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

Abstract

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.

Comparative biogeography: innovations and the rise to dominance of the North Pacific biota

“…Large-effect innovations in the North Atlantic appeared in the Pliocene or later: durophagy by the sea mink (Mustela macrodon) in eastern North America during the Late Pleistocene [4], suction-feeding in the planktovorous auk Alle alle from fish-eating ancestors during the Pliocene [54,55], and flightlessness in the great auk Pinguinus [27]. Two refugial innovations evolved during the Pliocene: stipe excavation by the limpet Patella pellucida [33] and sinistral coiling in the buccinid Neptunea and the extinct North Sea 'Terebra' inversa [37].…”

Field-based hearing measurements of two seabird species

“…The Auk family contains some species with highly derived and extreme secondary aquatic adaptations, including birds with impressive dive, physiological and behavioral capabilities (Barrett and Furness, 1990;Croll et al, 1992;Elliott et al, 2013;Enstipp et al, 2018). This taxon is particularly relevant to understanding the impact of underwater noise and acoustic health, given that two species of Auks are listed as endangered (the Guadalupe murrelet Synthliboramphus hypoleucus and the marbled murrelet Brachyramphus marmoratus) (BirdLife International, 2018a,c).…”

Same but different: aquatic prey capture in paedomorphic and metamorphic Alpine newts

“…It might be argued that the general requirements for suction feeding are similar for vertebrates, regardless of their morphology or phylogenetic position. In fact, rapid oropharyngeal volume expansion is common in all suction-feeding vertebrates, as described in cartilaginous and bony fishes [1, 3, 4, 41, 68, 75], lissamphibians [6, 54, 59, 65], turtles [37, 46, 67], mammals [35, 48, 70, 71] and birds [19]. In most cases, oropharyngeal volume expansion is achieved by rapid gape opening and hyobranchial/hyolingual depression, resulting in similar kinematics.…”