Related Experiment Video
Updated: Jun 12, 2026
12:00
Procedures for Identifying Infectious Prions After Passage Through the Digestive System of an Avian Species
Published on: November 6, 2013
Lazy group members are substitute helpers in carrion crows
Vittorio Baglione1, Daniela Canestrari, Elisa Chiarati
1Department of Agro-forestry, Sustainable Forest Management Research Institute, University of Valladolid, Avenida de Madrid 44, 34004 Palencia, Spain. baglione@agro.uva.es
Proceedings. Biological Sciences
|June 4, 2010
Summary
Lazy carrion crows (Corvus corone corone) act as an insurance workforce. Even the least active helpers increased provisioning when a carer was impaired, ensuring reproductive success and group stability.
Area of Science:
- Animal Behavior
- Evolutionary Biology
- Ornithology
Background:
- Cooperative breeding systems exhibit variable helping effort among individuals.
- Dominant tolerance of 'lazy' subordinates in these societies remains an evolutionary puzzle.
- Carrion crow helpers at the nest boost breeder success, but provisioning is uneven.
Purpose of the Study:
- To investigate the role of 'lazy' non-breeders in cooperatively breeding carrion crows.
- To determine if inactive subordinates compensate for reduced provisioning effort by others.
- To understand the contribution of potential versus current helping effort to group stability.
Main Methods:
- Experimental impairment of a single nest carer to reduce its provisioning rate.
- Monitoring provisioning rates of all non-breeders before and after carer impairment.
- Comparing the responses of different categories of non-breeders (active vs. inactive).
Main Results:
- Lazy non-breeders significantly increased their provisioning rates when a carer was experimentally impaired.
- Individuals previously refraining from helping initiated provisioning in response to impairment.
- Breeding pairs did not increase their own provisioning effort to compensate.
Conclusions:
- Lazy subordinates function as a crucial 'insurance workforce' in carrion crow societies.
- The potential contribution of all group members, not just current effort, stabilizes groups.
- This buffering capacity of inactive individuals is key to maintaining reproductive success under adverse conditions.
Related Concept Videos
01:37Social Loafing
Another way in which a group presence can affect performance is social loafing—the exertion of less effort by a person working together with a group. Social loafing occurs when our individual performance cannot be evaluated separately from the group. Thus, group performance declines on easy tasks (Karau & Williams, 1993). Essentially individual group members loaf and let other group members pick up the slack. Because each individual’s efforts cannot be evaluated, individuals become less...
04:49Robbers Cave
During the 1950s, the landmark Robbers Cave experiment demonstrated that when groups must compete with one another, intergroup conflict, hostility, and even violence may result. At the Oklahoman summer camp, two troops of boys—termed the Rattlers and the Eagles—took part in a week-long tournament. During this time, their negativity culminated in derogatory name-calling, fistfights, and even vandalism and destruction of property. However, this work also revealed that such tension could be...
00:48Optimal Foraging
How animals obtain and eat their food is called foraging behavior. Foraging can include searching for plants and hunting for prey and depends on the species and environment.
01:03Altruism
Altruistic behaviors are “unselfish” behaviors—those that help another individual at the expense of the individual carrying out the behavior. Despite the negative consequences for the altruistic animal, these behaviors are thought to have evolved for several reasons.
01:13Nonconscious Mimicry
Nonconscious mimicry occurs when individuals alter their mannerisms to match the behaviors and expressions of those nearby, without intention.
01:34Groupthink
When in group settings, we are often influenced by the thoughts, feelings, and behaviors around us. Groupthink is another phenomenon of conformity where modification of the opinions of members in a group aligns with what they believe is the group consensus (Janis, 1972). In such situations, the group often takes action that individuals would not perform outside the group setting because groups make more extreme decisions than individuals do. Moreover, groupthink can hinder opposing trains of...