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 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>

Depleting wild prey compels common leopard (Panthera pardus) to sustain on livestock

2019 ◽  
Vol 69 (2) ◽  
pp. 213-230 ◽  
Author(s):  
Abid Hussain ◽  
Tariq Mahmood ◽  
Faraz Akrim ◽  
Shaista Andleeb ◽  
Hira Fatima ◽  
...  
Keyword(s):  
Prey Species ◽  
Winter Season ◽  
Wide Distribution ◽  
Iucn Red List ◽  
Critically Endangered ◽  
Panthera Pardus ◽  
Jammu And Kashmir ◽  
The Common ◽  
Prey Remains ◽  
Endangered Status

Abstract The wide distribution of a predator can reflect its flexibility in adapting to various ecosystems. The common leopard (Panthera pardus) is “Critically Endangered” in Pakistan while the IUCN Red List categorizes it globally as “Vulnerable”. This study investigated the distribution of the common leopard and the contribution of livestock in its diet in District Sudhanoti of Azad Jammu and Kashmir. During the surveys, scats, pugmarks, prey remains, and dead bodies of the common leopard were recovered in a scanned area of approximately 262 km2. The scats were mostly found on tracks and trails in hilly terrain, and pugmarks in the riparian zone and nallas, while prey remains were found mostly in dense bushes and rocks. Dead common leopards were recovered within or around village areas. All signs of the species were found between 418 m and 2016 m elevation above sea level. Scat analysis revealed a total of ten prey species including seven domestic mammals and only three wild meso-mammals. Domestic animals were most frequently consumed while wild prey contributed significantly less. The consumption of domestic prey species was found not to differ between the summer and winter season. We conclude that the common leopard was sustaining mainly on livestock with a much smaller contribution from wild prey. This fact, along with the “Critically Endangered” status of the species in the country, demands effective conservation measures to be taken to save common leopards.

Winter diet of Long-eared Owls (Asio otus) in the southern Pannonian Plain (Serbia, Vojvodina)

2021 ◽  
pp. 175815592110365
Author(s):  
Filip Tulis ◽  
Nadja Poljak ◽  
Milan Ruzic ◽  
Ján Obuch
Keyword(s):  
Diet Composition ◽  
Prey Species ◽  
Common Vole ◽  
Bird Species ◽  
Wood Mouse ◽  
Winter Diet ◽  
Pannonian Plain ◽  
The Common ◽  
Food Niche ◽  
Qualitative Changes

Owl diets undergo qualitative changes across the different regions of their area of distribution. During the four winters (from 2014–15 to 2017–18), Long-eared Owls’ pellets were collected at three winterroosts located at the southern part of Pannonian Plain, in the Serbian province of Vojvodina. In 8070 prey items from pellets, we identified 16 mammal and 32 bird species. The Common Vole was the dominant prey species with a proportion in a range from 27.4% to 71.6%. The Muridae family formed a supplementary part of the diet: Mus sp., wood mouse and harvest mouse, during all winters. Birds were also a major supplementary prey during winter 2014–15, comprising 10.6%. A comparison of our results with the diet of Long-eared Owls wintering at the northern Pannonian plain (southwestern Slovakia) indicated an increase the proportion of some species in the southern part. How different land uses in agriculture and environmental conditions may be reflected in the food supply are discussed in relation to the diet composition of Long-eared Owls and an environment whose is richer provides both growing diversity in the diet of these owls and an expansion of their food niche. Our study described the Long-eared Owl as opportunistic predators expanding their food niche in the presence of diversified prey.

scholarly journals Biometric properties and diet of common pandora, Pagellus erythrinus (Osteichthyes: Sparidae), from the eastern Adriatic sea

2011 ◽  
Vol 63 (1) ◽  
pp. 217-224 ◽  
Author(s):  
M. Santic ◽  
Biljana Radja ◽  
Antonela Paladin ◽  
Andreja Kovacevic
Keyword(s):  
Diet Composition ◽  
Prey Species ◽  
Adriatic Sea ◽  
The Black Sea ◽  
Biometric Analysis ◽  
Dorsal Fin ◽  
Opportunistic Predator ◽  
Eye Diameter ◽  
The Common ◽  
Common Pandora

Biometric properties and diet composition were examined in 120 specimens of the common pandora caught in the eastern Adriatic Sea. Biometric analysis of the morphometric and meristic characteristics indicate a homogenous morphology stock of P. erythrinus in the eastern Adriatic Sea. Changes in some of the morphometric characteristics obtained in conjunction with an increase in body length showed that smaller specimens have a longer dorsal fin, standard length, eye diameter and postorbital distances than larger specimens. The meristic characteristics of the common pandora from Italian waters and the Black Sea are mostly in agreement with data in our study. The prey species identified in the stomachs belong to five groups: Decapoda, Bivalvia, Polychaeta, Teleostei and Euphausiacea. Decapods were the most important ingested prey group while bivalves were second in importance. Various prey groups and species found in the stomach indicate that the common pandora could be an opportunistic predator.

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>

Seasonal and between-year variations in the diet of harbour seals in the Moray Firth, Scotland

1996 ◽  
Vol 74 (6) ◽  
pp. 1110-1121 ◽  
Author(s):  
D. J. Tollit ◽  
P. M. Thompson
Keyword(s):  
Diet Composition ◽  
Gadus Morhua ◽  
Prey Species ◽  
Temporal Variations ◽  
Short Term ◽  
Harbour Seals ◽  
Faecal Samples ◽  
Poor Indicator ◽  
Moray Firth ◽  
Merlangius Merlangus

Predictions concerning the effect of seals upon prey stocks require an understanding of temporal variations in diet composition. This study examined the extent of between-year and seasonal variations in the diet of harbour seals (Phoca vitulina) from the Moray Firth, Scotland, between 1989 and 1992. Analyses of fish otoliths and cephalopod beaks collected from 1129 faecal samples were used to derive estimates of the contribution made by each of 35 prey species, based on the number and mass consumed. The key prey, by mass, were sand eels (Ammodytidae) (47%), lesser octopus (Eledone cirrhosa) (27%), whiting (Merlangius merlangus) (6%), flounder (Platichthys flesus) (5%), and cod (Gadus morhua) (4%). Between-year and seasonal fluctuations in the contributions of these species were observed. Sand eels contributed 86–20% in summer and 91–49% in winter. Lesser octopus contributed 0–62% in summer and < 5% in winter, whilst whiting and cod contributed 2–34% in winter and 1–4% in summer. In contrast to 1988, clupeids were unimportant in winter. Differences in diet composition appeared to reflect local changes in the availability of food, especially overwintering clupeids. Results indicate that dietary information obtained from short-term studies can be a poor indicator of subsequent diet composition and should be treated with caution when used to predict the effect of seals on prey populations.

scholarly journals Feeding Ecology of Short-Toed Snake-Eagle (Circaetus gallicus [Gmelin, 1788]) in the Montados of Iberian Peninsula

2020 ◽  
Vol 28 (2) ◽  
pp. 155-179
Author(s):  
Nuno Onofre ◽  
Luís Sampaio
Keyword(s):  
Relative Abundance ◽  
Diet Composition ◽  
Prey Species ◽  
Prey Selection ◽  
Prey Type ◽  
Generalist Predator ◽  
Important Prey ◽  
Psammodromus Algirus ◽  
Circaetus Gallicus ◽  
Water Snakes

The diet of Short-toed Snake-eagle (Circaetus gallicus) during the breeding season in an area dominated by cork and holm oak parkland forests (Montados) was analyzed in this study. As expected, results showed that snakes are the dominant prey in the diet of this eagle, comprising up to 92.5% of the identified items, if potential secondary prey species were excluded. The Montpellier Snake (Malpolon monspessulanus) was the most consumed one (42.2%), followed by the Ladder Snake (Zamenis scalaris) (28.0%), and the water snakes (Natrix spp.) (14.2%). According to the same criteria, lizards (mainly Psammodromus algirus) and mammals represent between 4.8 and 2.2%, respectively. Other animals such as pond turtle and amphibians are irregular prey (<1%), and no bird remains were found at all. Short-toed Snake-eagle is usually referred as a stenophagic predator where snakes are by far its most important prey type, and where within this taxonomic group it behaves as a generalist predator. In this study this premise was then tested comparing the relative abundance of the snake species with their proportion in the diet composition of the eagle in order to know whether or not prey selection exists with regard to the species of snakes in this region. Results point to a quite plausible "preference" for the Ladder Snake and an "avoidance" for the smooth snakes group (Macroprotodon brevis/Coronella girondica), and possibly for the Horseshoe Whip (Hemorrhois hippocrepis). The avoidance to the Horseshoe Whip must be indirect and habitat related, while in relation to the two smooth snakes it may be due in large extend to its small size, in particular.

scholarly journals Different alternative diets within two subgroups in a winter roost of long-eared owls

2019 ◽  
Vol 13 (1) ◽  
pp. 139-144
Author(s):  
Filip Tulis ◽  
Tomáš Veselovský ◽  
Simon Birrer
Keyword(s):  
Prey Species ◽  
Common Vole ◽  
Wood Mouse ◽  
Alternative Prey ◽  
The Common

Abstract In winter 2013/2014 a roost of long-eared owls in Bojnice Spa (central Slovakia) was formed by two subgroups situated 12 meters apart from each other. The diets of both subgroups and the direction of the owls’ departure from the roost were studied at monthly intervals. Owls of the Pinus-subgroup left the roost in a significantly different direction compared with the owls in the Picea-subgroup. The common vole was the most hunted prey in both subgroups. However, comparing the alternative prey of the two subgroups, the wood mouse and other mammals were found significantly more often in pellets of the Picea-sub-group, whereas birds were more frequent in pellets of the Pinus-subgroup. Our results suggest that the different prey hunted by the two subgroups may be a consequence of diverging hunting areas with different availability of alternative prey species.

Raptor Prey Remains

2020 ◽  
Author(s):  
Ed Drewitt
Keyword(s):  
Feeding Ecology ◽  
Prey Species ◽  
Local Level ◽  
Body Parts ◽  
Change Over Time ◽  
The Common ◽  
Prey Remains ◽  
Over Time ◽  
Prey Populations

Are you curious about the remains of an animal you have found? This compilation of the most likely found body parts of animals eaten by raptors will help you identify your discovery. Including over 100 species of bird and mammal prey of raptors such as sparrowhawks, peregrines and hen harriers, this photographic guide highlights the common feathers, fur and other body parts found at raptor nests, roosts, plucking posts and other opportunistic spots. Discovering what raptors eat is an important part of confirming their feeding ecology and how this might change over time, vary on a local level or in response to changing prey populations, as well as dispelling myths and assumptions about what certain raptor species eat. Diet studies are vital for the conservation of raptor species; the more we know about what they need for survival the more we can predict and plan long-term for the protection and survival of raptors that may be vulnerable and in decline. This is the first book to show in detail the actual parts of a bird, mammal or other animal that you are likely to find in a garden, woodland or beneath a raptor roost. As more people take an interest in raptors and watch species such as peregrines via webcams and through watch groups, there is greater opportunity for finding prey remains. This book provides the first and most important step in identifying a prey species.

scholarly journals Dive behaviour and foraging effort of female Cape fur seals Arctocephalus pusillus pusillus

2019 ◽  
Vol 6 (10) ◽  
pp. 191369 ◽  
Author(s):  
S. P. Kirkman ◽  
D. P. Costa ◽  
A.-L. Harrison ◽  
P. G. H. Kotze ◽  
W. H. Oosthuizen ◽  
...  
Keyword(s):  
Prey Species ◽  
Foraging Ecology ◽  
Critical Role ◽  
Ecosystem Structure ◽  
Depth Range ◽  
Dive Behaviour ◽  
Top Predators ◽  
Fur Seals ◽  
Cape Fur Seal ◽  
Benthic Diving

While marine top predators can play a critical role in ecosystem structure and dynamics through their effects on prey populations, how the predators function in this role is often not well understood. In the Benguela region of southern Africa, the Cape fur seal ( Arctocephalus pusillus pusillus ) population constitutes the largest marine top predator biomass, but little is known of its foraging ecology other than its diet and some preliminary dive records. Dive information was obtained from 32 adult females instrumented with dive recorders at the Kleinsee colony (29°34.17′ S, 16°59.80′ E) in South Africa during 2006–2008. Most dives were in the depth range of epipelagic prey species (less than 50 m deep) and at night, reflecting the reliance of Cape fur seals on small, vertically migrating, schooling prey. However, most females also performed benthic dives, and benthic diving was prevalent in some individuals. Benthic diving was significantly associated with the frequency with which females exceeded their aerobic dive limit. The greater putative costs of benthic diving highlight the potential detrimental effects to Cape fur seals of well-documented changes in the availability of epipelagic prey species in the Benguela.

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