The glossy black-cockatoo (Calyptorhynchus lathami halmaturinus) spends little time and energy foraging on Kangaroo Island, South Australia

2005 ◽  
Vol 53 (3) ◽  
pp. 177 ◽  
Author(s):  
Tamra F. Chapman ◽  
David C. Paton

The endangered Kangaroo Island glossy black-cockatoo (Calyptorhynchus lathami halmaturinus) relies entirely on the seeds of the drooping sheoak (Allocasuarina verticillata) for food. The time budget of the glossy black-cockatoos and their foraging behaviour was recorded to provide an indication of whether their food supply was likely to be limiting. The foraging behaviour of non-breeding and breeding cockatoos was also compared to record the strategy they used to collect the additional energy needed to raise young. Glossy black-cockatoos spent a relatively small proportion of their time foraging, suggesting that the food supply was abundant in the habitats used for feeding. Non-breeding birds spent only 26% of their time feeding and breeding birds spent only 36% of their time feeding. The cockatoos spent 0.4% of their time flying, foraged in a mean of only five trees per day and harvested cones in no more than five bouts per tree. This shows that the cockatoos made few movements between drooping sheoaks and within the canopy of the sheoaks when foraging. When breeding, the cockatoos spent significantly more time per day foraging, cropped cones in significantly more bouts per tree and harvested significantly more cones per tree than non-breeding birds. This shows that breeding birds increased their energy intake without greatly increasing movement between trees. The small number of movements made by glossy black-cockatoos when foraging on Kangaroo Island reflects the abundance of food trees and may be a strategy to reduce the risk of predation.

2011 ◽  
Vol 57 (3) ◽  
pp. 223-246 ◽  
Author(s):  
Solomon A. Tadesse ◽  
Burt P. Kotler

Nubian ibex (Capra nubiana) prefer steep terrain in their landscape to reduce risks of predation and human nuisance disturbances. They also use vigilance and time allocation to manage risk of predation. We studied time budgets and habitat selection of Nubian ibex to: (1) identify the habitat variables to which Nubian ibex were behaviorally responsive; (2) investigate how time budget responses of Nubian ibex were related to season, slope condition, group size, and sex-age structure; and (3) develop behavioral-based models that account for the variations in the behaviors of Nubian ibex across the landscape and seasons.To quantify time budgets, we took regular field observations on focal individuals of Nubian ibex classified according to their habitat, group size, sex, and age. For each focal observation, we quantified environmental variables that were thought to influence the behavioral responses of ibex. Then, we developed behavioral models by correlating the proportion of behaviors measured in focal animal observations to the influential environmental variables. The behaviors of Nubian ibex significantly varied with sex and age structure, season, habitat type, and slope conditions. Adult females are more vigilant than adult male ibex, especially in the spring. This correlates with breeding and nursing activities. Based on the characteristics of the habitat, ibex behave to minimize risks of predation and human nuisance disturbances while maximizing their food intake.


2018 ◽  
Vol 11 (2) ◽  
pp. 67-73
Author(s):  
Brad T. McLeod ◽  
Gary Ritchison

Breeding is energetically costly and, if energy-limited, birds may alter their time budgets, spending less time engaged in some activities and more time in others. Investigators who have provided breeding birds with supplemental food have noted changes in time budgets, but the extent and types of changes have been found to vary among species. Our objective was to determine how food supplementation might influence the time budgets and paternity status of male Indigo Buntings (Passerina cyanea). We studied Indigo Buntings from 8 May to 15 August 2009 in Madison County, Kentucky. Territories of male Indigo Buntings (n=30) were randomly assigned as either food supplemented (n=8) or controls (n=22). During time-budget observations, all behaviours were noted. To determine paternity status, blood samples were collected from adults and nestlings at 16 nests. Males with feeders in their territories spent significantly less time foraging and more time vocalising (chip notes) than males without feeders. Time spent singing and mate guarding by treatment and control males did not differ. Differences in the proportion of extra-pair young did not differ between nests in territories with and without supplemental food. Our results suggest that, when provided with supplemental food, male Indigo Buntings spend less time foraging and more time engaged in other activities. However, neither the presence of supplemental food nor differences in the behaviour of males in food-supplemented versus non-supplemented territories affected rates of extra-pair paternity.


2000 ◽  
Vol 48 (2) ◽  
pp. 155 ◽  
Author(s):  
Eve McDonald-Madden ◽  
Lian K. Akers ◽  
Deena J. Brenner ◽  
Sarah Howell ◽  
Blair W. Patullo ◽  
...  

Many eutherian mammals adjust their foraging behaviour according to the presence or threat of predators. Here, we examine experimentally whether an urban population of brushtail possums, Trichosurus vulpecula, similarly adjust their foraging behaviour. Our field experiments manipulated the quantity of food items in artificial feeders placed at different distances from trees. These experiments showed that the possums remained longer at feeders placed far from the trees, but their foraging behaviour did not change with the initial amount of food. The scanning behaviour of possums did not simply increase with distance from the trees, as predicted from studies of other vertebrates. Nevertheless, the number of physical conflicts between individuals increased as the amount of available food decreased. These data suggest that the changes in the foraging behaviour of the possums in this population do not reflect a simple trade-off between foraging efficiency and the risk of predation or competition.


1994 ◽  
Vol 42 (4) ◽  
pp. 449 ◽  
Author(s):  
BP Kotler ◽  
JS Brown ◽  
WA Mitchell

Predation greatly influences many aspects of the ecology of desert rodents, from foraging behaviour to mechanisms of species coexistence to the evolution of specialised morphologies. Using a foraging-theory approach, we examine consequences of predation for assemblages of desert rodents from North America and the Middle East. In particular, we review experimental evidence that examines the influence of predation on foraging costs and foraging behaviour, explore how predation can act to structure communities, and discuss the role that predation may have played in the evolution of bipedal locomotion. Finally, we compare the importance of predation for the evolution of anti-predator behaviours and morphology, for population dynamics, and for community processes, with its magnitude and heterogeneity. In regard to foraging behaviour, desert rodents treat the risk of predation as a cost of foraging. They combine assessments of food and safety to arrive at foraging decisions, exploiting resource patches less intensively in response to increased predatory risk. The cost of predation can be up to 91% of the foraging costs of desert rodents, but the proportion is greater for Middle Eastern rodents than for North American rodents. In regard to community structure, predation can provide the niche axis as well as the necessary tradeoff for species coexistence. Despite the importance of predation in shaping the foraging behaviour of desert rodents, predation may not always influence species coexistence. Predation contributes to species coexistence at sites in the Sonoran and Great Basin deserts. But in the Negev Desert, where predation costs are the greatest, predation does not provide a mechanism of species coexistence. In regard to bipedal locomotion, predation most likely confers superior ability to avoid predators by improving sprint speed and ability to take evasive action, but at the expense of foraging ability in safe microhabitats. The evolution of bipedality will be favoured by situations where the risk of predation is great: the open microhabitat is riskier than the bush, the richest patches are found in the riskiest places, and rich patches are far apart. The magnitude of predatory risk will affect the evolution of anti-predator behaviour and morphologies. However, the importance of predation in community processes is not determined by its magnitude, but by its heterogeneity in time and space relative to the abilities of potentially coexisting species.


2019 ◽  
Vol 27 (1) ◽  
pp. 85-98 ◽  
Author(s):  
Khalil Draidi ◽  
Badis Bakhouche ◽  
Naouel Lahlah ◽  
Imed Djemadi ◽  
Mourad Bensouilah

Abstract Although the Ferruginous Duck (Aythya nyroca) has thoroughly been studied, the foraging behaviour of this species is still not completely known. In the present paper we studied the diurnal feeding behaviour of ducks. We monitored the annual cycle of birds through two fieldtrips per month. The instantaneous behaviour of birds was recorded in regular 30-minute intervals from 7 a.m. to 4:30 p.m., amounting a total of 456 observation hours. Food searching activity corresponds to a quarter of the total diurnal time budget of the Ferruginous Duck. Foraging behaviour was classified into five categories dominated by the “diving”, which is almost 45.61% of the total search time. Foraging activities at the water surface considered to be secondary activities, including feeding by “bill”, “neck and head”, and “beak and head” in a rate of 19.86%, 14.53%, and 13.98%, respectively. The “toggle” remains a minor activity and represents only 5.99% of foraging time. The feeding behaviour of this species correlated to several environmental parameters (rainfall, temperature and wind velocity), and linked to the group size of ducks visiting the lake. Regarding the food intensity, our results show the highest values for “bill and head” behaviour. “Diving” has the longest feeding interval (16.16±14.1 minutes), while foraging by “bill” has the shortest (0.69 ± 0.48 minutes).


1999 ◽  
Vol 47 (1) ◽  
pp. 29 ◽  
Author(s):  
Robbie J. Henderson ◽  
Mark A. Elgar

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


Author(s):  
Seana Valentine Shiffrin

This chapter considers how the U.S. law of deceptive advertising embeds within it an extended form of responsibility, making advertisers sometimes responsible for consumers’ mistakes. The chapter justifies this pattern of liability as a division of moral labor that bolsters consumers’ ability to trust the quality of the food supply and the representations made about it. It answers worries about paternalism, arguing that the law is not predicated on distrust of consumers, but facilitates consumer autonomy, permitting consumers to direct their scarce time and energy to projects of their own choosing. The chapter also answers freedom of speech concerns about restricting advertisers’ ability to make factually true representations. It emphasizes that commercial speakers have a special responsibility to ensure accurate uptake by consumers because property law affords commercial producers the ability to exclude consumers and their representatives from verifying speech about speakers’ products for themselves.


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