scholarly journals Foraging ecology of tropicbirds breeding in two contrasting marine environments in the tropical Atlantic

2019 ◽  
Author(s):  
Steffen Oppel
Keyword(s):  
Protected Areas ◽  
Feeding Ecology ◽  
Trophic Ecology ◽  
Foraging Ecology ◽  
Foraging Strategies ◽  
Gps Tracking ◽  
Marine Environments ◽  
Shelf Slope ◽  
St Helena ◽  
La Madeleine

Studying the feeding ecology of seabirds is important not only to understand basic aspects of their ecology and threats but also for the conservation of marine ecosystems. In this regard, tropical seabirds have been relatively neglected, and in particular the trophic ecology of tropicbirds is scarcely known. We combined GPS tracking, environmental variables and sampling of regurgitates during incubation and brooding to understand the feeding ecology of red-billed tropicbirds Phaethon aethereus as well as how foraging strategies may change between 2 contrasting marine environments: a coastal island in the Canary Current upwelling (Îles de la Madeleine) and an oceanic island in the middle of the south Atlantic (St Helena). Tropicbirds breeding on the Îles de la Madeleine headed west, foraging on and beyond the shelf slope, probably to associate with subsurface predators which bring pelagic fish close to the surface. Birds from St Helena showed a greater foraging effort and a strong attraction to areas with the greatest species richness of Scombridae, possibly due to a greater difficulty in finding prey in the oligotrophic oceanic waters. Tropicbirds ranged much beyond the extension of the protected areas around their colonies, indicating that current protected areas are insufficient for these populations. We found no evidence to suspect direct mortality of tropicbirds in regional fisheries, but overexploitation of small epipelagic fish and tuna may decrease feeding opportunities and lead to competition with fisheries. The substantial differences in foraging behaviour demonstrated by individuals from both colonies indicates that caution should be taken when extrapolating foraging patterns of tropical seabirds breeding in contrasting oceanographic environments.

scholarly journals Integrating multiple chemical tracers to elucidate the diet and habitat of Cookiecutter Sharks

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Aaron B. Carlisle ◽  
Elizabeth Andruszkiewicz Allan ◽  
Sora L. Kim ◽  
Lauren Meyer ◽  
Jesse Port ◽  
...  
Keyword(s):  
Trophic Ecology ◽  
Foraging Ecology ◽  
Isotope Analysis ◽  
Environmental Dna ◽  
Small Sample ◽  
Apex Predators ◽  
Central Pacific ◽  
Chemical Tracers ◽  
Important Prey ◽  
Tracer Techniques

AbstractThe Cookiecutter shark (Isistius brasiliensis) is an ectoparasitic, mesopelagic shark that is known for removing plugs of tissue from larger prey, including teleosts, chondrichthyans, cephalopods, and marine mammals. Although this species is widely distributed throughout the world’s tropical and subtropical oceanic waters, like many deep-water species, it remains very poorly understood due to its mesopelagic distribution. We used a suite of biochemical tracers, including stable isotope analysis (SIA), fatty acid analysis (FAA), and environmental DNA (eDNA), to investigate the trophic ecology of this species in the Central Pacific around Hawaii. We found that large epipelagic prey constituted a relatively minor part of the overall diet. Surprisingly, small micronektonic and forage species (meso- and epipelagic) are the most important prey group for Cookiecutter sharks across the studied size range (17–43 cm total length), with larger mesopelagic species or species that exhibit diel vertical migration also being important prey. These results were consistent across all the tracer techniques employed. Our results indicate that Cookiecutter sharks play a unique role in pelagic food webs, feeding on prey ranging from the largest apex predators to small, low trophic level species, in particular those that overlap with the depth distribution of the sharks throughout the diel cycle. We also found evidence of a potential shift in diet and/or habitat with size and season. Environmental DNA metabarcoding revealed new prey items for Cookiecutter sharks while also demonstrating that eDNA can be used to identify recent prey in stomachs frozen for extended periods. Integrating across chemical tracers is a powerful tool for investigating the ecology of elusive and difficult to study species, such as meso- and bathypelagic chondrichthyans, and can increase the amount of information gained from small sample sizes. Better resolving the foraging ecology of these mesopelagic predators is critical for effective conservation and management of these taxa and ecosystems, which are intrinsically vulnerable to overfishing and exploitation.

scholarly journals Foraging niche partitioning in sympatric seabird populations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Christina Petalas ◽  
Thomas Lazarus ◽  
Raphael A. Lavoie ◽  
Kyle H. Elliott ◽  
Mélanie F. Guigueno
Keyword(s):  
Interspecific Competition ◽  
Niche Partitioning ◽  
Niche Differentiation ◽  
Sympatric Species ◽  
Foraging Strategies ◽  
Gps Tracking ◽  
Seabird Species ◽  
Foraging Range ◽  
Common Murre ◽  
Prey Items

AbstractSympatric species must sufficiently differentiate aspects of their ecological niche to alleviate complete interspecific competition and stably coexist within the same area. Seabirds provide a unique opportunity to understand patterns of niche segregation among coexisting species because they form large multi-species colonies of breeding aggregations with seemingly overlapping diets and foraging areas. Recent biologging tools have revealed that colonial seabirds can differentiate components of their foraging strategies. Specifically, small, diving birds with high wing-loading may have small foraging radii compared with larger or non-diving birds. In the Gulf of St-Lawrence in Canada, we investigated whether and how niche differentiation occurs in four incubating seabird species breeding sympatrically using GPS-tracking and direct field observations of prey items carried by adults to chicks: the Atlantic puffin (Fratercula arctica), razorbill (Alca torda), common murre (Uria aalge), and black-legged kittiwake (Rissa tridactyla). Although there was overlap at foraging hotspots, all species differentiated in either diet (prey species, size and number) or foraging range. Whereas puffins and razorbills consumed multiple smaller prey items that were readily available closer to the colony, murres selected larger more diverse prey that were accessible due to their deeper diving capability. Kittiwakes compensated for their surface foraging by having a large foraging range, including foraging largely at a specific distant hotspot. These foraging habitat specialisations may alleviate high interspecific competition allowing for their coexistence, providing insight on multispecies colonial living.

Condition-dependent foraging strategies in a coastal seabird: evidence for the rich get richer hypothesis

2018 ◽  
Vol 30 (2) ◽  
pp. 356-363 ◽  
Author(s):  
Brock Geary ◽  
Scott T Walter ◽  
Paul L Leberg ◽  
Jordan Karubian
Keyword(s):  
Individual Variation ◽  
Multiple Scales ◽  
Foraging Ecology ◽  
Population Level ◽  
Foraging Strategies ◽  
Significant Relationships ◽  
Fitness Consequences ◽  
Brown Pelicans ◽  
The Rich ◽  
Foraging Movements

Abstract The degree to which foraging individuals are able to appropriately modify their behaviors in response to dynamic environmental conditions and associated resource availability can have important fitness consequences. Despite an increasingly refined understanding of differences in foraging behavior between individuals, we still lack detailed characterizations of within-individual variation over space and time, and what factors may drive this variability. From 2014 to 2017, we used GPS transmitters and accelerometers to document foraging movements by breeding adult Brown Pelicans (Pelecanus occidentalis) in the northern Gulf of Mexico, where the prey landscape is patchy and dynamic at various scales. Assessments of traditional foraging metrics such as trip distance, linearity, or duration did not yield significant relationships between individuals. However, we did observe lower site fidelity and less variation in energy expenditure in birds of higher body condition, despite a population-level trend of increased fidelity as the breeding season progressed. These findings suggest that high-quality individuals are both more variable and more efficient in their foraging behaviors during a period of high energetic demand, consistent with a “rich get richer” scenario in which individuals in better condition are able to invest in more costly behaviors that provide higher returns. This work highlights the importance of considering behavioral variation at multiple scales, with particular reference to within-individual variation, to improve our understanding of foraging ecology in wild populations.

scholarly journals Subcolony Variation in Breeding Success in the Tufted Puffin (Fratercula Cirrhata): Association With Foraging Ecology and Implications

The Auk ◽  
2007 ◽  
Vol 124 (4) ◽  
pp. 1149-1157
Author(s):  
J. Mark Hipfner ◽  
Mathieu R. Charette ◽  
Gwylim S. Blackburn
Keyword(s):  
Stable Isotope ◽  
Breeding Success ◽  
Large Scale ◽  
Foraging Ecology ◽  
Isotope Analysis ◽  
Egg Yolk ◽  
Foraging Strategies ◽  
Small Scale ◽  
Carbon And Nitrogen ◽  
Tufted Puffin

Abstract Large-scale oceanographic processes are the main drivers of seabird breeding success, but small-scale processes, though not as well understood, can also be important. We compared the success of Tufted Puffins (Fratercula cirrhata) breeding at two subcolonies only 1.5 km apart on Triangle Island, British Columbia, Canada, 2002–2005. In addition, we used stable-isotope analysis to test the hypothesis that parental foraging strategies differed between the two subcolonies, potentially underlying the variation in breeding success. Success was concordant across years at the two sites but, overall, Tufted Puffins bred more successfully at Strata Rock than at Puffin Rock. They raised chicks in all four years at Strata Rock, but in only three years at Puffin Rock; in two of those three years, Strata Rock chicks were, on average, 60 g and 100 g heavier than Puffin Rock chicks just before fledging. Discriminant analysis of carbon and nitrogen stable-isotope ratios in egg yolk and chick blood in 2004 and 2005 indicated that parental foraging differed between the two subcolonies, with both spatial (δ13C) and trophic-level (δ15N) differences involved. Thus, our study demonstrates the existence of foraging asymmetries in a pelagic seabird at a small spatial scale (between subcolonies), complementing patterns found at larger scales (between colonies). Moreover, the foraging asymmetries were associated with inequalities in fitness measures. We conclude that small-scale processes—in this case, systematic differences in the foraging ecology of local groups—can interact with large-scale oceanographic processes to determine seabird breeding success. Variation sous-coloniale du succès de reproduction de Fratercula cirrhata: Association avec l'écologie de la quête alimentaire et implications

scholarly journals Behavioral and trophic segregations help the Tahiti petrel to cope with the abundance of wedge-tailed shearwater when foraging in oligotrophic tropical waters

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Andreas Ravache ◽  
Karen Bourgeois ◽  
Henri Weimerskirch ◽  
Angélique Pagenaud ◽  
Sophie de Grissac ◽  
...  
Keyword(s):  
Trophic Ecology ◽  
Isotope Analysis ◽  
Foraging Strategy ◽  
Gps Tracking ◽  
Ecological Niches ◽  
Extensive Search ◽  
Tropical Area ◽  
Time Space ◽  
Dna Metabarcoding ◽  
Breeding Seasons

Abstract Two species breeding in sympatry are more likely to coexist if their ecological niches are segregated either in time, space or in trophic habits. Here, we combined GPS-tracking, stable isotope analysis and DNA metabarcoding analysis to understand how the rare Tahiti petrel Pseudobulweria rostrata (TP) copes with the very abundant (i.e. 500,000 breeding pairs) wedge-tailed shearwater Ardenna pacifica (WTS) when breeding in sympatry in a tropical area. WTS foraged in restricted areas along their path, while TP predominantly foraged using extensive search behavior, suggesting a more opportunistic foraging strategy. Interspecific overlap of foraging areas was higher than intraspecific overlap. Breeding seasons largely overlap between species during the study, but TP seems to be asynchronous breeders. TP fed upon prey with higher δ15N values than WTS, and their diet was mainly composed of deep-sea organisms. TP could feed upon dead prey floating at the surface while WTS preyed mainly upon fish species that generally move in schools. Our study highlights several segregating mechanisms (temporal, behavioral and trophic) that could facilitate the coexistence of the two species despite the predominant number of WTS, and provides the very first information on the foraging and trophic ecology of the poorly-known TP.

Combined usage of stable isotopes and GPS-based telemetry to understand the feeding ecology of an omnivorous bird, the Ring-billed Gull (Larus delawarensis)

2013 ◽  
Vol 91 (10) ◽  
pp. 689-697 ◽  
Author(s):  
É. Caron-Beaudoin ◽  
M.-L. Gentes ◽  
M. Patenaude-Monette ◽  
J.-F. Hélie ◽  
J.-F. Giroux ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Feeding Ecology ◽  
Blood Cells ◽  
Urban Areas ◽  
Dietary Habits ◽  
Treatment Plant ◽  
Gps Tracking ◽  
Food Items ◽  
Larus Delawarensis ◽  
Positive Correlations

The aim of the present study was to investigate the feeding ecology of an omnivorous bird, the Ring-billed Gull (Larus delawarensis Ord, 1815), breeding in a highly urbanized and heterogeneous landscape (Montréal area, Quebec, Canada). We used gastrointestinal (G.I.) tract content analysis, GPS-based tracking information, and stable isotope profiles of carbon (δ13C) and nitrogen (δ15N) in selected tissues and major food items. Based on GPS tracking data (1–3 days), Ring-billed Gulls were categorized according to their use of three main foraging habitats: agricultural, St. Lawrence River, and anthropogenic (comprising urban areas, landfills, and wastewater treatment plant basins). Ring-billed Gulls that foraged predominantly in anthropogenic habitats exhibited significantly lower δ15N in blood cells and higher total C to N ratios (C:N) in liver. These lower δ15N and higher C:N ratios were characteristic of profiles determined in food items consumed by Ring-billed Gulls at these urbanized sites (e.g., processed foods). The strong positive correlations between δ13C and δ15N in Ring-billed Gull tissues (plasma, blood cells, and liver) that differed in isotopic turnover times, as well as the strong positive correlations in both δ13C and δ15N between tissue pairs, indicated that Ring-billed Gulls exhibited conserved dietary habits throughout the nesting period. This study demonstrates that combining conventional dietary examination, tissue stable isotope analysis, and fine-scale GPS tracking information may improve our understanding of the large intrapopulation variations in foraging behaviour (and isotopic profiles) commonly observed in omnivorous birds.

Using Animal-Borne Imaging to Assess Green Turtle (Chelonia mydas) Foraging Ecology in Moreton Bay, Australia

2007 ◽  
Vol 41 (4) ◽  
pp. 9-13 ◽  
Author(s):  
Karen E. Arthur ◽  
Judith M. O'Neil ◽  
Colin J. Limpus ◽  
Kyler Abernathy ◽  
Greg Marshall
Keyword(s):  
Feeding Ecology ◽  
Green Turtle ◽  
Foraging Ecology ◽  
Chelonia Mydas ◽  
Lyngbya Majuscula ◽  
Imaging Device ◽  
Green Turtles ◽  
Moreton Bay ◽  
Turtle Population ◽  
Insight Into

Traditional techniques for studying green turtle foraging ecology, such as the analysis of food availability and ingested dietary material, have concluded that green turtles are primarily herbivorous but selective foragers. However, green turtles that forage during Lyngbya majuscula blooms are exposed to toxins produced by the cyanobacterium overgrowing the seagrass. We used the Crittercam, an animal-borne imaging device, to observe green turtle foraging behavior in Moreton Bay, Australia, and to evaluate the system for assessing the impacts of Lyngbya blooms on green turtles. Eight large green turtles were captured while foraging on seagrass flats and each was fitted with a Crittercam. The deployments yielded over 28 hours of video and associated time-depth records. Turtles swam almost continuously and rarely stopped to feed on seagrass. Six turtles were observed feeding and all six consumed gelatinous animals from the water column. This prey source was previously undocumented in the Moreton Bay green turtle population but described in other green turtle populations using the Crittercam. Only one turtle was observed foraging on seagrass. The results of this study indicate that Crittercam technology can provide insight into turtle diet selection and that it will be a useful tool in identifying the impacts of Lyngbya blooms on green turtle feeding ecology. This study has also demonstrated that turtles in Moreton Bay may have a more flexible diet than previously described, indicating they could potentially supplement their diet with alternate prey items when seagrass quality or quantity is compromised. Longer deployment times, with an initial acclimation phase, are required to more fully understand questions pertaining to feeding ecology.

scholarly journals Foraging Behaviour of Three Sympatric Babblers (Family: Timaliidae)

2020 ◽  
Vol 3 (2) ◽  
pp. a26-34
Author(s):  
JONATHON JULIANA ◽  
DENCY FLENNY GAWIN
Keyword(s):  
National Park ◽  
Foraging Behaviour ◽  
Foraging Ecology ◽  
Secondary Forest ◽  
Structural Complexity ◽  
Foraging Strategies ◽  
Dipterocarp Forest ◽  
Fruit Orchard ◽  
Disturbed Forest ◽  
Mixed Dipterocarp Forest

We investigated the foraging ecology of three species of babblers in Kampung Gumbang, Kampung Padang Pan and Dered Krian National Park, Bau. Vegetation in Kampung Gumbang include tall trees, shrubs and patches of kerangas. Dered Kerian National Park consists of mixed dipterocarp forest and limestone forest, which is surrounded by orchards and few villages. In Kampung Padang Pan, the vegetation is a mixed fruit orchard and secondary forest. Foraging data were obtained to compare foraging behaviour in three species. From 133 observations, suspended dead leaves was the most frequently used substrate by the three species. Stachyris maculate showed the most general foraging behavior, and it adopted probing strategy. Cyanoderma erythropterum and Mixnornis gularis obtained food items by gleaning. These three babblers utilize different foraging strategies and substrates, irrespective of their resemblances in other characteristics.  C. erythropterum and S. maculate forage mainly among dead and curled, twisted leaves in understory vegetation at significantly different heights. M. gularis forages on dead and living leaves and this species can be found abundantly in disturbed forest and plantation or farm habitats. All the three areas were observed never lacked falling leaves and structural complexity required as foraging substrates by those three babbler species. All three babblers occupy different foraging niches, and therefore interspecific competitions among themselves are minimized.

scholarly journals Feeding ecology of Walia Ibex Capra walie (Mammalia: Artiodactyla: Bovidae) in Simien Mountains National Park, Ethiopia

2021 ◽  
Vol 13 (5) ◽  
pp. 18132-18140
Author(s):  
D. Ejigu ◽  
A. Bekele ◽  
L. Powell
Keyword(s):  
Feeding Ecology ◽  
National Park ◽  
Sampling Method ◽  
Foraging Ecology ◽  
Community Based ◽  
Community Based Conservation ◽  
Before And After ◽  
Dry Seasons ◽  
Time Spent Feeding ◽  
Wet And Dry Seasons

Walia Ibex Capra walie is an endemic and endangered species residing in Simien Mountains National Park, Ethiopia.  It has shifted its range within the Park in the last decade, and in this study our main objective was to provide information on their feeding ecology to inform recovery goals.  We used a scan sampling method to collect foraging information during October 2009 to November 2011.  Our observations suggest a diverse diet of more than 28 species of grasses, forbs, and shrubs.  The most commonly used plants were Festuca sp., Lobelia rhynchopetalum, Helichrysum citrispinum, and Helichrysum horridum.  Walia Ibex were active in feeding before and after mid-day, and time spent feeding was the highest compared with other diurnal activities.  The percentage of time spent feeding on major plant species did not differ between wet and dry seasons (p> 0.05).  Walia Ibex, however, tended to spend more time browsing than grazing.  The generalist nature of foraging behaviour in Walia Ibex most likely contributes to complaints from the local people who witness Walia Ibex raiding crops cultivated in and around the Park.  Thus, the contribution of crop raiding to the shifts in the species’ range towards higher altitudes at Sebatminch within Simien Mountains National Park emphasizes the need to consider foraging ecology as community-based conservation efforts are developed to support Walia Ibex in the Park. 

STRUCTURE OF TRILOBITE COMMUNITIES ALONG A DELTA-MARINE GRADIENT (LOWER ORDOVICIAN; NORTHWESTERN ARGENTINA)

Palaios ◽  
2021 ◽  
Vol 36 (2) ◽  
pp. 39-52
Author(s):  
FERNANDA SERRA ◽  
DIEGO BALSEIRO ◽  
ROMAIN VAUCHER ◽  
BEATRIZ G. WAISFELD
Keyword(s):  
Taxonomic Composition ◽  
Ecological Niches ◽  
Marine Environments ◽  
Key Factors ◽  
Physiological Conditions ◽  
Marine Deposits ◽  
Shelf Slope ◽  
Composition And Structure ◽  
Lower Ordovician ◽  
Nested Structure

ABSTRACTThroughout their long history, trilobites occupied various ecological niches, colonizing a wide variety of marine environments. However, the paleoecology of this group is mostly based on shelf–slope environments and less is known about their distribution in marginal environments. To understand how trilobite communities respond to a deltaic influence, we studied changes in the taxonomic composition and structure of a diverse and well-known Lower Ordovician olenid-dominated fauna from the Argentine Cordillera Oriental along a delta–marine gradient. Cluster analysis revealed two distinct associations, and ordination analysis revealed a clear biotic gradient within each. The ecological structure and diversity trends of both associations follow a predictable response to a depth-related gradient. Impoverished communities with a highly nested structure characterize the lower offshore, whereas rich and even communities occur in the upper offshore. The trend towards higher diversity and greater taxonomic turnover in shallower environments corresponds to greater habitat heterogeneity. Towards the other extreme, only the ubiquitous genus Jujuyaspis was a successful colonizer in deltaic settings. This marked contrast with the more diverse and abundant assemblages of fully marine deposits indicates stressful physiological conditions in marginal-marine environments, where alternating and contrasting normal-marine to brackish-water conditions and high input of siliciclastic material were among the key factors controlling the distribution of these early trilobite communities.

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