Semi-colon or colon?

I'm writing a descriptive piece, and can't figure out whether this is grammatically correct, or whether I ought to place a semi-colon between "entry" and "crooked":

"As I walked in using the cobbled path, a squadron of pigeons nestled upon the roof observed my entry, their heads crooked towards me like a sniper’s gun is crooked on an enemy fighter."

My only line of thought was that, perhaps, in the last clause, rephrasing it to "their heads were crooked" would make the clause independent whereas without "were", as it is presented above, the clause is dependent?

Kind regards,

JP.

I would definitely use a comma. A semi-colon joins two related sentences and you have only one, albeit long, sentence.

If you do do "their heads were crooked" then you do have two sentences, but I would use a period, not a semi-colon.

I don't know your experience with English, but rarely do you need a semi-colon. If you have 2 sentences, a period works.