scholarly journals Breeding stage, not sex, affects foraging characteristics in masked boobies at Rapa Nui

2020 ◽  
Vol 74 (12) ◽  
Author(s):  
Miriam Lerma ◽  
Nina Dehnhard ◽  
Guillermo Luna-Jorquera ◽  
Christian C. Voigt ◽  
Stefan Garthe
Keyword(s):  
Prey Availability ◽  
General Pattern ◽  
Sexual Segregation ◽  
Food Distribution ◽  
Rapa Nui ◽  
Breeding Stage ◽  
Horizontal Competition ◽  
Show Evidence ◽  
Competition For Food ◽  
The Difference

Abstract Sexual segregation in foraging occurs in some species and populations of boobies (Sulidae), but it is not a general pattern. Sexual segregation in foraging may occur to avoid competition for food, and this competition may intensify during specific stages of breeding. We examined sexual segregation in foraging in relation to breeding stage in masked boobies Sula dactylatra at Rapa Nui by tracking simultaneously incubating and chick-rearing birds using GPS recorders (n = 18) and collected a total of 11 regurgitate samples. Stable isotope analyses (δ13C and δ15N) of whole blood samples were carried out in 20 birds. There were no differences in foraging trip parameters or diet between females and males. Both sexes traveled farther and for longer while incubating than while rearing chicks. Isotopic niches (δ13C and δ15N) overlapped to some degree among all groups at all times, but the lowest overlap between sexes occurred during incubation. While preying on ephemerally distributed flying fish, vertical or horizontal competition avoidance may be almost impossible, and thus females and males share their foraging grounds. Since birds were tracked simultaneously, shorter foraging trips of chick-rearing birds must be an effect of the constraints of provisioning the chick. Differences observed in δ15N and δ13C values between sexes may be caused by subtle differences in their foraging behaviors, or by differences in physiology linked to breeding. Our findings suggest that local oceanography and its inherent food distribution are determinants for sexual segregation in foraging patterns in masked boobies and possibly also other booby species. Significance statement In some animals, females and males forage on different areas or prey on different species to avoid competition for food resources. In boobies (Sula sp.), some studies show evidence of sexual segregation in foraging and others do not. Here, we tested if sexual segregation in foraging occurred in masked boobies on the Pacific island of Rapa Nui by studying simultaneously incubating and chick-rearing birds. We found no evidence of sexual segregation on foraging behavior or diet. We discuss that the difference between this and other studies in boobies may be an effect of the local prey availability. When the prey community is more diverse and heterogeneously distributed, each sex may access different resources and thus sexual foraging segregation will occur. In contrast, in areas like Rapa Nui where prey resources are distributed ephemerally, sexual segregation in foraging will not be useful and is thus less likely to occur.

TEMPORAL PATTERNS OF PARENTAL RESOURCE DISTRIBUTION IN THE RED-NECKED GREBE: EQUALIZING THE SHARE OF THE SURVIVORS

Behaviour ◽  
2001 ◽  
Vol 138 (11-12) ◽  
pp. 1355-1370 ◽  
Author(s):  
Janusz Kloskowski
Keyword(s):  
Resource Allocation ◽  
Dominance Hierarchy ◽  
Food Distribution ◽  
Brood Reduction ◽  
Male And Female ◽  
Investment Allocation ◽  
Parental Aggression ◽  
Competition For Food ◽  
Podiceps Grisegena ◽  
Over Time

AbstractFood distribution within brood and parental aggression to chicks were studied in the asynchronously hatching red-necked grebe Podiceps grisegena throughout the whole period of parental care. When carrying young - during the first two weeks after hatching - parents did not interfere in sibling competition for food. The proportions of food received by each brood member reflected the dominance hierarchy. After this period, parents showed aggression to offspring, especially to the older chicks and the within-brood hierarchy of received food was gradually reversed. Junior chicks were also longer cared for than their older sibling. Male and female parents did not differ in the food apportionment among differentrank chicks. It is suggested that red-necked grebe parents change the within-brood investment allocation over time. In the first weeks after hatching, they allow biased food distribution and in consequence even brood reduction. Later, they intervene in resource allocation and attempt to equalize the post-fledging survival of all chicks. Parental aggression appears to be a means both for counteracting the competitive advantage of older sibs and for forcing the chicks to independence.

Crosslinguistic influence in bilingual language acquisition: Italian and French as recipient languages

2001 ◽  
Vol 4 (1) ◽  
pp. 1-21 ◽  
Author(s):  
Natascha Müller ◽  
Aafke Hulk
Keyword(s):  
Romance Languages ◽  
Bilingual Children ◽  
Positive Evidence ◽  
Grammatical Analysis ◽  
Target Form ◽  
Universal Principles ◽  
Show Evidence ◽  
The Difference ◽  
Italian Children ◽  
Crosslinguistic Influence

In this paper we want to compare the results from monolingual children with object omissions in bilingual children who have acquired two languages simultaneously. Our longitudinal studies of bilingual Dutch–French, German–French, and German–Italian children show that the bilingual children behave like monolingual children regarding the type of object omissions in the Romance languages. They differ from monolingual children with respect to the extent to which object drop is used. At the same time, the children differentiate the two systems they are using. We want to claim that the difference between monolingual and bilingual children concerning object omissions in the Romance languages is due to crosslinguistic influence in bilingual children: the Germanic language influences the Romance language. Crosslinguistic influence occurs once a syntactic construction in language A allows for more than one grammatical analysis from the perspective of child grammar and language B contains positive evidence for one of these possible analyses. The bilingual child is not able to map the universal strategies onto language-specific rules as quickly as the monolinguals, since s/he is confronted with a much wider range of language-specific syntactic possibilities. One of the possibilities seems to be compatible with a universal strategy. We would like to argue for the existence of crosslinguistic influence, induced by the mapping of universal principles onto language-specific principles – in particular, pragmatic onto syntactic principles. This influence will be defined as mapping induced influence. We will account for the object omissions by postulating an empty discourse-connected PRO in pre-S position (Müller, Crysmann, and Kaiser, 1996; Hulk, 1997). Like monolingual children, bilingual children use this possibility until they show evidence of the C-system (the full clause) in its target form.

Kant as Seen by Hegel

1982 ◽  
Vol 13 ◽  
pp. 93-109
Author(s):  
W. H. Walsh
Keyword(s):  
Special Care ◽  
Pure Reason ◽  
Critique Of Pure Reason ◽  
Show Evidence ◽  
The Difference ◽  
Main Ideas ◽  
The Impact

Few major philosophers show evidence of having studied the works of their predecessors with special care, even in cases where they were subject to particular influences which they were ready to acknowledge. Hume knew that he was working in the tradition of ‘some late philosophers in England, who have begun to put the science of man on a new footing’—‘Mr Locke, my Lord Shaftsbury, Dr Mandeville, Mr Hutchinson, Dr Butler, &c.’ But there is not much sign in the Treatise or elsewhere in Hume's writings of any close acquaintance with the works of these authors; the presumption must be that he had read them at some time and extracted the main ideas, but was not in the habit of returning to their texts. He had something more important to do, namely to work at philosophical problems of his own. Similarly Kant, though he said that the Critique of Pure Reason was not meant to be ‘a critique of books and systems, but of the faculty of reason in general’, had clearly felt the impact of the thought of some important past philosophers, but equally had never spent much time in finding out just what these philosophers had to say. Plato, Aristotle, Descartes, Locke, Leibniz and Hume all get fairly frequent mention in his pages. But Kant takes his knowledge of Plato and Aristotle from J. J. Brucker's Historia critica philosophiae, a six-volume compilation which first appeared in 1742, or from doubtful sources such as Mendelssohn's doctored translation of the Phaedo, and though he doubtless knew the more recent authors at first hand clearly felt no need to study them in any depth. This was true even of writers to whom he attributed a particular importance, such as Leibniz and Hume. The references to Hume in the Critique and Prolegomena are all disappointingly general, and though the summary of Leibniz's philosophy in the section called ‘The Amphiboly of Concepts of Reflection’ has a certain force, it is not documented with references to Leibnizian texts. Kant knows that there is a difference between the views of the historical Leibniz and those which constituted the ‘Leibnizian-Wolffian system’ of his successors. But he is not very curious about the difference, or inclined to explore it.

Interspecific relationships between two species of sympatric Afrotropical water snake in relation to a seasonally fluctuating food resource

2005 ◽  
Vol 22 (1) ◽  
pp. 91-100 ◽  
Author(s):  
Luca Luiselli
Keyword(s):  
Prey Size ◽  
Prey Availability ◽  
Interference Competition ◽  
Food Resource ◽  
Wet Season ◽  
Snake Species ◽  
Water Snake ◽  
Body Sizes ◽  
The Difference ◽  
Increased Activity

In this paper, the ecological relationships and the resource partitioning patterns in a two-species system of sympatric aquatic snakes (Grayia smythii and Afronatrix anoscopus) from a riverine forest area in southern Nigeria, West Africa, were tested. The monthly availability of their food resources in the field, and the monthly variation in the feeding relationships between these snakes and their preys, were also studied. Food items of 1245 snakes, i.e. 554 Grayia smythii, and 691 Afronatrix anoscopus, were examined. The mean body length of Grayia smythii was significantly larger than that of Afronatrix anoscopus in any interspecific comparison, i.e. males versus males, females versus females, and females versus males; however, in both species the females attained significantly larger body sizes than the males. 676 prey items were obtained from the stomachs of Afronatrix anoscopus, and 390 from those of Grayia smythii. Both species of snake exhibited an increased activity in the open during the wet months, and this increased activity was positively correlated to the higher abundance of prey during the wet season. In both species the diet consisted of a great variety of different amphibian and fish species. Direct interference competition was not observed. The month-by-month dietary patterns exhibited by the two snake species were similar. Mean prey size was significantly larger in the larger species, and the difference in prey size between the two snake species increased during the dry season, i.e. during the period of reduced prey availability. The monthly availability of the three main food types for these snakes varied, and were significantly more abundant during the wet season (April–September). A positive relationship between prey availability and prey use by snakes strongly suggests that the two snake species are predatory generalists, utilizing prey in relation to their abundance in the field.

The effect of plane of nutrition during rearing on growth, production, reproduction and health of dairy cattle. II. Growth to maturity

1960 ◽  
Vol 2 (01) ◽  
pp. 45-57 ◽  
Author(s):  
J. A. Crichton ◽  
J. N. Aitken ◽  
A. W. Boyne
Keyword(s):  
General Pattern ◽  
Live Weight ◽  
Body Dimension ◽  
Continuous Growth ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Treatment Groups ◽  
Growth Production ◽  
The Difference ◽  
Mature Size

1. The four systems of rearing dairy heifer calves, described in Part 1 of this series are now studied for their effect on absolute and relative growth rates to maturity.2. Data on live-weights and measurements and the percentages of mature size attained by these at 44, 80, 104, 132, 182, 260 and 312 weeks of age are tabulated.3. In all groups the measurement to reach maturity earliest was circumference of metacarpus followed in order by length of back, height at withers and width of hooks.4. By 6 years of age all groups had attained approximately the same body size. Maturity in the LL group in terms of four skeletal measurements was delayed by only 9 months, and in the case of HL and LH animals by 5 and 4 months respectively.5. All groups showed the same general pattern of relative growth but the effect of restricted feeding was to increase at the younger ages the difference i n percentage of mature size between early and late maturing measurements. After 44 weeks of age the rate of growth was most rapid in those measurements which were furthest from maturity then.6. The rate of tissue deposition was markedly increased in high plane animals during early pregnancy compared with low plane. Evidence is presented to show that much of this was lost during lactation.7. At first oestrus, animals in all four treatment groups had reached the same percentage of mature size for each body dimension (except for length of back in the LL group).8. From data on 5 animals it is shown that although growth in height at withers and length of back ceased by 6 years of age there was slow but continuous growth in live-weight, middle and heart girths and width of hooks to 9 years of age.

scholarly journals Intuitive Feeling of Closeness to Solution Preceding Insight in Anagram Tasks

2019 ◽  
Vol 6 (4) ◽  
pp. 16-23
Author(s):  
Alexey Medyntsev ◽  
◽  
Alena Kogan ◽  
Pavel Sabadosh ◽  
Olga Dyatlova ◽  
...  
Keyword(s):  
Analytical Solutions ◽  
Visual Features ◽  
Final Solution ◽  
Unconscious Processing ◽  
Main Research ◽  
Successful Solution ◽  
Show Evidence ◽  
Research Questions ◽  
The Difference

One of the main research questions related to creativity is the dilemma of specificity vs. non-specificity of the mechanisms underlying insight solutions as compared to analytical solutions of a problem. The first goal of our study was to verify insight solution specificity on solving anagram tasks. The second goal was to test a hypothesis about the existence of unconscious processing prior to insight solutions. We presented two types of stimuli to participants: anagrams and pseudowords. During the experiment, participants had to perform two successive tasks. First they had to judge whether they were being shown an anagram or a pseudoword, and then they had to solve the anagram. Anagrams and pseudowords differed in some visual features, of which the participants were not aware. It was expected that unconscious processing (if it exists) would be influenced by the implicit difference between the appearance of stimulus categories. During the solving process, participants had to rate how close they were to a solution. After a successful solution, they also had to indicate which way they found it: analytically or with insight. Our results showed that prior to an insight solution, participants felt that they were farther from the final solution than in the case of an analytical solution. These results confirm Metcalfe and Wiebe’s (1987) conclusions on the difference between insight and analytical solutions. According to these data, we can propose different specific mechanisms for insight solutions and analytical solutions in anagram tasks. At the same time, the presence of visual differences between stimulus categories did not influence the anagram solving process. The current results did not show evidence for an important role of unconscious processing before insight solutions of anagrams

Spatial behaviour of yellow-footed rock-wallabies, Petrogale xanthopus, changes in response to active conservation management

2011 ◽  
Vol 59 (1) ◽  
pp. 1 ◽  
Author(s):  
Matt W. Hayward ◽  
Keith Bellchambers ◽  
Kerryn Herman ◽  
Joss Bentley ◽  
Sarah Legge
Keyword(s):  
Movement Patterns ◽  
Capra Hircus ◽  
Home Ranges ◽  
Nutrient Requirements ◽  
Gps Telemetry ◽  
Winter Range ◽  
Introduced Herbivores ◽  
Ranging Behaviour ◽  
Competition For Food ◽  
The Difference

Competition for food is predicted to influence faunal movement patterns as animals have to range further to satisfy their nutrient requirements. Research between 1979 and 1984 found that yellow-footed rock-wallabies, Petrogale xanthopus, in Middle Gorge, Buckaringa Sanctuary, had home ranges (134–169 ha in winter) that were much larger than predicted, which was attributed to competing livestock and cropping. We studied the ranging behaviour of this population using GPS telemetry after the cessation of farming and following several years of fox, Vulpes vulpes, and goat, Capra hircus, control to determine whether the reduction in competition and predation pressure has affected movement patterns of this endangered species. Mean winter range size of the four GPS-collared rock-wallabies was 4.3 ha (kernel or 5.5-ha MCP), which is a much smaller area than the rock-wallabies used before farming ceased and fox and goat control was implemented. The rock-wallabies primarily used the mid- to lower slopes of the gorge country and preferred redgum creeks and gorge habitats. The rock-wallabies exhibited a crepuscular activity pattern. We hypothesise that the difference in movements has arisen because the rock-wallabies are no longer competing for resources with introduced herbivores, and are able to meet their forage requirements from a smaller area.

Toxoplasmosis in prey species and consequences for prevalence in feral cats: not all prey species are equal

Parasitology ◽  
2007 ◽  
Vol 134 (14) ◽  
pp. 1963-1971 ◽  
Author(s):  
E. AFONSO ◽  
P. THULLIEZ ◽  
D. PONTIER ◽  
E. GILOT-FROMONT
Keyword(s):  
Prey Species ◽  
Prey Availability ◽  
Igg Antibodies ◽  
Antibody Prevalence ◽  
Feral Cats ◽  
Modified Agglutination Test ◽  
Infection Dynamics ◽  
Predation Efficiency ◽  
The Difference ◽  
Effect Of Age

SUMMARYToxoplasma gondiiis largely transmitted to definitive felid hosts through predation. Not all prey species represent identical risks of infection for cats because of differences in prey susceptibility, exposure and/or lifespan. Previously published studies have shown that prevalence in rodent and lagomorph species is positively correlated with body mass. We tested the hypothesis that different prey species have different infection risks by comparing infection dynamics of feral cats at 4 sites in the sub-Antarctic Kerguelen archipelago which differed in prey availability. Cats were trapped from 1994 to 2004 and anti-T. gondiiIgG antibodies were detected using the modified agglutination test (⩾1:40). Overall seroprevalence was 51·09%. Antibody prevalence differed between sites, depending on diet and also on sex, after taking into account the effect of age. Males were more often infected than females and the difference between the sexes tended to be more pronounced in the site where more prey species were available. A difference in predation efficiency between male and female cats may explain this result. Overall, our results suggest that the composition of prey items in cat diet influences the risk ofT. gondiiinfection. Prey compositon should therefore be considered important in any understanding of infection dynamics ofT. gondii.

Effects of winterkill on population structure, body size, and prey consumption patterns of pumpkinseed in isolated beaver ponds

1990 ◽  
Vol 68 (12) ◽  
pp. 2489-2498 ◽  
Author(s):  
Michael G. Fox ◽  
Allen Keast
Keyword(s):  
Body Size ◽  
Prey Availability ◽  
Small Body ◽  
Consumption Patterns ◽  
Lepomis Gibbosus ◽  
Small Body Size ◽  
Stunted Growth ◽  
Beaver Ponds ◽  
The Difference ◽  
Annual Mortality

Beaver ponds are a ubiquitous, but rarely studied, aquatic habitat that are subject to hypoxia and other catastrophic events that can affect fish populations. We examined the population dynamics and feeding ecology of pumpkinseeds (Lepomis gibbosus) inhabiting two isolated Ontario beaver ponds and adjacent Lake Opinicon to determine the persistence of and reasons for small body size in pond populations. Pumpkinseed populations fluctuated drastically in both ponds as a result of winterkills (from hypoxia and a decline in water level). These winterkills eliminated as many as 96% of the older pumpkinseeds and resulted in populations consisting mainly of age 0–2 individuals. Pond pumpkinseeds rarely survived to age 5, whereas lake conspecifics lived to age 8 or older. The diet of pond pumpkinseeds consisted mainly of chironomids, ephemeropterans, odonates, and molluscs, whereas lake pumpkinseeds ate mainly molluscs. The difference in diets was attributed mainly to differences in prey availability in the two habitats. Despite lower prey biomass and higher population density, pond pumpkinseeds grew as fast as, or faster than, their lake conspecifics owing mainly to early warming of water in the spring and the absence of bluegills and other major competitors. We conclude that small body size in pond pumpkinseed populations is due to high annual mortality and not stunted growth.

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