Spatiotemporal habitat use by breeding sooty shearwaters Puffinus griseus

Abstract

Breeding sooty shearwaters Puffinus griseus cycle between long (11 to 14 d) and short (1 to 2 d) foraging bouts at sea, but no information exists on bird behavior during these trips. We tested the hypothesis that shearwaters use these long trips to travel to distant Antarctic waters compared to remaining in local waters. Patterns of habitat use of 28 breeding sooty shearwaters were studied using 6 g archival data loggers that recorded location, environmental temperature, and diving behavior. Dive activity was compared to remotely-sensed environmental data to characterize the habitats visited by shearwaters on long and short trips. Sooty shearwaters traveled predominantly (70% of all long trips) to cold oceanic waters along the Polar Front (mean ± SD, 1970 ± 930 km from colony) on long trips or remained within warmer neritic waters of the New Zealand shelf (515 ± 248 km from colony) on short trips. Diving depths (mean depth 15.9 ± 10.8 m, max depth 69.9 m, n = 2007 dives) were not significantly different between excursion types. Activity patterns suggest that shearwaters commuted between distant foraging grounds (e.g. Polar Front) and the breeding colony and that more than 95% of diving activity occurred during daylight hours. Although shearwaters traveled primarily to Antarctic waters on long trips, occasional trips around New Zealand waters were observed; all but 2 birds were from the northern-most study colony. Oceanic habitats in Antarctic waters were substantially different from neritic habitats around New Zealand, indicating that shearwaters experience dramatically different environmental conditions associated with each excursion type. The ability of sooty shearwaters to use 2 vastly different habitats provides greater flexibility for maximizing resource acquisition during breeding and reduces competition near the colony.

A new algorithm for the identification of dives reveals the foraging ecology of a shallow-diving seabird using accelerometer data

“…used in several seabirds (Shaffer et al 2009;Ronconi et al 2010;Paiva et al 2010a;Grémillet et al 2014). However, even high-accuracy TDRs might not be enough to identify feeding events occurring in shallow water or close to the sea surface.…”

Breeding parameters of the Sooty Shearwater (Ardenna grisea) on Long Island, New Zealand

“…The ability of Sooty Shearwaters, and other seabirds, to travel vast distances and to forage for long periods (Weimerskirch 1998) may counteract any spatial inconsistencies in food availability in any given year (Shaffer et al 2009). Of six Sooty Shearwaters tracked for one breeding season from Mana Island, which is near the Marlborough Sounds, only one bird travelled to more-productive oceanic waters to the southeast of the island and the rest remained in less-productive coastal waters (Shaffer et al 2009). This pattern differed from the two other southern populations studied, which showed the use of (Richdale 1954(Richdale , 1963 Snares Islands (48 S, 166 E) Macquarie Island (55 S, 159 E) (Brothers 1984) Date of laying 20 Nov. …”

“…On Long Island, failure was 7% more likely during the incubation period than during the nestling period in the breeding season studied here. Sooty Shearwaters can forage >2000 km from their breeding colonies (Shaffer et al 2009). The ability of Sooty Shearwaters, and other seabirds, to travel vast distances and to forage for long periods (Weimerskirch 1998) may counteract any spatial inconsistencies in food availability in any given year (Shaffer et al 2009).…”

“…Sooty Shearwaters can forage >2000 km from their breeding colonies (Shaffer et al 2009). The ability of Sooty Shearwaters, and other seabirds, to travel vast distances and to forage for long periods (Weimerskirch 1998) may counteract any spatial inconsistencies in food availability in any given year (Shaffer et al 2009). Of six Sooty Shearwaters tracked for one breeding season from Mana Island, which is near the Marlborough Sounds, only one bird travelled to more-productive oceanic waters to the southeast of the island and the rest remained in less-productive coastal waters (Shaffer et al 2009).…”

“…An estimate; authors indicate dates more likely to resemble those of Richdale (1963) Breeding of Sooty Shearwaters in New Zealand Emumultiple habitats, hypothesised to allow them greater flexibility in their resource acquisition (Shaffer et al 2009). The distance of the Marlborough Sounds Sooty Shearwater colonies from productive Southern Ocean waters may affect breeding success and condition of juvenile Shearwaters compared with those populations breeding at higher latitudes.…”