Foraging behaviour of oystercatchers Haematopus ostralegus during a diet switch from worms Nereis diversicolor to clams Scrobicularia plana

1989 ◽  
Vol 67 (9) ◽  
pp. 2225-2231 ◽  
Author(s):  
J. Sherman Boates ◽  
John D. Goss-Custard
Keyword(s):  
Food Intake ◽  
Foraging Behaviour ◽  
Capture Rate ◽  
Handling Time ◽  
Intake Rate ◽  
Nereis Diversicolor ◽  
Scrobicularia Plana ◽  
Haematopus Ostralegus ◽  
Food Value ◽  
Food Intake Rate

On the mudflats of the Exe Estuary in southwest England, oystercatchers Haematopus ostralegus switched from eating worms Nereis diversicolor to clams Scrobicularia plana during autumn. A decline in the profitability of worms (from 17 to 4 mg/s handling time) and the food intake of oystercatchers eating worms (from 1300 to < 200 mg/15 min) occurred prior to and during the switch to clams. Declines in profitability and food intake rate were due to seasonal changes in the size and food value of worms available to oystercatchers. Capture rate on worms varied little prior to, or during, the switch. Oystercatchers appeared to switch diets in response to changes in the reward offered by worms rather than in response to relative changes in the reward offered by the two prey species. This is because individual oystercatchers were never observed eating a mixed diet of worms and clams, and may explain why it took 6 weeks (11 October to 25 November) for the population to complete the switch.

Foraging behaviour of oystercatchers Haematopus ostralegus specializing on different species of prey

1992 ◽  
Vol 70 (12) ◽  
pp. 2398-2404 ◽  
Author(s):  
J. Sherman Boates ◽  
John D. Goss-Custard
Keyword(s):  
Foraging Behaviour ◽  
Prey Species ◽  
Prey Size ◽  
Handling Time ◽  
Littorina Littorea ◽  
Intake Rate ◽  
Prefer Prey ◽  
Rate Maximization ◽  
Scrobicularia Plana ◽  
Haematopus Ostralegus

Adult oystercatchers Haematopus ostralegus specializing on four prey species, the mussel Mytilus edulis, the winkle Littorina littorea, the ragworm Nereis diversicolor, and the clam Scrobicularia plana, were compared. Some clear trends from mussels to winkles to clams to worms were identified. First, mean biomass (size) of prey decreased but more prey were attacked per unit time and, since fewer attacks were aborted, more prey were actually captured per unit time. Second, handling time decreased, and birds raised their heads less often while handling a prey item and carried prey less frequently. Third, foraging density, attack rate, and avoidance rate all decreased. However, average rates of food intake did not follow the same order and were inconsistent with the expected preference for prey. The greatest intake rate was achieved by birds specializing on clams, the least preferred prey. The rate of intake of mussels, the most preferred prey, was significantly lower. Alternatives to the energy rate maximization model to explain prey preference are discussed and dismissed. The results of this study contrast with those from several studies on prey-size selection within a single prey species, which show that oystercatchers prefer prey that maximize their intake rates. We suggest that the basis for selecting a prey species and for selecting different size classes within one prey species may be quite different.

Differential effects of predation risk and competition over vigilance variables and feeding success in Eurasian siskins (Carduelis spinus)

Behaviour ◽  
2013 ◽  
Vol 150 (14) ◽  
pp. 1665-1687 ◽  
Author(s):  
Jordi Pascual ◽  
Juan Carlos Senar
Keyword(s):  
Food Intake ◽  
Predation Risk ◽  
Foraging Behaviour ◽  
Interference Competition ◽  
Ecological Factors ◽  
Intake Rate ◽  
Similar Length ◽  
Feeding Success ◽  
High Predation ◽  
Food Intake Rate

Many investigations have studied the effects of predation risk and competition over vigilance and feeding success, but they have proven to be difficult to discriminate. Moreover, none of the studies that have avoided the confusion has considered all the vigilance variables, food intake rate and time spent in the foraging patch. In this study, we designed an experiment with Eurasian siskinsCarduelis spinusforaging on three bird table feeders: one with low predation risk and competition, one with low predation risk and high competition and one with high predation risk and intermediate competition. Birds responded to increasing interference competition by increasing mean scan durations (probably due to the birds having to be vigilant for both other flock members and predators) and maintaining the length of mean inter-scan durations, while they responded to increasing predation risk by reducing mean inter-scan durations (probably in order to detect the predator sooner) while maintaining similar length of mean scan durations. Birds were often ejected from the feeder or departed because of disturbances, so time spent on feeders was reduced both because of competition and predation risk. Pecking rates were affected by competition but not by predation risk. Our results clearly show that birds vigilance strategy while foraging might be very different when they are mainly concerned with scanning for predators or when they primarily monitor competing flock companions. In addition, they stress the importance of recording all the vigilance and feeding variables when studying the effect of ecological factors over the foraging behaviour of birds.

scholarly journals An evaluation of the relation between food consumption rate and equilibrium body-weight in male rats

1988 ◽  
Vol 60 (1) ◽  
pp. 151-160 ◽  
Author(s):  
Tom W. Gettys ◽  
Susan Mills ◽  
Donald M. Henrickst
Keyword(s):  
Body Weight ◽  
Food Intake ◽  
Food Consumption ◽  
Consumption Rate ◽  
Growth Efficiency ◽  
Intake Rate ◽  
Total Intake ◽  
Food Consumption Rate ◽  
Maintenance Requirements ◽  
Food Intake Rate

1. Two experimental approaches were employed to assess the relation between food consumption rate and maintenance requirements in male weanling rats. The first approach involved restricting food intake in rats previously given free access to food from weaning to 59 d of age. The second approach involved restriction of food intake to various levels after weaning. Maintenance requirements (g foodid per g body-weight (W)) were estimated by dividing the rate of food consumption by the resulting equilibrium W (EBW) for each animal. In addition, food consumption was partitioned into growth-independent (maintenance) and growth-dependent (gain) components by alternately setting W and specific growth rate (W') to zero in an equation relating food intake rate to W and W. Coupling coefficients representing maintenance consumption (g food/d per g W) and gain consumption (g food/g gain) were estimated for each animal by least squares.2. Both techniques for estimating maintenance consumption provided similar estimates within and across experiments, and regardless of when food restriction was imposed or its severity, consumption for maintenance was about 5% W/d.3. The EBW to which animals in each treatment group aspired was directly proportional to that group's food intake rate.4. Coventional measures of growth efficiency were also related to food intake; efficiency decreased with decreasing food intake. Partitioning food consumption into maintenance and gain components revealed that as the rate of food intake decreased, the proportion of total intake consumed for maintenance increased. The results suggest that growth efficiency declines during food intake restriction because proportionately more of total intake is used for maintenance, leaving less available for gain.

The effects of urea supplements on the utilization of straw plus molasses diets by sheep

1963 ◽  
Vol 14 (1) ◽  
pp. 70 ◽  
Author(s):  
JB Coombe ◽  
DE Tribe
Keyword(s):  
Food Intake ◽  
Nitrogen Balance ◽  
The Body ◽  
Intake Rate ◽  
Crude Fibre ◽  
Cellulose Digestion ◽  
Dietary Nitrogen ◽  
Ad Libitum ◽  
Voluntary Intake ◽  
Food Intake Rate

Three experiments with sheep were carried out to investigate the effect of urea, added to a diet of straw plus molasses, on roughage intake and digestion, and on the nitrogen status of the animal. Urea, added to straw and molasses at the level of 3% of the amount of straw, increased the ad libitum food intake, rate of cellulose (cotton thread) digestion in the rumen, and rate of passage of food through the gut. When different amounts of urea were fed, the highest levels of intake, rate of cellulose digestion, and rate of passage occurred with 8–16 g urea per sheep per day. Increasing the amount of urea fed to 32 g per day caused significant decreases in rate of passage and intake, within diets containing urea. These were not accompanied by significant changes in rate of cellulose digestion in the rumen. With diets of straw and molasses, with and without urea, crude fibre digestibility was positively correlated with the rate of cellulose digestion in the rumen. Voluntary intake of these diets was positively correlated with rate of passage. When the effect of rate of passage was eliminated, voluntary intake was not significantly correlated with the rate of cellulose digestion in the rumen. Under the feeding conditions used in these experiments, once sufficient urea had been added to the diet to bring the animal into a small, positive nitrogen balance, additional dietary nitrogen supplied as urea was practically all excreted in the urine. It is concluded that, under these feeding conditions, the primary function of a urea supplement is to enable an animal to maintain nitrogen equilibrium rather than store significant amounts of nitrogen in the body.

Effect of Age on the Foraging Behaviour of Grey Heron Ardea Cinerea L., 1758 at a Submontane Dam Reservoir in the Post-Breeding Season

2017 ◽  
Vol 10 (2) ◽  
pp. 76-83
Author(s):  
Robert Gwiazda ◽  
Adam Flis ◽  
Piotr Skórka ◽  
Wioleta Oleś
Keyword(s):  
Foraging Behaviour ◽  
Capture Rate ◽  
Success Probability ◽  
Handling Time ◽  
Small Fish ◽  
Foraging Success ◽  
Grey Heron ◽  
Ardea Cinerea ◽  
Probability Number ◽  
Effect Of Age

The components of foraging behaviour and success of adult and juvenile Grey Heron Ardea cinerea were studied at the Dobczyce Reservoir (southern Poland) in July and September 2015. Juvenile and adult birds moved at similar rates during both months. Fish capture attempt rate was significantly higher for juvenile birds than for adults in July but not in September. Capture rate and foraging success probability (number of captures over all attempts) was significantly lower in juveniles in July but not in September. The foraging success probability of juveniles increased from July to September. Adult and juvenile birds caught mostly small fish, with no differences in size. However, handling time in juvenile birds was much longer than in adults in July but not in September, after controlling for differences in prey size. Thus, juvenile Grey Heron increased their efficiency of catching fish from July to September by reducing the number of mistakes, probably as a result of experience.

Vigilance and food intake rate in paired and solitary Zenaida DovesZenaida aurita

Ibis ◽  
2011 ◽  
Vol 154 (1) ◽  
pp. 161-166 ◽  
Author(s):  
FRANK CEZILLY ◽  
ISMAEL KEDDAR
Keyword(s):  
Food Intake ◽  
Intake Rate ◽  
Food Intake Rate
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