Ecological theory predicts that animals with similar foraging strategies should not be able to co‐exist without segregating either in space, time or diet. In communities, intra‐specific competition is thought to be more intense than the competition among species, because of the lack of niche partitioning between conspecifics. Hence, while different seabird species can overlap in their foraging distribution, intra‐specific competition can drive the neighboring populations of the same species to spatial segregation of foraging areas. To investigate ecological segregation within and among species of diving seabirds, we used a multi‐species GPS‐tracking approach of seabirds of four species on a small island in the Southwest Atlantic. The present study goes beyond previous work by analyzing simultaneous effects of species and colonies. We observed strikingly strong spatial foraging segregation among birds of the same species, breeding in colonies as close as 2 km from each other. Conspecifics from neighboring colonies used foraging places adjacent to their own colony, and there was little or no overlap with birds from the other colony. A zone with increased predator concentration was completely avoided during foraging trips, likely contributing to the spatial segregation. In addition to spatial segregation, we also observed intra‐specific differences in other components of foraging behavior, such as time of day, dive depth and diet. These were most likely caused by optimal foraging of individuals in relation to habitat differences on a local scale, leading to a complex pattern of interactions with environmental covariates, in particular foraging daytime, foraging water layer temperature and depth, distance to coast and bathymetric depth of foraging areas. As mechanisms leading to the spatial segregation we propose a combination of optimal foraging and avoidance of predation.

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BackgroundStarting from Western Europe, the house mouse (Mus musculus domesticus) has spread across the globe in historic times. However, most oceanic islands were colonized by mice only within the past 300 years. This makes them an excellent model for studying the evolutionary processes during early stages of new colonization. We have focused here on the Kerguelen Archipelago, located within the sub-Antarctic area and compare the patterns with samples from other Southern Ocean islands.ResultsWe have typed 18 autosomal and six Y-chromosomal microsatellite loci and obtained mitochondrial D-loop sequences for a total of 534 samples, mainly from the Kerguelen Archipelago, but also from the Falkland Islands, Marion Island, Amsterdam Island, Antipodes Island, Macquarie Island, Auckland Islands and one sample from South Georgia. We find that most of the mice on the Kerguelen Archipelago have the same mitochondrial haplotype and all share the same major Y-chromosomal haplotype. Two small islands (Cochons Island and Cimetière Island) within the archipelago show a different mitochondrial haplotype, are genetically distinct for autosomal loci, but share the major Y-chromosomal haplotype. In the mitochondrial D-loop sequences, we find several single step mutational derivatives of one of the major mitochondrial haplotypes, suggesting an unusually high mutation rate, or the occurrence of selective sweeps in mitochondria.ConclusionsAlthough there was heavy ship traffic for over a hundred years to the Kerguelen Archipelago, it appears that the mice that have arrived first have colonized the main island (Grande Terre) and most of the associated small islands. The second invasion that we see in our data has occurred on islands that are detached from Grande Terre and were likely to have had no resident mice prior to their arrival. The genetic data suggest that the mice of both primary invasions originated from related source populations. Our data suggest that an area colonized by mice is refractory to further introgression, possibly due to fast adaptations of the resident mice to local conditions.

Key facets of the foraging ecology of seabirds during the inter-breeding period still remain poorly understood because of the difficulty of studying them at sea, including during the energy-demanding molting stage. Here, the extent to which three sympatric petrels (Antarctic and thin-billed prions, and blue petrel) from the subantarctic Kerguelen Islands modify their foraging ecology during molt was investigated using a combination of complementary tools, namely miniaturized saltwater immersion geolocators (GLS) and the isotopic method. Firstly, molting behavior was first characterized in the blue petrel, a reference species that is known to renew its plumage in autumn. GLS and feather stable isotopes ( 13 δ C as a proxy of the birds' foraging habitat) indicated that the post-breeding molt of blue petrel occurred in Antarctic waters. Importantly, activity recorders showed that molt was marked by a strong peak in time spent daily sitting on water, which thereafter declined to lower values during the remaining winter months. Secondly, the peak in time spent sitting on water was used as a proxy to characterize the contrasted molt strategies of the two prion species. As blue petrels demonstrated, thin-billed prions molted during the post-breeding period in cold Antarctic waters where they fed primarily on low trophic level prey, most likely Antarctic krill ( 15 δ N as a proxy of the birds' diet). By contrast, Antarctic prions presented an unexpected pre-breeding molt of longer duration that took place further north, in warm subtropical waters. Interestingly, the two Antarctic molting species, the blue petrel and thin-billed prion, renewed their plumage at the same time and within the same oceanic zone that is likely to be a previously undescribed hot spot of seabird diversity during the Austral autumn. The study contributes to a growing body of evidence that closely-related species exhibit various foraging strategies allowing ecological segregation and sheds new light on the poorly known critical molting stage of seabirds.

BackgroundDuring the non-breeding period, many birds migrate to milder areas, found closer to the equator than their breeding sites. Opposite movements are very rare. In the Southern Ocean, the abundance of 13C declines markedly with more southern latitude, providing a characteristic 13C isoscape. This can be used as a tracer for the movement of seabirds between breeding and inter-breeding areas, by comparing stable isotope ratios of feathers grown at different times of the year.ResultsWe studied seasonal movements of Thin-billed prions (Aves, Procellariiformes), breeding at the Subantarctic Falkland/Malvinas Islands, compared with those of Wilson's storm-petrels breeding in the Antarctic South Shetland Islands. The two species showed opposite migratory movements. While Wilson's storm-petrels moved to warmer waters north of the Drake Passage in winter, Thin-billed prions showed a reversed movement towards more polar waters. Carbon stable isotope ratios in recent and historical feathers indicated that poleward winter movements of Thin-billed prions were less common historically (45% in 1913-1915), and have only recently become dominant (92% in 2003-2005), apparently in response to warming sea temperatures.ConclusionsThis study shows that pelagic seabirds can rapidly change migration strategies within populations, including migration towards more poleward waters in winter.

The rockhopper penguins Eudyptes chrysocome have recently been split into the northern E. moseleyi and the southern E. chrysocome rockhopper penguin. It is therefore crucial to have a comprehensive understanding of the biology of each species in order to develop appropriate conservation measures. We investigated the breeding biology of the southern rockhopper on New Island, in the western part of the Falklands Islands, by following the breeding attempt of 160 pairs during the 2006/2007 season and examining the eVect of lay time and colony habitat on breeding success. SpeciWcally, we compared survival and growth parameters between A-and B-eggs and chicks from non-manipulated and artiWcially manipulated nests to investigate why southern rockhopper penguins in the Falkland Islands are more able to Xedge an A-egg (Wrst laid) than conspeciWcs elsewhere. Breeding was highly synchronous, with no signiWcant diVerence in the breeding success between early and late breeders or between pairs breeding in diVerent habitats. We demonstrate for the Wrst time that the A-egg produced by the southern rockhopper penguin has, when alone, the same theoretical intrinsic potential to lead to a Xedged chick as the B-egg. In contrast, the hatching success and survival of the B-chick was similar when alone or in a two-egg clutch.

Quantifying species distributions using species distribution models (SDMs) has emerged as a central method in modern biogeography. These empirical models link species occurrence data with spatial environmental information. Since their emergence in the 1990s, thousands of scientific papers have used SDMs to study organisms across the entire tree of life, with birds commanding considerable attention. Here, we review the current state of avian SDMs and point to challenges and future opportunities for specific applications, ranging from conservation biology, invasive species and predicting seabird distributions, to more general topics such as modeling avian diversity, niche evolution and seasonal distributions at a biogeographic scale. While SDMs have been criticized for being phenomenological in nature, and for their inability to explicitly account for a variety of processes affecting populations, we conclude that they remain a powerful tool to learn about past, current, and future species distributions -at least when their limitations and assumptions are recognized and addressed. We close our review by providing an outlook on prospects and synergies with other disciplines in which avian SDMs can play an important role.

Aim Pelagic seabirds exploit large areas of ocean when acting as central‐place foragers during the breeding season, and ranges are even more extensive outside the breeding period. Spatial niche partitioning is known to occur among species that breed sympatrically, but is less apparent during the non‐breeding period when there is increased potential for overlap among closely related species from neighbouring island groups. This applies to several species of prion, Pachyptila spp., in the Southern Ocean; although extremely abundant, their at‐sea distribution was virtually unknown because they are difficult to distinguish while at sea. To understand spatial niche partitioning at large scales, we investigated the year‐round distribution of thin‐billed prions (Pachyptila belcheri) from the Falkland Islands (Islas Malvinas) and Antarctic prions (Pachyptila desolata) from South Georgia. Location South Atlantic Ocean. Methods Recently, geolocation devices have become small enough to be deployed on small seabirds. During 2009–10, we tracked 20 thin‐billed prions and 9 Antarctic prions with miniaturized geolocators. We applied ecological niche models to compare environmental conditions in the habitat utilized year‐round. Results We show that two prion species from the south‐west Atlantic Ocean have divergent patterns of migration, and that this has resulted in nearly complete spatial segregation (0–5% overlap by month in the 95% kernel density polygons). Nineteen of 20 thin‐billed prions migrated to an area > 3000 km east of their breeding site, whereas all Antarctic prions migrated a much shorter distance, and to the north‐west. The non‐breeding distribution of thin‐billed prions included the waters around South Georgia, but only when the Antarctic prions were absent. The models highlighted large differences in the realized niche between the two species, and between the habitat characteristics of breeding and non‐breeding areas of thin‐billed and Antarctic prions. Main conclusions Our results are consistent with the prediction that spatial niche partitioning occurs at large scales, allowing the co‐existence of related species. The methods applied here will enable predictive maps of the distributions of other prion populations to be created, once data become available from other breeding sites in the Southern Ocean.