The Pebble and the Penguin

The Edinburgh Zoo is recently providing and laying out pebbles to help its male Gentoo penguins (Pygoscelis papua) find a mate. The keepers place large doughnut-shaped nesting rings in the enclosures during the mating season for the Gentoo penguins to build their nests in, and then pebbles are gathered and placed within the ring as a blanket for the eggs to be laid on. Pebbles are useful materials for nest-building especially in areas without plants; such nests could possibly save an egg or a chick from drowning if there is a flood.

The male penguin basically sifts through the available pebbles to find the smoothest (slightly flat) one — these pebbles tend to sit the best in the nesting rings — to present to its intended mate, and if the female penguin accepts the pebble and puts it on the nest she’s sitting on, a marriage would be formed — she has accepted the male penguin. Zookeeper Roslyn Talbot mentions that this courtship process also provides an opportunity for the penguin couple to bond. And ‘pebble envy’ could even occur, where the male penguin actually steals pebbles from other penguins, but naturally not without some defensive behaviour from the pebble owners.

Pebbles in Gentoo penguin enclosure at the Edinburgh Zoo

Gentoo penguin with pebble

Gentoo penguin with pebble

This courtship/mating ritual is not only evident in the Gentoo penguins, but also in the Adelie penguins (Pygoscelis adeliae) of Antarctica. In fact, this rather cute courtship behaviour inspired the production of an animated musical film The Pebble and the Penguin back in 1995!

I guess this gives new meaning to “picking someone up”!



Gentoo Penguin nesting,” by M. Pettitt. Flickr, 10 Jul 2006. URL:

LT Ronald J. Koss, 1963. Report of dental officer for Antarctic support activities for operation deep freeze ’62. Rubicon Foundation, 415: 1-41.

“Pebbles help penguins mate,” by BBC News. BBC News, 31 Mar 2010. URL: (accessed on 3 Apr 2010).

Stone, L.M, 2002. Penguins. Google Books, URL: (accessed on 7 Apr 2010).

“The Pebble and the Penguin family fun edition DVD,” by FunkMonk. Wikipedia, 11 Dec 2008. URL: (accessed on 6 Apr 2010).

“The way to a Penguin’s heart… a pebble?,” by P. Dickinson. Zoo News Digest, 31 Mar 2010. URL: (accessed on 6 Apr 2010).

The breeding behavior of Happy feet

The Emperor Penguin (Aptenodytes forsteri) is the tallest and heaviest of all living penguin species and is mainly living Antarctica. The male and female are similar in height and size: 122 cm in height and weighing anywhere from 22 to 45 kg. Their dorsal side and head are black and sharply delineated from the white belly, pale-yellow breast and bright-yellow ear patches. Like all penguins it can’t fly, instead wings stiffened and flattened into flippers for a marine habitat. They live and breed at the beginning of winter, on the fast ice all around the Antarctic continent. The total population is estimated to be about 200,000 breeding pairs. Emperor penguins can mate when they are 4 years old and can live to be 20 years of age.

Emperor_Penguins,_Weddell_Sea,_Antarctica (Source: Telegraph)

The penguins start courtship in March or April, when the temperature can be as low as −40 °C. A lone male will stand still and place its head on its chest before inhaling and giving a courtship call for 1–2 seconds. After that, it will move around the colony and repeat the call.   Before copulation, the birds bows deeply to each other. Emperor Penguins are serially monogamous. They have only one mate each year, and stay faithful to that mate.


(Image source:

Breeding pairs of emperor penguins face a problem as they don’t have breeding territories. Therefore, they defend their partnership by staying together during this period.This defense extends to their vocalizing — they remain silent until the egg is laid, so that an unpaired penguin can’t disrupt them.

Yet to keep warm and conserve energy during mating season, emperors must huddle with hundreds of other birds. Huddles form for a few hours, break up for a while and re-form again with different birds, over and over during the Antarctic winter. It’s the penguin equivalent of a mosh pit.

So how does a silent pair of emperors avoid becoming separated amid all the confusion? The answer, according toa study in The Proceedings of the Royal Society B: Biological Sciences, is that they stick close by each other in the crowd.


(Image source:

After the female lays its egg, it transfers to the male who will incubate it, alone, for several months.The female will return to care for the chick once it hatches; at that time  the male will go to the open sea to feed. The male will return in a few weeks and both male and female will tend to the chick by keeping it warm and feeding it food from their stomachs.

After 7 weeks of care, the chicks form groups called “crèches” and huddle together for protection and warmth. They are still fed by the parents. The chicks know their parents by the sound of their call. The chicks are fully grown in 6 months, which is the beginning of the summer season in the Antarctic. At this time all the penguins will return to the open sea.


(Image source: Telegraph)


Breeding Penguin Couples Stay Close in a Crowd.

Emperor penguins behavior

Antarctic Penguins

Emperor penguin mates: keeping together in the crowd

Emperor penguins

Roy & Silo – Gay penguins, no i’m serious, they’re gay


American idol Adam Lambert recently openly admitted to himself being gay on national television.   While some commended him for being open about it, many others condemned him for his sexual orientation.  In today’s society, homosexuality is still considered taboo in many countries.  Little do people know that homosexual and bisexual activities have been ongoing in the animal kingdom. 

Meet Roy and Silo (above), two male chinstrap penguins at New York’s Central Park Zoo.  They have been inseperable for six years since 1998, openly displaying homosexual behavior.  Together, they have displayed classic penguin pair-bonding behavior such as the entwining of necks, mutual preening, flipper flapping, etc.  You may find it hard to believe, but yes, they also had sex, while ignoring potential female mates.  Together, they raised a child, obtained from a surrogate mother penguin.   While the pair has already broken up in 2005, zoos from all around the world have been finding similar patterns of homosexuality in their penguins as well.  A German zoo, in Bremerhaven, northern Germany, claims that their two male penguins, Z and Vielpunkt have hatched a chick and are now rearing it together as its adoptive parents. 

Homosexual or bisexual behavior is not an uncommon observation amongst animals.  James Owen from National Geographic mentioned in his article that birds do it too, so do beetles, sheeps, orang utans, dolphins, fruit bats, etc.  Such behavior to be seems extremely intriguing.  I would usually presume that male animals will be on the lookout for female animals for mating purposes, and not male animals.  I tried doing more research on the topic and have found out possible reasons for such behavior.  Some animals appear to go through a homosexual phase before they become fully mature.  Others form temporal sexual relationships for social reasons – to establish lifelong bonds within their kind. 

It is interesting to point out that despite such behavior being common amongst animals, they have only  been documented relatively recently due to zoologists fear of stepping into a political mindfield of homosexuality and hetrosexuality.

The Gay Penguins of Central Park Zoo


“Homosexual Activity Among Animals Stirs Debate” by J. Owen.  National Geographic News, 23rd July 2004. URL: (accessed on 2nd April 2010)

“New Love Breaks Up a 6-Year Relationship at the Zoo” by J. Miller. New York Times, 24th September 2005. URL: (accessed on 3rd April 2010)

“The Gay Penguins of the Central Park Zoo” by M. Balan, 19th August 2006. URL: (accessed on 4th April 2010)

M. Renner, J. Valencia, S. David, D. Saez & C. Orlando, 1998. “Sexing of Adult Gentoo Penguins in Antarctica using Morphometrics”. Journal of Colonial Waterbirds. 21(3): 444-449 (accessed from Jstor on 4th April 2010)