I have come across two bits of evidence for my hobbyhorse concerning the intelligence of other animals.
You will enjoy this delightful essay by Yami Heimbruch about learning the language of songbirds.
Sure, those little feathered people have birdbrains, but they are also complex, intelligent beings when allowed to do their thing in their own world. You and I would probably do terribly on an IQ test designed by a lark or a robin.
But at least, if we take the time, we can learn their language.
Second is this another essay by Joel Boyce, about genuine tool use demonstrated by a wide variety of animals including dolphins, octopuses, otters and monkeys.