Intellectual Capacities in Vocalization and Problem-Solving Correlate with Brain Size in European Starlings

The European starling, renowned for its versatile vocal capabilities, has been highlighted as an outstanding problem solver in scholarly research conducted by The Rockefeller University.

New evidence indicates that European starlings not only excel in vocal learning but are also proficient in problem-solving tasks. This suggests that vocal learning, cognitive functions, and relative brain size may have co-evolved in these birds.

Noted for their facility in mastering a range of chirps, melodies, and calls throughout their lifetimes, European starlings are recognized as premier avian vocal learners. Recent research published in the journal Science establishes that starlings, along with other complex vocal learners, are equally adept at solving problems.

Jean-Nicolas Audet, a research associate at the laboratory of Erich Jarvis at The Rockefeller University, states, “The prevalent hypothesis has been that only the most cognitively advanced animals are capable of intricate vocal learning. If this is accurate, complex vocal learners should demonstrate superior cognitive performance—yet this has never been empirically verified before.”

Characterizing Vocal Learners

Only a limited number of animal groups manifest the capability for complex vocal learning, which is essentially the aptitude to acquire and remember a broad spectrum of sounds. These groups include mammals like humans, elephants, whales, seals, and bats, along with avian species such as songbirds, parrots, and hummingbirds. The Jarvis laboratory principally investigates songbirds, evaluating their vocal learning based on three factors: the variety of sounds in the bird’s repertoire, the bird’s capacity for lifelong vocal learning, and its proficiency in imitating other species.

Credit: Laboratory of Neurogenetics of Language at The Rockefeller University

Investigative Methodology

To probe the possible relationship between vocal learning and cognitive prowess in songbirds, Audet and his colleagues captured hundreds of birds from 21 different species over a period of three years. They utilized mist nets at The Rockefeller University Field Research Center, an expansive 1,200-acre preserve featuring diverse ecosystems in New York’s Hudson Valley.

Mélanie Couture, a research assistant involved in the study, notes, “The area is protected, which means that the birds have minimal human interaction. This provides optimal conditions for investigating the natural behaviors of these wild birds.”

After evaluating the captured birds’ vocal learning abilities, three species distinguished themselves: starlings, blue jays, and gray catbirds (akin to mockingbirds). Interestingly, these were the only species capable of mimicking other species, a feat Audet considers “the zenith of vocal learning.”

Cognitive Assessments on Avian Subjects

Subsequently, the research team conducted an array of cognitive tests on 214 birds from 23 different species, which included two species raised in a laboratory setting. These tests measured problem-solving skills by asking the birds to undertake tasks like removing lids, puncturing foil, or pulling sticks to obtain a reward. Self-control was tested by putting a clear barrier between each bird and a treat, then observing how long it took the birds to circumvent the obstacle. Further tests examined the birds’ capacity to link specific colors with food rewards and their adaptability when this associated color was altered.

Statistical scrutiny confirmed a robust correlation between problem-solving and vocal learning capabilities. Not only were starlings, blue jays, and gray catbirds the most advanced vocal learners, but they were also the most proficient at problem-solving tasks.

The Relationship Between Brain Size and Cognitive Abilities

The study also uncovered that advanced vocal learners and efficient problem solvers possessed relatively larger brain sizes when compared to their body sizes, providing a biological rationale for these competencies. “Our subsequent phase of research aims to delve into the neurological basis of these advanced traits,” mentions Audet. “While we understand the regions of the brain involved in vocal learning, the areas responsible for problem-solving are yet to be identified.”

In summation, the study posits a co-evolution of vocal learning, cognitive capabilities, and brain size, potentially as a mechanism for enhancing biological fitness. Augmenting this study and prior research regarding the rhythmic abilities of vocal learners, Jarvis has introduced the term “vocal learning cognitive complex” to delineate this cluster of attributes.

“Our discoveries lend empirical support to a previously uncorroborated theory—that the development of intricate behaviors such as spoken language, contingent on vocal learning, is synchronized with the co-evolution of other sophisticated behaviors,” states Jarvis.

Reference: “Avian species displaying advanced vocal learning capabilities exhibit superior problem-solving skills and larger brain sizes” by Jean-Nicolas Audet, Mélanie Couture, and Erich D. Jarvis, published on 14 September 2023 in the journal Science. DOI: 10.1126/science.adh3428

Frequently Asked Questions (FAQs) about European starlings and cognitive abilities

More about European starlings and cognitive abilities

• The Original Study in Science Journal
• The Rockefeller University Research Overview
• Understanding Vocal Learning in Birds
• Neurological Basis of Vocal Learning
• Avian Cognitive Abilities
• Co-evolution of Traits
• Behavioral Research in Birds
• Complex Behaviors and Cognitive Functions