The article for this post discusses this. Many animals have complex behaviors. For instance, the two links you have posted are examples. But faced with new problems they buckle and cannot deal.
The ravens are interesting, I will read that study. But saying they're intelligent is not the same thing as saying they are cogitative, for they don't possess the language to express cogitative experiences in the same we, and only we, do.
This has been a discussion point in Analytical Philosophy for a number of years, particularly during the rise of Cognitive Neuroscience. PMS Hacker, in particular, has written a lot about this topic, I would recommend his two books:
(https://www.amazon.com/Human-Nature-Categorial-Framework-Hac...) "This major study examines the most fundamental categories in terms of which we conceive of ourselves, critically surveying the concepts of substance, causation, agency, teleology, rationality, mind, body and person, and elaborating the conceptual fields in which they are embedded."
(https://www.amazon.com/Intellectual-Powers-Study-Human-Natur...) "The Intellectual Powers is a philosophical investigation into the cognitive and cogitative powers of mankind. It develops a connective analysis of our powers of consciousness, intentionality, mastery of language, knowledge, belief, certainty, sensation, perception, memory, thought, and imagination, by one of Britain’s leading philosophers. It is an essential guide and handbook for philosophers, psychologists, and cognitive neuroscientists."
Both of which heavily interact with relevant research and articles in cognitive neuroscience and neuroscience more broadly.
Did you intend to address this?
Is your whole perspective shaped by this one author? I am extremely wary when people cite books, as opposed to papers, when discussing scientific topics.
They don't need to do it in the same way humans do; they don't do it in the same way humans do. In the absence of language, they have no way of expressing the depths of cogitation in the same way humans can.
In regards to your last question, I have found PMS Hacker a particularly compelling author in this area. He is a very good analytical philosopher. His works are peer-reviewed, and extensively researched and amply sourced. He's an established professional philosopher. He has also written extensively with M.R. Bennet, an established neuroscientist with many papers, a good book of theirs is: The Philosophical Foundations of Neuroscience (http://ca.wiley.com/WileyCDA/WileyTitle/productCd-140510838X...)
I'm not a professional scientist, I don't have access to papers. I have access to books.
Perhaps some animals, or even most animals, don't have language.
But whalesong and bird songs can be very complex, and I am not at all convinced that they do not have language.
Can you prove that they don't have language?