Resource partitioning in three congeneric sympatrically breeding seabirds: Foraging areas and prey utilization

Robertson, Gail; Bolton, Mark; Grecian, W. James; Wilson, Linda J.; Davies, W. Eric; Monaghan, Pat

doi:10.1642/auk-13-243.1

Cited by 42 publications

(40 citation statements)

References 42 publications

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“…Such ecologically similar species are likely to have to partition resources to coexist (Schoener 1974, Jonsson et al 2008, Robertson et al 2014. Such ecologically similar species are likely to have to partition resources to coexist (Schoener 1974, Jonsson et al 2008, Robertson et al 2014.…”

Section: Our Results Demonstrated a Clear Split In Collaredmentioning

confidence: 99%

Diversification of a ‘great speciator’ in the Wallacea region: differing responses of closely related resident and migratory kingfisher species (Aves: Alcedinidae:Todiramphus)

O’Connell

Kelly

Lawless

et al. 2018

Ibis

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The Collared Kingfisher species complex is the most widespread of the ‘great speciator’ lineages of the Indo‐Pacific. They have shown a remarkable ability to spread and diversify. As a result of this rapid diversification, Todiramphus species are often found in secondary sympatry. In Southeast Sulawesi, Indonesia, two Todiramphus species are present, the breeding resident Collared Kingfisher Todiramphus chloris and the overwintering migratory Sacred Kingfisher Todiramphus sanctus. We investigated the effect of isolation on these closely related species by comparing their populations on mainland Sulawesi and its larger continental islands, with populations on the small, oceanic Wakatobi Islands. Within our wider analysis we provide further support for the distinctiveness of the Sulawesi Collared Kingfisher population, perhaps isolated by the deep water barrier of Wallace's line. Within Sulawesi we found that populations of Collared Kingfisher on the Wakatobi Islands had diverged from those on mainland Sulawesi, differing both in morphology and in mitochondrial DNA. In contrast, there was no divergence between Sacred Kingfisher populations in either morphology or mitochondrial DNA. We propose that a difference in habitat occupied by Collared Kingfisher populations between the mainland and continental islands vs. oceanic islands has caused this divergence. Mainland Collared Kingfishers are predominately found inland, whereas Wakatobi Collared Kingfishers are also found in coastal habitats. The larger body size of Wakatobi Collared Kingfisher populations may be a result of increased competition with predominantly coastal Sacred Kingfisher populations. The uniform nature of Sacred Kingfisher populations in this region probably reflects their consistent habitat choice (coastal mangrove) and their migratory nature. The demands of their breeding range are likely to have an even stronger selective influence than their Sulawesi wintering range, limiting their scope for divergence. These results provide insight into the adaptability of the widespread Todiramphus lineage and are evidence of the need for further taxonomic revision of Collared Kingfisher populations.

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Section: Our Results Demonstrated a Clear Split In Collaredmentioning

confidence: 99%

Diversification of a ‘great speciator’ in the Wallacea region: differing responses of closely related resident and migratory kingfisher species (Aves: Alcedinidae:Todiramphus)

O’Connell

Kelly

Lawless

et al. 2018

Ibis

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“…Sandeels are high energy prey for seabirds (Rindorf, Wanless, & Harris, ; Wanless, Harris, Redman, & Speakman, ), and Shetland lacks suitable alternatives (Furness & Tasker, ). Juvenile age classes (0‐ and 1‐group) are especially important because their smaller size, greater abundance and availability within surface waters than older sandeels gives access to a wider range of seabirds (Rindorf et al., ; Robertson et al., ). Recent sandeel scarcity around Shetland is attributed to low recruitment in most years since the mid‐1980s, linked to hydroclimatic changes affecting hatching dates, survival and transport of larvae from major spawning areas north/west of Orkney (Poloczanska, Cook, Ruxton, & Wright, ; Wright & Bailey, ).…”

Section: Discussionmentioning

confidence: 99%

“…Specifically, we aim to (a) model population and productivity trends for Arctic skua, great skua and their hosts since the 1990s; (b) test for differences in Arctic skua trends according to local great skua and host densities; (c) determine whether variation in breeding success is driving Arctic skua population trends; (d) quantify effects of host productivity (an index of food availability) and great skua density (predation pressure) on Arctic skua breeding success. If bottom‐up pressures are driving Arctic skua declines, we predict steeper declines at colonies where host productivity is lowest, which is most likely where Arctic skuas are dependent entirely on terns for food, as these hosts are highly sensitive to localised food availability (Robertson et al., ). Large colonies of cliff‐nesting hosts such as auks, whose diving ability, flexible time budgets and greater foraging ranges make them less vulnerable than ground‐nesting terns to local food shortage, may buffer availability of food to Arctic skuas in years when terns fail to breed successfully (Furness & Tasker, ).…”

Section: Introductionmentioning

confidence: 93%

Combined bottom‐up and top‐down pressures drive catastrophic population declines of Arctic skuas in Scotland

Perkins

Ratcliffe

Suddaby³

et al. 2018

Journal of Animal Ecology

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Understanding drivers of population change is critical for effective species conservation. In the northeast Atlantic Ocean, recent changes amongst seabird communities are linked to human and climate change impacts on food webs. Many species have declined severely, with food shortages, and increased predation reducing productivity. Arctic skua Stercorarius parasiticus, a kleptoparasite of other seabirds, is one such species. The aim of the study was to determine relative effects of bottom-up and top-down pressures on Arctic skuas across multiple colonies in a rapidly declining national population. Long-term monitoring data were used to quantify changes in population size and productivity of Arctic skuas, their hosts (black-legged kittiwake Rissa tridactyla, common guillemot Uria aalge, Atlantic puffin Fratercula arctica, Arctic tern Sterna paradisaea) and an apex predator (great skua Stercorarius skua) over 24 years (1992-2015) in Scotland. We used digital mapping and statistical models to determine relative effects of bottom-up (host productivity) and top-down (great skua density) pressures on Arctic skuas across 33 colonies, and assess variation between three colony types classified by host abundance. Arctic skuas declined by 81% and their hosts by 42%-92%, whereas at most colonies great skuas increased. Annual productivity declined in Arctic skuas and their hosts, and reduced Arctic skua breeding success was a driver of the species' population decline. Arctic skua productivity was positively associated with annual breeding success of hosts and negatively with great skua density. Intercolony variation suggested Arctic skua trends and productivity were most sensitive to top-down pressures at smaller colonies of host species where great skuas had increased most, whereas bottom-up pressures dominated at large colonies of host species. Scotland's Arctic skua population is declining rapidly, with bottom-up and top-down pressures simultaneously reducing breeding success to unsustainably low levels. Marine food web alterations, strongly influenced by fisheries management and climate change, are driving the decline, and this study demonstrates severe vulnerability of seabirds to rapid change in human-modified ecosystems. Potential but untested conservation solutions for Arctic skuas include marine protected areas, supplementary feeding within colonies and management of great skuas.

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“…Terns have a high level of variability in foraging modes (Eglington et al 2014) both within and across years, and appear to rely on trophic level segregation rather than spatial segregation to avoid competition (Robertson et al 2014). This is likely to reflect the foraging behaviour of these groups, which are restricted to smaller home ranges due to their high flight costs, in contrast with pelagic species.…”

Section: Comparison Of Foraging Radius Distributions With Aerial Survmentioning

confidence: 99%

“…In contrast biologging studies provide detailed information on the fine-scale distribution of seabirds, usually during the breeding season (Wakefield et al 2013, Dean et al 2015, Soanes et al 2016, and on broader scale movements during the nonbreeding season (Frederiksen et al 2012, Jessopp et al 2013, Grecian et al 2016. Furthermore, foraging areas can vary annually depending on environmental fluctuations (Robertson et al 2014), a factor that is predicted to increase with climate change (Grémillet andBoulinier 2009, Daunt andMitchell 2013). The temporal scale of tracking is also usually heavily restricted by resources (Wakefield et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Assessing the effectiveness of foraging radius models for seabird distributions using biotelemetry and survey data

et al. 2019

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Relatively simple foraging radius models have the potential to generate predictive distributions for a large number of species rapidly, thus providing a cost-effective alternative to large-scale surveys or complex modelling approaches. Their effectiveness, however, remains largely untested. Here we compare foraging radius distribution models for all breeding seabirds in Ireland, to distributions of empirical data collected from tracking studies and aerial surveys. At the local/colony level, we compared foraging radius distributions to GPS tracking data from seabirds with short (Atlantic puffin Fratercula arctica, and razorbill Alca torda) and long (Manx shearwater Puffinus puffinus, and European storm-petrel Hydrobates pelagicus) foraging ranges. At the regional/national level, we compared foraging radius distributions to extensive aerial surveys conducted over a two-year period. Foraging radius distributions were significantly positively correlated with tracking data for all species except Manx shearwater. Correlations between foraging radius distributions and aerial survey data were also significant, but generally weaker than those for tracking data. Correlations between foraging radius distributions and aerial survey data were benchmarked against generalised additive models (GAMs) of the aerial survey data that included a range of environmental covariates. While GAM distributions had slightly higher correlations with aerial survey data, the results highlight that the foraging radius approach can be a useful and pragmatic approach for assessing breeding distributions for many seabird species. The approach is likely to have acceptable utility in complex, temporally variable ecosystems and when logistic and financial resources are limited.

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Resource partitioning in three congeneric sympatrically breeding seabirds: Foraging areas and prey utilization

Cited by 42 publications

References 42 publications

Diversification of a ‘great speciator’ in the Wallacea region: differing responses of closely related resident and migratory kingfisher species (Aves: Alcedinidae:Todiramphus)

Diversification of a ‘great speciator’ in the Wallacea region: differing responses of closely related resident and migratory kingfisher species (Aves: Alcedinidae:Todiramphus)

Combined bottom‐up and top‐down pressures drive catastrophic population declines of Arctic skuas in Scotland

Assessing the effectiveness of foraging radius models for seabird distributions using biotelemetry and survey data

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