Actually a human put the drugs into the backpack then put the backpack on the bird.

How do you know? They should at least keep those pigeons in custody until they know for sure. Drugs don’t kill people, pigeons do.

That’s correct, albeit pedantic.

The human is the handler, and the pigeon is still the actual smuggler.

So in a (very) liberal interpretation, someone found a way of transforming a pigeon into a mule.

I feel drawn to this Garden as by an electric current. I comprehend that You, powerful magnet of my wounded heart, are calling me; and I run, thinking to myself: ‘What are these attractions of love that I feel within me?

It's probably due to what You have in your Backpack :)

That’s what the pigeons want us to think. When we get wise about it, it will be too late.

The revolution has already started

They don't really talk about where the pigeons were raised.

Aren't homing pigeons getting back to their "home" ? So the pigeon must have been raised in the prison, right ?

Yet another blatant misuse of RFC 1149

https://www.rfc-editor.org/rfc/rfc1149

I see that the prison experience must significantly differ from my naive assumption. I struggle to envision a scenario where I would cheerfully trip balls surrounded by people who have committed violent crimes.

Unless the drugs are to give other inmates, I suppose.