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Little Blue Penguins
|Little Blue Penguins (Eudyptula minor)
This penguin is called little blue penguin, little penguin, or fairy penguin and to Captain James Cook in the log of his voyages of 1772-1775 it was known as the Southern Blue penguin.
The latin name of the penguin is Eudyptula minor. The Greek word Eudyptula means good little diver and minor means small. Its grey/black plumage has a bluish tinge. At an adult weight of about 1kg (2lb) and height of 41-44cm (16-17 inches) the little penguin is one of the smallest of the world’s penguins. Its claim to be the smallest is disputed by the Galapagos penguin! Male little penguins are a bit larger than females and have a stronger beak. Little penguins breed in colonies along the southern coast of Australia, as far north as Port Stephens in the east to Fremantle in the west, Tasmania, New Zealand and New Zealand sub-Antarctic Islands. Very little is known about the little penguins total populations but estimates are 500,000 in total, with 110,000-190,000 breeding pairs in Tasmania, of which, 5% or less are found on mainland Tasmania.
Little Blue Penguins at Sea
|Life at Sea
Like all its relatives the little penguin is superbly adapted to life at sea. The classic streamlined shape and efficient propulsion from its flippers (used to fly underwater enables it to seek prey in dives of several minutes usually 10-30m deep, occasionally down to 60m. The webbed feet are excellent for manoeuvring on the surface and have claws for digging and climbing slippery rocks. Penguins will vigorously defend themselves with their stout beak. Their eyes are large with retinas specially adapted for detecting movement in low light. Unlike us little penguins have flattened corneas so they can see clearly both under and above water.
In common with other penguins and many other sea creatures the little penguin uses counter shading as camouflage; the upper surface being dark to blend in from the with the sea from above while the underside is silvery-white, similar to surface reflections from below. This helps penguins avoid the attentions of predatory birds from above and seals and sharks from below and also means prey may not detect them.
Although buoyant at the surface the penguins’ buoyancy is neutral at their operating depth of 5-20m because the pressure compresses their lungs and plumage (they often leave a trail of bubbles when diving). Waterproofing, insulation and buoyancy is by an almost airtight interlacing of feathers and oil from a preen gland at the base of the tail. Penguins can stay at sea for many days and can sleep on the water. When they float on the sea their sitting up posture is just like that of ducks.
Little Blue Penguins Diet
Little penguin diet varies from place to place depending on local availability but consists mainly of small school fish such as pilchards and silversides, some squid and small crustaceans, such as shrimps and krill. Occasionally crab larvae or sea horses are taken from the sea floor. Penguins around Tasmania have a more varied diet than those on other parts of Australia and are thus less affected by shortages of any particular food. Prey is caught with rapid jabs of the beak and swallowed whole, aided by barbs like a raft of teeth on the roof of the mouth and tongue. These point throat-wards to help the fish go down. Little penguins need to eat about 25% of their body weight each day just to maintain condition; more if feeding young or putting on condition to moult. If there is not enough food available due competition from human fisheries the penguins and chicks may starve to death. Rather than have a crop, which would unbalance them they store food centrally in a large gut.
Little Blue Penguins on Land
Little Blue penguins on land
Little penguins must come ashore to breed and moult and for some rest and socialising. Most resident birds in a colony return to their burrows in small groups within an hour or so of darkness to avoid diurnal predators such as gulls, ravens and raptors. However on mainland Tasmania they have to cope with terrestrial predators such as Tasmanian devils and humans, one reason they prefer to nest on islands. Thus they are very nervous of people waiting on the beach for them to appear; to them it is an ambush. They first gather beyond the surf barking to each other and come ashore in a flock because there is safety in numbers, not so much in actual defence but more in detecting and confusing predators. This dash to the shore, sometimes porpoising right to the beach is dangerous because they are vulnerable to seals in the shallows.
The penguins then hesitate, standing at the sea’s edge to check the coast is clear and then make their way up the beach dispersing as they reach the colony. Sometimes these “marches?are on well-worn runways showing lots on footprints. However, their return can be easily interrupted (even reversed) by a fright, the penguins postponing their return to the colony. Penguins go to sea just before first light, straight from the burrow to the sea where possible.
Little Blue Penguins Breeding Rookeries
Essentials of colonies seem to be proximity of food (another reason islands are favoured – they are right amongst the food), ground cover and secure nest sites.
Like the spheniscus penguins the little penguins prefer to nest in burrows, which they excavate in sand or soil, but they will also breed in caves or under rocks. When I visited the tourist attraction on Phillips Island in Australia little nest boxes had been provided in the visitor centre behind a glass partition and the penguins were actually breeding in these. Visitors could actually lift up a flap and peep in at the chicks and parents. I was not really impressed with the unruly behaviour of some of the young visitors at this site though the wardens were really doing their best for the penguins.
Nests are usually at least 2 m apart and generally consist of a 60-80cm tunnel ending in a grass or seaweed nest bowl just big enough for several penguins. Other nests may vary from mere scrapes beneath a clump of tussock, to elaborate connecting tunnels or a home amongst coastal rocks, even under buildings in culverts or artificial burrows. Little penguins may have to compete with shearwaters, water rats, snakes and more recently rabbits and cats for burrows and colony space since human developments are often by the sea.
Song and displays are used to attract mates, stave off intruders and as a duet unite a pairs attachment to each other. The distinctive individual song moves from a trumpeting cry, accompanied by flipper, beak and body movements. These calls and displays vary in intensity from a half trumpet display to a fever pitch of sound and body activity. At night and especially during the breeding season the noisy din of o penguin colony can be considerable. Barks are used to communicate at sea.
Little Blue Penguins Egg Laying
Between June and August male penguins return to either renovate old burrows or dig new ones. Noisy male courting displays greet arriving female penguins. Although only one mate is chosen, they will usually not be their sole partner for life. Birds breed annually, but in eastern Australia the usual clutch of 2 eggs may be found as early as May or as late as October. In successful years, two clutches might be reared in one season, which is unusual for penguins. The penguin pair share incubation shifts of usually 1-2 days and hatching takes place within 33-37 days. About 60% of eggs in a colony hatch.
Little Blue Penguin Hatchlings
Little Blue Hatchlings
At hatching the chicks are sooty black and weigh little more than 25gm. After a few days their eyes open and growth begins in earnest. Both parents feed the chicks, which eat up to half their weight per day and at 40 days they may even be heavier than their parents.
Little Blue Chicks Fledging
At this age the chicks are very active, at night waiting outside their burrows to be fed, even chasing adults. They then start to lose their dark fluffy down to their final blue and white plumage. Within 3 weeks they are ready to fledge, moving to the sea, some dispersing widely and distantly. About 70% of chicks reach this stage but only about 15% will live to maturity at 2 years old, most returning to their natal colony. On average, little penguins live 6 years although some have managed 20 years.
Little Blue Penguin Moulting
After breeding, the adults feed frantically to put on condition for their 2 week moult ashore. They must nearly double their weight because they will not feed or drink during the moult. They cannot go to sea as they are not waterproof and so are particularly vulnerable to land predators. If nests are large moulting will occur there but often the penguins choose a roomier place where they can more easily preen and scratch. Such places are obvious from the thousands of feathers scattered about. It is a very itchy and miserable time for them.
Little Penguins Seasonal Variations
Variations in food supplies caused by changes in ocean currents or other factors determine the pattern of life for each local population of fairy penguins and may differ considerably.
In vary favourable years, eggs may be laid as early as May or up to October, with 2 or even 3 broods of chicks reared in one year. After breeding, adults feed frantically to put on condition (some nearly double their weight in a few weeks) so they may survive the 2-3 week annual moult ashore. Some penguins return consistently to their burrows year round but most stay at sea for many days throughout the autumn-winter period and can sleep on the water. When they float on the sea their sitting up posture is just like ducks.
Little Blue Penguins - Threats
Nestlings may be killed by heat or infested with ticks. Seasonal changes in natural food supplies from year to year cause many young birds to starve and wash up dead or in weak condition on beaches.
Being small little penguins have many predators. Australian and New Zealand fur both eat little penguins as do leopard seals. Large gulls can kill penguins and inshore white-bellied sea eagles catch many. Around the colonies water rats take eggs and chicks and ravens and raptors patrol these areas for exposed eggs, chicks and adults as do quolls and Tasmanian devils at night on mainland Tasmania. However little penguins have evolved alongside these predators and can cope with them.
It is the extra predation from introduced rats, dogs, cats and humans that is the problem. Uncontrolled dogs can wreak havoc on penguin colonies. When I visited the Low Head colony at the mouth of the Tamar River near Launceston in Tasmania in Jan 1999, cats were supposed to be curfewed because they kill both adults and chicks. However I saw a very fat ginger cat laying in wait as the penguins came ashore. These cats can be confiscated by the Wildlife Service in Tasmania.
There is a plethora of human caused “accidental deaths” such as road and rail kills. Vegetation burn-off can be disastrous for penguins and in some areas many burrows are crushed by stock. Some little penguins are drowned in gill nets or hit by speed- boats. Oil spills spell disaster for penguins and other sea birds. Not only is oil toxic when ingested, but also the buoyancy and insulation of penguin plumage is damaged.
When I visited the Low Head penguin colony near Launceston in Tasmania I was told of a terrible tragedy when a 37,500 ton ship called the Iron Barron ran aground on Hebe reef at the mouth of the Tamar River on the evening of Monday 10th July 1995. Members of the colony of fairy penguins swam through heavy fuel oil that had spilled from the Iron Baron. The affected penguins were cleaned and then they were taken to a distant penguin colony, midway on the east coast of the island and released in the hope that they would colonise there. Seven days later they returned to the Tamar River where they swam through the spilled heavy fuel oil again. The first penguin to return after this mammoth 7 day swim was named Kieren after a famous Australian Olympic distance swimmer. Sometime later it was discovered that this amazing penguin was of the fairer gender. As a result of this revelation, the outstanding penguin was then renamed Karen. I am indebted to Leigh of the Tasmanian Wilderness Travel Service who told me this story and many other fascinating facts.
Plastic pieces may be mistaken for food, plastic six pack can become a noose around a penguin neck and discarded fishing line entangles head, flippers or feet, sometimes hooking the penguins. Over fishing or pollution causing loss of food is also a constant threat. Disturbance or habitat damage from tourism can be a problem but one that can be managed for the advantage of all.
Like penguins all over the world these penguins are faced with huge, mostly human generated problems and threats to survival caused by loss of habitat, over fishing, over development of coastal areas, oil spills, discarded debris, etc etc. It is shameful to think that a species that successfully co-existed and survived the dinosaurs from 65 million years ago should be forced into extinction by careless and greedy human endeavours.
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