The effect of group size on vigilance and feeding rate in spice finches (Lonchura punctulata)

1997 ◽  
Vol 75 (9) ◽  
pp. 1526-1531
Author(s):  
Guy Beauchamp ◽  
Barbara Livoreil
Keyword(s):  
Group Size ◽  
Feeding Rate ◽  
Lonchura Punctulata

The effect of group size on vigilance and feeding rate in spice finches (Lonchura punctulata)

1997 ◽  
Vol 75 (9) ◽  
pp. 1526-1531 ◽  
Author(s):  
Guy Beauchamp ◽  
Barbara Livoreil
Keyword(s):  
Group Size ◽  
Feeding Rate ◽  
Confounding Factor ◽  
Handling Time ◽  
Feeding Time ◽  
Nearest Neighbour ◽  
Feeding Rates ◽  
Search Speed ◽  
Lonchura Punctulata ◽  
The Many

We investigated group-size effects on individual vigilance levels and feeding rates in captive groups of spice finches (Lonchura punctulata). The "many-eyes" hypothesis predicts a reduction in vigilance levels in larger groups that can cause higher feeding rates if the time thus saved is used for foraging. We adopted a within-subject procedure whereby in each of six replicates we observed one adult male searching for food in groups varying in size from one to five. As predicted, vigilance levels decreased with group size up to four birds but increased in groups of five. Birds also collected seeds more quickly in larger groups, reflecting (i) a decrease in vigilance levels in larger groups, (ii) a decrease in handling time, and (iii) an increase in search speed. Nearest neighbour distances were smaller in larger groups, a potential confounding factor in the analysis of vigilance time. Although the results are partly consistent with the many-eyes hypothesis, we suggest that the arrow of causation from vigilance to feeding time could be reversed: the increase in feeding rates in larger groups, with a concomitant decrease in vigilance levels, would be caused by increased competition.

Group Size and Feeding Rate in Bluegills

Copeia ◽  
1984 ◽  
Vol 1984 (4) ◽  
pp. 998 ◽  
Author(s):  
Gary Mittelbach
Keyword(s):  
Group Size ◽  
Feeding Rate

scholarly journals The relationships between feeding-group size and feeding rate vary from positive to negative with characteristics of food items in wild Japanese macaques (Macaca fuscata)

Behaviour ◽  
2013 ◽  
Vol 150 (2) ◽  
pp. 175-197 ◽  
Author(s):  
N. Kazahari ◽  
Y. Tsuji ◽  
N. Agetsuma
Keyword(s):  
Group Size ◽  
Feeding Rate ◽  
Group Living ◽  
Japanese Macaques ◽  
Food Density ◽  
Food Items ◽  
Feeding Group ◽  
Negative Impacts ◽  
The Relationship ◽  
Negative Relationships

To understand the costs and benefits of group-living, it is important to clarify the impacts of other individuals on foraging success. Previous studies on group-living primates have focused on the relationship between feeding-group size and feeding rate in food patches, and have exhibited inconsistent results, showing positive, neutral, or negative relationships. The relationship realized will depend on the balance of positive and negative impacts of co-feeding on feeding rate. The intensity of negative impacts (i.e., feeding competition) may vary with some characteristics of food items such as (1) patch size, (2) within-patch food density, (3) within-patch distribution pattern of food, (4) the abundance and (5) distribution pattern of within-habitat food trees, and (6) the relative energy content among available food items. Thus, the balance of positive and negative impacts of co-feeding, and ultimately the relationship between feeding-group size and feeding rate, is expected to change with characteristics of food items. In this study of wild Japanese macaques (Macaca fuscata), the relationship between feeding-group size and feeding rate, and the above six characteristics of 12 main food items were assessed over six seasons. Positive, neutral, or negative relationships between feeding-group size and feeding rate were detected among these food items. Positive relationships were consistently associated with within-patch food density; higher food density within food patches was likely to lead to positive relationships. Thus, various relationships between feeding-group size and feeding rate should be attributed to these specific characteristics of food items, which alter the degree of feeding competition.

scholarly journals Mechanisms determining relationships between feeding group size and foraging success in food patch use by Japanese macaques (Macaca fuscata)

Behaviour ◽  
2010 ◽  
Vol 147 (11) ◽  
pp. 1481-1500 ◽  
Author(s):  
Nobuko Kazahari ◽  
Naoki Agetsuma
Keyword(s):  
Group Size ◽  
Feeding Rate ◽  
Japanese Macaques ◽  
Feeding Competition ◽  
Foraging Success ◽  
Feeding Groups ◽  
Social Monitoring ◽  
Monitoring Frequency ◽  
Feeding Group ◽  
Group Members

AbstractWe evaluated the effects of social monitoring and feeding competition on foraging success in relation to the feeding group size of wild Japanese macaques (Macaca fuscata). Social monitoring is visual scanning by group members that assists them in following their own group. Individuals in smaller feeding groups may frequently use social monitoring while foraging, because they have an increased risk of losing their group. Therefore, social monitoring could be a cost for group-foraging animals. We made four predictions: (1) individuals in smaller feeding groups tend to abandon food patches to follow group members; (2) social monitoring frequency is higher in smaller feeding groups; (3) feeding rate decreases with increased social monitoring frequency; and (4) feeding rate initially increases with feeding group size because decreased social monitoring outweighs increased feeding competition, but after the feeding group reaches a certain size, feeding rate declines with increasing feeding group size due to the high costs of feeding competition. These predictions were supported by our results. Thus, the relationship between feeding group size and feeding rate can show three patterns (positive, neutral and negative) in response to the balance between the costs of social monitoring and feeding competition.

scholarly journals Sex differences in responsiveness to begging in a cooperative mammal

2008 ◽  
Vol 4 (4) ◽  
pp. 334-337 ◽  
Author(s):  
Sinead English ◽  
Hansjoerg P Kunc ◽  
Joah R Madden ◽  
Tim H Clutton-Brock
Keyword(s):  
Sex Differences ◽  
Parental Care ◽  
Group Size ◽  
Feeding Rate ◽  
Foraging Success ◽  
Sensitive Measure ◽  
Food Items ◽  
Suricata Suricatta ◽  
Cooperatively Breeding ◽  
Consistent Tendency

In species where young are provisioned by both parents, males commonly contribute less to parental care than females, and are less responsive to variation in begging rates. Similar differences in the care of young occur among adults in cooperative breeders, but fewer studies have investigated whether these are associated with differences in responsiveness. Here, we present results from a playback experiment investigating responsiveness to begging in the meerkat ( Suricata suricatta ), a cooperatively breeding mammal. Although increased begging rate raised the feeding rate of adults of both sexes, there was no consistent tendency for females to be more responsive than males. However, when we examined changes in the proportion of food items found that were fed to pups (generosity), we found that females were more responsive than males to increased begging rate. These results can be explained in terms of sex differences in dispersal: in meerkats, females are philopatric and receive considerable benefits from investing in young, both directly, by increasing group size, and indirectly, by recruiting helpers if they inherit the breeding position. In addition, they emphasize that generosity provides a more sensitive measure of responsiveness to begging than feeding rate, as it accounts for variation in foraging success.

An ecological basis for large group size in Colobus angolensis in the Nyungwe Forest, Rwanda

2001 ◽  
Vol 39 (1) ◽  
pp. 83-92 ◽  
Author(s):  
Cheryl Fimbel ◽  
Amy Vedder ◽  
Ellen Dierenfeld ◽  
Felix Mulindahabi
Keyword(s):  
Group Size ◽  
Large Group ◽  
Colobus Angolensis ◽  
Ecological Basis
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