Predator-prey interactions: why do larger albatrosses eat bigger squid?

Publication Type:Journal Article
Year of Publication:2007
Authors:J. C. Xavier, Croxall J. P.
Journal:Journal of Zoology (London)
ISBN Number:0952-8369
Keywords:.Mollusca .Aves ..Procellariiformes ...Diomedeidae, Atlantic Ocean, Atlantic Ocean islands, Avian predators, biometrics, Cephalopoda, Cephalopoda : (Mollusca) : Prey, Diet, Diomedea & Thalassarche, Diomedea exulans, Diomedea exulans : (Diomedeidae) : Predator, Ecology, Feeding behaviour, Food availability, Interactions with molluscan prey, Land zones, Marine zones, Molluscan prey, Nutrition, Oceanic islands, Predator prey interactions, Predators, Prey, relations between predator mass & prey size, size, South Atlantic, South Georgia, Thalassarche chrysostoma, Thalassarche chrysostoma : (Diomedeidae) : Predator, Thalassarche melanophrys, Thalassarche melanophrys : (Diomedeidae) : Predator, weight

The relationship between predator sizes and prey sizes is well documented for terrestrial but rarely for marine ecosystems. We show that wandering albatrosses, the biggest albatross species, feed on larger cephalopod prey than those consumed by smaller albatrosses (grey-headed and black-browed albatrosses). This reflects differences in timing of breeding, foraging ecology and their feeding methods. Wandering albatrosses breed later in the year, during the austral winter, than smaller albatrosses (therefore catching older squid) and forage most of the year in Antarctic open waters, sub-Antarctic, subtropical and tropical waters, overlapping minimally with the smaller albatrosses' foraging range while breeding. Also, wandering albatrosses mostly scavenge whereas smaller albatrosses feed more on live prey. Prey ecology may also play a key role because many squid species might experience post-spawning mortality during the austral winter, becoming easily available to wandering albatrosses. Spawning in winter can be linked to predator avoidance (i.e. reduction in mortality in winter by avoiding pelagic predators) and would allow squid larvae to develop and take advantage of the high productivity (i.e. Antarctic phytoplankton bloom) in spring and at the beginning of summer. Thus, aspects of prey and predator ecology may combine to generate observed differences in prey size.

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith