Foraging ecology of the Cook’s petrel Pterodroma cookii during the austral breeding season: a comparison of its two populations

Abstract

This study examined divergence in the foraging distribution, at-sea behaviour and provisioning strategies of a small procellarid, the Cook's petrel Pterodroma cookii, during chick-rearing at 2 islands off New Zealand, separated latitudinally by ~1000 km. There was little overlap in foraging distribution between adults from Little Barrier Island (LBI), which ranged to the west into the Northern Tasman Sea and east into the Pacific Ocean, and conspecifics from Codfish Island (CDF), which foraged west of the South Island in the south Tasman Sea in association with the subtropical convergence zone. Although birds from CDF ranged further than those from LBI, there was no difference in mean foraging trip duration. Cook's petrels from CDF foraged over deeper, cooler water, with higher primary productivity, than conspecifics from LBI. At-sea behaviour also differed: adults from LBI spent less time in flight, and showed less variation in total flight time per day. Overall, Cook's petrels spend much more time in flight than albatrosses, and approximately the same amounts of time on the water during the night as during the day, suggesting a high portion of nocturnal foraging. Dive depths did not differ between colonies but were greater than expected for a gadfly petrel. Stable isotope signatures of blood indicated population-specific diets, and suggested that birds from LBI primarily consume cephalopods and fish, whereas those from CDF eat more crustaceans. Chicks at CDF received more food. These results suggest a broad divergence in foraging strategies between geographically well-separated colonies in response to regional differences in oceanography. KEY WORDS: Foraging distribution · Geolocation loggers · Stable isotopes · Subtropical convergence · Gadfly petrel Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 370: [271][272][273][274][275][276][277][278][279][280][281][282][283][284] 2008 ever, there have been relatively few studies of highly pelagic species from more widely separated populations, where there is nonetheless the potential for some overlap and interaction at sea. Such comparisons are particularly interesting given the potential for genetic isolation between populations, as most seabirds display a high degree of natal philopatry (Warham 1996). In addition, the high degree of behavioural flexibility of adults may also lead to divergence in foraging strategies, particularly between distant colonies in dissimilar oceanographic domains.Until recently, owing to the relatively large size of the available technology, detailed studies on the movements of pelagic seabirds had been restricted to medium to large species to which attachment of equipment was feasible without impacting the animal's behaviour (Weimerskirch et al. 1993, Stahl & Sagar 2000a. Information on the distribution and behaviour of smaller species (< 300 g) at sea was therefore restricted to band recoveries (Patterson & Hunter 2000) and shipboard observations (Bartle et al. 1990). However,...

Year-round distribution and habitat preferences of the Bugio petrel

“…and other mid-North Atlantic species such as Calonectris diomedea (Raimos et al 2009). During their resident non-breeding period, which is also part of their moulting period, birds could benefit from a sit and wait foraging strategy as described by Catry et al (2004) or Rayner et al (2008). However, there is no scientific evidence that moulting can affect feeding behaviour of the Bugio petrel or produce a flightless period.…”

“…Nevertheless, these data allowed the designation of a Marine Important Bird Area (PTM16-Desertas) in 2008, which was presumed to cover some of the key areas used by breeding birds (Ramírez et al 2008). Previous studies of the movements of Pterodroma species clearly indicate that they disperse over large ocean areas, even during the breeding season (MacLeod et al 2008, Rayner et al 2008, Pinet et al 2012 and are highly migratory (Pinet et al 2011b, Rayner et al 2011. Given the lack of information on the location of core habitat for the Bugio petrels beyond the boundary of the ship surveys, including areas used during the nonbreeding period, the purpose of the present study was to analyse the at-sea distribution, movements and activity patterns of Bugio petrels tracked year-round.…”

Foraging areas of streaked shearwaters in relation to seasonal changes in the marine environment of the Northwestern Pacific: inter-colony and sex-related differences

“…To compare the difference in atsea distribution between sexes as well as between months, we calculated the mean latitude, mean longitude, and mean distance from the breeding colony of the daily bird locations. We identified the day of return to the breeding colony using the light and immersion data (Rayner et al 2008). Streaked shearwaters generally come ashore only at night.…”

Escaping the oligotrophic gyre? The year-round movements, foraging behaviour and habitat preferences of Murphy’s petrels

“…Knowledge of their at-sea distributions is often limited to shipboard observations, where data collection can be challenging as these highly pelagic birds are usually observed in very low densities (Spear et al 2007); however, a few species have been tracked using geolocators in recent years (Rayner et al 2008, Pinet et al 2011, Ramirez et al 2013, Ramos et al 2016, Nicoll et al 2017). In the Pacific Ocean, where the majority (21 of 34 species) breed (Brooke 2004), there is published information on the movements of just 5 species, all confined to New Zealand and Australian breeding sites (MacLeod et al 2008, Rayner et al 2008, 2012, Priddel et al 2014.…”