually quite common in the animal kingdom.

Homosexual behaviour consists of 5 different categories:

  1. Courtship
  2. Affection
  3. Sexual behaviour
  4. Pair-bonding
  5. Parenting

Different combinations of these behaviours can be observed in different species. Some animals form long term homosexual pair-bonds that sometimes extend throughout their lives. This is seen in dolphins where male dolphin pairs travel together in search of female dolphins for procreation. The male-female bond is however only temporary.

Females also have their fair share of homosexual behaviour. This is best seen in parenting, for instance, among birds such as geese and ducks. Single females will lay eggs in a homosexual pair’s nest and the parenting is left to the homosexual couples. Homosexual couples also tend to be better at raising the young than heterosexual couples.

bonobo monkey

Male giraffes can be particularly affectionate towards one another when they rub and entangle their necks. Lions similarly nuzzle, caress, mount and even engage in sex to strengthen their bonds.  Perhaps one of the most promiscuous species would be Bonobo monkeys. They creatively come up with different ways to derive sexual pleasure for themselves and others. This includes masturbation, oral sex and use of sex toys. Sexual play among one another is also effective in resolving conflicts for these species.

When it comes to sex, animals in the wild are truly wild…

Do check out the video: Homosexuality in animals

References

1. National Geographic News, “Homosexual Activity Among Animals Stirs Debate”. 23 July 2004  <http://news.nationalgeographic.com/news/2004/07/0722_040722_gayanimal.html>((  ( Accessed on: 4th April 2010)

2. Sexplorations, “Homosexuality in Animals”, 22 March 2008

<http://www.youtube.com/watch?v=VUwza5Grxos>

(Accessed on: 1st April 2010)

3. Telegraph, “Homosexual behaviour widespreaf in animals according to new study”. 16 June 2009

< http://www.telegraph.co.uk/science/science-news/5550488/Homosexual-behaviour-widespread-in-animals-according-to-new-study.html>

(Accessed on: 5th April 2010)

4. The Medical News, “1,500 animal species practice homosexuality”. 23 October 2006

<http://www.news-medical.net/news/2006/10/23/20718.aspx>.

(Accessed on: 2nd April 2010)

Photo credits

1. Elodie, Ä memorable experience for young & old: The Zoo of Barcelona”, 1 April 2009

< http://www.perfecttravelblog.com/leisure/>

( Accessed on: 6th April 2010)

2. Ho, Raymond, “Homosexuality: Was Darwin Wrong On Sexual Selection?”, 3 November 2009

<http://theprancingpapio.blogspot.com/2009_11_01_archive.html >.

(Accessed on: 6th April 2010)

Video credit

National Geographic, “Homosexuality in Animals”, 6 October 2006

< http://www.youtube.com/watch?v=7RlTAyNI8WE>

(Accessed on 6th April 2010)

Cleaners in the waters?

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Have you ever wondered how fishes keep themselves clean?

Or do they even need to be cleaned?

Well, small animals called the cleaner shrimps, such as the Periclimenes longicarpus, as shown in the picture below, cleans the fishes! The shrimps will be hanging around the cleaning stations in the waters and when a fish stops by, the shrimps will climb onto the fish. They will then use their claws to pick off detritus, dead skins, ectoparasites and tiny pieces of food. If the mouth of the fish is open, the shrimp will also climb into its mouth to clean.

Periclimenes longicarpus

These cleaner shrimps are actually much more than we can imagine – they clap to indicate their hunger levels. This means that when these cleaner shrimps are hungry, they will clap their claws! The rate of signaling in the shrimps will increase when they are deprived of food, that is, the demand for cleaning is low. Signaling by the shrimps can also be seen as a form of advertisement of service, so that the exchange of commodities ( the cleaner shrimps get food while the fishes get cleaned up) with clients – the fishes, will be better. Moreover, clapping may serve as both visual and auditory or vibration identity signals (Hasson 1997) as many reef fishes have low resolution power (Marshall 2000). Hence this will enable the fishes to locate the cleaner shrimps.

These cleaner shrimps are brave too!

In the marine cleaning interaction, the symbiotic relationship formed between the shrimp and the fish is of great trust. This is because some of these fishes that stop by at the cleaning stations can be predatory fishes which can just prey on the cleaner shrimps easily when they are cleaning them.

So fishes in the marine environment do actually “bathe” as well! Their bodies are being clean by “cleaners” in the waters such as the cleaner shrimps. To end this post, follow the link and enjoy this youtube video about the cleaning symbiosis among Hawaiian reef fishes, moray eels, sea turtles and cleaner shrimps. It illustrates that not only fishes get cleaned but other marine animals as well, even humans!

Cleaners in the Marine Environment

 

References:

Journals

Hasson, O. 1997. Towards a general theory of biological signaling. Journal of Theoretical Biology, 185, 139–156.

 Lucille Chapuis, Redouan Bshary, Signalling by the cleaner shrimp Periclimenes longicarpus. Animal Behaviour, Volume 79, Issue 3, March 2010, Pages 645-647

 Marshall, N. J. 2000. Communication and camouflage with the same ‘bright’ colours in reef fishes. Philosophical Transactions of the Royal Society B, 355, 1243–1248.

Articles

“Odd Couples” by Amy Sarver. National Geographic Explorer. Pages 6-11, January-February 2006 issue. URL: http://magma.nationalgeographic.com/ngexplorer/0601/articles/mainarticle.html (accessed on 3 April 2010)

“Photos get the flavour of science” by Jonathan Amos. BBC News, 28 September 2005. URL: http://news.bbc.co.uk/2/hi/science/nature/4291912.stm (accessed on 3 April 2010)

 Photographs/ Video

 “El Gouna 02.2009 422” by Alain76. Alain76’s photostream: El Gouna, Egypte 2009 (Set). URL: http://www.flickr.com/photos/12163936@N03/3268716503/ (accessed on 3 April 2010)

 “Hawaiian Showers – Cleaning Stations in Hawaii + Scuba Diving” by LivingOceanProd, Youtube Channel, 17 March 2008. URL: http://www.youtube.com/watch?v=OMFiI2at1p4&feature=related (accessed on 3 April 2010) 

Long tails no enough?

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There is a considerable amount of sexual dimorphism in great-tailed grackles (Quiscalus mexicanus), a type of blackbird. Sexual dimorphism is the difference in form between individuals of different sex in the same species.

Male great-tailed grackles can grow up to about 43 cm, including a tail that is almost as long as the body, and are jet-black in colour with a violet-blue iridescent sheen to the feathers. Females, on the other hand, are significantly smaller at about 33 cm, and are mainly brownish-black, with a pale brown throat and belly.

Great-tailed Grackle (Quiscalus mexicanus), Male

Great-tailed Grackle (Quiscalus mexicanus), Male

Great-tailed Grackle (Quiscalus mexicanus), Female

Great-tailed Grackle (Quiscalus mexicanus), Female

Sexual dimorphism is mainly attributed to sexual selection. Longer tail length has always been associated with territory acquisition and social mate attraction, in combination with size.

There can also be another explanation to sexual selection. Larger males have the advantage in acquiring territories, and females preferred to settle on the territories of larger males, probably because larger males were able to acquire trees with the most desirable nest sites.

Larger males have the advantage in acquiring territories

Larger males have the advantage in acquiring territories

Recently, it came into question whether animals also use glossiness, where their hair or feathers reflect light like a mirror, to signal to the opposite sex.

In a recent study conducted by PhD researcher Mr Matthew Toomey and colleagues from Arizona State University, Tempe, US, birds were captured, with photographs taken of them and their tails measured before being released. The glossiness of the bird’s feathers in each photograph was calculated using a reflectance spectrophotometer and computer software.

According to Mr Toomey, it was found that male great-tailed grackles were significantly glossier than females. Another discovery was that males with the glossiest feathers also had the longest tails. One possibility arising from this study is that glossiness may play a role in visual signaling and glossier males may be more attractive and better competitors for mates.

Glossiness may play a role in visual signaling

Glossiness may play a role in visual signaling

Glossiness can be a potential step towards the evolution of iridescence where selection for glossiness can result in a refinement of the microstructure of a feather.

Long tails are no longer enough to attract mates? Further research will be required to prove this theory.

References:

“Female birds find males with glossy feathers more sexy,” by Jody Bourton. BBC, 23 March 2010. URL: http://news.bbc.co.uk/earth/hi/earth_news/newsid_8577000/8577316.stm (accessed on 3 April 2010).

Kristine Johnson, Emily DuVal, Megan Kielt & Colin Hughes, 2000. Male mating strategies and the mating system of great-tailed grackles. Behavioural Ecology, 11(2): 132-141

William A. Searcy and Ken Yasukawa, 1981. Sexual Size Dimorphism and Survival of Male and Female Blackbirds (Icteridae). The Auk, 98(3): 457-465

William A. Searcy, 1979. Sexual Selection and Body Size in Male Red-Winged Blackbirds. Evolution, 33(2): 649-661

“2 of 2 Great-tailed Grackle (Quiscalus mexicanus), Male,” by Michael “Mike” L. Baird, mike at mikebaird.com. URL: http://www.flickr.com/photos/mikebaird/4495734086/in/photostream/ (accessed on 5 April 2010)

“Great-tailed Grackle (Female) (Quiscalus mexicanus),” by Mike Baird, BairdPhotos.com. URL: http://www.flickr.com/photos/mikebaird/339193969/ (accessed on 5 April 2010)

“Quiscalus mexicanus,” by Pablo Lèautaud. URL: http://www.flickr.com/photos/pleautaud/2662384817/ (accessed on 5 April 2010)

“Quiscalus mexicanus,” by Pablo Lèautaud. URL: http://www.flickr.com/photos/pleautaud/3217071624/ (accessed on 5 April 2010)

Why arrows? Strike with love darts!

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Why let the cupids decide? Learn from the helicid land snails ( for e.g. Helix Aspersa) and do it yourself!

 Most of us know that snails are hermaphrodites, meaning they have both male and female sexual organs, and they do not self-fertilize. But do you know that their genitals are on the necks, right behind their eye-stalks?

 Not interesting enough?

 They are the cupids themselves! But instead of arrows, the “male” (male sexual organs at work) shoots mucus-covered calcium “love darts” during the final stages of courtship to its partner preceding copulation!

Initially, it was thought that the “love darts” were gifts of nutrients, just like how we give presents to the person we fancy. However, further research has shown that there is more to it!

dart with mucus

“Love darts” are actually filled with sperm. When it is being shot to the partner, it penetrates into the body of the recipient and may get digested. However, the mucus outside paralyses the partner’s reproductive tract, allowing the sperm to avoid digestion and thus greater number of sperms can make it to the sperm storage sacs within the reproductive system (Pomiankowski et al. 2001). Good news, as the stored sperms may be enough to be used over a period of months or even years! Say YAY to more offspring!

So, why is there a need for “love dart” when snails can just simply copulate? Sadly, the chance of survival of sperm through copulation is extremely low, like only thousands in millions. Thus with “love dart”, it provides the edge over reproduction because more sperm will be available: Applying Darwin’s theory of sexual selection, snails want to reproduce as much as they can, so if one snail has a way of ensuring that its sperm and not others’ is used to fertilize the eggs, it will have advantage over other snails and sire more offspring!

Sperm competition is somehow present. Basically, 2 or more snails can shoot “love dart” at the same partner (they are promiscuous!). The depth of penetration will determine how good the shot is; the deeper the higher amount of sperm stored! Thus, if one snail is better than the other, higher percentage of the newborn will be its offspring since its sperm has greater chances of being selected by the female for fertilization!

2 snails

Sounds cool right? While the “male” can enjoy shooting the “love dart” showing its affection, the recipient would be OOL (ouching out loud). This may be a very horrifying process because the darts are just like hypodermic needle and can rip off the skin of the recipients!  So sometimes snails will try to avoid getting hit on! How apt to human beings relationship, right? =p

References:

Website

“Are Snails’ ”Love Darts” Source of Cupid Lore?” by Ian Popple. National Geographic, February 13, 2002. URL: http://news.nationalgeographic.com/news/2002/02/0213_020213_wiresnail.html (accessed on 5 April 2010)

Journals

 Menno Schilthuizen, 2005. The darting game in snails and slugs. TRENDS in Ecology and Evolution 20 (11):581-584.

Janet L. Leonard, 1992. The “love dart” in helicid snails: a gift of calcium or a firm commitment? J.theor.Biol 159:513-521.

Pomiankowski.A and Reguera.P, 2001. The point of love. TRENDS in Ecology & Evolution 16(10):533-534

Photo

Dr Ron Chase- Home Pagehttp://biology.mcgill.ca/faculty/chase/ (accessed on 6 April 2010)

MULTIPLE SEX PARTNERS??

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Deep sea anglerfish, Melanocetus Johnsoni, are found in the most inhospitable place on the planet; the cold, dark bottom of the sea. There are over 200 species of Anglerfish, each differing in terms of body structures and size.


However, their most common and distinctive feature is a slender, antenna-like projection extending from its head or mouth, known as a dorsal spine. The spine supports a light-producing organ called a photophore, which acts like a “fishing-rod” as prey are attracted to the luminescent bubble.

Here are some examples of the various species of Anglerfish

http://tolweb.org/Ceratioidei/22000/2007.10.02#AboutThisPage



However, what is most interesting about deep sea Anglerfish is not just their grotesque appearance and their preying manner, but even more so their mating behavior. The role of males in deep sea Anglerfish is completely reduced. Being barely 1/10th of the size of a female, the male anglerfish live as parasites on females.


A female Anglerfish

SeaDevil


From the moment of birth, male anglerfishes seem to have no other role than to search out a female. The tiny male has no bioluminescent lure, instead, they have larger eyes presumably for spotting the flashing lure of the female and a greater olfactory organ (organ of smell, or nose) above its eyes.  The reasons behind these physical differences between the sexes could be because in the vast ocean, sexual pheromones are highly essential in locating a mate. Thus, in the dark and vast ocean, heightened sensitivity to the female pheromones is crucial in the reproductive lifestyle of the Anglerfishes.


The Male Anglerfish

Male Angler fish

Upon locating a female anglerfish, the puny male attaches itself to her body by biting into her. His teeth and jaw then recedes and a chemical is released which fuses the skin and blood systems of both parties. Thereafter, it becomes entirely dependent on the female for its nutrients and oxygen, similar to that of a parasite. In time, the male anglerfish’s eyes and other digestive organs regresses and its body degenerates into essentially a pair of sperm producing testicles.


At this juncture, the female essentially becomes a hermaphrodite, with up to 6 of these male parasites attached to various parts of her body. As a functional hermaphrodite, the female is able to have fertilize her eggs from the moment she releases them from her body.


example of female Anglerfish with attached male parasitesattached males

However this is not all, even more intriguing in fact is that the female anglerfish can carry as many as 6 of these parasitic males  at one time! thus a single female could have six pairs of testicles at her beck and call, supplying her with a fresh supply of sperms at any point in time!

Here is a video of the strange mating behavior of deep sea anglerfish

Angler fish mating customs


References:

Perun, Blane. (1999) “Deep Sea Angler Fish”

http://www.thesea.org/TheSea/deep_sea_angler_fish.html

Nationalgeographic.com (1996-2010) “Anglerfish”

http://animals.nationalgeographic.com/animals/fish/anglerfish/

“Angler Fish Mating Customs” by howtofaint. Youtube Channel, 7 april 2009

URL: http://www.youtube.com/watch?v=Lsmxs0uDXMo


Passion for Electricity

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The red imported fire ants, Solenopsis invicta, also known as the RIFA is native to South America. In 1930, the RIFA were introduced into United States through the seaport of Alabama. Ships from Brazil unloaded goods infested with RIFA and since then they have spread through America. The ants respond to pheromones released by the first ant that attacks and sting together at the same time. They are highly aggressive and their sting contains necrotising, alkaloid venom resulting in itchy, painful pustules. Fire ants live in colonies of 100,000 to 500,000 ants. The queen ant can lay from 1500 to 5000 eggs a day thus explaining its high population.

These ants are attracted to electric circuits and therefore accumulate in electrical equipments like traffic light and air conditioner. The damage to traffic lights in Texas is because of these ants. So how do these ants gather at the electric circuits. Research has shown that ants respond to electric stimulus by producing semiochemicals which in turn attracts more ants and this invasion causes damages and short circuiting of the electric circuits (Vander Meerl, Slowik & Thorvilson, 2002). Research has also shown that the attraction is directly proportional to the field strength of direct current and alternating current (Mackay, 1992).

The actual reason of attraction is still not really known but this attraction has caused America billions of dollars a year because of the damage to electrical equipment such as air conditioners, electrical and utility units, traffic signal boxes, telephone junctions,  electric pumps for oil and water wells, airport landing lights, computers, and even car electrical systems.

References:

“Fire ants vs humans – BBC” by BBC Worldwide Youtube Channel, 9 March 2008. URL: http://www.youtube.com/watch?v=3vVUh-194vU&feature=fvw (accessed on 7 March 2010).

Mackay, W. P., S. Bradleigh Vinson, J. Irving, S. Majdi, C. Messer, 1992. Effect of electrical fields on the red imported fire ant (hymenoptera: formicidae). Environmental Entomology, 21(4): 866-870.

“Red imported fire ant (Solenopsis invicta)” by Arizona-Sonora Desert Museum. URL: http://www.desertmuseum.org/invaders/invaders_fireant.htm (accessed on 7 March 2010).

“Solenopsis invicta” by Alex Wild. The University of Texas at Austin. URL: http://www.sbs.utexas.edu/fireant/Images/Solenopsis_invicta1.JPG (accessed on 7 March 2010).

Vander Meer, R. K., T. J. Slowik and H. G. Thorvilson, 2002. Semiochemicals released by electrically stimulated red imported fire ants, Solenopsis invicta. Journal of Chemical Ecology, 28(12): 2585-2600.

Animal Homosexuality in Bonobos- Pleasure or Social Bonding?

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Bonobo Homosexuality

Bonobo Homosexuality

Image Source: http://www.psychologytoday.com/blog/your-inner-bonobo/201004/can-animals-be-gay-are-you-serious-nyt

Pleasure seeking activities or Hedonic Ethology and it’s association with Animal Homosexuality has been widely documented and debated on the internet and the scientific world. However, it remains an elusive and under-researched topic till today. In this article, we will try to examine a controversial animal, the Bonobo or pan paniscus to unravel the link between their pleasure-seeking activities and their acts of homosexuality.

In Hedonic Ethology, since pleasure-seeking activities such as masturbation and fellatio has no effect on procreation. Why do animals still engage in such behaviour? Scientists suggest several reasons; firstly, pleasure is adaptive and is a product of evolution. Pleasure seeking stimulates complex sensory systems that enable animals to perceive environment and react to different forms of stimuli, the evolutional benefit of pleasure seeking activities rewards the individual for performing behavior that promote survival and bonding.

Secondly, pleasure-seeking encourages animal play, or simply put, having fun. It enables greater social bonding between communities of different individuals and social learning takes place from the observation of these behavior. Since learning stems largely from the observation and the interaction with other animals, animal play becomes evidently important to teach younger offsprings to learn the actions required for sexual behavior when they reach sexual maturity.

Currently, at least 300 species of vertebrates are known to practice homosexuality (Bagemihl, 1999). But homosexuality has been termed as ‘unnatural’ or ‘maladaptive’ since it has no procreational purpose.

In Bonobos, researchers have found that both male and female bonobos engage in sexual behavior with the same or opposite sex. 75% of all their sexual activity are bisexual. Some scientists, such as Paul Vasey, animal behavior professor at the University of Lethbridge, Albert suggests that such behavior are simply acts of animals seeking sexual gratification, much like humans. Other scientists such as  Frans de Waal, author of Bonobo: The Forgotten Ape, believes bonobos use sex to resolve conflicts between individuals and reduce social tensions.

References:

Balcombe, J. 2009. Animal pleasure and its moral significance. Applied Animal Behaviour Science 118 (2009) 208–216

“Sexploration – Animal Homosexuality” by MSNBC. YouTube Channel, 22 Mar 2008. URL: http://www.youtube.com/watch?v=VUwza5Grxos (accessed on 06 Apr 2010)

Courtship in Birds; Same Old Song and Dance?

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  “Everyone likes birds,” Sir David Attenborough.

Wilson's Bird Of Paradise

The birds-of-paradise, (Paradisaeidae), are pretty close to our shores. These colorful little birds (especially the males with their long plumes) are actually found in rainforests in surrounding islands of Indonesia and New Guinea.

Perhaps, even closer to home, is how close their mating behavior is to the courtship behavior in human beings.

The Birds-of-Paradise have developed a social mating system based on arenas or leks. Essentially, this is a stage that is cleared for the male to do his song and dance; a highly elaborate courtship display that features the magnificent plumage.

Wilson’s Bird of Paradise’s elaborate courtship ritual

The star of the video above is actually of the species of the Paradisaeidae, the Wilson’s Bird of Paradise (Cincinnurus respublica). He starts by actually clearing the arena, of twigs and leaves. This allows his magnificent color coat of feathers and unusually long plumes to be more visible to the potential female mate. At one point of time, it even displays its distinctive breast shield.

The video below features another, not so magnificently colored male species of the Paradisaeidae, using a similar stage or arena, for courtship behavior. Similarly after clearing away leaves and twigs, the stage is set for the male to put on his phenomenal dance show. Taking the ritual very seriously, he evens warms up before beginnings his elaborate display as this may last up to a few hours!

Beautiful Plumed Bird of Paradise

Studies have also shown that there is a strong correlation between achieving female preference if they were more conspicuous as possibly indicates a higher survival and fecundity for the female.

Interestingly, these elaborate displays seems to be learned behavior as the younger males stay on the fringes of the arena to practice clumsily before the star of the show takes over in the centre stage.

Does this parallel post modern society’s courtship rituals? Sir David Attenborough would probably beg to differ:

“These birds are so romantic and they have legends surrounding them. They all do the most extraordinary things, each with its individual dance and display.”

Beautiful Plumed Bird of Paradise's Dancing Ritual

Works Cited

Research Articles:

Davies, G. H. (n.d.). Meet Sir David. Retrieved March 31, 2010, from The Life Of Birds: http://www.pbs.org/lifeofbirds/sirdavid/index.html

Irestedt, M., Jonsson, K. A., Fjeldsa, J., Christidis, L., & Ericson, P. G. (2009). An unexpectedly long history of sexual selection in birds-of-paradise. BMC Evolutionary Biology .

Kirkpatrick, M., & Ryan, M. J. (1991). The evolution of mating preferences and the paradox of the lek. Nature , 33-38.

Videos:

BBC Wildlife. (2007, June 12). David Attenborough finds the rare exotic Wilson’s bird of paradise. Retrieved April 07, 2010, from YouTube: http://www.youtube.com/watch?v=fmmp3wrf9gg&feature=channel

BBC Wildlife. (2007, June 12). David Attenborough finds the rare exotic Wilson’s bird of paradise. Retrieved April 03, 2010, from YouTube: http://www.youtube.com/watch?v=fmmp3wrf9gg&feature=channel

Pictures Taken From:

Kirby, R. (2003). Wilson’s bird-of-paradise. Retrieved April 01, 2010, from Arkive: Images of Life on Earth: http://www.arkive.org/wilsons-bird-of-paradise/cicinnurus-respublica/image-G51010.html

Rhino, Tickbird Stuck In Dead-End Symbiotic Relationship

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The Onion reports:

“Feed off the embedded ticks on his hide, chirp when the predators come. Feed off the embedded ticks on his hide, chirp when the predators come. Where’s the passion, the heat?” the tickbird continued.

The rhino and tickbird pass another morning on the African savannah not saying one word to each other.

The rhino and tickbird pass another morning on the African savannah not saying one word to each other. - The Onion

Amusing article aside, it is true that rhinos and tickbirds may not get along as well as you think.

The diet of tickbirds, also known as oxpeckers (family Buphagidae), consists of parasites such as ticks. These parasites are in abundance in the hides of large mammals. Thus tickbirds are often found on the backs of these large mammals, pecking away.

On the surface, both animals benefit from this relationship. The oxpecker enjoys a guaranteed source of food, while the host mammal is rid of parasites. According to Wikipedia, this is a symbiotic relationship! We trust Wikipedia, right?

However, it is not clear if the oxpeckers even reduce tick loads. More after the jump.

Continue reading →

You are my one and only… OR ARE YOU?

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Though Adelie penguins (Pygoscelis adeliae) are monogamous, the couple does not spend the winter together. In fact, the pair migrates separately and will only return to the rookery where they last mate during the breeding season (from November to February). The males will arrive at the breeding site prior to the females to build the nesting sites. Unless one of the partners fails to return, the couple will reunite every breeding season. The penguins are able to recognise its mate’s call or even, physical features.

For first time breeders, there are generally three distinct types of visual/auditory courtship displays. (Watch this – courtship of penguins)

  1. Ecstatic. The male penguins will swing their head, and flap their flippers. These actions show possession of a breeding site, to attract females, and to keep other male intruders away.
  2. Mutual. Once paired, both the male and female penguins will stretch their head and neck upward.
  3. Bowing (Figure 1). Bowing displays reduce aggression; strengthen bonds and recognition between partners.
Figure 1 (Source: http://www.coolantarctica.com/gallery2/birds_1000_pic0012.html)

Figure 1 (Source: http://www.coolantarctica.com/gallery2/birds_1000_pic0012.html)

Are Adelie penguins truly monogamous?

Research has found that both male and female Adelie penguins may have more than one breeding partner in its life (F. M. Hunter, G. D. Miller and L.S. Davis, 1995). In fact, about 21-30% of the female penguins were involved in mating with more than one male in a single breeding season, either through extra pair copulations (EPC’s) or mate-switching (Harshaw, 2005).

A female may copulate with multiple partners to enhance genetic quality or diversity of her offspring. The female penguin may also mate with numerous males to (1) ensure that her eggs are fertilised in the event of her partner being infertile, (2) gain potential partners in the future years should her partner leave her (F. M. Hunter, G. D. Miller and L.S. Davis, 1995).

In addition, it seems that the females engage in EPC’s so as to collect more stones or nesting materials to build a better nest. This will benefit the males in terms of living conditions as well. Furthermore, after the eggs have been laid, the males have the responsibility to incubate them. As such, the male is unable to leave the nest to protect its mate from engaging in EPC’s since an unguarded nest will invite predation.

While we decide whether the Adelie penguins are indeed monogamous, it is important to note that the survival of all species of penguins is greatly challenged by weather conditions and food availability. According to Dee Boersma, a University of Washington biology professor, the population of penguins in the Punta Tombo colony has reduced by more than 20% in the last 22 years (Science Daily, 2009). Some possible reasons for the decline are human activities such as oil pollution and overfishing. As such, it is crucial human amend their ways to save our declining ecosystem.

References:

“Adelie Penguins”, by Keith Dreher, n.d. URL: http://www.keithdreher.com/adelie.html (accessed on 6 April 2010).

“Adelie Penguins”, by National Geographic, n.d. URL: http://animals.nationalgeographic.com/animals/birds/adelie-penguin/ (accessed on 6 April 2010)

“Adiele Penguins – courtship 10”, by Paul Ward, 2001. URL: http://www.coolantarctica.com/gallery2/birds_1000_pic0012.html (accessed on 6 April 2010)

“Adiele Penguins – courtship, mating and chick hatching”, by BBC Natural History Unit, n.d. URL: http://www.arkive.org/adelie-penguin/pygoscelis-adeliae/video-09b.html? (accessed on 5 April 2010)

“Mating System”, by Lauren Harshaw, 2005. URL: http://www.bio.davidson.edu/people/vecase/Behavior/Spring2005/Harshaw/MatSys.html (accessed on 5 April 2010).

“Penguins”, by Sea World, n.d. URL: http://www.seaworld.org/animal-info/info-books/penguin/reproduction.htm (accessed on 6 April 2010)

“Penguins Marching into Trouble”, by Science Daily, 13 February 2009. URL: http://www.sciencedaily.com/releases/2009/02/090212171936.htm (accessed on 6 April 2010)

“Penguin Parenting: Adelie penguins reunite for their annual breeding rituals”, by Michelle Alten, July-August 1997. URL: http://findarticles.com/p/articles/mi_m0FRO/is_n4_v130/ai_19634761/ (accessed on 5 April 2010)

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