Using animal-borne video cameras, marine scientists have investigated the type, duration and energetic consequences of predator-prey interactions in little penguins (Eudyptula minor) from two colonies in Bass Strait, south-eastern Australia.
A representative image from animal-borne camera of prey (mackerel, Trachurus spp.) captured by a little penguin (Eudyptula minor). Image credit: Petrovski et al., doi: 10.1098/rsos.221595.
Little penguins are ubiquitous seabirds in south-eastern Australia and are significant consumers of marine resources.
The highest concentration of little penguins is in Bass Strait with an estimated 85,000-152,000 breeding pairs.
They are considered to be generalist and opportunistic feeders, with diet variation reflecting food resource availability and breeding stages.
The oceanographic variability in Bass Strait is known to influence little penguin foraging and breeding success.
Consequently, a reduction in prey, by natural means or human activities, would have a serious effect on survival and reproductive success.
“While foraging behavior in little penguins has been extensively documented, some aspects of their foraging strategies are not well understood,” said Deakin University researcher John Arnould and colleagues.
“The aims of our study were to investigate in little penguins: (i) the factors influencing prey chase and handling times and (ii) the energetic consequences associated with these durations.”
The researchers tracked little penguins in Bass Strait using video cameras, which showed prey specific hunting behavior.
They also observed penguins consuming bellowsfish (Macroramphosus scolopax), and other fish species that were swimming underneath jellyfish.
“A total of seven main prey items were observed and consumed by little penguins,” the authors said.
“Penguins were observed to consume prey types and use strategies that have not been previously documented.”
“These included consumption of bellowsfish and other fish species captured sheltering around jellyfish or extracted dead from the tentacles.”
“Chase and handling time varied with prey type and lasted approximately 2 seconds for most prey.”
“Profitability varied among prey types, with a greater amount of low profitable prey being consumed, suggesting a trade-off between minimizing energetic costs, and increasing capture rates.”
“These results highlight the use of animal-borne video data loggers to further understand the foraging adaptations of important predators in the marine environment.”
The findings were published in the journal Royal Society Open Science.
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Natalie Petrovski et al. 2023. Energetic consequences of prey type in little penguins (Eudyptula minor). R. Soc. open sci 10 (8): 221595; doi: 10.1098/rsos.221595
