The Association of Marine Birds and Feeding Gray Whales

Mixed-species foraging groups are well known for a broad range of taxonomic groups. Explanations have focused around 2 primary mechanisms: anti-predator behaviour and maximising foraging efficiency. In the ocean, feeding assemblages can involve seabirds, fish, cetaceans, pinnipeds and combinations of these groups. Here we examine association patterns between North Atlantic minke whales and seabirds. Based on the unique feeding strategies of different seabird guilds, predictions were made on the relationship between seabirds and whales in joint feeding assemblages (who profits from whom). These predictions were tested by modelling the presence of a whale with seabird aggregations using logistic regressions, involving presence/absence of seabird guilds, group sizes and measures of diversity as explanatory variables. A strong positive relationship was found between the presence of a whale with a seabird aggregation and the presence and group size of auks, the only seabird group able to concentrate fish on their own. No other seabird guild was relevant in predicting the presence of a whale. This suggests that 'beater' or 'pirate' theory best explains the relationship, with minke whales taking advantage of prey concentrations generated by the feeding behaviour of auks, and other bird groups taking advantage of dead, stunned or scattered prey left by the whales.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Role of feeding strategies in seabird–minke whale associations

Anderwald¹,

Evans²,

Gygax³

et al. 2011

“…have also been observed with gray whales (Harrison 1979, Obst & Hunt 1990. Seabird-whale associations are likely to be important for many seabirds seasonally, depending on whale migration and seabird breeding restrictions.…”

Section: Discussionmentioning

confidence: 93%

“…This feeding may have an important influence on benthic community structure (Nelson & Johnson 1987, and possibly on the pelagic community through turning over nutrients from the bottom to surface waters. Seabirds have been repeatedly observed feeding in association with whales (Harrison 1979, Obst & Hunt 1990. The purpose of our study was to investigate the association of seabirds with whales and to consider how they are beneficiaries of the productive benthic community.…”

Section: Introductionmentioning

confidence: 99%

Seabird feeding on benthic amphipods facilitated by gray whale activity in the northern Bering Sea

Grebmeier¹,

Harrison²

1992

Ampeliscid amphipods are the dominant benthic fauna in the northern Bering Sea and the major food of the California gray whale. Field studies indicate that benthic amphipods brought to the surface during gray whale feeding provide a food source for surface-feeding birds (northern fulmars, red phalaropes, black-legged kittiwakes) as well as diving birds (thick-billed murres). A sampling grid was used to document zooplankton and benthic population structure. Neuston tows, behavioral observations and collections of birds for stomach content analyses were made within and outside of 'whale slicks', the muddy plumes at the sea surface marking a site where a feeding whale has surfaced. Results indicate that infaunal amphipods are abundant at the surface in whale slicks, and that abundance and size-class of these floating amphipods directly reflect relative abundance and size-class of the major amphipod species found in the underlying benthos. Surface-feeding birds ate mostly small anlphipods at the slicks, which were the dominant amphipod size-class observed in the tows. Birds as divergent in size as northern fulmars (700 g) and red phalaropes (60 g) consumed small amphipods or fragments less than 2 mm in length. Thick-billed murres, which dive to feed, caught the larger amphipods that sank. Location and abundance of northern fulmars and red phalaropes feeding in the study area were positively related to occurrence of feeding whales. The breeding thick-billed murres and black-legged kittiwakes were in a more restricted distribution on the east side of the grid, nearest the seabird colonies on I n g Island, Alaska, USA. The local distribution of all 4 species is shaped by whale feeding activity, and their diet is a direct reflection of benthic population structure of the northern Bering Sea.

“…During summer in the Bering and Chukchi Seas, foods brought to the surface by feeding gray whales may support hundreds of thousands of seabirds (Harrison 1979), with local numbers of red phalaropes Phalaropus fulicaria and black-legged kittiwakes Rissa tridactyla feeding almost exclusively in mud plumes created by gray whales (Obst & Hunt 1990). Feeding by Parkinson's petrels Procellaria parkinsoni on remains of fish left by 2 dolphin species may even be obligatory (Pitman & Ballance 1992).…”

Section: Introductionmentioning

confidence: 99%

Gray whales may increase feeding opportunities for avian benthivores

Anderson

Lovvorn²

2008

Feeding by gray whales Eschrichtius robustus along the eastern Pacific coast between the Bering Sea and Baja, Mexico, appears to be increasing. Gray whale feeding can disturb large fractions of intertidal and shallow subtidal sediments, altering the distributions of benthic invertebrates for many months. Increased gray whale feeding may be modifying foraging profitability for other bottom-feeding vertebrates along the coast, but such effects have not been documented. This paper is the first report of a feeding association between a cetacean and bottom-feeding birds, namely a migrating gray whale and diving sea ducks. Local counts and condition of surf scoters Melanitta perspicillata in Puget Sound, Washington, suggest that gray whale feeding can provide important foraging opportunities for scoters during spring, when other foods may have declined and requirements to prepare for migration and reproduction are high. Complementary data are needed to evaluate the importance to scoters of this seasonal interaction with gray whales. However, given the large and protracted impacts of gray whales on benthic communities, our observations suggest that whale feeding may have increasing influence on the foraging patterns and trophic relations of a range of bottom-feeding vertebrates.