SPECIES

Pink-footed Shearwater Ardenna creatopus Scientific name definitions

Ryan D. Carle, Valentina Colodro, Jonathan Felis, Joshua Adams, and Peter J. Hodum
Version: 2.0 — Published April 9, 2022

Habitat

Introduction

Pelagic species. At-sea habitat is associated with the Humboldt and California Current Systems in the eastern Pacific, both productive eastern-boundary upwelling currents. Breeds in colonies on three islands off central Chile, generally on steep slopes in both open and forested habitats.

Habitat in Breeding Range

The most important breeding requirement for the Pink-footed Shearwater and many other seabird species is nesting habitat free of mammalian predators. Based on the limited breeding range in or near the Humboldt Current, they also appear to require breeding colonies located within foraging range of highly productive waters.

Isla Mocha holds the world’s largest breeding population (33, 4). Located 34.2 km offshore of the mainland of south-central Chile, Isla Mocha has a densely forested central mountain range that rises to 390 m elevation and is protected as a Chilean National Reserve. On this island, breeds colonially in dense Valdivian coastal rainforest dominated by olivillo tree (Aextoxicon punctatum), on moderate to steep mountain slopes with exposed roots (34, 35). Colonies are often near mountain ridges, and most burrows occur above approximately 150 m elevation (34, 35) though aggregations of up to 50 burrows occur down to 120 m (Oikonos, unpublished data). Steep slopes and ridges may provide access to windy conditions and trees to climb to facilitate take-off. Areas with exposed roots may be easier to dig burrows in, and/or protect burrows from erosion on steep slopes. Pink-footed Shearwater may historically have bred in low-lying areas, such as the coastal plain of the island, before those areas were heavily modified by human development.

Islas Robinson Crusoe and Santa Clara, in the Juan Fernández Islands, are volcanic in origin and have rugged, steep topography. On Isla Robinson Crusoe, the species nests in four distinct colonies ranging from approximately 1,000–3,500 burrows each (36, 37, 38), as well as in lower density areas with scattered burrows (Oikonos, unpublished data). Within the Juan Fernández Islands breeding colonies tend to be on steep slopes in windy areas, from sea level up to nearly 600 m elevation (4). Pink-footed Shearwater does not nest at the highest elevations of Isla Robinson Crusoe (which tend to be rocky knife-edge ridges), likely due to inadequate soil for burrowing (PJH). On the smaller Isla Santa Clara, burrows are distributed extensively throughout the island, with various clusters of 100–300 burrows, and many solitary burrows (PJH). Many parts of Isla Robinson Crusoe and Isla Santa Clara have been deforested and native vegetation has been destroyed or degraded by herbivory from introduced mammals (39). In most Juan Fernández breeding colonies, the ground cover is sparse herbaceous vegetation composed of predominantly non-native species (36). An exception is the Vaquería colony on Isla Robinson Crusoe, which is within a forest of the endemic luma tree (Myrceugenia fernandeziana; PJH). Given that the species nests in dense forest on Isla Mocha and in the luma forest at Vaquería, it is likely that many breeding colonies on Isla Robinson Crusoe were once forested.

Foraging habitat during the breeding period depends on colony location. Chick-rearing adults tracked with GPS from Isla Mocha remained exclusively in Chilean waters, with persistent inter-annual foraging hotspots in continental shelf waters (29). Tracked birds spent 86% of time over continental shelf waters, with occasional forays to continental slope and abyssal offshore waters (29; Oikonos, unpublished data). Breeding birds tracked with satellite transmitters from the Juan Fernández Islands foraged primarily in oceanic waters around the archipelago, and in waters over the continental shelf and slope adjacent to the mainland (Oikonos unpublished data). See Movement for details about at-sea behavior and habitat.

Habitat in Nonbreeding Range

Habitat in Migration

In post-breeding migration northward to waters of the northern Humboldt Current System off central and northern Peru, concentrates in continental shelf and slope waters off north-central Chile, with more dispersed movements over slope and abyssal waters past northern Chile and southern Peru, occasionally straying up to 1,100 km from shore (16). Movement from northern Peru to Baja California, Mexico, is rapid and direct, essentially on an approximate straight line across the Gulf of Panama, 400–1,700 km from shore (16).

Habitat in Overwintering Range

In the nonbreeding period, occurs mainly in waters of the outer continental shelf (100–200 m depth) and continental slope (200–1,000 m depth) (40, 41, 42, 16, 43). Sometimes associates with seamounts up to approximately 250 km offshore of British Columbia (27). Based on at-sea surveys off the western coast of the United States, prevalence was greatest during March–May over the outer shelf and shelf-break off southern to central California, becoming more abundant in June–August off the coasts of Oregon and Washington (15, 43). In Canada, numbers off the west coast peak between late May through August–October (44). Flocks estimated at 1,400 and 2,500 birds, respectively, have occurred in the second half of May and in mid-July, near the entrance to the Strait of Juan de Fuca southwest of Vancouver Island, British Columbia (27). Depending on the location, numbers decrease and distribution becomes patchier in September–October and few are present after October (15, 44, 43) .

Recommended Citation

Carle, R. D., V. Colodro, J. Felis, J. Adams, and P. J. Hodum (2022). Pink-footed Shearwater (Ardenna creatopus), version 2.0. In Birds of the World (P. G. Rodewald and B. K. Keeney, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.pifshe.02