Intake Rate Maximization and the Foraging Behaviour of Crossbills

1989 ◽  
Vol 20 (1) ◽  
pp. 65 ◽  
Author(s):  
Craig W. Benkman
Keyword(s):  
Foraging Behaviour ◽  
Intake Rate ◽  
Rate Maximization

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.

Foraging behaviour of Armadillidium vulgare (Isopoda: Oniscidea) in heterogeneous environments

Behaviour ◽  
2004 ◽  
Vol 141 (2) ◽  
pp. 233-244 ◽  
Author(s):  
Joanne Tuck ◽  
Mark Hassall
Keyword(s):  
Leaf Litter ◽  
Foraging Behaviour ◽  
Walking Speed ◽  
Optimal Foraging Theory ◽  
Heterogeneous Environments ◽  
Intake Rate ◽  
High Quality ◽  
Turning Angle ◽  
Quality Food ◽  
Armadillidium Vulgare

AbstractForaging behaviour of Armadillidium vulgare was observed in laboratory arenas in which the spatial distribution of patches of high quality food (powdered dicotyledonous leaf litter) was varied within a background of low quality food (powdered grass leaf litter). The hypotheses that the foraging behaviour and foraging path of A. vulgare would be influenced by food quality and the patchiness of high quality food resources were tested. More time was spent in high quality food patches than in low quality food backgrounds than expected by chance in all heterogeneity treatments, but an increasingly higher percentage of time was spent in low quality food as the high quality food became more clumped in space. More time was spent searching, but less time was spent feeding in low quality food backgrounds than in high quality food patches in all the treatments. Walking speed was found to be lower in high quality food patches than in low quality food backgrounds and this was not affected by treatment. Turning frequency and turning angle were found to be higher in high quality food patches than in low quality backgrounds. Turning frequency in low quality food backgrounds decreased as the high quality food became more clumped in space, whereas turning angle in high quality food patches significantly increased in the patchy, but then decreased again in the clumped treatment. The effects of varying the spatial heterogeneity of high quality foods on the trade-off between costs of searching and intake benefits for saprophages are discussed in relation to predictions from optimal foraging theory for circumstances when intake rate maximisation is affected by the constraint of limited nutrients.

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.

Ewes increase their intake when offered a choice of herbage species at pasture

2006 ◽  
Vol 82 (2) ◽  
pp. 183-191 ◽  
Author(s):  
C. Cortes ◽  
J. C. Damasceno ◽  
J. Jamot ◽  
S. Prache
Keyword(s):  
Festuca Arundinacea ◽  
Foraging Behaviour ◽  
Latin Square ◽  
Intake Rate ◽  
Food Diversity ◽  
Resource Degradation ◽  
Digestible Organic Matter ◽  
Effect Of Food ◽  
Free Grazing ◽  
Preferred Species

AbstractIn stall-feeding conditions, food diversity has been shown to increase an animal's motivation to eat and its level of food intake. This effect has also been suggested, but not demonstrated, for free-grazing animals. In free-grazing conditions, however, animals may have to search for the preferred plant species and this may reduce their intake rate. Moreover, the management of diverse swards faces a risk of overgrazing the preferred species and undergrazing the less preferred species, leading to resource degradation. We investigated the effect of food diversity on foraging behaviour and intake in grazing sheep, in interaction with the type of diversity (conterminal monocultures v. mixtures) and management (two monocultures offered simultaneously v. successively over time). Five treatments were compared with five groups of five dry INRA 401 ewes for five periods, using a Latin-square design: LOL=grazing a monoculture of Lolium perenne cv. Herbie (L); FES=grazing a monoculture of Festuca arundinacea cv. Florine (F); STRIPS=grazing conterminal monocultures of L and F, 0·5:0·5 by ground area, with animals having a free choice between both species; TIME=grazing L from 16:00 to 09:00 h and F from 09:00 to 16:00 h; MIX=grazing an intermeshed mixture of L and F. Sward height was maintained at 9 cm. Each period comprised a 5-day adaptation subperiod followed by a 5-day measurement subperiod. Dietary choices and intake were measured using n-alkanes, and grazing time was assessed using the Ethosys® recording system. Intake rate was calculated as the ratio of intake to grazing time. Intake in the monoculture treatments were higher than predictions made for housed animals given similar forages ad libitum, demonstrating that sward conditions were favourable for the expression of voluntary intake in all treatments. Intake was higher in LOL than in FES, this result being consistent with predictions for stall-feeding conditions. There was no difference in diet composition, foraging behaviour and intake between the bispecific treatments (STRIPS, TIME and MIX). Intake was higher in the bispecific treatments than in LOL (1666 v. 1492 g digestible organic matter per day, P<0·001). Grazing time was higher in STRIPS and MIX than in LOL (420 and 430 min respectively v. 366 min, P<0·01). Dry ewes increase their intake when offered a choice of herbage species at pasture, this being mediated via an increase in grazing time rather than an increase in intake rate. There was no interaction with type of diversity or type of management.

DIET SELECTION IN GOATS: A TEST OF INTAKE-RATE MAXIMIZATION

Ecology ◽  
1999 ◽  
Vol 80 (3) ◽  
pp. 1008-1018 ◽  
Author(s):  
A. W. Illius ◽  
I. J. Gordon ◽  
D. A. Elston ◽  
J. D. Milne
Keyword(s):  
Diet Selection ◽  
Intake Rate ◽  
Rate Maximization

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 and food habits of Stone's sheep

1985 ◽  
Vol 63 (7) ◽  
pp. 1638-1646 ◽  
Author(s):  
Dale R. Seip ◽  
Fred L. Bunnell
Keyword(s):  
Food Habits ◽  
Foraging Behaviour ◽  
Intake Rate ◽  
Acid Detergent Fiber ◽  
Winter Snow ◽  
Biting Rate ◽  
Ovis Dalli ◽  
Chemical Deterrents ◽  
Physical And Chemical ◽  
Foraging Time

Foraging behaviour of Stone's sheep (Ovis dalli stonei) was compared between different times of the year and between burned and unburned ranges. Seasonal habitat selection resulted in the sheep feeding on the ranges which provided the highest quality available forage. In winter, snow severely restricted the area that provided available forage. Sheep fed primarily on grasses, although forbs and browse were also important foods in the spring and summer. Plant species selected by the sheep in summer were not higher in protein or lower in acid detergent fiber than avoided species, but rather lacked the physical and chemical deterrents present in avoided plants. Intake rate (estimated from biting rate of ewes and foraging time) appeared to be independent of herbage quantity on spring ranges.

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