AIM: Enhanced management of areas important for marine biodiversity are now obligations under a range of international treaties. Tracking data provide unparalleled information on the distribution of ...marine taxa, but there are no agreed guidelines that ensure these data are used consistently to identify biodiversity hotspots and inform marine management decisions. Here, we develop methods to standardize the analysis of tracking data to identify sites of conservation importance at global and regional scales. LOCATION: We applied these methods to the largest available compilation of seabird tracking data, covering 60 species, collected from 55 deployment locations ranging from the poles to the tropics. METHODS: Key developments include a test for pseudo‐replication to assess the independence of two groups of tracking data, an objective approach to define species‐specific smoothing parameters (h values) for kernel density estimation based on area‐restricted search behaviour, and an analysis to determine whether sites identified from tracked individuals are also representative for the wider population. RESULTS: This analysis delineated priority sites for marine conservation for 52 of the 60 species assessed. We compiled 252 data groupings and defined 1052 polygons, between them meeting Important Bird and Biodiversity Area criteria over 1500 times. Other results showed 13% of data groups were inadequate for site definition and 10% showed some level of pseudo‐replication. Between 25 and 50 trips were needed within a data group for data to be considered at least partially representative of the respective population. MAIN CONCLUSIONS: Our approach provides a consistent framework for using animal tracking data to delineate areas of global conservation importance, allowing greater integration into marine spatial planning and policy. The approaches we describe are exemplified for pelagic seabirds, but are applicable to a range of taxonomic groups. Covering 4.3% of the oceans, the sites identified would benefit from enhanced protection to better safeguard the threatened species populations they contain.
The distributions of many marine birds, particularly those that are highly pelagic, remain poorly known outside the breeding period. Here we use geolocator-immersion loggers to study trans-equatorial ...migration, activity patterns and habitat use of sooty shearwaters Puffinus griseus from Kidney Island, Falkland Islands, during the 2008 and 2009 nonbreeding seasons. Between mid March and mid April, adults commenced a similar to 3 wk, >15000 km northward migration. Most birds (72%) staged in the northwest Atlantic from late April to early June in deep, warm and relatively productive waters west of the Mid-Atlantic Ridge ( similar to 43-55 degree N, similar to 32-43 degree W) in what we speculate is an important moulting area. Primary feathers grown during the moult had average delta super(15)N and delta super(13)C values of 13.4 +/- 1.8ppt and -18.9 +/- 0.5ppt, respectively. Shearwaters moved into shallow, warm continental shelf waters of the eastern Canadian Grand Bank in mid June and resided there for the northern summer. Migrant Puffinus shearwaters from the southern hemisphere are the primary avian consumers of fish within this ecosystem in summer. During migration birds flew for 78% of the day and 59% of the night, whereas when resident in the northern hemisphere they spent much of their time on the water (70% daylight, 90% darkness). Shearwaters moved south late August to mid September, completing the similar to 30000 km figure-of-eight round trip migration in similar to 2 to 3 wk. The Northern Patagonian Shelf and Argentine Basin were used as a terminal stopover site, where most (79%) shearwaters spent similar to 1 wk before first returning to the breeding colony for the season. Year-round tracking of seabirds aids the identification of important marine areas and highlights regions where conservation efforts need to be focused.
The spatial and temporal distribution of prey directly influences the foraging and feeding behaviour of predators. To investigate predator–prey interactions through the diel cycle, we examined ...continuous records of diving activity by a pursuit-diving seabird, the common murreUria aalge, in conjunction with fine-scale data on the vertical distribution of their main prey, capelinMallotus villosus, off the northeast Newfoundland coast, Canada. Diurnal patterns in the diving activities of murres closely reflected changes in the vertical distribution and movements of capelin. During daylight hours, 43% of murre dives were deep (≥50 m), bringing murres into sub-0°C water in the Cold Intermediate Layer (CIL; ~40 to 240 m), when 82% of capelin biomass was located within or below the CIL. At night, murres concentrated diving activity at shallower depths (94% of dives were <50 m) when 86% of capelin biomass was in the upper water column. Capelin migrated through the water column during twilight periods, moving up at dusk and down at dawn. In response, murres’ diving frequency increased and diving depths were graduated, becoming shallower through dusk and deeper through dawn. Crepuscular habits indicate that capelin are more accessible during twilight periods. In summary, though murres are constrained by commuting costs, they show exceptional behavioural flexibility in their efforts to access capelin throughout their diel vertical migration (DVM). The various trade-offs involved in such predator–prey interactions are discussed, as are the ecological consequences of the DVM pattern across trophic levels.
Limited knowledge of year-round seabird distributions hinders efforts to assess consequences of anthropogenic threats and climate-induced changes in the marine environment. In particular, there is ...urgent need to understand how populations from different breeding colonies share and partition ocean habitat. Using geolocators, we identified winter habitat use patterns of 115 adult murres Uria spp. from 7 colonies, spanning the eastern Canadian coast from the high Arctic to Newfoundland, during 2007 to 2010. Thick-billed murres U. lomvia dispersed throughout the region (Davis Strait, Labrador Sea, Orphan Basin, Grand Bank) with 0 to 45% overlap of core wintering areas (50% kernel home range) among breeding populations. Common murres U. aalge concentrated on the Grand Bank and Orphan Basin, with 50 to 67% overlap among breeding populations. For both species, most individuals (up to 70%) wintered offshore, in shelf (≤500 m deep) and oceanic zones (>500 m); fewer than one-third (30%) of individuals used nearshore zones (≤50 km to shore). Tracked common murres representing >80% of the eastern Canadian breeding population converged in winter in areas of high risk from hydrocarbon exploration and extraction activity. In contrast, tracked thick-billed murres, representing ~34% of the eastern Canadian population, dispersed over a larger area and displayed more variable wintering strategies. Thus population vulnerability to spatially constrained risks may be greater for common than thick-billed murres. Populations from several colonies of both species converged on the Grand Bank and Orphan Basin, with the implications for each breeding population depending on its particular dispersal pattern. We demonstrate the utility of tracking data for highlighting areas of risk, and improving the targeting of broad-scale marine conservation efforts.
Geolocators provide information on the year-round movements of birds. The effect of the year-round deployment of such devices has, however, largely been examined via measures that are relatively ...insensitive to small changes in nutritional condition, such as return body mass, return rate and reproductive success. To address this issue, we equipped 34 common murresUria aalgeand 35 thick-billed murresU. lomviaat 6 colonies in the eastern Canadian Arctic and sub-Arctic with geolocators for 1 yr and measured baseline corticosterone levels (4 colonies) and body mass (6 colonies) upon device retrieval. Across all colonies, birds equipped with geolocators averaged higher levels of corticosterone and lower body mass than controls, although there were substantial differences among colonies. Despite effects of the devices on corticosterone and body mass, survival (90%) in equipped birds was no different than in control birds at the one colony where long-term resighting data were available, and chick feeding rates were also similar between equipped and unequipped birds. We suggest that even very small devices can cause chronic stress when applied over long periods, at least for a diving bird with a very high wing loading, but effects on birds in the present study were not sufficiently pronounced to influence adult survival or chick provisioning rates.
To study the influence of inter- and intra-specific interactions on patterns of ecological segregation in nonbreeding habitat, we used geolocators to track year-round movements of congeneric and ...partially sympatric Thick-billed Murres (Uria lomvia (L., 1758)) and Common Murres (Uria aalge (Pontoppidan, 1763)) from seven Canadian colonies during 2007–2011. Locations from 142 individuals were (i) examined for species- and colony-specific spatiotemporal patterns, (ii) mapped with environmental data, and (iii) used to delineate core wintering areas. Compared with Common Murres, Thick-billed Murres dispersed across a wider range of latitudes and environments, had larger winter ranges, and showed greater variation in seasonal timing of movements. These interspecific differences were consistent at two scales: among colonies spanning a wide latitudinal range and at a sympatric colony. Intraspecifically, nonbreeding ecological segregation was more pronounced among colonies of Thick-billed Murres than of Common Murres: colonies of Thick-billed Murres tended to follow distinct movement patterns and segregate by latitude, whereas colonies of Common Murres segregated very little; moreover, the extent of segregation was more variable among Thick-billed Murres than Common Murres. For Thick-billed Murres, rather than complete divergence of winter ecological niche from Common Murres, we found a “widening” of an overlapping niche. This strategy of increased movement flexibility may enable Thick-billed Murres to mitigate competition both intra- and inter-specifically; we propose this movement strategy may have played a role in species divergence.
The Grand Bank ecosystem has undergone significant shifts during the past two decades owing to oceanographic and fishing effects. Effects on upper trophic level seabirds (dietary shifts, reduced ...reproductive performance) have been mediated through changes in the biology and behaviour of capelin (
Mallotus villosus
(Müller, 1776)), the focal forage species. To explore for effects at lower trophic levels, we combine dietary (1987-1988, 2003-2006) and distributional (1966-1990, 1998-1999) data for Leach's storm-petrel (
Oceanodroma leucorhoa
(Vieillot, 1818)), a small, abundant, and highly pelagic seabird. Fish and crustaceans formed the bulk of nestling diet at two colonies, with fish dominating in all sampling periods and years (occurrence >70%, reconstructed mass >75%). Five families were represented, but mature myctophids (glacier lanternfish (
Benthosema glaciale
(Reinhardt, 1837)), horned lanternfish (
Ceratoscopelus maderensis
(Lowe, 1839)),
Protomyctophum arcticum
(Lütken, 1892)) and sandlance (genus
Ammodytes
L., 1758) dominated. Crustaceans occurred frequently but typically comprised ≤10% by mass;;
Hyperia galba
(Montagu, 1813) dominated this prey class. General diet composition was similar through time with birds relying heavily on myctophid fishes in 1987-1988 and 2003-2006. Crustacean diversity, however, declined with fewer species of hyperiid amphipods and no small euphausiids (genus
Thysanoessa
Brandt, 1851) consumed in 2003-2006. The latter parallels changes in spring diets of capelin and winter diets of murres (genus
Uria
Brisson, 1760) in the region. Associations of storm-petrels with deep water are consistent with the predominance of mesopelagic prey in their diets.
Seabirds and other marine animals are at risk from anthropogenic activities that target them directly and those that can harm them incidentally. We integrate year‐round tracking and vessel studies to ...assess risks for a globally important seabird population in the North‐West Atlantic. The eastern Canadian Grand Bank has a rich and diverse food web that supports an abundance of apex predators. Major resource extraction industries (hydrocarbon production and fisheries) operate in the area, and, in addition to shipping and hunting, pose risks for marine birds. Understanding the relative risks has been hampered by poor information on bird distribution at sea. Here, we deployed global location sensors (loggers or geolocators) on common murres Uria aalge at Funk Island, the species' largest North American breeding colony. Adults (n=10) were resident on the Grand Bank and in adjacent pelagic waters year round. Within 10 days of leaving the colony, males dispersed offshore (<50°W), south–south‐east of Funk Island. Females departed later and spent 10–47 days in coastal waters before moving offshore. All birds were in the vicinity of offshore oil platforms during November and December, but remained outside the area of the coastal Newfoundland and Labrador murre hunt. Three of six tracked females, but only one of four tracked males moved closer to shore during January and February where vulnerability to the hunt may have increased. Vessel‐based surveys confirmed the importance of offshore, shelf‐edge habitats for murres in winter. Our results highlight the relative risk to wintering murres from different human activities, providing a sound scientific rationale for focusing conservation and management actions. This information is particularly timely given the continued expansion of deep‐water drilling in the North‐West Atlantic and increasing risk of oil pollution for seabirds attracted to platforms.
The foraging zones and behaviour of shy albatross Thalassarche cauta were studied at Albatross Island, Tasmania, Australia, during the 1995/96 and 1996/97 breeding seasons, using a combination of ...archival recorders and satellite telemetry. Birds foraged exclusively in the neritic zone, at a maximum distance of 200 km from the colony, making wide use of continental shelf waters off northwest Tasmania. The duration of foraging trips, the distances traveled and the activity ranges of the birds (i.e. 95% isopleths from Kernel home range analyses) were greatest during incubation (2.8 d, 754 km, 24667 km super(2)), least during chick-brood (1.1 d, 273 km, 19067 km super(2)), and intermediate during early chick-rearing (1.8 d, 426 km, 19400 km super(2)). At the population level, the foraging zones of the birds (i.e. the 50% home range isopleths) were highly consistent between years, overlapping by 43% during both the incubation and chick-brooding stages across 3 breeding-seasons. Overall, the foraging zones of males and females were similar in both size and location. Individual birds did not return to the same locations to feed from 1 trip to the next; however, their foraging was not random. On successive trips birds maintained a constant heading from the colony, repeatedly searching the same broad patches of ocean, a degree of site fidelity maintained within a single breeding stage. They flew for 72% of the daytime and 39% of the night, and their rate of travel was significantly higher during the day. Combined with a diet predominated by prey found at or near the surface during the day, these data suggest that shy albatross are largely diurnal feeders. Nocturnal activity was strongly influenced by moon phase, with increased time spent flying and increased flight speed during full moon. Consistent traveling speeds, foraging trip durations and foraging locations across years suggest relatively stable prey availability and/or accessibility for shy albatross breeding off the northwest coast of Tasmania.
We studied parental provisioning and chick growth rates of Cassin’s aukletPtychoramphus aleuticusat Triangle Island, British Columbia, Canada, from 1996 to 1999. Auklet reproductive performance and ...ocean climate conditions during these years were highly variable, and reflected in the diet composition. Chick growth was maximal when the diet was predominated by copepods, in particularNeocalanus cristatus. Provisioning and growth were high in 1999, intermediate in 1997 and poor in 1998. Exceptional was 1996, when growth was low but provisioning rates were high. Provisioning and growth were depressed late in 1997 and throughout 1998 when larval rockfishSebastesspp. (5200 cal g–1) replacedN. cristatus(6236 cal g–1) in the nestling diet. Zooplankton surveys indicated thatN. cristatuswas substantially more abundant in May 1999 than in May 1998, and during 1999 the auklets foraged in areas with the highest concentrations of copepods. Through impacts on prey availability, variation in ocean climate affects the reproductive performance of Cassin’s auklet. Performance tends to be favorable in years when spring is late and cold, and poor when spring is early and warm. Equations for predicting food delivery rates from 24 h mass changes of chicks were highly year-specific, precluding their application in other years or at other sites where Cassin’s auklets breed. Between-year differences were also found in relationships between adult provisioning and chick growth. These were strongly positively related in 1999, positively related in 1996 and 1997, but unrelated in 1998; differences attributed to the magnitude of temporal variation in the nestling diet. Finally, we detected annual differences in parental response to chick needs. In 1999, parents delivered more food to chicks in poor condition and less to those in better condition, responses not observed in 1998. Different responses between years may have reflected variation in the availability of prey.
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