I think it is time to look at crows again. There are three interesting papers want to commented on. What reminds me of crows is that I stumbled across a few years old blog by a linguist (he has probably changed his tune – so no references) who ridiculed the idea that birds were at all smart because they had tiny brains with no ‘higher’ brain anatomy. He was unwilling to take seriously any of the work of Pepperberg with her parrot Alex. How the climate has changed in a few years.
The most recent paper is review in ScienceDaily (here) : Martinho, Burns, von Bayern, Kacelnik. “Monocular Tool Control, Eye Dominance, and Laterality in New Caledonian Crows.” Current Biology, 2014. It deals with the seeming ‘handedness’ in the way crows hold tools. It is actually ‘eyedness’; the crows hold the tool on one side of the beak, so that they see the end of the tool and the target with their preferred eye. Caledonia crows have have unusually forward looking eyes and a substantial area of binocular vision. The researchers found that the crows use a monocular part of the opposite side eye to see clearly when using a tool. This implies that they are anatomically adapted to tool use. “In other words, the birds are using their notable binocular vision for better monocular vision, allowing each eye to see further toward the other side of the beak. The birds’ unusually wide binocular field is among the first known examples of a physical adaptation to enable tool use, the researchers say.”
In another paper from the spring (citation below), Jelbert and others investigate the extant of New Caledonian crow’s understanding of how to displace water to receive a reward and found that they had the causal understanding level of a 5-7 year-old child. Wild crows, after short training, were tested in 6 Aesop fable type tasks. They could solve 4 of them: dropping stones into water but not sand filled tubes, dropping sinking not floating and solid not hollow objects, and dropping into tubes with higher water levels. They failed to solve 2 of them: understanding tubes of difference diameter and U shaped tubes. The results show the understanding the causal idea of volume displacement at about the level of the 5-7 year old child. “These results are striking as they highlight both the strengths and limits of the crows’ understanding. In particular, the crows all failed a task which violated normal causal rules, but they could pass the other tasks, which suggests they were using some level of causal understanding when they were successful.“
Last year there was a paper reviewed by ScienceDaily (here): Veit, Nieder. “Abstract rule neurons in the endbrain support intelligent behaviour in corvid songbirds.” Nature Communications, 2013; 4. This paper dealt with how crows make strategic decisions. As crows do many things that are thought of as primate strengths and yet have a very different brain architecture, this is a way to look at intelligence in a fundamental way that would apply to both primates and crows.
Crows were trained to do a memory test. On a computer screen they were shown an image, they had to remember the image and later pick one of two images on the screen. The hard part was that sometimes they had to pick the image that was the same and other times the one that was different. They had to switch back and forth between two rules-of-the -game. They could use this mental flexibility, which even takes effort for humans. While the birds were engaged in this task their nidopallium caudolaterale area of the brain was monitored. One group of cells was active for the different image rule and another for the same image rule.
“Crows and primates have different brains, but the cells regulating decision-making are very similar. They represent a general principle which has re-emerged throughout the history of evolution. “Just as we can draw valid conclusions on aerodynamics from a comparison of the very differently constructed wings of birds and bats, here we are able to draw conclusions about how the brain works by investigating the functional similarities and differences of the relevant brain areas in avian and mammalian brains.“
Citation: Sarah A. Jelbert, Alex H. Taylor, Lucy G. Cheke, Nicola S. Clayton, Russell D. Gray. Using the Aesop’s Fable Paradigm to Investigate Causal Understanding of Water Displacement by New Caledonian Crows. PLoS ONE, 2014; 9 (3): e92895 DOI: 10.1371/journal.pone.0092895
Veit, L., & Nieder, A. (2013). Abstract rule neurons in the endbrain support intelligent behaviour in corvid songbirds Nature Communications, 4 DOI: 10.1038/ncomms3878