Seabird and dolphin associations: do seabirds benefit from feeding in association with dusky dolphins in Patagonia?

Abstract

The objective of this study was to describe associations between several species of seabirds and dusky dolphins. We investigated during what dolphin activities seabirds were most commonly associated, and the size of flock in relation to the number of dolphins in a group. Since both seabirds and dolphins may display different feeding strategies, we also investigated if benefits differed among seabird species. Data were collected in Golfo Nuevo (42820 ′ S65800 ′ W) on-board a research vessel between 2001 and 2008. A total of 224 mixed groups of seabirds were encountered during this study. The seabird-dolphin associations were mainly observed during dusky dolphin surface feeding. Shearwaters and kelp gulls were mainly observed in flocks that were associated with dolphins, while Magellanic penguins and cormorants were mainly observed without dolphins. Seabirds may be conditioned to the foraging strategy of dolphins, since birds are associated with dolphins only during dolphin surface feeding. This association probably helped seabirds to find prey, but there were no obvious benefits to dolphins.

Multi-Species Feeding Association Dynamics Driven by a Large Generalist Predator

“…This overlap may be due to opportunistic feeders such as gulls and terns, or seabirds feeding on zooplankton co-occurring with schooling fish (Zeldis and Willis, 2015), blurring the boundaries between fish-and zooplankton-feeding events. The association of shearwaters and common dolphins is an example of facultative commensalism, with the shearwaters benefitting from the dolphins' activity but not critically depending on it (Degrati et al, 2014).…”

“…Previous studies have attempted to classify species based on their role in MSFAs, defining categories such as initiators, catalysts, joiners, scroungers, disruptors or terminators (Camphuysen and Webb, 1999;Anderwald et al, 2011). The cooperation between species, beneficial for at least one and with no negative effect on either species, as shown when cetacean or large fish predators aggregate prey at the surface making it more accessible to seabirds, is an example of facilitation (Au and Pitman, 1986;Degrati et al, 2014). Plankton feeding seabirds such as fulmars (Fulmarus spp.)…”

Marine mammal research: its relationship to other scientific disciplines and to wider society

“…Inter-specific interactions were the subject of the study by Degrati et al (2014) who investigated associations between seabirds of various species and dusky dolphins Lagenorhynchus obscurus , in Golfo Nuevo, Argentina. Certain species of seabirds, such as Magellanic penguins, Spheniscus magellanicus, were not found to associate with dolphins at all, while others, like shearwaters, were mainly observed in association with dolphins, but mostly when the dolphins were engaged in surface feeding.…”

“…Certain species of seabirds, such as Magellanic penguins, Spheniscus magellanicus, were not found to associate with dolphins at all, while others, like shearwaters, were mainly observed in association with dolphins, but mostly when the dolphins were engaged in surface feeding. Degrati et al (2014) suggest that the birds may be utilizing the dolphins as a foraging strategy, but find no benefit to the dolphins in the interactions.…”