Feeding ecology, isotopic niche, and ingestion of fishery-related items of the wandering albatross Diomedea exulans at Kerguelen and Crozet Islands

Abstract

the Indian, Pacific, and Atlantic Oceans (Weimerskirch et al. 2015; www.acap.aq/). Its large size and tameness make the wandering albatross an ideal model animal for long-term demographic and biologging investigations. The species is one of the best ABSTRACT: Feeding ecology and isotopic niche of the wandering albatross Diomedea exulans were investigated in the poorly studied population on the Kerguelen Islands and compared to that on the Crozet Islands. Fish (48% by mass) and cephalopods (46%) were similarly important in chick food at Kerguelen, while cephalopods (87%) dominated the diet at Crozet. Fish prey included mainly deep-sea species, with the Patagonian toothfish Dissostichus eleginoides being the main item. Cephalopod beaks were identified, most of which were from adult oceanic squids. Albatrosses preyed upon the same taxa at both localities, but in different proportions. Histioteuthis atlantica (30% by number), Galiteuthis glacialis (13%), and Kondakovia longimana (10%) were the main squid prey at Kerguelen, while K. longimana (35%) and H. eltaninae (23%) dominated at Crozet. Chick feather δ 15 N values were higher in wandering albatrosses than in other oceanic seabirds of the 2 communities, indicating that the wandering albatross is an apex consumer together with the sperm whale and sleeper shark that have similar δ 15 N values. Satellitetracked wandering albatrosses foraged in local subantarctic waters and farther north, with some Crozet birds overlapping with those from the Kerguelen population in western Kerguelen waters. Anthropogenic items (e.g. plastic fragments, hooks) were found in half the food samples. All fishery-related items were from the local toothfish fishery. The high number of hooks from Crozet indicated the presence of a fairly large number of illegal longliners in the area during the Austral winter 1998. A review of the feeding habits of Diomedea spp. highlights the need for more dietary investigations to achieve effective conservation and management of this endangered group of charismatic seabirds.

Linking demographic processes and foraging ecology in wandering albatross—Conservation implications

“…The wind is therefore a major determinant of the foraging efficiency ( Figure 1). During breeding, birds cover extensive distances to search for prey, mainly squids (Cherel, Xavier, de Grissac, Trouvé, & Weimerskirch, 2017), that are dispersed, and found on average every 64 km (Weimerskirch, Gault, & Cherel, 2005;Weimerskirch, Pinaud, Pawlowski, & Bost, 2007). The search strategy is to cover extensive distances at low costs while searching for prey dispersed over the huge surface of ocean.…”

Amino acid δ13C and δ15N from sclerotized beaks: a new tool to investigate the foraging ecology of cephalopods, including giant and colossal squids

“…A new approach to investigate cephalopod feeding ecology was developed by combining the use of their predators as biological samplers together with measurements of the stable isotopic values of their beaks (Cherel & Hobson 2005, Cherel et al 2009b). Predators as samplers have 2 main advantages: (1) they catch larger specimens and a greater diversity of cephalopods than fisheries sampling gear (Rodhouse 1990), and (2) they accumulate hundreds to thousands of beaks in their stomachs, because beaks are hard sclerotized structures that resist digestion (Clarke 1980, Cherel et al 2017.…”

Use of radar detectors to track attendance of albatrosses at fishing vessels

“…; Cherel et al. ). The reason albatrosses are attracted so strongly to vessels is not clear, particularly because attending sailing vessels has been reported for over 2 centuries.…”