scholarly journals The diet of white-chinned petrels Procellaria aequinoctialis, Linnaeus 1758, in years of contrasting prey availability at South Georgia

1999 ◽  
Vol 11 (3) ◽  
pp. 283-292 ◽  
Author(s):  
Simon D. Berrow ◽  
John P. Croxall
Keyword(s):  
Breeding Success ◽  
Prey Item ◽  
Prey Availability ◽  
Euphausia Superba ◽  
Feeding Frequency ◽  
South Georgia ◽  
Important Prey ◽  
Breeding Failure ◽  
Feeding Methods ◽  
Procellaria Aequinoctialis

The diet of breeding white-chinned petrels was studied during the summers of 1996 and 1998 at South Georgia. Krill abundance/availability was high throughout 1996 but apparently low at the beginning of the 1998 breeding season. The diet of white-chinned petrels was similar between years and consistent with previous studies. Krill Euphausia superba (41–42% by weight) was the single most important prey item followed by fish (39–29%) and squid (19–25%). Meal mass was consistent (110 g in 1996, 119 g in 1998) between years but a significant decrease (46%) in feeding frequency in 1998 (0.54 meals day−1 compared to 0.75 meals day−1 in 1996) resulted in 19% less food delivered to chicks in 1998 than in 1996. Breeding success, however, was consistent between years at 44% and similar to that recorded previously at Bird Island. This is in contrast to black-browed and grey-headed albatrosses, both of which experienced almost total breeding failure in 1998. It is suggested that their varied and versatile feeding methods, together with their greater diving ability, capacity to feed at night and extensive foraging range, help white-chinned petrels minimise the effects of krill shortage.

New data on Martialia hyadesi feeding in the Scotia Sea during winter; with emphasis on seasonal and annual variability

2004 ◽  
Vol 84 (4) ◽  
pp. 785-788 ◽  
Author(s):  
J. Dickson ◽  
S.A. Morley ◽  
T. Mulvey
Keyword(s):  
Prey Availability ◽  
Stomach Contents ◽  
Euphausia Superba ◽  
The South ◽  
Scotia Sea ◽  
South Georgia ◽  
Annual Variability

The diet of the seven star flying squid, Martialia hyadesi, from the South Georgia sector of the Scotia Sea was described from stomach contents collected in winter (June) 2001. Diet was dominated by the hyperiid amphipod, Themisto gaudichaudii, fish (nine species, mainly myctophids) and cephalopods (mainly cannibalism). The absence of krill, Euphausia superba, and the presence of larger myctophids in the diet are discussed in terms of seasonal and annual prey availability.

scholarly journals Variation among colonies in breeding success and population trajectories of wandering albatrosses Diomedea exulans at South Georgia

Polar Biology ◽  
2021 ◽  
Author(s):  
Carola Rackete ◽  
Sally Poncet ◽  
Stephanie D. Good ◽  
Richard A. Phillips ◽  
Ken Passfield ◽  
...  
Keyword(s):  
Body Condition ◽  
Breeding Success ◽  
Population Trends ◽  
Contributing Factors ◽  
South Georgia ◽  
Vortex Model ◽  
Demographic Rates ◽  
Diomedea Exulans ◽  
Adult Body ◽  
Provisioning Rate

AbstractThe wandering albatross, Diomedea exulans, is a globally threatened species breeding at a number of sites within the Southern Ocean. Across the South Georgia archipelago, there are differences in population trends even at closely located colonies. Between 1999 and 2018 the largest colony, at Bird Island, declined at 3.01% per annum, while in the Bay of Isles, the decline was 1.44% per annum. Using mean demographic rates from a 31-year study at Bird Island and an 11-year study of breeding success at Prion Island in the Bay of Isles in a VORTEX model, we show that differences in breeding success do not fully explain observed differences in population trends. Other potential contributing factors are differential use of foraging areas, with possible knock-on effects on adult body condition, provisioning rate and breeding success, or on bycatch rates of adults or immatures.

Irruptive White Ibis breeding is associated with use of freshwater crayfish in the coastal Everglades

The Condor ◽  
2021 ◽  
Vol 123 (1) ◽  
Author(s):  
Tasso C Cocoves ◽  
Mark I Cook ◽  
Jeffrey L Kline ◽  
Lori Oberhofer ◽  
Nathan J Dorn
Keyword(s):  
Prey Availability ◽  
Freshwater Crayfish ◽  
Seasonal Wetlands ◽  
Important Prey ◽  
Procambarus Alleni ◽  
Eudocimus Albus ◽  
Hydrologic Restoration ◽  
Prey Composition ◽  
White Ibis ◽  
Nesting Activity

Abstract As avian reproductive success is generally prey limited, identifying important prey types or sizes and understanding mechanisms governing prey availability are important objectives for avian conservation ecology. Irruptive White Ibis (Eudocimus albus) nesting at coastal colonies in the southern Everglades numbered over 100,000 nests in the 1930s. A century of drainage and altered hydrologic patterns reduced aquatic prey availability and eliminated large nesting events; nesting activity in recent decades has been typically less than 5% of historical peaks. Hydrologic restoration is expected to increase ibis nesting activity, but which prey types will support high nesting effort is less clear. In 2017 and 2018, we collected food boluses from White Ibis chicks at coastal colonies in Everglades National Park. We also monitored regional nesting activity from 1999 to 2018. In 2017, the region had 1,075 nests, typical of the past several decades; but in 2018, there were 30,420 nests, representing the highest recorded nesting activity in 87 yr. Prey composition varied between years; estuarine crabs dominated nestling boluses in 2017, while crayfish and fish were dominant prey in 2018. Crayfish, especially Procambarus alleni, were heavily exploited by ibis early in the 2018 breeding season, while fish were used more at the end. Crayfish abundances in wetlands near the colonies were higher prior to 2018, and more crayfish-producing short-hydroperiod wetlands remained available for ibis foraging in 2018. Our results support previous studies indicating that crayfish are important prey for breeding ibises and suggest that unprecedented, extensive flooding of seasonal wetlands promoted crayfish production and initiated the irruptive breeding in 2018. Our observations indicate that rehydration of the southern Everglades could restore ibis nesting activity at coastal colonies, but further investigations of hydrologic variation, crayfish production, and ibis foraging and nesting activity will be helpful to understand these dynamics and the importance of short-hydroperiod wetlands.

scholarly journals Diet of St. Lawrence Estuary Beluga (Delphinapterus leucas) in a changing ecosystem

2020 ◽  
Vol 134 (1) ◽  
pp. 21-35
Author(s):  
Véronique Lesage ◽  
Stéphane Lair ◽  
Samuel Turgeon ◽  
Pierre Béland
Keyword(s):  
Prey Availability ◽  
Population Decline ◽  
Delphinapterus Leucas ◽  
Anthropogenic Factors ◽  
Adult Males ◽  
Current Time ◽  
Lawrence Estuary ◽  
The Past ◽  
Important Prey ◽  
St Lawrence Estuary

Ecosystems and community structure fluctuate over time as a result of natural and anthropogenic factors that may affect prey availability and population dynamics. Most of what we know about St. Lawrence Estuary (SLE) Beluga (Delphinapterus leucas) diet comes from stomach contents collected 80 years ago mainly from a hunting site that Beluga no longer use. How reflective these data are of Beluga diet at other sites and at the current time is unknown. In the context of the recent population decline, general information of prey species alone may help identify useful conservation actions for potentially important prey or habitats. Here, we examined the diet of SLE Beluga using digestive tracts collected from carcasses recovered over the past 30 years, in the context of historical diet data and recent changes in the St. Lawrence ecosystem. We showed they have a varied diet composed of fish and invertebrates generally <30 cm in length, and that adult males and females differ in their summer diet in a way that is consistent with the sex segregation observed in this population. Our results also indicate that polychaete worms, squid, and cod are still among the most prevalent prey, and that species such as redfish (Sebastes spp.) might be important prey items. This study shows that Beluga diet has changed since the 1930s, and that prey from digestive tracts identified to species are valuable for making comparisons to the past, and for improving applications of molecular analyses, such as stable isotopes and fatty acids.

scholarly journals Diet of Ameerega braccata (Steindachner, 1864) (Anura: Dendrobatidae) from Chapada dos Guimarães and Cuiabá, Mato Grosso State, Brazil

2011 ◽  
Vol 71 (1) ◽  
pp. 189-196 ◽  
Author(s):  
LR. Forti ◽  
ASO. Tissiani ◽  
T. Mott ◽  
C Strüssmann
Keyword(s):  
Body Size ◽  
Niche Breadth ◽  
Prey Availability ◽  
Feeding Habits ◽  
Close Association ◽  
Mato Grosso ◽  
Important Prey ◽  
Phylogenetic Perspective ◽  
Toxic Alkaloids ◽  
Two Populations

The understanding of feeding habits is important for anurans in general, both from an ecological and a phylogenetic perspective. For diurnal poison frogs belonging to the Dendrobatidae family, diet aspects play a crucial role in their defense and survival. Herein, we investigated feeding habits, foraging behaviour, and overall effects of habitat, sex, and body size on the diet of individuals of Ameerega braccata, a poorly known dendrobatid species. Specimens were observed and collected in the type-locality, Chapada dos Guimarães, and in the neighbouring municipality of Cuiabá, both in the State of Mato Grosso, Midwestern Brazil. The most important prey categories for A. braccata were Formicidae, Isoptera, and Acari, whose representatives were caught during active foraging. Individuals from Chapada dos Guimarães population consumed more Acari but fewer Isoptera than individuals from Cuiabá. Despite this, niche breadth values were narrow and similar for the two populations. Individuals from two distinct habitats (campo sujo and cerrado stricto sensu) showed differences in their diet, probably as an effect of differential prey availability. Females consumed more Isoptera than males. The number of prey categories used as food was not influenced by the variation of body size of the target species. However, the abundance and the volume of consumed Acari were statistically correlated with body size. The main results suggest that Ameerega braccata has a narrow niche breadth, as well as a specialised diet in ants, termites, and mites, which reinforces the hypotheses of close association between Acari consumption and the presence of skin toxic alkaloids, already found in other species of Dendrobatidae. Although differences in prey consumption between sexes are uncommon among poisonous frogs, differences in the diet composition between age classes, which probably reduce intraspecific competition, are frequently reported.

scholarly journals Breeding success and causes of breeding failure of curlewNumenius arquatain Northern Ireland

1999 ◽  
Vol 36 (1) ◽  
pp. 59-74 ◽  
Author(s):  
Murray C. Grant ◽  
Chris Orsman ◽  
Jon. Easton ◽  
Chris Lodge ◽  
Malcolm Smith ◽  
...  
Keyword(s):  
Northern Ireland ◽  
Breeding Success ◽  
Breeding Failure

The white-chinned petrel (Procellaria aequinoctialis) on South Georgia: population size, distribution and global significance

Polar Biology ◽  
2009 ◽  
Vol 32 (4) ◽  
pp. 655-661 ◽  
Author(s):  
A. R. Martin ◽  
S. Poncet ◽  
C. Barbraud ◽  
E. Foster ◽  
P. Fretwell ◽  
...  
Keyword(s):  
Population Size ◽  
Size Distribution ◽  
South Georgia ◽  
Procellaria Aequinoctialis ◽  
Georgia Population

Mortality and breeding failure of little penguins, Eudyptula minor, in Victoria, 1995 - 96, following a widespread mortality of pilchard, Sardinops sagax

2000 ◽  
Vol 51 (4) ◽  
pp. 355 ◽  
Author(s):  
Peter Dann ◽  
F. I. Norman ◽  
J. M. Cullen ◽  
F. J. Neira ◽  
A. Chiaradia
Keyword(s):  
At Risk ◽  
Breeding Season ◽  
Breeding Success ◽  
Egg Laying ◽  
First Year ◽  
Breeding Failure ◽  
Food Species ◽  
Intestinal Parasitism ◽  
Western Victoria

In May 1995, numbers of little penguins, Eudyptula minor, coming ashore declined at Phillip Island and St Kilda concurrently with deaths of many penguins in western Victoria and a massive mortality of one of their food species (pilchard) throughout southern Australia. Among 1926 dead penguins reported were 131 banded birdsrecovered from Phillip Island (86% adults and 14% first-year birds), 26 from Rabbit Island and six from St Kilda. The number of banded penguins found dead per number of adult Phillip Island birds at risk was 2.3% in 1995 compared with an annual mean of 0.7% for 1970–93. Of 29 corpses autopsied, at least 26 died of starvation associated with mild–severe gastro-intestinal parasitism. Following the pilchard mortality, egg-laying by penguins in the subsequent breeding season (1995–96) was ~2 weeks later than the long-term mean and 0.3 chicks were fledged per pair compared with the long-term mean of 1.0. Unlike previous years, few penguins were recorded in Port Phillip Bay in September–October 1995, a period when pilchard schools were infrequently seen. It is concluded that the increase in penguin mortality in northern Bass Strait and the significant reduction in breeding success were associated with the widespread pilchard mortality.

Comparison between the feeding habits of spotted eagle ray (Aetobatus narinari) and their potential prey in the southern Gulf of Mexico

2018 ◽  
Vol 99 (3) ◽  
pp. 661-672 ◽  
Author(s):  
F. Serrano-Flores ◽  
J.C. Pérez-Jiménez ◽  
I. Méndez-Loeza ◽  
K. Bassos-Hull ◽  
M.J. Ajemian
Keyword(s):  
Gulf Of Mexico ◽  
Prey Species ◽  
Prey Availability ◽  
Feeding Habits ◽  
Small Scale ◽  
Potential Prey ◽  
Important Prey ◽  
Ecological Aspects ◽  
Southern Gulf Of Mexico ◽  
Spotted Eagle Ray

In the southern Gulf of Mexico, the spotted eagle ray (Aetobatus narinari) is the second most frequently caught batoid in small-scale fisheries off Campeche. Ecological aspects of this ray are unknown in this region, hampering the understanding of the relationship between its distribution and prey availability in the fishing area. In order to study the feeding habits of this batoid and characterize its potential prey in the study area, stomachs and intestines of 154 specimens (68 females and 86 males) were analysed. The results indicated that A. narinari near Campeche is a specialist and selective predator that feeds mainly on gastropods (92.7% IRI), with no significant differences in the diet found between sexes, size groups, or between stomach and intestine contents. In addition, the results indicated that the most important prey species in the diet were among the most common benthic species in three of the four sampling transects positioned in or adjacent to fishing areas for rays. These most important prey species were Strombus pugilis (53.33% IRI) and Americoliva reticularis (25.6% IRI). Other prey species included Lobatus costatus (5.6% IRI) and Petrochirus diogenes (3.6% IRI). This study suggests that this widely distributed ray species feeds in Campeche's coastal waters and that the study of its potential prey increases the understanding of ecological aspects of the species, which emphasizes the added importance of monitoring fishery impacts on prey species (e.g. the conch fishery off Campeche) to help support integrated assessment and management of fisheries.

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