Life Cycle of the Gentoo Penguin

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Life Cycle of the Gentoo Penguin

Letter Rate (75p) Part No: ST011794
Airmail Rate (65p) Postcard Coils Part No: ST011797               
CTO Part No: ST011795 
FDC: Part No: ST011796

Gentoo penguins are the third largest species of penguin, after the emperor and king penguin. They reach heights of between 75 – 90cms and weigh between 5-6.5kgs, males being slightly. They belong to the genus Pygoscelis, which includes the Adélie and chinstrap penguin. Gentoo are black and white birds and can be easily distinguished from other penguins by their bright orange-red bill and the white patches above their eyes, which usually meet across the crown. They have brown eyes, yellow-orange feet and the most prominent tail of all penguins. As the gentoo walks its tail sweeps from side to side, hence the name Pygoscelis, which means ‘brush-tailed’.

Gentoos are the most northerly of the 4 Antarctic species. They have a circumpolar distribution, breeding on sub-Antarctic islands and the Antarctic Peninsula (46-65°S). They have a life expectancy of up to 20 years and the total breeding population is estimated to be 314,000 pairs. Breeding colonies rarely comprise more than a few hundred pairs, much smaller than other similar penguins. Unlike other species that nest alongside them they wait until the sea ice has retreated before heading for the nesting grounds, so are the last to arrive.

Each pair will set about the task of constructing nests from stones, tussock grass, old feathers and moss. Nests can contain as many as 1,700 individual stones and stone theft is common. If a gentoo has an opportunity to peck another penguin it will, so nests tend to be spaced slightly out of reach of each other. Into these nests they lay two spherical white eggs which are incubated by both the male and female for up to 39 days. If necessary they are the only penguins that are able to lay a replacement clutch of 2 eggs. Egg-laying is usually completed by late October with both parents sharing the incubation duties for the next 34-36 days.

Hatching is followed by 25-35 days when the chicks are brooded and guarded by their parents. After this time, the chicks are then large enough to become mobile and form into crèches. They are fed daily by both parents until eventually they fledge at 80-100 days.
 
Gentoo penguins reach sexual maturity at the age of two years, although most start breeding at 3–4 years. They remain faithful to both their nesting sites and their breeding partners, with many forming long-lasting pair bonds.

On land the gentoo walks with a humorous waddle, but once in the water they are the fastest underwater swimming bird. They can reach speeds of up to 36km per hour (with an average of 6.5km per hour) and are capable of diving to depths of 170m in pursuit of prey. They mainly feed on krill (50%) and fish (30%) with squid and other crustaceans as available making up the remaining 20%. They tend to prefer feeding inshore near to the breeding colony during daylight with most achieving depths of up to 50m. At sea they are subject to predation by leopard seals, sea lions and orcas, whilst skuas prey on eggs and chicks.

Base A Port Lockroy is a designated Historic Site and Monument under the Antarctic Treaty and is now a museum and the British Antarctic Territory’s main post office managed by the UK Antarctic Heritage Trust (UKAHT). It is also known for its gentoo penguins, who return to the island each year to build their pebble nests, lay their eggs and raise their chicks during the short Antarctic summer months. It is believed the gentoos first begun nesting on the island in 1985. There are now an estimated 3000 gentoo penguins that return to Goudier Island each year to breed.

The UKAHT, through its team on the ground, ensures that everything possible is done to minimise any tourism impact on them. Part of Goudier Island is cordoned off as a 'Penguin Control Colony' where visitors are not permitted. This allows the UKAHT team to monitor and compare the population size, distribution and breeding success of the 'control colony', who have very little contact with humans, with the other breeding penguins on the island, who are in close proximity both to the staff and visitors. Monitoring the penguins is carried out three times a year and the results are forwarded to the British Antarctic Survey. Evaluation of the statistics (records start in 1996) show that there has been no discernible impact from tourism on the gentoo penguins at Port Lockroy.
 
Technical details:
Designer: Bee Design
Printer (sheet stamps): BDT International Security Printing Ltd
Printer (reel stamps): Lowe-Martin
Process: Lithography
Perforation: 14 per 2cms
Stamp size: 30.56 x 38mm
Reel stamp size: 25.3mm x 20.8mm (self-adhesive).
Sheet Layout: 10
Release date: 13 November, 2016
Production Co-ordination: Creative Direction (Worldwide) Ltd