Modeling profitability for the smallest marine endotherms: auklets foraging within pelagic prey patches

Lovvorn, James R.

doi:10.3354/ab00210

Cited by 7 publications

(6 citation statements)

References 82 publications

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“…However, most dives of little auks at sea are relatively shallow (Harding et al, 2009), probably allowing visual detection. Furthermore, in a study modelling the foraging profitability of auklets (Cassin's auklets, Ptychoramphus aleuticus, and least auklets, Aethia pusilla) in pelagic prey patches, Lovvorn (2010) found that changes in light condition over a depth range of 20 m had little effect on intake rates of zooplankton prey, as intake rates were limited by capture time ( pursuit and handling after detection) and not by prey visibility.…”

Section: Resultsmentioning

confidence: 99%

“…Other planktivorous seabird species (e.g. alcids) are assumed to use raptorial feeding (Lovvorn, 2010), which is puzzling considering the very high numbers of zooplankter that they are supposed to ingest. Notably, Harding et al (2009) estimated that the little auk, Alle alle (Linnaeus 1758), a 150 g diving seabird of the North Atlantic, should ingest 59,800 copepods per day to cover its energy requirements, thereby catching 6 prey items per second underwater.…”

Section: Introductionmentioning

confidence: 99%

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Almost like a whale – First evidence of suction-feeding in a seabird

Enstipp

Descamps

Fort

et al. 2018

Journal of Experimental Biology

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Little auks () are one of the most numerous seabird species in the world and feed primarily on copepods in arctic waters. Their high daily energy requirements leave them vulnerable to current changes in the arctic plankton community, where a smaller, less-profitable copepod species () becomes increasingly abundant. Little auks have been estimated to require ∼60,000 copepods per day, necessitating prey capture rates of ∼6 copepods per second underwater. To achieve such performance, it has been suggested that little auks capture their prey by (non-visual) filter feeding. We tested this hypothesis by exposing little auks to varying copepod densities within a shallow experimental pool and filming their prey capture behaviour. At none of the copepod densities tested did birds filter feed. Instead, all birds captured copepods by what we identified as visually guided suction feeding, achieved through an extension of their sub-lingual pouch. Suction feeding is very common in fish and marine mammals, but to the best of our knowledge, this is the first time that it has been specifically identified in a seabird species. While presumably less efficient than filter feeding, this behaviour may allow little auks to foster higher resilience when facing the consequences of arctic climate change.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Almost like a whale – First evidence of suction-feeding in a seabird

Enstipp

Descamps

Fort

et al. 2018

Journal of Experimental Biology

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“…Thus, it seems plausible that the birds also use optical cues to verify/ search for appropriate foraging sites. Nevertheless, when food patches are already localised, underwater light conditions have little effect on ingestion rates of food items collected from zooplankton swarms (Lovvorn 2010).…”

Section: Discussionmentioning

confidence: 99%

Visual prey availability and distribution of foraging little auks (Alle alle) in the shelf waters of West Spitsbergen

et al. 2013

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As diving seabirds use vision underwater, it is presumed they should preferentially select sites where their preferred food items are not only abundant but also clearly visible. To test this, we studied the optical properties of the seawater in the West Spitsbergen Shelf, in combination with zooplankton abundance in the feeding grounds of the planktivorous little auks from the nearby colonies in Hornsund. We estimated the relative attractiveness of the foraging sites using a novel parameter-visual prey availability (VPAv), which relates density and proportion of the preferred food item (Calanus glacialis) of the little auk, in total zooplankton, to the optical properties of the seawater. We found a significant positive correlation between the density of foraging little auks and VPAv values. Birds chose areas where C. glacialis was both abundant and clearly visible, because of the clarity of the water and low proportion of other zooplankton species. The birds avoided foraging over the warmer Atlantic-type waters, characterised by a high abundance of zooplankton taxa mostly ignored by birds and where VPAv values were low. VPAv values could potentially also be applied to other visual planktivores for which prey preference and visual acuity are known.

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“…The absence of small marine mammals is strange given that some diving birds (auklets) can weigh as little as 41 g [70]. The loss of heat from an endothermic animal in water is mitigated in a large body with a high volume-to-surface ratio and by a coat of insulating fur or feathers.…”

Section: Endothermymentioning

confidence: 99%

Forbidden phenotypes and the limits of evolution

Vermeij¹

2015

Interface Focus.

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Evolution has produced an astonishing array of organisms, but does it have limits and, if so, how are these overcome and how have they changed over the course of time? Here, I review models for describing and explaining existing diversity, and then explore parts of the evolutionary tree that remain empty. In an analysis of 32 forbidden states among eukaryotes, identified in major clades and in the three great habitat realms of water, land and air, I argue that no phenotypic constraint is absolute, that most constraints reflect a limited time–energy budget available to individual organisms, that natural selection is ultimately responsible for both imposing and overcoming constraints, including those normally ascribed to developmental patterns of construction and phylogenetic conservatism, and that increases in adaptive versatility in major clades together with accompanying new ecological opportunities have eliminated many constraints. Phenotypes that were inaccessible during the Early Palaeozoic era have evolved during later periods while very few adaptive states have disappeared. The filling of phenotypic space has proceeded cumulatively in three overlapping phases characterized by diversification at the biochemical, morphological and cultural levels.

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Modeling profitability for the smallest marine endotherms: auklets foraging within pelagic prey patches

Cited by 7 publications

References 82 publications

Almost like a whale – First evidence of suction-feeding in a seabird

Almost like a whale – First evidence of suction-feeding in a seabird

Visual prey availability and distribution of foraging little auks (Alle alle) in the shelf waters of West Spitsbergen

Forbidden phenotypes and the limits of evolution

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