The global diet diversity spectrum in avian apex predators

Area of Science:

• Ecology
• Zoology
• Food Web Dynamics

Background:

• Predator diets vary significantly, ranging from specialists to generalists.
• The ecological factors driving this variation in diet breadth remain poorly understood.
• Apex predators, such as raptors, play crucial roles in ecosystem structure and function.

Purpose of the Study:

• To investigate the factors contributing to diet variation in apex predators.
• To establish a diet diversity spectrum for raptors based on prey frequency.
• To link diet diversity to ecological and evolutionary factors.

Main Methods:

• Analyzed diet species richness and Shannon entropy of prey frequencies for raptors globally.
• Compared observed diet entropy to expectations based on prey abundance distributions (lognormal).
• Correlated diet diversity spectrum positioning with evolutionary history and prey characteristics.

Main Results:

• A strong link exists between diet species richness and diet entropy in raptors.
• Many raptor diets approach maximum entropy, indicating high evenness not predicted by random sampling theory.
• Diet diversity is influenced by evolutionary history, prey accessibility, and cross-habitat foraging.

Conclusions:

• Raptor diet diversity is shaped by a combination of factors beyond simple prey availability.
• Raptors may act as significant food web integrators, stabilizing terrestrial ecosystems.
• The findings highlight the important role of apex predators in maintaining biodiversity.