Stereotyping starlings are more 'pessimistic'

Area of Science:

• Animal behavior
• Cognitive bias research
• Avian welfare

Background:

• Negative affect is linked to pessimistic interpretations of ambiguous stimuli in humans and animals.
• Captive environments may induce negative affect, potentially influencing cognitive biases.

Purpose of the Study:

• To investigate if reduced environmental enrichment in captive European starlings leads to negative affect and pessimistic biases.
• To determine if individual differences in stereotypic behavior, specifically somersaulting, predict pessimism.

Main Methods:

• European starlings were trained on a conditional discrimination task with differential rewards based on background shade.
• Ambiguous stimuli were presented to assess judgment bias, with a preference for the smaller reward indicating pessimism.
• Stereotypic somersaulting behavior was recorded and correlated with performance on the bias task.

Main Results:

• Contrary to predictions, changes in cage enrichment levels did not significantly affect the birds' pessimism.
• Birds learned to identify unreinforced trials with ambiguous stimuli.
• A significant correlation was found: birds exhibiting somersaulting were more likely to make pessimistic judgments.

Conclusions:

• Reduced environmental enrichment did not induce pessimism in European starlings.
• Stereotypic somersaulting behavior in captive starlings is a predictor of pessimistic cognitive bias.
• Somersaulting may represent a behavioral indicator of a negative affective state and stress response in captive birds.