scholarly journals Up for grabs: prey herding by penguins facilitates shallow foraging by volant seabirds

2019 ◽  
Vol 6 (6) ◽  
pp. 190333 ◽  
Author(s):  
A. M. McInnes ◽  
P. A. Pistorius
Keyword(s):  
Group Size ◽  
Inverse Relationship ◽  
Vertical Displacement ◽  
Foraging Efficiency ◽  
Shallow Waters ◽  
Foraging Success ◽  
Seabird Species ◽  
Marine Communities ◽  
Prey Biomass ◽  
Strong Inverse Relationship

Visual and olfactory signals are commonly used by seabirds to locate prey in the horizontal domain, but foraging success depends on prey depth and the seabird's ability to access it. Facilitation by diving seabirds has long been hypothesized as a mechanism to elevate deep prey to regions more accessible to volant seabirds, but this has never been demonstrated empirically. Footage from animal-borne video loggers deployed on African penguins was analysed to establish if volant seabird encounters involved active cuing by seabirds on penguins to obtain prey and, during mutual prey encounters, if interactions were driven by the vertical displacement of prey by penguins. Independent of prey biomass estimates, we found a strong inverse relationship between penguin group size, a proxy for visibility, and the time elapsed from the start of penguins' dive bouts to their first encounter with other seabirds. Most mutual prey encounters (7 of 10) involved schooling prey elevated from depths greater than 33 m by penguins and only pursued by other seabird species once prey was herded into shallow waters. This is likely to enhance foraging efficiency in volant seabird species. As such, penguins may be integral to important processes that influence the structure and integrity of marine communities.

scholarly journals Natural dimethyl sulfide gradients would lead marine predators to higher prey biomass

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Kylie Owen ◽  
Kentaro Saeki ◽  
Joseph D. Warren ◽  
Alessandro Bocconcelli ◽  
David N. Wiley ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
Dimethyl Sulfide ◽  
Zooplankton Biomass ◽  
Foraging Success ◽  
Spatially Correlated ◽  
Prey Biomass ◽  
Marine Predators ◽  
Predator Foraging ◽  
The Impact

AbstractFinding prey is essential to survival, with marine predators hypothesised to track chemicals such as dimethyl sulfide (DMS) while foraging. Many predators are attracted to artificially released DMS, and laboratory experiments have shown that zooplankton grazing on phytoplankton accelerates DMS release. However, whether natural DMS concentrations are useful for predators and correlated to areas of high prey biomass remains a fundamental knowledge gap. Here, we used concurrent hydroacoustic surveys and in situ DMS measurements to present evidence that zooplankton biomass is spatially correlated to natural DMS concentration in air and seawater. Using agent simulations, we also show that following gradients of DMS would lead zooplankton predators to areas of higher prey biomass than swimming randomly. Further understanding of the conditions and scales over which these gradients occur, and how they are used by predators, is essential to predicting the impact of future changes in the ocean on predator foraging success.

Group size modulates time budget and foraging efficiency in captive Skylarks, Alauda arvensis

2011 ◽  
Vol 153 (2) ◽  
pp. 485-490 ◽  
Author(s):  
Thibaut Powolny ◽  
Cyril Eraud ◽  
Vincent Bretagnolle
Keyword(s):  
Group Size ◽  
Time Budget ◽  
Foraging Efficiency ◽  
Alauda Arvensis

Moss distribution in streams of the Quebec Laurentian Mountains

2000 ◽  
Vol 78 (6) ◽  
pp. 748-752 ◽  
Author(s):  
Antonella Cattaneo ◽  
Lucie Fortin
Keyword(s):  
Water Depth ◽  
Inverse Relationship ◽  
Competitive Interaction ◽  
Filamentous Cyanobacterium ◽  
Patchy Distribution ◽  
Moss Cover ◽  
Aquatic Mosses ◽  
Water Ph ◽  
Strong Inverse Relationship ◽  
Substratum Size

To model the distribution of aquatic mosses, we measured their cover in 33 Quebec streams. The variation in moss cover among streams was explained mostly (42%) by substratum size (percentage >25 cm in diameter). Water pH and depth also explained a significant amount of variation (9 and 10%, respectively). Within a stream, moss cover was again positively correlated to the availability of large substrata and negatively to water depth. There was a strong inverse relationship between covers of moss and of the filamentous cyanobacterium Stigonema, suggesting a competitive interaction. This study confirms previous observations that moss distribution is mainly controlled by substratum size. Chemistry explains part of the among-stream variation. Stigonema-moss competition partly accounts for the patchy distribution within a stream.Key words: aquatic mosses, Fontinalis, streams, Quebec.

Redistributing Control between the Elements of a Compound Stimulus

1970 ◽  
Vol 22 (3) ◽  
pp. 478-483 ◽  
Author(s):  
C. G. Miles ◽  
N. J. Mackintosh ◽  
R. F. Westbrook
Keyword(s):  
Discrimination Training ◽  
Inverse Relationship ◽  
Compound Stimulus ◽  
Strong Inverse Relationship

Twenty-eight pigeons were given discrimination training. Four groups were run in which for 0, 2, 4 and 9 sessions of training colour was an irrelevant cue and tone was relevant. Generalization tests were given in extinction; the training colour (C1) and another colour (C2) were presented with tone (T) and noise (N). Responding to these four stimulus combinations, TC1, TC2, NC1 and NC2, allowed the assessment of control by colour and tone. A reduction of control by colour and an increase in control by tone were found to be positively related to the amount of training with colour irrelevant. Tests showed a strong inverse relationship between control by colour and tone.

scholarly journals Quadratic relationships between group size and foraging efficiency in a herbivorous primate

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Cyril C. Grueter ◽  
Andrew M. Robbins ◽  
Didier Abavandimwe ◽  
Veronica Vecellio ◽  
Felix Ndagijimana ◽  
...  
Keyword(s):  
Group Size ◽  
Foraging Efficiency

scholarly journals Feeding in murky waters: acclimatization and landmarks improve foraging efficiency of zebrafish ( Danio rerio ) in turbid waters

2019 ◽  
Vol 15 (7) ◽  
pp. 20190289
Author(s):  
M. A. Sekhar ◽  
Richa Singh ◽  
Anuradha Bhat ◽  
Manjari Jain
Keyword(s):  
Foraging Efficiency ◽  
Visual Environment ◽  
Behavioural Plasticity ◽  
Foraging Success ◽  
Visual Landmarks ◽  
Water Turbidity ◽  
Turbid Waters ◽  
And Function ◽  
Extended Exposure

Fish inhabiting human-dominated ecosystems are prone to altered sensory environments in which they must live and function. Increased turbidity is one such change that they must deal with. We tested whether an increase in water turbidity and the presence of visual landmarks (coloured stones) affect the foraging efficiency of wild zebrafish. We also tested the influence of extended exposure to differing turbidity levels on the subsequent foraging efficiency of acclimatized individuals. Feeding latency (time taken to find food) increased significantly with increase in turbidity levels from a minimum of 4 s to ca 300 s. However, extended exposure of fish to varying levels of turbidity decreased feeding latencies in acclimatized conditions, indicating that acclimatization to the immediate visual environment plays an important role in determining foraging success. Most significantly, we found that feeding latencies in turbid conditions decreased significantly if visual landmarks were present. This demonstrates that zebrafish use visual landmark cues to navigate to foraging sites when visibility is impaired. This study has important implications on the role of behavioural plasticity and spatial learning in animals that allow them to cope with altered sensory environments such as episodes of enhanced turbidity that could be natural or anthropogenic.

THE EFFECT OF HANDLING TIME ON INTERFERENCE AMONG HOUSE SPARROWS FORAGING AT DIFFERENT SEED DENSITIES

Behaviour ◽  
2001 ◽  
Vol 138 (5) ◽  
pp. 597-614 ◽  
Author(s):  
Cheryl Johnson ◽  
James W.A. Grant ◽  
Luc-Alain Giraldeau
Keyword(s):  
Group Size ◽  
Ideal Free Distribution ◽  
Passer Domesticus ◽  
Handling Time ◽  
Foraging Success ◽  
House Sparrows ◽  
Interference Models ◽  
Foraging Time ◽  
Ideal Free ◽  
The Ideal

AbstractInterference models of the ideal free distribution (IFD) assume competition among foraging animals causes intake rates to decline with increasing competitor density and that the strength of the decline influences forager distributions among food patches. However, the resulting distributions of animals may depend on which components of foraging success contribute to interference. We examined the effect of group size (1-13 birds) on the prey encounter rates, handling times, and foraging rates of house sparrows, Passer domesticus, feeding at three seed densities in a suburban backyard. House sparrows did not experience interference during search. Interference arose primarily from foraging time lost handling seeds. Foraging rates decreased with increasing seed density as a consequence of increased handling times. Also, birds experiencing significant increases in handling time with group size suffered most from interference. Our results suggest that animals adjust handling time to avoid costly aggressive interactions, indicating that handling time may be an important component of interference in some foraging systems. Future studies estimating interference should try to identify which components of foraging contribute to interference, paying particular attention to handling times for species that monitor and avoid competitors.

scholarly journals COMPARAÇÃO DA EFICIÊNCIA DE FORRAGEIO DAS GARÇAS EGRETTA CAERULEA E EGRETTA THULA NO ESTUÁRIO DE PARANAGUÁ, PARANÁ, SUL DO BRASIL

2021 ◽  
Vol 25 (01) ◽  
pp. 59-68
Author(s):  
Danila Syriani Veluza ◽  
◽  
Juliana Rechetelo ◽  
Emygdio Leite de Araújo Monteiro-Filho ◽  
Luiz Augusto Macedo Mestre ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Shallow Water ◽  
Capture Efficiency ◽  
Foraging Efficiency ◽  
Shallow Waters ◽  
Success Rates ◽  
Local Conditions ◽  
Foraging Site ◽  
Egretta Thula

The foraging efficiency of birds may vary according to local conditions as a result of the balance between energy consumption and expenditure. The foraging efficiency of Egretta thula (adults n=11) and Egretta caerulea (adults n=69 and juveniles n= 17) was compared in Paranaguá city estuary, in Paraná, Brazil. In 14 hours of observation divided into 2 minutes sessions per individual, were recorded foraging site (mud or shallow water), number of steps, total peckings and successful peckings, and were calculated the success rates, energy effort and capture efficiency. In shallow water E.thula was more efficient than E. caerulea. There was no intraspecific differences in E. thula regarding environments. Adults of E. caerulea were more efficient than juveniles, with greater efficiency in mud than in shallow waters environments. Differences in foraging efficiency between species may be related to the type of foraging according to feeding location.

scholarly journals Foraging behaviour and the risk of predation in the black house spider, Badumna insignis (Desidae)

1999 ◽  
Vol 47 (1) ◽  
pp. 29 ◽  
Author(s):  
Robbie J. Henderson ◽  
Mark A. Elgar
Keyword(s):  
Foraging Behaviour ◽  
Foraging Efficiency ◽  
Foraging Success ◽  
Short Term ◽  
Risk Of Predation ◽  
House Spider ◽  
The Web ◽  
Model Predator

Many animals adjust their behaviour according to the presence or threat of predators. However, the foraging behaviour of sit-and-wait predators is typically thought to be inflexible to short-term changes in the environment. Here we investigate the foraging behaviour of the nocturnally active black house spider, Badumna insignis. Experiments in which different kinds of prey were introduced into the web during either the day or night indicated that the foraging success of Badumna is compromised by behaviours that reduce the risk of predation. During the day, spiders generally remain within the retreat and take longer to reach the prey, which may reduce their foraging success. In contrast, spiders sat exposed at the edge of the retreat at night, and from here could usually reach the prey before it escaped. The spiders were able to escape from a model predator more rapidly if they were at the edge of the retreat than if they were out on the web. These data suggest that the costs to Badumna of reduced fecundity through poor foraging efficiency may be outweighed by the benefits of reducing the risk of predation

scholarly journals A call for observations of birds with sublingual oral fistulas in central and eastern Europe, and beyond

2021 ◽  
Vol 29 (2) ◽  
pp. 188-194
Author(s):  
S. James Reynolds
Keyword(s):  
Eastern Europe ◽  
Western Europe ◽  
Central And Eastern Europe ◽  
Science Research ◽  
Foraging Efficiency ◽  
Research Project ◽  
Ongoing Research ◽  
Seabird Species ◽  
Ascension Island ◽  
In The Wild

Abstract Birds with major physical abnormalities do not live for extended periods and, therefore, are rarely observed in the wild. This is particularly the case for birds with defects in their feeding apparatus that succumb to mortality rapidly through precipitous declines in their foraging efficiency and body condition. Sublingual oral fistulas are such an abnormality and involve the development of an opening (or fistula) in the floor of the oral cavity through which the tongue extends, resulting in its permanent exclusion from the mouth. The tongue dehydrates and dies. First described in the 2000s in Stitchbirds (Notiomystis cincta) in New Zealand, it has rarely been reported in other species. However, following our recent discovery of two seabird species on Ascension Island in the South Atlantic displaying oral fistulas, in 2016 I launched a citizen science research project requesting reports of birds with the condition in the world’s avifauna. To date, I have received 188 reports of birds of 82 different species with many contributed from western Europe. However, with only one report from central and eastern Europe, I am now requesting the assistance of birders in the region and in other parts of the world to contribute to this ongoing research project.

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