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Author = Jessopp, Mark J.;
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Displaying Results 1 - 9 of 9 on page 1 of 1
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Acoustic activity across a seabird colony reflects patterns of within-colony flight rather than nest density
(2019)
Arneill, Gavin E.; Critchley, Emma Jane; Wischnewski, Saskia; Jessopp, Mark J.; Quinn, ...
Acoustic activity across a seabird colony reflects patterns of within-colony flight rather than nest density
(2019)
Arneill, Gavin E.; Critchley, Emma Jane; Wischnewski, Saskia; Jessopp, Mark J.; Quinn, John L.
Abstract:
Passive acoustic monitoring is increasingly being used as a cost‐effective way to study wildlife populations, especially those that are difficult to census using conventional methods. Burrow‐nesting seabirds are among the most threatened birds globally, but they are also one of the most challenging taxa to census, making them prime candidates for research into such automated monitoring platforms. Passive acoustic monitoring has the potential to determine presence/absence or quantify burrow‐nesting populations, but its effectiveness remains unclear. We compared passive acoustic monitoring, tape‐playbacks and GPS tracking data to investigate the ability of passive acoustic monitoring to capture unbiased estimates of within‐colony variation in nest density for the Manx Shearwater Puffinus puffinus. Variation in acoustic activity across 12 study plots on an island colony was examined in relation to burrow density and environmental factors across 2 years. As predicted fewer calls were re...
http://hdl.handle.net/10468/8320
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Assessing the effectiveness of foraging radius models for seabird distributions using biotelemetry and survey data
(2019)
Critchley, Emma Jane; Grecian, W. J.; Bennison, Ashley; Kane, Adam; Wischnewski, Saskia...
Assessing the effectiveness of foraging radius models for seabird distributions using biotelemetry and survey data
(2019)
Critchley, Emma Jane; Grecian, W. J.; Bennison, Ashley; Kane, Adam; Wischnewski, Saskia; Cañadas, A.; Tierney, D.; Quinn, John L.; Jessopp, Mark J.
Abstract:
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 specie...
http://hdl.handle.net/10468/9346
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Habitat-mediated dive behavior in free-ranging grey seals
(2013)
Jessopp, Mark J.; Cronin, Michelle A.; Hart, Tom
Habitat-mediated dive behavior in free-ranging grey seals
(2013)
Jessopp, Mark J.; Cronin, Michelle A.; Hart, Tom
Abstract:
Understanding the links between foraging behaviour and habitat use of key species is essential to addressing fundamental questions about trophic interactions and ecosystem functioning. Eight female grey seals (Halichoerus grypus) were equipped with time-depth recorders linked to Fastloc GPS tags following the annual moult in southwest Ireland. Individual dives were coupled with environmental correlates to investigate the habitat use and dive behaviour of free-ranging seals. Dives were characterised as either pelagic, benthic, or shallow (where errors in location and charted water depth made differentiating between pelagic and benthic dives unreliable). Sixty-nine percent of dives occurring in water >50 m were benthic. Pelagic dives were more common at night than during the day. Seals performed more pelagic dives over fine sediments (mud/sand), and more benthic dives when foraging over more three-dimensionally complex rock substrates. We used Markov chain analysis to determine the...
http://hdl.handle.net/10468/2378
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KRILLBASE: a circumpolar database of Antarctic krill and salp numerical densities, 1926-2016
(2017)
Atkinson, Angus; Hill, Simeon L.; Pakhomov, Evgeny A.; Siegel, Volker; Anadon, Ricardo;...
KRILLBASE: a circumpolar database of Antarctic krill and salp numerical densities, 1926-2016
(2017)
Atkinson, Angus; Hill, Simeon L.; Pakhomov, Evgeny A.; Siegel, Volker; Anadon, Ricardo; Chiba, Sanae; Daly, Kendra L.; Downie, Rod; Fielding, Sophie; Fretwell, Peter; Gerrish, Laura; Hosie, Graham W.; Jessopp, Mark J.; Kawaguchi, So; Krafft, Bjørn A.; Loeb, Valerie; Nishikawa, Jun; Peat, Helen J.; Reiss, Christian S.; Ross, Robin M.
Abstract:
Antarctic krill (Euphausia superba) and salps are major macroplankton contributors to Southern Ocean food webs and krill are also fished commercially. Managing this fishery sustainably, against a backdrop of rapid regional climate change, requires information on distribution and time trends. Many data on the abundance of both taxa have been obtained from net sampling surveys since 1926, but much of this is stored in national archives, sometimes only in notebooks. In order to make these important data accessible we have collated available abundance data (numerical density, no.m-2) of postlarval E. superba and salp individual (multiple species, and whether singly or in chains). These were combined into a central database, KRILLBASE, together with environmental information, standardisation and metadata. The aim is to provide a temporal-spatial data resource to support a variety of research such as biogeochemistry, autecology, higher predator foraging and food web modelling in addition ...
http://hdl.handle.net/10468/3872
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Sampling strategies for species with high breeding-site fidelity: A case study in burrow-nesting seabirds
(2019)
Arneill, Gavin E.; Wood, Matt J.; Murphy, David; Pisani, Luca; Jessopp, Mark J.; Quinn,...
Sampling strategies for species with high breeding-site fidelity: A case study in burrow-nesting seabirds
(2019)
Arneill, Gavin E.; Wood, Matt J.; Murphy, David; Pisani, Luca; Jessopp, Mark J.; Quinn, John L.
Abstract:
Sampling approaches used to census and monitor populations of flora and fauna are diverse, ranging from simple random sampling to complex hierarchal stratified designs. Usually the approach taken is determined by the spatial and temporal distribution of the study population, along with other characteristics of the focal species. Long-term monitoring programs used to assess seabird population trends are facilitated by their high site fidelity, but are often hampered by large and difficult to access colonies, with highly variable densities that require intensive survey. We aimed to determine the sampling effort required to (a) estimate population size with a high degree of confidence, and (b) detect different scenarios of population change in a regionally important species in the Atlantic, the Manx shearwater (Puffinus puffinus). Analyses were carried out using data collected from tape-playback surveys on four islands in the North Atlantic. To explore how sampling effort influenced co...
http://hdl.handle.net/10468/8747
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Search and foraging behaviors from movement data: a comparison of methods
(2018)
Bennison, Ashley; Bearhop, Stuart; Bodey, Thomas W.; Votier, Stephen C.; Grecian, W. Ja...
Search and foraging behaviors from movement data: a comparison of methods
(2018)
Bennison, Ashley; Bearhop, Stuart; Bodey, Thomas W.; Votier, Stephen C.; Grecian, W. James; Wakefield, Ewan D.; Hamer, Keith C.; Jessopp, Mark J.
Abstract:
Search behavior is often used as a proxy for foraging effort within studies of animal movement, despite it being only one part of the foraging process, which also includes prey capture. While methods for validating prey capture exist, many studies rely solely on behavioral annotation of animal movement data to identify search and infer prey capture attempts. However, the degree to which search correlates with prey capture is largely untested. This study applied seven behavioral annotation methods to identify search behavior from GPS tracks of northern gannets (Morus bassanus), and compared outputs to the occurrence of dives recorded by simultaneously deployed time-depth recorders. We tested how behavioral annotation methods vary in their ability to identify search behavior leading to dive events. There was considerable variation in the number of dives occurring within search areas across methods. Hidden Markov models proved to be the most successful, with 81% of all dives occurring ...
http://hdl.handle.net/10468/6510
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Short-term losses and long-term gains: the non-native species Austrominius modestus in Lough Hyne Marine Nature Reserve
(2017)
Gallagher, Mary C.; Culloty, Sarah C.; Davenport, John; Harman, Luke; Jessopp, Mark J.;...
Short-term losses and long-term gains: the non-native species Austrominius modestus in Lough Hyne Marine Nature Reserve
(2017)
Gallagher, Mary C.; Culloty, Sarah C.; Davenport, John; Harman, Luke; Jessopp, Mark J.; Kerrigan, Caroline; Murray, Colette; O'Riordan, Ruth M.; McAllen, Rob
Abstract:
The non-native barnacle species Austrominius modestus was first recorded in Ireland, close to Lough Hyne marine nature reserve in 1957. This species was not recorded inside the Lough until 1980, but by 2001 was the dominant intertidal barnacle within the reserve. It has been suggested that increases in the abundance of this species at other locations in Europe may be linked to increasing sea surface temperatures, and that A. modestus is an “ecological sleeper”. Despite an overall trend for increasing sea surface temperatures, this long term warming is punctuated by extreme events such as severely cold winters. A. modestus is warm water adapted, and has been recorded to decrease in abundance following cold winters. The winters of 2009/2010 and 2010/2011 were amongst the coldest recorded in Ireland in past decades. In the present study, higher levels of mortality were recorded for A. modestus than native barnacle species in Lough Hyne following these cold winters. Additionally, this s...
http://hdl.handle.net/10468/3959
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Spatial overlap of grey seals and fisheries in Irish waters, some new insights using telemetry technology and VMS
(2016)
Cronin, Michelle A.; Gerritsen, H.; Reid, D.; Jessopp, Mark J.
Spatial overlap of grey seals and fisheries in Irish waters, some new insights using telemetry technology and VMS
(2016)
Cronin, Michelle A.; Gerritsen, H.; Reid, D.; Jessopp, Mark J.
Abstract:
Seals and humans often target the same food resource, leading to competition. This is of mounting concern with fish stocks in global decline. Grey seals were tracked from southeast Ireland, an area of mixed demersal and pelagic fisheries, and overlap with fisheries on the Celtic Shelf and Irish Sea was assessed. Overall, there was low overlap between the tagged seals and fisheries. However, when we separate active (e.g. trawls) and passive gear (e.g. nets, lines) fisheries, a different picture emerged. Overlap with active fisheries was no different from that expected under a random distribution, but overlap with passive fisheries was significantly higher. This suggests that grey seals may be targeting the same areas as passive fisheries and/or specifically targeting passive gear. There was variation in foraging areas between individual seals suggesting habitat partitioning to reduce intra-specific competition or potential individual specialisation in foraging behaviour. Our findings...
http://hdl.handle.net/10468/3195
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Spatial variation in a top marine predator’s diet at two regionally distinct sites
(2019)
Gosch, Martha; Cronin, Michelle A.; Rogan, Emer; Hunt, William; Luck, Cian; Jessopp, Ma...
Spatial variation in a top marine predator’s diet at two regionally distinct sites
(2019)
Gosch, Martha; Cronin, Michelle A.; Rogan, Emer; Hunt, William; Luck, Cian; Jessopp, Mark J.
Abstract:
In ecological studies it is often assumed that predator foraging strategies and resource use are geographically and seasonally homogeneous, resulting in relatively static trophic relationships. However, certain centrally placed foragers (e.g. seals) often have terrestrial sites for breeding, resting, and moulting that are geographically distinct, and associated with different habitat types. Therefore, accurate estimations of predator diet at relevant spatial and temporal scales are key to understanding energetic requirements, predator-prey interactions and ecosystem structure. We investigate geographic variation in the diet of grey seals (Halichoerus grypus), a relatively abundant and widely distributed central place forager, to provide insights into geographic variation in resource use. Prey composition was identified using scat samples collected over concurrent timescales and a multivariate approach was used to analyse diet from two contrasting habitats. Regional differences in pr...
http://hdl.handle.net/10468/7928
Displaying Results 1 - 9 of 9 on page 1 of 1
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