Little Penguin

The little penguin (''Eudyptula minor'') is the smallest species of penguin. It originates from New Zealand. It is commonly known as the fairy penguin, little blue penguin, or blue penguin, owing to its slate-blue plumage and is also known by its Māori name . It is a marine neritic species that dives for food throughout the day and returns to burrows on the shore at dusk, making it the only nocturnal penguin species on land.
The Australian little penguin (''Eudyptula novaehollandiae''), from Australia and the Otago region of New Zealand, is considered a separate species.

''Eudyptula minor'' feathers are dense in melanosomes, which increase water resistance and give them their unique blue colour.

Taxonomy

The little penguin was first described by German naturalist Johann Reinhold Forster in 1781. Several subspecies are known, but a precise classification of these is still a matter of dispute. The holotypes of the subspecies ''E. m. variabilis'' and ''Eudyptula minor chathamensis'' are in the collection of the Museum of New Zealand Te Papa Tongarewa. The white-flippered penguin (''E. m. albosignata'' or ''E. m. minor morpha albosignata'') is currently considered by most taxonomists to be a colour morph or subspecies of ''Eudyptula minor.'' In 2008, Shirihai treated the little penguin and white-flippered penguin as allospecies. However, as of 2012, the IUCN and BirdLife International consider the white-flippered penguin to be a subspecies or morph of the little penguin.

Little penguins from New Zealand and Australia were once considered to be the same species, called ''Eudyptula minor''. Analysis of mtDNA in 2002 revealed two clades in '' Eudyptula'': one containing little penguins of New Zealand's North Island, Cook Strait and Chatham Island, as well as the white-flippered penguin, and a second containing little penguins of Australia and the Otago region of New Zealand.Banks, Jonathan C.; Mitchell, Anthony D.; Waas, Joseph R. & Paterson, Adrian M. (2002): An unexpected pattern of molecular divergence within the blue penguin (''Eudyptula minor'') complex. ''Notornis'' 49(1): 29–38
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/ref> Preliminary analysis of braying calls and cluster analysis of morphometrics partially supported these results. A 2016 study described the Australian little penguin as a new and separate species, ''Eudyptula novaehollandiae''. ''E. minor'' is endemic to New Zealand, while ''E. novaehollandiae'' is found in Australia and Otago. A 2019 study supported the recognition of ''E. minor'' and ''E. novaehollandiae'' as separate species.

The IUCN assessment for ''Eudyptula minor'' uses ''Eudyptula minor'' and ''Eudyptula novaehollandiae'' interchangeably throughout the report to specify location, but considers them as two genetically distinct clades within the same species.

Description

Like those of all penguins, the wings of '' Eudyptula'' species have developed into flippers used for swimming.

''Eudyptula'' species typically grow to between tall and on average weigh 1.5 kg (3.3 lb). The head and upper parts are blue in colour, with slate-grey ear coverts fading to white underneath, from the chin to the belly. Their flippers are blue in colour. The dark grey-black beak is 3–4 cm long, the irises pale silvery- or bluish-grey or hazel, and the feet pink above with black soles and webbing. An immature individual will have a shorter bill and lighter upperparts.

Like most seabirds, the ''Eudyptula'' species have a long lifespan. The average for the species is 6.5 years, but flipper ringing experiments show that in very exceptional cases they may live up to 25 years in captivity.

''Eudyptula minor'' does not have the distinct bright blue feathers that distinguish ''Eudyptula novaehollandiae.'' In addition, the vocalisation patterns of the New Zealand lineage located on Tiritiri Matangi Island vary from the Australian lineage located in Oamaru. Females are known to prefer the local call of the New Zealand lineage.

There are also behavioural differences that help differentiate these penguins. Those of the Australian lineage will swim together in a large group after dusk and walk along the shore to reach their nesting sites. This may be an effective predator avoidance strategy by traveling in a large group simultaneously. This has not been seen by those of the New Zealand lineage. ''Eudyptula'' ''minor'' only recently encountered terrestrial vertebrate predators, while ''Eudyptula novaehollandiae'' would have had to deal with carnivorous marsupials.

Distribution and habitat

''Eudyptula minor'' breeds along most of the coastline of New Zealand, including the Chatham Islands. The chicks are raised in nests constructed in burrows along the shoreline, both dug by ''Eudyptula minor'' and by other animals. ''Eudyptula minor'' does not occur in Otago, which is located on the east coast of New Zealand's South Island. The Australian species ''Eudyptula novaehollandiae'' occurs in Otago. ''E. novaehollandiae'' was originally endemic to Australia. Using ancient-DNA analysis and radiocarbon dating using historical, pre-human, as well as archaeological ''Eudyptula'' remains, the arrival of the Australian species in New Zealand was determined to have occurred roughly between AD 1500 and 1900. When the ''E. minor'' population declined in New Zealand, it left a genetic opening for ''E. novaehollandiae''. The decrease of ''E. minor'' was most likely due to anthropogenic effects, such as being hunted by humans as well as introduced predators, including dogs brought from overseas.

It has been determined using multilocus coalescent analyses that the population of ''Eudyptula novaehollandiae'' in Otago arrived less than 750 years ago, more recently than previously estimated.

Outside of the Otago region, all colonies are expected to belong to the subspecies ''Eudyptula minor.'' Many of these colonies are smaller and more patchily distributed than larger ''Eudyptula novaehollandiae'' colonies that exist in Australia and Otago. Extensive research exists on Philip Island and Oamaru colonies as they are sites of large colonies which attract large groups of tourists Mattern, Thomas & Wilson, Kerry-Jayne. (2018). New Zealand penguins - current knowledge and research priorities. 10.13140/RG.2.2.16180.50564/3.
Population size and trends of colonies in New Zealand remain poorly documented. What are known as colonies in New Zealand commonly consist of smaller fragmented groups in comparison to Australia's larger colonies, some with <10 breeding pairs. This is largely attributed to NZs fragmented coastline separating the larger colonies. This is commonly seen in Kaikōura where 6–7 smaller colonies have been found along 1.7% of coastline

Behaviour

Little penguin swimming in Otago region

Feeding

Little penguins are central place foragers, meaning they will travel distances to forage but always return to the same nest or colony. They are also a species where both parents are required to raise chicks, and alternate foraging trips while the other is guarding and incubating the nest during the post guard stage. These stints can last anywhere between 1–10 days during incubation. Despite nesting on the shore, little penguins forage at sea and feed on a diet ranging from small schooling fish, to cephalopods, krill, and microzooplankton. As the species is widely distributed across a range of habitats in New Zealand and Australia, variation in diet and foraging choice has also arisen. Important little penguin prey items include arrow squid, slender sprat, Graham's gudgeon, red cod, and ahuru.Flemming, S.A. (2013)

. ''In Miskelly, C.M. (ed.)'' ''New Zealand Birds Online''

Little penguins feed by hunting small Clupeidae, clupeoid fish, cephalopods, and crustaceans, for which they travel and dive quite extensively,Flemming, S.A., Lalas, C., and van Heezik, Y. (2013)
Little penguin (''Eudyptula minor'') diet at three breeding colonies in New Zealand
. ''New Zealand Journal of Ecology'' 37: 199–205 Accessed 30 January 2014. including to the sea floor. Foraging efficiency has been found to be significantly influenced by age. Foraging success appears to stabilise selection for middle-aged penguins, as feeding is a learnt behaviour but also requires good physical condition.Pelletier, L., Chiaradia, A., Kato, A., & Ropert-Coudert, Y. (2014). Fine-scale spatial age segregation in the limited foraging area of an inshore seabird species, the little penguin. Oecologia, 176(2), 399+.

For the Philip Island and other southern Australian colonies, Australian anchovies are the primary food source.Dann, P., & Chambers, L. (2013). Ecological effects of climate change on little penguins Eudyptula minor and the potential economic impact on tourism eview of Ecological effects of climate change on little penguins Eudyptula minor and the potential economic impact on tourism Climate Research, 58(1), 67–79. https://www.jstor.org/stable/24896130 Although the diet of the Philip Island colony has diversified to include selections of cephalopods and krill during the post guard stage of their life cycle where greater amounts of energy is required for chick development and egg production, resident penguins predominantly rely on anchovies when more energy is required.

The nature of their diet also impacts foraging methods, which may vary by colony depending on what food is available. When prey is larger and individuals are only catching 1-2 items at a time, they are more likely to hunt alone to reduce competition, whereas smaller and more mobile prey, or schooling prey species, promote group hunting to enable efficient encirclement. The Oamaru colony predominantly feeds on smaller schooling species such as sprat and gudgeon, while penguins from the Stewart/Codfish Island colonies more often hunt alone. The latter is likely linked to a predominantly cephalopods diet (58% of prey items at < 10 gm each).

Prey availability

Rising ocean temperatures have seen a trend towards earlier onset of breeding in '' Eudyptula minor'' which does not always align with the availability of their prey. This is because higher sea surface temperatures are associated with early onset of nesting, but also associated with lower nutrients and oxygen availability. During the breeding season, parents are restricted to a short foraging area close to their nest and are therefore vulnerable to small regional changes. La Niña events increasing the sea surface temperature along the New Zealand coastline cause prey such as schooling fish and krill to either become more regionally scarce or migrate to new habitats. Graham's Gudgeon once dominated the diet of the Oamaru colony of ''Eudyptula minor'', however in 1995 the availability of the species dropped from 20% in December to 0% in January the following year. Penguins were able to successfully adapt their diet to consist of slender sprat and pigfish.Agnew, P., Lalas, C., Wright, J., & Dawson, S. (2015). Variation in breeding success and survival of little penguins Eudyptula minor in response to environmental variation. Marine Ecology Progress Series, 541, 219–229.

Double brooding

If penguins produce a second clutch of eggs in a season once the first chicks have fledged, this is known as double brooding.(Agnew, P., Houston, D., Lalas, C. et al. Variation in reproductive performance of Little Penguins (Eudyptula minor) attributable to double brooding. J Ornithol 155, 101–109 (2014).) Thus far this behaviour has only been observed in the ''Eudyptula novaehollandiae'', the lineage of little blue penguins which inhabit Australian and Otago regions. There is no evidence to suggest this is an established behaviour within ''Eudyptula minor'', however double broods are occasionally noticed among the colonies in the Kaikoura coastline. It is as yet unclear whether this means double brooding is a genetically mediated behaviour. A study carried out on Oamaru penguin colony found double broods to increase breeding success by up to 75% per season. Double brooding is more likely to occur in individuals who lay their first clutch, prior to mid-September. While there is some interannual variability, the most common period for little penguins to lay their first clutch is in spring, mid-September is considered early and gives individuals time left in the season to lay a second clutch of eggs after the first have fledged.

The onset of double brooding can be strongly influenced by sea surface temperature, age and food availability. Warmer sea surface temperature in summer and autumn correlated with earlier laying of first clutch of eggs increasing the chances of double brooding. In contrast, in New Zealand it was observed that during the La Niña phase of the El Niño Southern Oscillation when colder temperature water was brought to the surface, there was a delay in the onset of breeding for ''Eudyptula novaehollandiae'', thus resulting in a lower incidence of double brooding in the Otago colonies. Age is also believed to be a factor affecting double brooding because the pairs successfully able to double brood were most commonly strategic in reclaiming successful nests and pair-bonds. Little penguins show a high nest fidelity, and the ability to reclaim success early suggests it is likely that successful double brooding is a behaviour that improves with age. Another influencing factor is the availability of food, for larger colonies such as the Philip Islands, competition for food can increase significantly during the breeding season, particularly if there is variability in the amount of prey available. If this competition results in aggression between adults, this can also influence ability to successfully raise chicks, and successfully breed in the next season.

Foraging behaviour

Eudyptula minor foraging at the International Antarctic Centre in Christchurch

During the breeding season, ''Eudyptula minor'' are central place foragers. They travel within their home range to find food, but will return to their nest to feed both themselves and their chicks. Their foraging range is limited by how long chicks can fast, and the high energetic of costs of constant travelling for individuals. This behaviour results in a small foraging range, and therefore a higher probability of competition when prey availability is more scarce. Particularly , In order to survive ''Eudyptula minor'' adapt to these constraints by increasing the plasticity and variability in their foraging behaviour, such as spatial, age, or diet based segregation, during breeding season when energy demands for both parents and chicks are at their highest. During chick rearing, parents will make on average one day long foraging trips within a 30 km radius of their nest.

Research conducted on the Philip Island colony found the spatial segregation of foraging behaviour was primarily determined by age rather than biological sex. Middle aged individuals foraged at greater distances from their nests and were able to dive greater distances, whereas older penguins were found to forage closer to the shore than middle aged adults.

When foraging in groups for small schooling prey, they were also observed to all be of a similar age cohort. If the groups are segregated by age, this is likely because they are at the same foraging ability and occupy the same approximate range.

Threats

Introduced predators

Introduced mammalian predators present the greatest terrestrial risk to little penguins and include cats, dogs, rats, and particularly ferrets and stoats. Significant dog attacks have been recorded at the colony at Little Kaiteriteri Beach, and a suspected stoat or ferret attack at Doctor's Point near Dunedin, New Zealand, claimed the lives of 29 little blue penguins in November 2014.

Oil spills

Little penguin populations were significantly affected by a major oil spill with the grounding of the ''Rena'' off New Zealand in 2011, which killed 2,000 seabirds (including little penguins) directly, and killed an estimated 20,000 in total based on wider ecosystem impacts. Oil spills are the most common cause of the little penguins being admitted to the rehabilitation facilities at Phillip Island Nature Park (PINP). These oil spill recurrences have endangered not just the little penguins, but the entire penguin population. This can further decline the population, which can lead to possible extinction.

Fire

Increased frequency of drought and extreme temperatures in Southern Australia has led to an increased fire risk. Being flightless birds that nest on land, little blue penguins are especially vulnerable to fire. Behavioural traits such as reluctancy to abandon nests and emerging mostly during daylit hours is thought to be some of the main reasons for increased vulnerability in the future. The threats it provides include nest and habitat distruption, as well as deadly to eggs and individuals, despite this ''Eudyptula minor'' appears to show no fear towards fire when directly exposed. When observed, they have been to found to remain around or under vegetation until severely burnt or injured. Some have even been observed preening their feathers near to open flames.

Fires can also significantly alter the composition of vegetation in Eudyptula minor habitats. A large fire in Marion Bay, South Australia in 1994 saw the loss of two key plant species; introduced marram grass ''Ammophila'' and coastal wattle ''A.sophorae''. Following the fire, these grasses were replaced by invasive palms ''A.arenia'' and ''A.sophorae''grew back in dense thickets. This habitat became no longer suitable for ''Eudyptula minor'' and colony relocated.

Conservation

'' Eudyptula'' species are classified as "at risk - declining" under New Zealand's Wildlife Act 1953.
Overall, little penguin populations in New Zealand have been decreasing. Some colonies have become extinct, and others continue to be at risk. Some new colonies have been established in urban areas. The species is not considered endangered in New Zealand, with the exception of the white-flippered subspecies found only on Banks Peninsula and nearby Motunau Island. Since the 1960s, the mainland population has declined by 60-70%; though a small increase has occurred on Motunau Island. A colony exists in Wellington Harbour on Matiu / Somes Island.

Protestors have opposed the development of a marina at Kennedy Point, Waiheke Island in New Zealand for the risk it poses to little penguins and their habitat. Protesters claimed that they exhausted all legal means to oppose the project and have had to resort to occupation and non-violent resistance. Several arrests were made for trespassing. Construction of the marina was upheld by the Environment Court in 2012 and completed in 2022. Since the completion of the construction, little penguin burrows have still been found in the area, as well as one dead little penguin on the boat ramp there.

The West Coast Penguin Trust and DOC have worked in collaboration to maintain data on penguin mortality, the West Coast South Island colonies are highlighted as one of the ''Eudyptula minor'' colonies currently facing decline The data shows highest level of penguin mortality is caused by roadkill, likely due to many of the colonies being close to coastal highway. To mitigate this issue, a penguin-proof fence was erected in 2019 across 3.3 km of highway where road kill was most prevalent, no roadkill deaths have been recorded since its implementation

The risk of fire damage to habitats in Philip Island has been partially mitigated through the planting of fire-resistant indigenous vegetation in and around the nesting sites. Thus far this planting has occurred primarily in the <10% of the colony most visible from tourist look-out points

In New South Wales, ''Eudyptula minor'' was listed as an endangered species in 1997 under the Endangered Species Act 1995. Since then conservation efforts such as public education, nest monitoring and labelling it as "critical habitat" were implemented. Despite these efforts, this mainland colony was met with additional challenges from threats from wild dogs and foxes, to lack of available local prey. The species is now listed as at-risk declining under the same act.

Zoological exhibits

Zoological exhibits featuring purpose-built enclosures for '' Eudyptula'' species can be seen in Australia at the Adelaide Zoo, Melbourne Zoo, the National Zoo & Aquarium in Canberra, Perth Zoo, Caversham Wildlife Park (Perth), Ballarat Wildlife Park, Sea Life Sydney Aquarium, and the Taronga Zoo in Sydney. Enclosures include nesting boxes or similar structures for the animals to retire into, a reconstruction of a pool and in some cases, a transparent aquarium wall to allow patrons to view the animals underwater while they swim.

''Eudyptula'' penguin exhibit exists at Sea World, on the Gold Coast, Queensland, Australia. In early March 2007, 25 of the 37 penguins died from an unknown toxin following a change of gravel in their enclosure. It is still not known what caused the deaths of the penguins, and it was decided not to return the 12 surviving penguins to the same enclosure where the penguins became ill. A new enclosure for the little penguin colony was opened at Sea World in 2008.

In New Zealand, ''Eudyptula'' penguin exhibits exist at the Auckland Zoo, the Wellington Zoo, the International Antarctic Centre and the National Aquarium of New Zealand. Since 2017, the National Aquarium of New Zealand, has featured a monthly "Penguin of the Month" board, declaring two of their resident animals the "Naughty" and "Nice" penguin for that month. Photos of the board have gone viral and gained the aquarium a large worldwide social media following.

In the United States, ''Eudyptula'' penguins can be seen at the Louisville Zoo the Bronx Zoo, and the Cincinnati Zoo.

See also

* Smallest organisms

Notes

References

Further reading

*

External links

State of Penguins: Little (blue) penguin – detailed and current species account of ''(Eudyptula minor)'' in New Zealand
at the International Penguin Conservation
West Coast Penguin Trust
(New Zealand)
Philip Island Nature Park website
* Gould's '' The Birds of Australia'
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{{Taxonbar, from=Q203628

little penguin
little penguin
Subterranean nesting birds
Birds of New Zealand
Birds described in 1781