Role of begging and sibling competition in foraging strategies of nestlings

Abstract Live-trapped, adult American Woodcock (Scolopax minor) were tested in a series of laboratory experiments designed to evaluate the role of soil as a proximal cue for selecting feeding sites and to investigate foraging strategies for capturing earthworms (Lumbricidae). Foraging trials were conducted in a circular arena and showed that color, which tends to be correlated with the soil types and moisture regimes preferred by earthworms, was an important proximal cue for selecting feeding sites. Woodcock captured earthworms most efficiently in areas of relatively high prey density, because they used a nonrandom search pattern following an initial capture.

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The role of body size in individual-based foraging strategies of a top marine predator

Ecology ◽

10.1890/08-1554.1 ◽

2010 ◽

Vol 91 (4) ◽

pp. 1004-1015 ◽

Cited By ~ 59

Author(s):

Michael J. Weise ◽

James T. Harvey ◽

Daniel P. Costa

Keyword(s):

Body Size ◽

Foraging Strategies ◽

Marine Predator

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Reversed Sexual Size Dimorphism: Effect on Resource Defense and Foraging Behaviors of Nonbreeding Northern Harriers

The Auk ◽

10.1093/auk/103.1.70 ◽

1986 ◽

Vol 103 (1) ◽

pp. 70-78 ◽

Cited By ~ 24

Author(s):

Ethan J. Temeles

Keyword(s):

Sexual Size Dimorphism ◽

Sexual Differences ◽

Foraging Strategies ◽

Resource Defense ◽

Aggressive Interactions ◽

Nonbreeding Season ◽

Males And Females ◽

Circus Cyaneus ◽

Reversed Sexual Size Dimorphism

Abstract Sexual differences in resource defense and foraging behaviors during the nonbreeding season are detailed for Northern Harriers (Circus cyaneus) in California. Female harriers hunted more frequently in high (>0.5 m) vegetation than males. In addition, females hunted at slower speeds and used different hunting behaviors than males. Females in high vegetation showed a significantly greater response (i.e. attack) rate to approaching harriers than males, and females won nearly all (28/29) aggressive interactions with males. These results suggest that sexual differences in harrier foraging behavior during the nonbreeding season result from females excluding males from preferred foraging areas and males adopting alternative foraging strategies. Foraging strategies of harrier sexes are compared with foraging strategies of sexes of birds in which males are larger than females to examine the role of body size in determining sexual foraging strategies.

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Abyssal traces and megafauna: comparison of productivity, diversity and density in the Arctic and Antarctic

Paleobiology ◽

10.1017/s0094837300005844 ◽

1978 ◽

Vol 4 (2) ◽

pp. 171-180 ◽

Cited By ~ 39

Author(s):

Jennifer A. Kitchell ◽

James F. Kitchell ◽

G. Leonard Johnson ◽

Kenneth L. Hunkins

Keyword(s):

Food Availability ◽

Deep Sea ◽

Foraging Strategy ◽

The Arctic ◽

Foraging Strategies ◽

Behavioral Complexity ◽

Productivity Differential ◽

The Antarctic ◽

Trace Density

The megafauna and associated behavioral traces of two deep-sea benthic environments, the central Arctic and Antarctic, with a surface primary productivity differential of 104 were compared to assess the role of food availability in foraging strategy and community structure. Bottom photographs, analyzed for megafauna and trace density and diversity at comparable depths in the Arctic Canada Basin and the Antarctic Bellingshausen Basin, indicated that trace frequency was inversely proportional to organism density but that trace diversity directly reflected organism diversity. Those traces identified in the fossil record to represent efficient foraging strategies, i.e., the Nereites facies, were conspicuously absent at all depths in the Arctic and present at all depths in the Antarctic, in contradiction of the paradigm of increasing behavioral complexity and sediment exploitation as food availability decreases. Presence or absence of surface-grazing organisms seems to exert a greater influence on trace diversity than depth or nutrient supply. Trace density, however, may reflect episodic sedimentation events which intermittently influence the deep-sea trophic regime.

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Host Adaptation in Entomopathogenic Nematodes: An Approach to Enhancing Biological Control Potential

10.32747/1996.7613023.bard ◽

1996 ◽

Author(s):

Itamar Glazer ◽

Randy Gaugler ◽

Yitzhak Spiegel ◽

Edwin Lewis

Keyword(s):

Entomopathogenic Nematodes ◽

Insect Pests ◽

Lectin Binding ◽

Natural Populations ◽

Foraging Strategies ◽

Host Recognition ◽

Field Activity ◽

Biological Control Potential ◽

The Common

The overall objective of our research was to develop methods to match species of entomopathogenic nematodes against the insect pests which they would be best adapted to control. The underlying hypothesis for this work was that entomopathogenic nematodes should be most effective when used against insect species to which they are naturally adapted to parasitize. Toward this end, we undertook a number of related studies focusing primarily on nematode foraging strategies. We found that foraging strategies affected host associations directly and indirectly. Nematodes' responses to host cues, and the role of their sensory organs based on lectin binding, led to new approaches to determining host range for these parasites. Based on this work, we developed a laboratory bioassay of host recognition behavior designed to predict field results. We also determined that nematodes that forage in a stationary manner (ambushers) have a slower metabolic rate than do active forgers (cruisers), thus their infective stage juveniles are longer lived. This study helps predict the duration of field activity after application and may partially explain field distributions of natural populations of entomopathogenic nematodes. The common thread linking all of these studies was that they led to a deeper understanding of the associations between entomopathogenic nematodes and insects as hosts.

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An experimental study of the role of seedling density and neighbor relatedness in the persistence of Rumex acetosella in an old-field succession

Canadian Journal of Botany ◽

10.1139/b94-155 ◽

1994 ◽

Vol 72 (9) ◽

pp. 1273-1281 ◽

Cited By ~ 13

Author(s):

Josep Escarré ◽

Claudie Houssard ◽

John D. Thompson

Keyword(s):

Resource Allocation ◽

High Density ◽

Sibling Competition ◽

Old Field ◽

Rumex Acetosella ◽

Habitat Variation ◽

Key Words Density ◽

Different Populations ◽

Older Populations

Patterns in flowering and biomass allocation in seedlings of Rumex acetosella L. collected from five successional old fields, from 1 year old to 15 years old, have been examined in experimental pots varying in density (1, 2, and 4 plants/pot) and neighbor relatedness (sib, nonsib, other population) to determine the effects of successional habitat variation on patterns of resource allocation. The flowering of seedlings from the successionally young populations was not affected by density, whereas for seedlings from the older populations, increased density was correlated with increased variation in flower and seed production both within and between populations. At high density, seedlings from the successionally youngest population showed the greatest allocation of resources to flowering. As a result, differentiation along the successional gradient was such that the younger populations invested a greater proportion of resources to aerial biomass, while the older populations allocated relatively more resources to vegetative propagation. These trends were maintained at high density. The results of the sibling competition treatment showed no consistent trend related to the age of the populations but were density dependent. At high density, sexual biomass was higher between nonsibs than between sibs of the same population, suggesting greater competition among related plants. Finally, the sexual biomass of individual plants was less in competition with seedlings from a different population than with seedlings from the same population. Sprout biomass showed the reverse trend. The observed differentiation between successionally different populations in resource allocation irrespective of density may account for these results. Overall, our results provide evidence for biotic specialization of R. acetosella in relation to successional habitat change. Key words: density, sibling competition, succession, trade-off, Rumex acetosella, resource allocation.

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Structure of mutualistic ant–treehopper interactions in the Brazilian Atlantic Forest

Journal of Tropical Ecology ◽

10.1017/s0266467416000183 ◽

2016 ◽

Vol 32 (3) ◽

pp. 250-259 ◽

Cited By ~ 2

Author(s):

Yve Eligiêr Alves Gadelha ◽

Wesley Dáttilo ◽

Olivia Evangelista ◽

Benedito Cortês Lopes

Keyword(s):

Atlantic Forest ◽

Food Resource ◽

Recruitment Strategy ◽

Foraging Strategies ◽

Brazilian Atlantic Forest ◽

Ecological Interactions ◽

Tropical Environments ◽

Study Sites ◽

Number Of Individuals

Abstract:Ant–treehopper mutualisms are centred on the availability of honeydew, a sugary fluid offered by treehoppers to attract ants, which respond by defending their hosts against predators and parasitoids. However, due to differences in the treehopper social behaviour (i.e. the amount of food resource available) ants can monopolize treehopper aggregations in many ways. Here we evaluated the topological structure of quantitative ant–treehopper interaction networks in three Brazilian Atlantic Forest localities. Moreover, we specifically investigated the role of ant recruitment strategy and treehopper behaviour in the structure of these networks. For this, we sampled ant–treehopper interactions along representative transects (6 km per site) within each studied site and recorded the mean number of individuals of treehopper and ant species. We found that independent of variation in environmental factors among study sites, ant–treehopper networks were highly compartmentalized (Mean ± SD: Q = 0.34 ± 0.1) when compared with null models, and exhibit low connectance (C = 0.18 ± 0.01) and specialization (H2’ = 0.36 ± 0.08) values. In addition, we also observed that larger aggregations of treehoppers interacted with a higher number of ant species and ants that were locally dominant and showed massive recruitment interacted with a larger number of treehopper species. In summary, our results illustrate the importance of foraging strategies in shaping ecological interactions in tropical environments.

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Behavioural observations of foraging minke whales (Balaenoptera acutorostrata) in the outer Moray Firth, north-east Scotland

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315407054161 ◽

2007 ◽

Vol 87 (1) ◽

pp. 85-86 ◽

Cited By ~ 6

Author(s):

Kevin P. Robinson ◽

Michael J. Tetley

Keyword(s):

Foraging Strategies ◽

Balaenoptera Acutorostrata ◽

Rissa Tridactyla ◽

Herring Gulls ◽

North East ◽

The North ◽

Minke Whales ◽

Moray Firth ◽

The North Sea

The minke whale (Balaenoptera acutorostrata) is a widespread, opportunistic species showing spatial and seasonal variations in diet according to local availability of prey. Although previous research has been conducted on the foraging strategies of this small rorqual whale, in terms of prey aggregation and assimilation, relatively little has been published on the foraging association of this species with coastal seabirds. Over the past five years, minke whales occurring along the outer coastline of the southern Moray Firth in north-east Scotland during the summer and autumn months have been recorded foraging in the presence of seabirds, such as kittiwakes (Rissa tridactyla), herring gulls (Larus argentatus), guillemots (Uria aalge) and shearwaters, which form dense feeding rafts at the water's surface. The formation of bird rafts notably occurs independently of the presence of B. acutorostrata, believed instead to be the successive result of prey concentrated at the surface by predatory schooling fish from below rather than by activities of the whales themselves. In this area of the North Sea, schooling mackerel (Scomber scombrus) constitute the most significant component of the summer fish biomass and are believed to perform the role of compacting targeted sandeel (Ammodytes spp.) prey into concentrated bait balls almost exclusively. The resulting ball of prey is consequently available to the foraging whale, which can be seen opportunistically utilizing successive bird rafts rather than expending unnecessary energy corralling the Ammodytes prey by traditional, active entrapment methods. The role of the mackerel in increasing both the rate and density of sandeel ball formation (as indicated by the presence and activity of associated bird rafts) is therefore thought to be very significant in this inshore Scottish location. Changes in oceanographic variables such as water temperature have been directly correlated with the migration of S. scombrus. The observed inter-annual variability in B. acutorostrata distribution in the outer Moray Firth may subsequently be related to the respective distribution and abundance of these migratory, pelagic fish species.

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