Indeed. I would take it further and say these items are not spiritual experiences. To some extent they are tools used to have a spiritual experience but not in and of themselves spiritual.

I like your example of being aware of the bird songs. That's one example of the true definition of mindfulness, which is not a synonym for meditation, it's just awareness.

Anything that makes one aware of connection vs separation, is a spiritual experience.

Synchronicity is on the list.

"Aware people often say the universe sends us signals all the time, which we could see if we only knew how and where to look.

How: just be open-minded.

Where: Everywhere and Everyone"

Feeling the energy surge, sometimes described as or causing "the chills" that signifies the presence of a spirit is another.

That gentle "hearing" what we describe as "tinnitus" like because we have no better description for the gentle and not annoying vibration we sense that means we are in contact with a soul on the other side, that's my favorite. I wrote a short piece about that a few months ago. https://medium.com/channspirations/lets-talk-about-souls-and-energy-signatures-and-contact-and-perception-a0242dba9c7e

I published a prose poem last weekend about several subtle spiritual experiences I had on a walk I took. Walking is often meditation for me. https://medium.com/write-under-the-moon/communing-with-nature-and-spirits-in-the-material-world-a694e4a9bd9b Here's one passage:

"Mesmerized by the sight of yesterday’s rain emerging as groundwater from the farm’s hillside. Ants must perceive this natural wonder as people see the power of Niagra Falls."

I think you and your readers will enjoy the piece.