Diet and Foraging

Pink-footed Shearwater feeds mainly on fishes and squids, though its diet is not well studied. It feeds mainly by surface-seizing, pursuit plunges, shallow dives, and scavenging, and is attracted to fishing boats where it may feed in flocks of 1,000s, sometimes with other shearwaters, albatrosses, and gulls. Flocks of up to approximately 100 birds may forage over schools of herring (Clupea), salmon (Oncorhynchus), albacore tunas, and Stenella dolphins. Usually forages in outer continental shelf and slope waters in both the breeding and nonbreeding ranges.

Microhabitat for Foraging

Usually forages in outer continental shelf and slope waters in both the breeding and non-breeding ranges (45 Ainley, D. G., K. D. Dugger, R. G. Ford, S. D. Pierce, D. C. Reese, R. D. Brodeur, C. T. Tynan, and J. A. Barth (2009). Association of predators and prey at frontal features in the California Current: Competition, facilitation, and co-occurrence. Marine Ecology Progress Series 389:271–294. Close , 28 Adams, J., J. J. Felis, M. Czapanskiy, R. D. Carle, and P. J. Hodum (2019). Diving behavior of Pink-footed Shearwaters Ardenna creatopus rearing chicks on Isla Mocha, Chile. Marine Ornithology 47:17–24. Close , 29 Carle, R. D., J. J. Felis, R. Vega, J. Beck, J. Adams, V. López, P.J. Hodum, A. González, V. Colodro, and T. Varela (2019). Overlap of Pink-footed Shearwaters and central Chilean purse-seine fisheries: Implications for bycatch risk. Condor: Ornithological Applications 2019:1–13. Close , 16 Felis, J. J., J. Adams, P. J. Hodum, R. D. Carle, and V. Colodro (2019). Eastern Pacific migration strategies of Pink-footed Shearwaters Ardenna creatopus: Implications for fisheries interactions and international conservation. Endangered Species Research 39:269–282. Close ). In outer continental shelf and slope waters off northern California and southern Oregon, foraging was associated with areas where other predators, such as salmon, were foraging (45 Ainley, D. G., K. D. Dugger, R. G. Ford, S. D. Pierce, D. C. Reese, R. D. Brodeur, C. T. Tynan, and J. A. Barth (2009). Association of predators and prey at frontal features in the California Current: Competition, facilitation, and co-occurrence. Marine Ecology Progress Series 389:271–294. Close ).

In a study of 6 birds tagged with time-depth recorders and GPS devices from Isla Mocha, diving behavior occurred throughout the full extent of the breeding-period foraging area, and occurred most frequently within continental shelf waters near Valdivia, Chile (28 Adams, J., J. J. Felis, M. Czapanskiy, R. D. Carle, and P. J. Hodum (2019). Diving behavior of Pink-footed Shearwaters Ardenna creatopus rearing chicks on Isla Mocha, Chile. Marine Ornithology 47:17–24. Close ). Diving also occurred within approximately 20 km of Isla Mocha and north of Isla Mocha from Lebu to north of Talcahuano, Chile (28 Adams, J., J. J. Felis, M. Czapanskiy, R. D. Carle, and P. J. Hodum (2019). Diving behavior of Pink-footed Shearwaters Ardenna creatopus rearing chicks on Isla Mocha, Chile. Marine Ornithology 47:17–24. Close ), consistent with hot spots identified from a larger sample of GPS-tracked birds from Isla Mocha (29 Carle, R. D., J. J. Felis, R. Vega, J. Beck, J. Adams, V. López, P.J. Hodum, A. González, V. Colodro, and T. Varela (2019). Overlap of Pink-footed Shearwaters and central Chilean purse-seine fisheries: Implications for bycatch risk. Condor: Ornithological Applications 2019:1–13. Close ).

Food Capture and Consumption

As a group, shearwaters display variable modes of foraging including scavenging, surface seizing, shallow plunge-pursuits, "belly-flop" plunging, shallow diving, and deep diving (46 Kuroda, N. (1954). On the Classification and Phylogeny of the Order Tubinares, Particularly the Shearwaters (Puffinus), with Special Consideration on Their Osteology and Habit Differentiation. N. Kuroda, Tokyo, Japan. Close , 47 Brown, R. G. B., W. R. P. Bourne, and T. R. Wahl (1978). Diving by shearwaters. Condor 80:123–125. Close , 48 Burger, A. E. (2001). Diving depths of shearwaters. Auk 118(3):755–759. Close , 49 Shaffer, S. A., H. Weimerskirch, D. Scott, D. Pinaud, D. R. Thompson, P. M. Sagar, H. Moller, G. A. Taylor, D. G. Foley, Y. Tremblay, and D. P. Costa (2009). Spatiotemporal habitat use by breeding sooty shearwaters Puffinus griseus. Marine Ecology Progress Series 391:209–220. Close , 28 Adams, J., J. J. Felis, M. Czapanskiy, R. D. Carle, and P. J. Hodum (2019). Diving behavior of Pink-footed Shearwaters Ardenna creatopus rearing chicks on Isla Mocha, Chile. Marine Ornithology 47:17–24. Close ). Although there are few written descriptions, Pink-footed Shearwater appears to feed mainly by pursuit-plunging and shallow wing-and-foot-propelled diving from the water surface or several meters above the water; prey are also taken by surface-seizing and scavenging (47 Brown, R. G. B., W. R. P. Bourne, and T. R. Wahl (1978). Diving by shearwaters. Condor 80:123–125. Close ). Mean dive-depth of tagged birds was 1.6 m ± 1.2 SD (maximum depth 10.1 m), and dives usually lasted < 6 seconds (28 Adams, J., J. J. Felis, M. Czapanskiy, R. D. Carle, and P. J. Hodum (2019). Diving behavior of Pink-footed Shearwaters Ardenna creatopus rearing chicks on Isla Mocha, Chile. Marine Ornithology 47:17–24. Close ).

Attracted to fishing boats, where it may feed in flocks of 1,000s, sometimes associated with other shearwater species, albatrosses, and gulls (45 Ainley, D. G., K. D. Dugger, R. G. Ford, S. D. Pierce, D. C. Reese, R. D. Brodeur, C. T. Tynan, and J. A. Barth (2009). Association of predators and prey at frontal features in the California Current: Competition, facilitation, and co-occurrence. Marine Ecology Progress Series 389:271–294. Close , 2 Howell, S. N. G. (2012). Petrels, Albatrosses, and Storm-Petrels of North America: A Photographic Guide. Princeton University Press, Princeton, NJ, USA. Close ). Flocks of up to approximately 100 birds may forage over schools of Pacific herring (Clupea pallasii; K. Morgan, personal communication), salmon (Oncorhynchus spp.), other large fish (e.g., albacore tunas), and dolphins (50 Pitman, R. L., and L. T. Ballance (1992). Parkinson’s Petrel distribution and foraging ecology in the eastern Pacific: aspects of an exclusive feeding relationship with dolphins. Condor 94(4):825–835. Close , 45 Ainley, D. G., K. D. Dugger, R. G. Ford, S. D. Pierce, D. C. Reese, R. D. Brodeur, C. T. Tynan, and J. A. Barth (2009). Association of predators and prey at frontal features in the California Current: Competition, facilitation, and co-occurrence. Marine Ecology Progress Series 389:271–294. Close , 2 Howell, S. N. G. (2012). Petrels, Albatrosses, and Storm-Petrels of North America: A Photographic Guide. Princeton University Press, Princeton, NJ, USA. Close ).

Major Food Items

Feeds mainly on fishes and squids (51 Hoefer, C. J. (2000). Marine bird attraction to thermal fronts in the California current system. Condor 102:423–427. Close , 52 Baltz, D. M., and V. G. Morejohn (1977). Food habits and niche overlap of seabirds wintering on Monterey Bay, California. Auk 94:526–543. Close ), though diet has not been received in-depth study. Documented prey species in the nonbreeding range include squids (Doryteuthis opalescens and Onychoteuthis borealijaponicus) and northern anchovy (Engraulis mordax; 52 Baltz, D. M., and V. G. Morejohn (1977). Food habits and niche overlap of seabirds wintering on Monterey Bay, California. Auk 94:526–543. Close ). In the South American breeding range, commonly associates with fisheries for Peruvian anchoveta (Engraulis ringens) and common sardine (Strangomera bentincki; 53 Suazo, C. G., L. A. Cabezas, C. A. Moreno, J. A. Arata, G. Luna Jorquera, A. Simeone, L. Adasme, J. Azócar, M. García, O. Yates, and G. Robertson (2014). Seabird bycatch in Chile: A synthesis of its impacts, and a review of strategies to contribute to the reduction of a global phenomenon. Pacific Seabirds 41:1–12. Close ,29 Carle, R. D., J. J. Felis, R. Vega, J. Beck, J. Adams, V. López, P.J. Hodum, A. González, V. Colodro, and T. Varela (2019). Overlap of Pink-footed Shearwaters and central Chilean purse-seine fisheries: Implications for bycatch risk. Condor: Ornithological Applications 2019:1–13. Close ), indicating that these species are probable prey. Limited direct diet observations support this (PJH; C. Suazo, personal communication).

Quantitative Analysis

Stomach content analysis from 5 birds taken from September 1974 to April 1975 in Monterey Bay, California, indicated that squid (Doryteuthis opalescens and Onychoteuthis borealijaponicus) contributed 83% of the diet by number, with the remainder made up of northern anchovy (9%), and unidentified fishes and cephalopods (8%) (52 Baltz, D. M., and V. G. Morejohn (1977). Food habits and niche overlap of seabirds wintering on Monterey Bay, California. Auk 94:526–543. Close ). Doryteuthis opalescens occurred in 60% of stomachs, Onychoteuthis borealijaponicus in 40%, and northern anchovy in 60% (52 Baltz, D. M., and V. G. Morejohn (1977). Food habits and niche overlap of seabirds wintering on Monterey Bay, California. Auk 94:526–543. Close ). No quantitative data exist on diet in the Southern Hemisphere.

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