scholarly journals Characterising the foraging ecology and mercury exposure of the Nationally Critical Whenua Hou diving petrel

2021 ◽  
Author(s):  
Grace Tocker
Keyword(s):  
Breeding Season ◽  
Trophic Level ◽  
Interannual Variation ◽  
Prey Species ◽  
Foraging Ecology ◽  
Isotope Analysis ◽  
Mercury Exposure ◽  
Potential Threat ◽  
Breeding Seasons ◽  
Diving Petrel

<p>With seabird species in decline globally, significant research has gone into characterising their key prey species and foraging areas that need protection. Knowledge on the diet of a species has important implications for the development of conservation programmes. The sand dune system on Whenua Hou is home to the endemic Whenua Hou diving petrel (Pelecanoides whenuahouensis; hereafter WHDP) and a population of common diving petrels (Pelecanoides urinatrix; hereafter CDP). The WHDP is considered ‘Nationally Critical’ due to its small population size (~200 individuals) and restricted breeding range (0.018 km2) on Whenua Hou. The foraging ecology of the WHDP is relatively unknown, as is its exposure to sources of marine pollution. This thesis aimed to characterise the foraging ecology of the WHDP, the potential interspecific competition with the sympatric CDPs, the prey present in the diets of each species, and their resulting exposure to mercury from the environment. In chapter 2, I used stable isotope analysis to infer the trophic dynamics of the WHDP. By sampling and analysing both blood and feathers, I was able to investigate potential differences in WHDP foraging ecology between the breeding and non-breeding seasons. I found a difference between the foraging ecology of male and female WHDPs, with results indicating females forage further out to sea than males and on prey of lower trophic value. I found that WHDPs forage an entire trophic level higher during the breeding season than the non-breeding season. As my sampling effort spanned three consecutive breeding seasons (2017-2019), I was able to detect interannual variation in the foraging ecology of WHDPs. The results revealed that WHDPs foraged at a higher trophic level during the breeding season of 2018 compared to that of 2017 or 2019. By characterising the isotopic niches of both the WHDPs and CDPs over the three years, I was able to demonstrate a degree of trophic segregation between the two species during the breeding season. In chapter 3, I designed and went through the initial development stages for a novel multiplex-PCR assay to identify the prey species present in the diets of WHDPs and CDPs. The obstacles faced in the development of this protocol highlighted the suitability of DNA metabarcoding as an alternative method. In chapter 4, I analysed the mercury concentration in the same blood and feather samples used for stable isotope analysis. I demonstrated that male WHDPs had higher concentrations of mercury in their tissues than females, correlating with their foraging at a higher trophic level. The interannual variation in mercury concentration did not correlate with the trophic variation of WHDPs among years, indicating that the environmental fluctuations in mercury levels had a stronger effect on mercury exposure than diet. WHDP tissues consistently had higher concentrations of mercury than CDPs, correlating with their isotopic niche segregation and highlighting a potential threat to individual survival and reproductive success in WHDPs. Overall, my results describe patterns in the foraging ecology of the WHDP, as well as highlighting the potential threat from mercury exposure. This research can be used as a baseline for future investigations into the key prey species for the endangered WHDP and the impacts mercury exposure may be having on the population growth of this species. </p>

scholarly journals Characterising the foraging ecology and mercury exposure of the Nationally Critical Whenua Hou diving petrel

2021 ◽  
Author(s):  
Grace Tocker
Keyword(s):  
Breeding Season ◽  
Trophic Level ◽  
Interannual Variation ◽  
Prey Species ◽  
Foraging Ecology ◽  
Isotope Analysis ◽  
Mercury Exposure ◽  
Potential Threat ◽  
Breeding Seasons ◽  
Diving Petrel

<p>With seabird species in decline globally, significant research has gone into characterising their key prey species and foraging areas that need protection. Knowledge on the diet of a species has important implications for the development of conservation programmes. The sand dune system on Whenua Hou is home to the endemic Whenua Hou diving petrel (Pelecanoides whenuahouensis; hereafter WHDP) and a population of common diving petrels (Pelecanoides urinatrix; hereafter CDP). The WHDP is considered ‘Nationally Critical’ due to its small population size (~200 individuals) and restricted breeding range (0.018 km2) on Whenua Hou. The foraging ecology of the WHDP is relatively unknown, as is its exposure to sources of marine pollution. This thesis aimed to characterise the foraging ecology of the WHDP, the potential interspecific competition with the sympatric CDPs, the prey present in the diets of each species, and their resulting exposure to mercury from the environment. In chapter 2, I used stable isotope analysis to infer the trophic dynamics of the WHDP. By sampling and analysing both blood and feathers, I was able to investigate potential differences in WHDP foraging ecology between the breeding and non-breeding seasons. I found a difference between the foraging ecology of male and female WHDPs, with results indicating females forage further out to sea than males and on prey of lower trophic value. I found that WHDPs forage an entire trophic level higher during the breeding season than the non-breeding season. As my sampling effort spanned three consecutive breeding seasons (2017-2019), I was able to detect interannual variation in the foraging ecology of WHDPs. The results revealed that WHDPs foraged at a higher trophic level during the breeding season of 2018 compared to that of 2017 or 2019. By characterising the isotopic niches of both the WHDPs and CDPs over the three years, I was able to demonstrate a degree of trophic segregation between the two species during the breeding season. In chapter 3, I designed and went through the initial development stages for a novel multiplex-PCR assay to identify the prey species present in the diets of WHDPs and CDPs. The obstacles faced in the development of this protocol highlighted the suitability of DNA metabarcoding as an alternative method. In chapter 4, I analysed the mercury concentration in the same blood and feather samples used for stable isotope analysis. I demonstrated that male WHDPs had higher concentrations of mercury in their tissues than females, correlating with their foraging at a higher trophic level. The interannual variation in mercury concentration did not correlate with the trophic variation of WHDPs among years, indicating that the environmental fluctuations in mercury levels had a stronger effect on mercury exposure than diet. WHDP tissues consistently had higher concentrations of mercury than CDPs, correlating with their isotopic niche segregation and highlighting a potential threat to individual survival and reproductive success in WHDPs. Overall, my results describe patterns in the foraging ecology of the WHDP, as well as highlighting the potential threat from mercury exposure. This research can be used as a baseline for future investigations into the key prey species for the endangered WHDP and the impacts mercury exposure may be having on the population growth of this species. </p>

The diet of Pacific gulls (Larus pacificus) breeding at Seal Island in northern Bass Strait

2014 ◽  
Vol 62 (3) ◽  
pp. 216 ◽  
Author(s):  
Tamara N. Leitch ◽  
Peter Dann ◽  
John P. Y. Arnould
Keyword(s):  
Marine Environment ◽  
Diet Composition ◽  
Prey Species ◽  
Foraging Ecology ◽  
Wide Distribution ◽  
Analysis Of Similarity ◽  
Numerical Abundance ◽  
Important Predator ◽  
The Common ◽  
Diving Petrel

The endemic Pacific gull (Larus pacificus) is Australia’s largest larid, and though little is currently known of its foraging ecology, its size and wide distribution suggest that it may play an important role within the marine environment. In the present study, regurgitate pellets collected from Seal Island in northern Bass Strait were used to compare intra- and interannual trends in diet composition. The main taxa identified in pellets were the common diving-petrel (Pelecanoides urinatrix), leatherjacket species (Family Monacanthidae), short-tailed shearwater (Puffinus tenuirostris) and mirror bush (Coprosma repens). Analysis of similarity (ANOSIM) identified no significant differences in numerical abundance of the dominant prey species between years, suggesting that the prey base in this region is temporally consistent or that the gulls consume low enough numbers to be unaffected by fluctuation in prey populations. Diving-petrels were consumed in consistently high numbers, suggesting the gulls may be an important predator of this species, or that the gulls are particularly skilled at foraging for them.

scholarly journals Evidence for use of both capital and income breeding strategies in the mangrove tree crab, Aratus pisonii

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jade Carver ◽  
Morgan Meidell ◽  
Zachary J. Cannizzo ◽  
Blaine D. Griffen
Keyword(s):  
Breeding Season ◽  
Breeding Strategy ◽  
Reproductive Period ◽  
Breeding Strategies ◽  
Mangrove Tree ◽  
Income Breeding ◽  
Aratus Pisonii ◽  
Breeding Seasons ◽  
And Storage ◽  
Capital And Income Breeding

AbstractTwo common strategies organisms use to finance reproduction are capital breeding (using energy stored prior to reproduction) and income breeding (using energy gathered during the reproductive period). Understanding which of these two strategies a species uses can help in predicting its population dynamics and how it will respond to environmental change. Brachyuran crabs have historically been considered capital breeders as a group, but recent evidence has challenged this assumption. Here, we focus on the mangrove tree crab, Aratus pisonii, and examine its breeding strategy on the Atlantic Florida coast. We collected crabs during and after their breeding season (March–October) and dissected them to discern how energy was stored and utilized for reproduction. We found patterns of reproduction and energy storage that are consistent with both the use of stored energy (capital) and energy acquired (income) during the breeding season. We also found that energy acquisition and storage patterns that supported reproduction were influenced by unequal tidal patterns associated with the syzygy tide inequality cycle. Contrary to previous assumptions for crabs, we suggest that species of crab that produce multiple clutches of eggs during long breeding seasons (many tropical and subtropical species) may commonly use income breeding strategies.

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 Altitudinal movements and conservation of Bare-necked Umbrellabird Cephalopterus glabricollis of the Tilarán Mountains, Costa Rica

2003 ◽  
Vol 13 (1) ◽  
pp. 45-58 ◽  
Author(s):  
Johel Chaves-Campos ◽  
J. Edgardo Arévalo ◽  
Mariamalia Araya
Keyword(s):  
Costa Rica ◽  
Breeding Season ◽  
Protected Area ◽  
Radio Telemetry ◽  
Fruit Breeding ◽  
Potential Threat ◽  
Fruit Abundance ◽  
Transect Counts ◽  
Using Data ◽  
High Elevations

Bare-necked Umbrellabird Cephalopterus glabricollis is endemic to Costa Rica and western Panama. It eats fruit, breeding at high elevations (≥ 800 m) and migrating to lower elevations during the non-breeding season. Using data from transect counts and radio-telemetry, we monitored bird movements in a protected area (Monteverde–Arenal–San Ramón reserves) in the Tilarán Mountains, Costa Rica. We also monitored fruit abundance along an altitudinal gradient to explore the potential relationship between bird movements and the abundance of the fruits this species consumed. The presence and abundance of umbrellabirds at high elevations (1,400 m) during the breeding season (March–June) coincided with the highest peak of fruit abundance. The presence of umbrellabirds in the lowlands (400 m) during the non-breeding season overlapped with the period of highest fruit abundance at these elevations. At middle elevations, bird presence and abundance did not correlate with fruit abundance. Radio-tagged birds left the protected area during the non-breeding season and there were no umbrellabirds inside the protected area during this period. Habitats where this species bred were well represented in the protected area but the habitat where they spent the non-breeding season was poorly represented, and was not adequately protected. This represents a potential threat to this species in the Tilarán Mountains.

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 Density and Flock Size of the Raven (Corvus corax) In the Orawa - Nowy Targ Basin During Non-Breeding Season

Ring ◽  
2006 ◽  
Vol 28 (2) ◽  
pp. 119-125
Author(s):  
Michał Ciach ◽  
Dominik Wikar ◽  
Małgorzata Bylicka
Keyword(s):  
Breeding Season ◽  
Early Spring ◽  
Food Resources ◽  
High Density ◽  
Line Transect ◽  
Flock Size ◽  
Early Winter ◽  
Corvus Corax ◽  
Line Transect Method ◽  
Breeding Seasons

Density and Flock Size of the Raven (Corvus corax) In the Orawa - Nowy Targ Basin During Non-Breeding Season During the 2002/2003-2004/2005 non-breeding seasons the density of the Raven in the open habitats of the Orawa - Nowy Targ Basin was studied by line transect method. The results were analysed in four periods (autumn, early winter, winter and early spring). The median density of Ravens did not differ significantly between individual periods and was respectively: 3.5, 3.8, 4.8 and 3.8 indiv. / 10 km. Number of birds during particular controls varied from 1.0 to 24.8 indiv. / 10 km. However, while excluding flocks, the median density of single individuals and pairs of the Raven was considerably lower and in subsequent periods reached respectively: 2.2, 2.4, 2.2 and 1.7 indiv. / 10 km. Flock size did not differ significantly between individual periods. Single individuals and, less often, groups of two birds were recorded mostly. Small (3-5 indiv.) and medium (6-15 indiv.) flocks were recorded rarely and large flocks (16 indiv. and above) - only exceptionally. The high density and strong fluctuations of abundance of Ravens were determined by flocks presence, which was probably linked to irregular occurrence of food resources.

Phenotypic plasticity of the montane vole (Microtus montanus) in unpredictable environments

1992 ◽  
Vol 70 (11) ◽  
pp. 2121-2124 ◽  
Author(s):  
Norman C. Negus ◽  
Patricia J. Berger ◽  
Aelita J. Pinter
Keyword(s):  
Phenotypic Plasticity ◽  
Breeding Season ◽  
Growth Rates ◽  
Adaptive Strategy ◽  
Severe Drought ◽  
Microtus Montanus ◽  
Age Cohort ◽  
Montane Meadow ◽  
Study Sites ◽  
Breeding Seasons

From 1987 to 1989, the cohort dynamics of Microtus montanus populations were studied at two montane meadow sites approximately 160 km apart, in northwestern Wyoming. The 1987 and 1988 breeding seasons differed markedly from each other. In 1987, melt off occurred in April, and the first cohort was born in May (cohort 1). The entire breeding season was favorable owing to frequent rainfall throughout the summer. Cohort 1 animals grew rapidly and females began breeding at 4–5 weeks of age. Likewise, cohort 2 (June) animals exhibited rapid growth and females were breeding at 7–8 weeks of age. Cohort 3 (July and August) animals grew more slowly and most entered the winter as prepubertal animals of subadult size. At the end of the summer, cohort 3 animals represented >70% of the voles recruited during the breeding season. In 1988, following melt off in late April, precipitation was below normal and the situation intensified to severe drought through the summer. The growth rates of cohort 1 and 2 animals were significantly lower than 1987 growth rates, and very few females attained sexual maturity. At the end of the summer, cohort 3 animals represented <25% of the total recruitment at both study sites. Such apparent phenotypic plasticity of growth and maturation appears to be an evolved adaptive strategy that is responsive to several environmental cues. Both study sites, although widely separated, exhibited virtually identical patterns throughout the study.

scholarly journals Tracking data and retrospective analyses of diet reveal the consequences of loss of marine subsidies for an obligate scavenger, the Andean condor

2018 ◽  
Vol 285 (1879) ◽  
pp. 20180550 ◽  
Author(s):  
Sergio A. Lambertucci ◽  
Joan Navarro ◽  
José A. Sanchez Zapata ◽  
Keith A. Hobson ◽  
Pablo A. E. Alarcón ◽  
...  
Keyword(s):  
Marine Mammals ◽  
Foraging Ecology ◽  
Average Distance ◽  
Isotope Analysis ◽  
Terrestrial Ecosystems ◽  
Mountain Range ◽  
Marine Subsidies ◽  
Nesting Sites ◽  
Foraging Pattern ◽  
Andean Condor

Over the last century, marine mammals have been dramatically reduced in the world's oceans. We examined evidence that this change caused dietary and foraging pattern shifts of the Andean condor ( Vultur gryphus ) in Patagonia. We hypothesized that, after the decrease in marine mammals and the increase in human use of coastlines, condor diet changed to a more terrestrial diet, which in turn influenced their foraging patterns. We evaluated the diet by means of stable isotope analysis ( δ 13 C, δ 15 N and δ 34 S) of current (last decade) and historical (1841–1933) feathers. We further evaluated the movement patterns of 23 condors using satellite tracking of individuals. Condors reduced their use of marine-derived prey in recent compared with historical times from 33 ± 13% to less than 8 ± 3% respectively; however, they still breed close to the coast. The average distance between the coast and nests was 62.5 km, but some nests were located close to the sea (less than 5 km). Therefore, some birds must travel up to 86 km from nesting sites, crossing over the mountain range to find food. The worldwide reduction in marine mammal carcasses, especially whales, may have major consequences on the foraging ecology of scavengers, as well as on the flux of marine inputs within terrestrial ecosystems.

Flexibility of nuptial colouration in a unique ecotype of Threespine Stickleback (Gasterosteus aculeatus)

2021 ◽  
Author(s):  
Rachel Corney ◽  
Anne Haley ◽  
Laura Weir
Keyword(s):  
Breeding Season ◽  
Gasterosteus Aculeatus ◽  
Colour Change ◽  
Threespine Stickleback ◽  
Relative Role ◽  
Mate Quality ◽  
Breeding Seasons ◽  
Potential Signal ◽  
Intersexual Competition

Nuptial colouration in animals may serve as a signal of competitor and/or mate quality during breeding. In many temperate fishes, nuptial colouration develops during discrete breeding seasons and is a target of sexual selection. We examine nuptial colouration and behaviour of a unique ecotype of Threespine Stickleback (Gasterosteus aculeatus Linnaeus, 1758), wherein males turn from dull brown-grey to pearlescent white during the breeding season. The main goal of this work was to determine the relative role of white colouration in intersexual competition and mate choice. In a combination of a field and laboratory work, we found that males are brightest white when engaging in courtship activities in the presence of a female; this indicates that white colouration may be primarily related to enhancing signalling during mate attraction. White colouration intensity increased as the breeding season progressed and may be related to an influx of conspecifics. Colour change from cryptic grey to bright white occurred rapidly (< 90 seconds) and may be deployed to enhance behavioural signals. We conclude that bright white colouration in the white ecotype is a potential signal of mate quality and may have evolved from a previously existing capacity for colour plasticity in common Threespine Stickleback.

Sign in / Sign up

Export Citation Format

Share Document