Food of Little Penguins<i>Eudyptula minor</i>in Victoria: Comparison of Three Localities between 1985 and 1988

Cullen, J. M.; Montague, TL; Hull, Cindy L.

doi:10.1071/mu9910318

Cited by 73 publications

(91 citation statements)

References 28 publications

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“…The estimated mean clutch completion date on Motuara Island in this study (29 September) was 4-6 weeks later than in the 1995 and 1996 breeding seasons (Renner 1998). Such delays may be related to limited food supply earlier in the year, as suggested by Cullen et al (1992). The low body mass gain while foraging recorded for the earliest female breeder of the Oamaru study area supports this assumption.…”

Section: Motuara Islandsupporting

confidence: 68%

Prolonged foraging trips and egg desertion in little penguins (Eudyptula minor)

Numata

Davis

Renner

2000

New Zealand Journal of Zoology

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Penguins share incubation duties between the male and female of a pair. The one left on the nest must fast while its partner is foraging at sea. Nest attendance patterns during the incubation period reflect the way time is allocated between the conflicting demands of incubation and foraging. We conducted daily nest checks for little penguins (Eudyptula minor) at two localities in New Zealand (Motuara Island in the Marlborough Sounds and Oamaru, Otago) in the 1998/99 breeding season and found significant variation in nest attendance between the two areas. Penguins breeding at Motuara Island made significantly longer foraging trips and were in poorer body condition than those breeding at Oamaru. Foraging trip durations were significantly correlated with the body condition of birds at both areas: the poorer the condition, the longer the foraging trip durations. The increased risk of egg desertion observed at Motuara Island is probably a consequence of the prolonged foraging trips that limit the time available for incubation.

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Section: Motuara Islandsupporting

confidence: 68%

Prolonged foraging trips and egg desertion in little penguins (Eudyptula minor)

Numata

Davis

Renner

2000

New Zealand Journal of Zoology

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“…Very little information is available on the phenology of barracouta. However, and given that this species grows quickly (reaching 23-30 cm in the first year, Kailola et al, 1993), we can deduce little penguins are feeding on very young individuals (fish consumed range from 3 to 5 cm long Cullen et al, 1992;Chiaradia et al, 2003). Similarly, it is post-larval anchovy that are eaten at the times of year when this species is most frequent in the diet of penguins (Montague and Cullen, 1988).…”

Section: Proactive Decisions Vs Passive Consequencesmentioning

confidence: 99%

Stable Isotopes (δ13C, δ15N) Combined with Conventional Dietary Approaches Reveal Plasticity in Central-Place Foraging Behavior of Little Penguins Eudyptula minor

et al. 2016

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Marine top and meso predators like seabirds are limited by the need to breed on land but forage on limited or patchily distributed resources at sea. Constraints imposed by such central-place foraging behavior change during breeding or even disappear outside the breeding period when there is no immediate pressure to return to a central place. However, central place foraging is usually factored as an unchanging condition in life history studies. Here we used little penguin Eudyptula minor, a resident bird with one of the smallest foraging range among seabirds, to examine the different degree of pressure/constraints of being a central-place forager. We combined data on isotopic composition ( 13 δ C and 15 δ N), conventional stomach contents and body mass of little penguins breeding at Phillip Island, Australia over 9 years (2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011). We explored relationships between diet and body mass in each stage of the breeding season (pre-laying, incubation, guard, and post-guard) in years of "high" and "low" reproductive success. Values of 13 C and 15 δ δ N as well as isotopic niche width had similar patterns among years, with less variability later in the season when little penguins shorten their foraging range at the expected peak of their central-place foraging limitation. Body mass peaked before laying and hatching in preparation for the energetically demanding periods of egg production and chick provisioning. An increase of anchovy and barracouta in the diet, two major prey for little penguins, occurred at the critical stage of chick rearing. These intra-annual trends could be a response to imposed foraging constraints as reproduction progresses, while inter-annual trends could reflect their ability to match or mismatch the high energy demanding chick rearing period with the peak in availability of high-quality prey such as anchovy. Our findings underline the key advantages of using a stable isotope approach combined with conventional dietary reconstruction to reveal an otherwise intractable ecological issue of different constrains of being a central-place forager, such as the little penguin, which could be applied to other marine species.

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“…This estimate may be lower for incubating birds and those with very small chicks; however, this figure provides a benchmark on which to sanity test our observations. If all prey captures identified by the SVM represent actual prey captures, prey consumed by little penguins in our study had a mean mass of ~2.8 g. The mean mass of ingested fish species estimated from diet reconstruction for little penguins at Phillip Island, Victoria, Australia, ranged from 0.9 g (red cod) to 10.7 g (garfish), with a mean of ~4.9 g per item across all fish species (Cullen et al, 1991). Small (1-5 cm) schooling fish were the primary component of the diet of little penguins around Montague Island in 2013, with penguins also eating krill when transient swarms entered the area (G.C., unpublished data).…”

Section: Foraging Efficiency and Prey Capture Ratesmentioning

confidence: 99%

Supervised accelerometry analysis can identify prey capture by penguins at sea

Carroll

Slip

Jonsen

et al. 2014

Journal of Experimental Biology

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Determining where, when and how much animals eat is fundamental to understanding their ecology. We developed a technique to identify a prey capture signature for little penguins from accelerometry, in order to quantify food intake remotely. We categorised behaviour of captive penguins from HD video and matched this to time-series data from back-mounted accelerometers. We then trained a support vector machine (SVM) to classify the penguins' behaviour at 0.3 s intervals as either 'prey handling' or 'swimming'. We applied this model to accelerometer data collected from foraging wild penguins to identify prey capture events. We compared prey capture and non-prey capture dives to test the model predictions against foraging theory. The SVM had an accuracy of 84.95±0.26% (mean ± s.e.) and a false positive rate of 9.82±0.24% when tested on unseen captive data. For wild data, we defined three independent, consecutive prey handling observations as representing true prey capture, with a false positive rate of 0.09%. Dives with prey captures had longer duration and bottom times, were deeper, had faster ascent rates, and had more 'wiggles' and 'dashes' (proxies for prey encounter used in other studies). The mean (±s.e.) number of prey captures per foraging trip was 446.6±66.28. By recording the behaviour of captive animals on HD video and using a supervised machine learning approach, we show that accelerometry signatures can classify the behaviour of wild animals at unprecedentedly fine scales.

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Food of Little PenguinsEudyptula minorin Victoria: Comparison of Three Localities between 1985 and 1988

Cited by 73 publications

References 28 publications

Prolonged foraging trips and egg desertion in little penguins (Eudyptula minor)

Prolonged foraging trips and egg desertion in little penguins (Eudyptula minor)

Stable Isotopes (δ13C, δ15N) Combined with Conventional Dietary Approaches Reveal Plasticity in Central-Place Foraging Behavior of Little Penguins Eudyptula minor

Supervised accelerometry analysis can identify prey capture by penguins at sea

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