Grammar Introduces Logic I think the preposition can be labeled as being a particular type of conjunction. It is the conjunction of (among other categories) space and time — ucarr
Category error and general confusion here. Conjunctions join phrases, clauses, words, and sentences. They are defined in syntactical not physical or temporal terms. Prepositions can be prepositions of time or space, and those are distinct categories. Both terms originated in classical grammar. For the purposes of your OP, a functional grammar, like SFL, might be more useful.
Language is a very particuliar form of skilled behaviour that, yes, is not uni-modal; but nevertheless has very specific properties that are well defined and understood and distinguish it from other forms of skilled behavior and non-linguistic communication. So, American Sign Language, for example, is a perfectly valid language but me making a cup of tea or physically showing you how to do that, more analogical to your crow example, is not.
Some of the specific attributes that define language include:
1. Individual modifiable units
2. Negation
3. Question
4. Displacement (e.g. tense)
S. Hypotheticals and counterfactuals
6. Open endedness (novel utterances)
7. Stimulus freedom (open responses)
You can't make crow behaviour into individual units that can be reorganized to meet the criteria above. Not only is there no language there. There is almost nothing at all like a language,