Extrinsic stressors modulate resource evaluations: insights from territoriality under artificial noise

Area of Science:

• Behavioral Ecology
• Animal Competition
• Environmental Stressors

Background:

• Competition is linked to resource value, but stressor effects on this value are unknown.
• Environmental stress often reduces competition, possibly via resource devaluation, but evidence is lacking.
• Stressor effects on resource value are hypothesized to depend on attainment costs and resource benefits.

Purpose of the Study:

• To investigate how extrinsic stressors modulate resource value in animal competition.
• To test if noise-induced resource devaluation is conditional on attainment costs and resource benefits.
• To examine the impact of noise on territorial defense in Siamese fighting fish (Betta splendens).

Main Methods:

• Manipulated the acoustic environment using artificial noise playbacks.
• Tested hypotheses in territorial male Siamese fighting fish (Betta splendens).
• Assessed defense motivation, contest behavior, and nest-size changes under different noise and opponent conditions.

Main Results:

• Noise reduced defense motivation when territory owners faced larger opponents (higher injury costs).
• Noise did not reduce defense motivation when territories contained bubble nests (higher reproductive benefits).
• Nest size decreased after contests under noise, with changes influenced by noise intensity and opponent size.

Conclusions:

• Findings support the hypothesis that extrinsic stress modulates resource value.
• Noise impacts competition by altering resource valuation, conditional on costs and benefits.
• Results have implications for understanding competition under increasing anthropogenic noise pollution.