In most modern treatments of English grammar, no distinction is made between "participles" and "gerunds".
In some other languages (Old English as spoken before 1200, Latin) there are clear distinctions in form. For example audiens is a Latin present participle and audiendum is a gerund. This is pretty clear (the Latin word means "hearing")
In Modern English there is only one form "hearing" and asking "is it like a noun or like an adjective" only leads to confusion and mistakes. After all nouns can qualify other nouns (attributive nouns) and adjectives can be the complement in a sentence. The proper analysis is that a word like "hearing" is an "-ing form of a verb" or a "gerund-participle"
And that is proper analysis here. The word "scrabbling" is the "-ing form of the verb scrabble"; it is a "gerund-participle".