Editing Little penguin (section)

== Behaviour ==
[[file:Little Penguin swimming in the water.jpg|thumb|Little penguin swimming in Otago region]]
=== Feeding ===
[[File:Eudyptula minor, Auckland, New Zealand imported from iNaturalist photo 430247598.jpg|thumb|Feeding on [[Hyporhamphus ihi|New Zealand piper]] (''Hyporhamphus ihi''), [[Auckland]]]]
Little penguins are central place foragers, meaning they will travel distances to forage but always return to the same nest or colony.<ref>Olsson, O., Helf, K. L., & Brown, J. S. (2008). A guide to central place effects in foraging [Review of A guide to central place effects in foraging]. Theoretical Population Biology, 74(1), 22–33</ref> 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.<ref name="Mattern" /> 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.<ref>Braidwood, J., Kunz, J., & Wilson, K. J. (2011). Effect of habitat features on the breeding success of the blue penguin (Eudyptula minor) on the West Coast of New Zealand. New Zealand Journal of Zoology, 38(2), 131–141.</ref> 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 [[Nototodarus sloanii|arrow squid]], [[slender sprat]], [[Graham's gudgeon]], [[red cod]], and [[ahuru]].<ref name="Flemming1">Flemming, S.A. (2013) "[http://nzbirdsonline.org.nz/species/little-penguin]". ''In Miskelly, C.M. (ed.)'' ''New Zealand Birds Online''</ref> 
 
Little penguins feed by hunting small [[Clupeidae|clupeoid]] fish, [[cephalopod]]s, and [[crustacean]]s, for which they travel and dive quite extensively,<ref name="Flemming">Flemming, S.A., Lalas, C., and [[Yolanda van Heezik|van Heezik, Y.]] (2013) "[http://newzealandecology.org/nzje/new_issues/NZJEcol37_2_199.pdf Little penguin (''Eudyptula minor'') diet at three breeding colonies in New Zealand]". ''New Zealand Journal of Ecology'' '''37''': 199–205 Accessed 30 January 2014.</ref><ref>[http://www.aucklandcouncil.govt.nz/EN/environmentwaste/naturalenvironment/Documents/biodiversitylittlepenguinfactsheet.pdf "Little Penguin Factsheet"] ''Auckland Council'', New Zealand (28 February 2014). Retrieved 2014-07-26.</ref> 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.<ref name="Zimmer">{{Cite journal |last=Zimmer |first=Ilka |last2=Ropert-Coudert |first2=Yan |last3=Kato |first3=Akiko |last4=Ancel |first4=Andre |last5=Chiaradia |first5=Andre |date=2011-01-25 |title=Does Foraging Performance Change with Age in Female Little Penguins (Eudyptula minor)? |url=https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0016098 |journal=PLOS ONE |language=en |volume=6 |issue=1 |pages=e16098 |doi=10.1371/journal.pone.0016098 |issn=1932-6203 |pmc=3026794 |pmid=21283573 |doi-access=free}}</ref><ref name="Pelletier">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+.</ref>

For the Philip Island and other southern Australian colonies, [[Australian anchovy|Australian anchovies]] are the primary food source.<ref name= "Dann">Dann, P., & Chambers, L. (2013). Ecological effects of climate change on little penguins Eudyptula minor and the potential economic impact on tourism [Review 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</ref> 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.<ref>Chiaradia, A., Forero, M. G., Hobson , K. A., Swearer, S., Hume , F., Dann, P., & Renwick, L. (2011). Diet segregation between two colonies of little penguins Eudyptula minor in southeast Australia [Review of Diet segregation between two colonies of little penguins Eudyptula minor in southeast Australia]. Austral Ecology , 37(5), 610–619.</ref>

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.<ref>Sutton, G. J., Hoskins, A. J., & Arnould, J. P. Y. (2015). Benefits of Group Foraging Depend on Prey Type in a Small Marine Predator, the Little Penguin. PLoS ONE, 10(12).</ref> 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).<ref name="Mattern"/>

===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.<ref name="Dann"/> During the breeding season, parents are restricted to a short foraging area close to their nest and are therefore vulnerable to small regional changes.<ref>(Cullen, J. M., Chambers, L. E., Coutin, P. C., & Dann, P. (2009). Predicting onset and success of breeding in little penguins Eudyptula minor from ocean temperatures. Marine Ecology Progress Series, 378, 269–278.)</ref> 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.<ref name="Flemming"/> 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 [[Lagodon|pigfish]].<ref name ="Agnew">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.</ref>

===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.<ref name="P Agnew">(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).)</ref> 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.<ref>(Rowe, L. K., Weir, J. S., & Judkins, A. G. (2020). Breeding of little penguins (Eudyptula minor), including multiple brooding, at South Bay, Kaikōura, New Zealand, 2006–2017. Notornis, 67(2), 451-458.)</ref>  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.<ref name="P Agnew"/> Double brooding is more likely to occur in individuals who lay their first clutch, prior to mid-September.<ref name="Mattern"/> 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.<ref>(Chambers, L. E. (2004). Delayed breeding in Little Penguins–evidence of climate change. Australian Meteorological Magazine, 53(1), 13-19.)</ref>

The onset of double brooding can be strongly influenced by sea surface temperature, age and food availability.<ref>(Grosser, S., Burridge, C. P., Peucker, A. J., & Waters, J. M. (2015). Coalescent Modelling Suggests Recent Secondary-Contact of Cryptic Penguin Species. PloS one, 10(12), e0144966.)</ref> Warmer sea surface temperature in summer and autumn correlated with earlier laying of first clutch of eggs increasing the chances of double brooding.<ref 
name="P Agnew"/>  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.<ref>(Cullen, J. M., Chambers, L. E., Coutin, P. C., & Dann, P. (2009). Predicting onset and success of breeding in little penguins Eudyptula minor from ocean temperatures. Marine Ecology Progress Series, 378, 269–278.).</ref> 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.<ref name="Mattern"/> 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===

[[file:Little Blue Penguins at the Arctic Research Centre Christchurch.jpg|thumb|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.<ref>Berlincourt, M., Arnould,J. P., & Y. (2015). Influence of environmental conditions on foraging behaviour and its consequences on reproductive performance in little penguins. Marine Biology, 162(7), 1485-1501.</ref> This behaviour results in a small foraging range, and therefore a higher probability of competition when prey availability is more scarce.<ref name="Pelletier"/> 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.<ref>Diet segregation between two colonies of little penguins Eudyptulaminor in southeast Australia. Austral Ecology, 37: 610-619.</ref> During chick rearing, parents will make on average one day long foraging trips within a 30&nbsp;km radius of their nest.<ref name="Pelletier"/>

Research conducted on the Philip Island colony found the spatial segregation of foraging behaviour was primarily determined by age rather than biological sex.<ref name="Pelletier"/> 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.<ref>(Zimmer, I., Ropert-Coudert, Y., Kato, A., Ancel, A., & Chiaradia, A. (2011). Does Foraging Performance Change with Age in Female Little Penguins (Eudyptula minor)? PLoS One, 6(1))</ref><ref name ="Pelletier"/>

When foraging in groups for small schooling prey, they were also observed to all be of a similar age cohort.<ref>Sutton, G. J., Hoskins, A. J., & Arnould, J. P. Y. (2015). Benefits of GroupForaging Depend on Prey Type in a Small Marine Predator, the Little Penguin. PLoS ONE, 10(12)</ref> If the groups are segregated by age, this is likely because they are at the same foraging ability and occupy the same approximate range.<ref name="Pelletier"/>