Related Experiment Video
Updated: Aug 12, 2026
06:03
A Push-pull Protocol to Reduce Colonization of Bird Nest Boxes by Honey Bees
Published on: September 4, 2016
Reduced flocking by birds on islands with relaxed predation
1Faculty of Veterinary Medicine, University of Montreal, PO Box 5000, St-Hyacinthe, Quebec 72S 7C6, Canada. guy.beauchamp@umontreal.ca
Proceedings. Biological Sciences
|August 6, 2004
Summary
Bird flocking behavior is significantly influenced by predation avoidance. While flocking persists on islands with low predation, smaller flock sizes suggest other factors also contribute to this avian adaptation.
Area of Science:
- Evolutionary biology
- Behavioral ecology
- Ornithology
Background:
- Adaptive hypotheses for avian flocking often center on predation avoidance and foraging.
- The relative importance of these factors in flocking evolution remains debated.
- Predation pressure is a key variable to investigate for understanding flocking maintenance.
Purpose of the Study:
- To investigate the role of predation in the evolution of bird flocking.
- To compare flocking tendencies and sizes in island species versus mainland counterparts.
- To determine if flocking is maintained in the absence of significant predation risk.
Main Methods:
- Examined flocking tendencies, mean, and maximum flock size in bird species on islands with negligible predation.
- Compared island species with matched mainland species.
- Analyzed a dataset of 46 species pairs from 22 islands globally.
Main Results:
- Most island species retained the tendency to flock, but less so than mainland counterparts when flocking tendencies differed.
- Mean and maximum flock sizes were reduced on islands compared to the mainland.
- Factors like population density, nest predation, habitat, food, and body mass did not explain these differences.
Conclusions:
- Predation is a significant driver in the evolutionary maintenance of bird flocking.
- While predation is crucial, other factors like foraging benefits likely co-maintain flocking in many species.
- Flocking behavior in birds is shaped by a combination of ecological pressures.
Related Concept Videos
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.
01:07Speciation Rates
Speciation can proceed at markedly different rates, and evolutionary biologists commonly describe these differences through the models of gradualism and punctuated equilibrium. Both patterns explain how new species arise, but they differ in the tempo and continuity of evolutionary change. In both cases, evolutionary change arises from heritable variation within populations, with natural selection often shaping traits that improve survival and reproduction under specific environmental conditions.
01:21Frequency-dependent Selection
When the fitness of a trait is influenced by how common it is (i.e., its frequency) relative to different traits within a population, this is referred to as frequency-dependent selection. Frequency-dependent selection may occur between species or within a single species. This type of selection can either be positive—with more common phenotypes having higher fitness—or negative, with rarer phenotypes conferring increased fitness.Positive Frequency-Dependent SelectionIn positive...
02:39Predator-Prey Interactions
Predators consume prey for energy. Predators that acquire prey and prey that avoid predation both increase their chances of survival and reproduction (i.e., fitness). Routine predator-prey interactions elicit mutual adaptations that improve predator offenses, such as claws, teeth, and speed, as well as prey defenses, including crypsis, aposematism, and mimicry. Thus, predator-prey interactions resemble an evolutionary arms race.Although predation is commonly associated with carnivory, for...
02:04Conservation of Small Populations
Small population sizes put a species at extreme risk of extinction due to a lack of variation, and a consequent decrease in adaptability. This weakens the chances of survival under pressures such as climate change, competition from other species, or new diseases. Large populations are more likely to survive pressures such as these, as such populations are more likely to harbor individuals that have genetic variants that are adaptive under new stresses. Small populations are much less likely to...
02:07Conservation of Declining Populations
Conservation of declining population focuses on ways of detecting, diagnosing, and halting a population decline. The approach uses methods to prevent populations from going extinct.