4 results
Between-individual variation in nematode burden among juveniles in a wild host
- H. M. V. GRANROTH-WILDING, F. DAUNT, E. J. A. CUNNINGHAM, S. J. BURTHE
-
- Journal:
- Parasitology / Volume 144 / Issue 2 / February 2017
- Published online by Cambridge University Press:
- 22 November 2016, pp. 248-258
-
- Article
- Export citation
-
Parasite infection in young animals can affect host traits related to demographic processes such as survival and reproduction, and is therefore crucial to population viability. However, variation in infection among juvenile hosts is poorly understood. Experimental studies have indicated that effects of parasitism can vary with host sex, hatching order and hatch date, yet it remains unclear whether this is linked to differences in parasite burdens. We quantified gastrointestinal nematode burdens of wild juvenile European shags (Phalacrocorax aristotelis) using two in situ measures (endoscopy of live birds and necropsy of birds that died naturally) and one non-invasive proxy measure (fecal egg counts (FECs)). In situ methods revealed that almost all chicks were infected (98%), that infections established at an early age and that older chicks hosted more worms, but FECs underestimated prevalence. We found no strong evidence that burdens differed with host sex, rank or hatch date. Heavier chicks had higher burdens, demonstrating that the relationship between burdens and their costs is not straightforward. In situ measures of infection are therefore a valuable tool in building our understanding of the role that parasites play in the dynamics of structured natural populations.
12 - Impacts of oceanography on the foraging dynamics of seabirds in the North Sea
-
- By F. Daunt, NERC Centre for Ecology and Hydrology, Banchory Research Station, Hill of Brathens, Banchory AB31 4BW, UK, S. Wanless, NERC Centre for Ecology and Hydrology, Banchory Research Station, Hill of Brathens, Banchory AB31 4BW, UK, G. Peters, Centre d'Ecologie et Physiologie Energétiques, Centre National de la Recherche Scientifique, 23 rue Becquerel, 67087 Strasbourg Cedex 2, France, S. Benvenuti, Dipartimento di Etologia, Ecologia ed Evoluzione, Università di Pisa, Via Volta 6, I-56126 Pisa, Italy, J. Sharples, Proudman Oceanographic Laboratory, Bidston Observatory, Birkenhead CH43 7RA, UK, D. Grémillet, Centre d'Ecologie et Physiologie Energétiques, Centre National de la Recherche Scientifique, 23 rue Becquerel, F-67087 Strasbourg Cedex 2, France, B. Scott, Department of Zoology, School of Biological Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen AB24 2TZ, UK
- Edited by I. L. Boyd, University of St Andrews, Scotland, S. Wanless, NERC Centre for Ecology and Hydrology, UK
- C. J. Camphuysen, Royal Netherlands Institute for Sea Research
-
- Book:
- Top Predators in Marine Ecosystems
- Published online:
- 31 July 2009
- Print publication:
- 11 May 2006, pp 177-190
-
- Chapter
- Export citation
-
Summary
Prey densities of at least 100× the average are necessary for profitable foraging by auks
A. G. Gaston (2004)To meet the above requirement, seabirds rely on prey being distributed in patches (Gaston 2004). Oceanography has a profound impact on the distribution of marine life (Miller 2004), and top predators frequently congregate in areas with a high prey biomass (Boyd & Arnbom 1991, Hunt et al. 1999). However, the impact of ocean physics on top-predator foraging behaviour is poorly understood, largely because of the complex trophic linkages involved. In particular, a detailed understanding of the interaction between seabirds and their prey is lacking. Two main methods are currently available to quantify seabird behaviour: animal-borne instrumentation and at-sea observations (see Box 12.1). In this chapter, we examine the impacts of oceanography on the foraging dynamics of North Sea seabirds during the breeding season. The seabirds of the North Sea are primarily piscivorous, with the majority wholly or largely dependent on the lesser sandeel Ammodytes marinus in summer (Furness & Tasker 2000). Using three seabird species with contrasting foraging strategies and dependence on sandeels, we test three specific predictions from the hypothesis that oceanography determines seabird foraging location and behaviour, using data from animal-borne instrumentation, oceanography and primary production collected concurrently. We interpret our findings in the context of the behaviour of seabirds' prey.
13 - Foraging energetics of North Sea birds confronted with fluctuating prey availability
-
- By M. R. Enstipp, Centre d'Ecologie et Physiologie Energétiques, Centre National de la Recherche Scientifique, 23 rue Becquerel, F-67087 Strasbourg Cedex 2, France, F. Daunt, NERC Centre for Ecology and Hydrology, Banchory Research Station, Hill of Brathens, Banchory AB31 4BW, UK, S. Wanless, NERC Centre for Ecology and Hydrology, Banchory Research Station, Hill of Brathens, Banchory AB31 4BW, UK, E. M. Humphreys, Earth Biosphere Institute and School of Biology, Ecology and Evolution Group, University of Leeds, Leeds LS2 9JT, UK, K. C. Hamer, Earth Biosphere Institute and School of Biology, Ecology and Evolution Group, University of Leeds, Leeds LS2 9JT, UK, S. Benvenuti, Dipartimento di Etologia, Ecologia ed Evoluzione, Università di Pisa, Via Volta 6, I-56126 Pisa, Italy, D. Grémillet, Centre d'Ecologie et Physiologie Energétiques, Centre National de la Recherche Scientifique, 23 rue Becquerel, F-67087 Strasbourg Cedex 2, France
- Edited by I. L. Boyd, University of St Andrews, Scotland, S. Wanless, NERC Centre for Ecology and Hydrology, UK
- C. J. Camphuysen, Royal Netherlands Institute for Sea Research
-
- Book:
- Top Predators in Marine Ecosystems
- Published online:
- 31 July 2009
- Print publication:
- 11 May 2006, pp 191-210
-
- Chapter
- Export citation
-
Summary
In the western North Sea, a large seabird assemblage exploits a limited number of fish species. Sandeels are particularly important prey items in this system, with populations that show strong spatial and temporal variability. This variability might be triggered by oceanic climatic features but could also be influenced by human activities, especially fisheries. In order to assess how different sandeel consumers are buffered against fluctuations in prey availability, we studied the foraging energetics of common guillemots, black-legged kittiwakes, European shags and northern gannets at two major colonies in southeast Scotland. Our analysis was based on: (a) time budgets recorded with data loggers attached to breeding adults foraging at sea; (b) metabolic measurements of captive and free-ranging individuals; and (c) information on diet and parental effort. We calculated daily food intake and feeding rates of chick-rearing adults and examined a number of hypothetical scenarios, to investigate how birds might be buffered against reduced sandeel availability. Our results suggest that under the conditions currently operating in this region, shags and guillemots may have sufficient time and energy available to increase their foraging effort considerably, whereas kittiwakes and gannets are more constrained by time and energy respectively. Of the species considered here, gannets are working at the highest metabolic level during chick rearing, and hence, have the least physiological capacity to increase foraging effort. However, to compensate for their energetically costly life, gannets might make use of a highly profitable foraging niche.
4 - The use of biologically meaningful oceanographic indices to separate the effects of climate and fisheries on seabird breeding success
-
- By B. E. Scott, Department of Zoology, School of Biological Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen AB24 2TZ, UK, J. Sharples, Proudman Oceanographic Laboratory, Bidston Observatory, Birkenhead CH43 7RA, UK, S. Wanless, NERC Centre for Ecology and Hydrology, Banchory Research Station, Hill of Brathens, Banchory AB31 4BW, UK, O. N. Ross, University of Southampton, School of Ocean and Earth Sciences, Southampton Oceanography Centre, Empress Dock, Southampton S14 3ZH, UK, M. Frederiksen, NERC Centre for Ecology and Hydrology, Banchory Research Station, Hill of Brathens, Banchory AB31 4BW, UK, F. Daunt, NERC Centre for Ecology and Hydrology, Banchory Research Station, Hill of Brathens, Banchory AB31 4BW, UK
- Edited by I. L. Boyd, University of St Andrews, Scotland, S. Wanless, NERC Centre for Ecology and Hydrology, UK
- C. J. Camphuysen, Royal Netherlands Institute for Sea Research
-
- Book:
- Top Predators in Marine Ecosystems
- Published online:
- 31 July 2009
- Print publication:
- 11 May 2006, pp 46-62
-
- Chapter
- Export citation
-
Summary
An important issue when considering seabird breeding success is what factors affect prey availability. If availability reflects absolute prey abundance, different species preying on the same prey population should show synchronized variation in breeding success. If, on the other hand, species-specific foraging techniques coupled with prevailing oceanographic conditions result in differential access to prey, then, breeding success is likely to vary asynchronously between species. Furthermore, for each species, long-term variation in breeding success should be predictable using appropriate oceanographic covariates. Currently, commercial fishing quotas are set on the assumption that prey abundance is the only important factor for multispecies management. Therefore, it is essential to understand prey availability in the context of both climate change and fishing pressure. This requires an integrated approach and in this chapter we demonstrate the potential of combining long-term demographic data from seabirds with output from a one-dimensional physical–biological model. Using data from the North Sea, we examine relationships between breeding performance and biologically meaningful indices of the physical environment during a period of years with and without an industrial fishery. We speculate how the contrasting responses shown by two seabird species might reflect differences in prey availability mediated by foraging technique.
Over the last 20 to 30 years, seabirds in the North Sea have shown considerable temporal variability in breeding success (Ratcliffe 2004).