The first is simply the size. There are strict weight limits when flying, which is why birds pack enormous numbers of very small neurons into very small brains. Their axons, the long cable-like fibers that transmit electrical and chemical signals between cells, are shorter.
“Long lines take time. Short lines speed everything up,” Nieder said.
The second factor is temperature. The body temperature of humans is around 36.6° Celsius, for birds it is up to 41 or even 42° Celsius. This higher body temperature accelerates all chemical processes in the birds’ bodies.
“Each ion channel would open and close faster. Each transmitter would move faster through the synaptic cleft,” Nieder explained. “Evolution has really pushed their bodies to their limits. This is life on the fast track, not just in the brain, but also in the breathing, in the cardiovascular system – in birds everything is pushed to the limit.”
But calling crows (or birds in general) speed demons in decision-making comes with some caveats.
Choose the smartest
First, the study only included two birds, a rather small sample. “On the one hand, this is a valid restriction,” Nieder said. “On the other hand, if you look at monkey studies, that’s the standard number of animals we have for these very complex types of studies that combine behavior and electrophysiology.”
The decision time of 235 milliseconds for crows and over 400 milliseconds for primates is also not an absolute limit. These times apply to the random dot movement task, which basically involves waiting to see which direction things move.
Finally, it might be difficult to figure out whether the results extend specifically beyond corvids or crows. “The problem with a lot of other birds is that they’re not as smart as corvids and crows, and you need a smart bird to teach it exactly this task,” Nieder said.
So far, he admitted, we can’t be sure whether the excellent decision-making abilities of the crows in his lab are because birds’ brains are generally fast, or whether crows are simply smarter than other bird species. “Among birds, corvids are considered extremely intelligent, so maybe they have something special,” Nieder said.
Science, 2026. DOI: 10.1126/science.aed6459
