Birds like the berries. It's a good shrub/tree to have.

Both grow in eastern North America.

Here in WNC in highest elevations. Beautiful red berries adding to fall colors and a very good wildlife food source. I have seen lots of bear scat loaded with the berries and seeds.
It IS NOT a true Ash though, hence the dash between Mountsin and Ash in the common name.
Scratch the twigs and they have a strong scent of cherry.
The first tree I learned in college Dendrology class.
I got behind in lab that day and had to drive back up the mountain and with a dichotomous key, I had to find and ID the days species.
A favorite of mine.

Get the free Plantnet app. Take a picture of a plant, submit it and they'll tell you what it is. Awesome tool.

Spent 30 years teaching Dendrology in college. Here is the Southern Appalachian’s we have the most diverse number of species in America. Making it a great place to learn.
Just before I retired the phones were coming out with ID Apps, so during daily field trips, I had to crackdown on phone use for the 10 new species tested that week. Students still tried. Which resulted in a zero that day.
To this day, I trip a lot on trials, looking at trees and twigs.
120 species had to be learned with leaves and bark, then in winter they had to learn them all with twig characteristics only. I love the twig ID.

of southern Oregon and northern California. Both are occasional species. Lots of plant diversity in Klamath Mountains (my home). Took dendrology at university almost 50 years ago.

Both green and white, (pennsylvanica and americana) the emerald ash borer is becoming a serious issue.
I love your forest type. The International Dendrology Society gifted me a scholarship trip with them for a month, two years ago. From San Fran up the coast to Oregon and back down the eastern slopes of the mountains. We had Phd experts, professors, meet us along the trip to teach. My Fav was the professor from Humbolt that researchers with Nat Geo and lives in the tree tops. The climber.
He wife, also a scientist researches symbiotic species of mosses and lichens that grow in the canopies to the Costal Red Woods and Sequoias.
Hope to get back, but I am a poor ass educator, retired.
The free trip honoring my years of teaching trees was the gift of a lifetime.
I talked to Muir in those forests.
Cheers fellow tree hugger.

to be the smartass:
It's red and green.

step aside, armchair botanists!

Did not go well. Tasted, well

I have a poem about it on my Angelfire Website, dragon2 leaves and trees

The Tree of Life in Gadhelic Legend

II

A rowan tree grew on Loch Meve –
Southwards is seen the shore—
Every fourth and every month
Ripe fruit the rowan bore:
Fruit more sweet than honey-comb,
Its clusters’ virtues strong,
Its berries red could one but taste
Hunger they staved off long.

Its berries’ juice and fruit when red
For a year would life prolong:
From dread disease it gave relief
If what is told be our belief.

Yet though it proved a means of life
Peril lay closely nigh;
Coiled by its root a dragon lay
Forbidding passage by.

A messenger for Fraoch was sent
By Eochaidh’s daughter keen-
When sickness sore Meve rent:
“What ails?” quoth Fraoch, “the Queen?”

And Eochaidh’s daughter made reply-
Eochaidh of the festive horns-
That ne’er would she be whole
Till her soft palm were full
Of berries from the island in the lake-
Fraoch’s hand alone to pull.

“Such I ne’er cull’d,” said Idad’s son
Of blushing face;
“Yet will I what I yet ne’er willed,”
Quoth Fraoch, out of grace.

Sir Fraoch moved forward to his fate
Forth to the lake and swam the tide;
He found asleep the dragon-snake
Around the tree, mouth open wide.
(On Cluan Fraoich a friend doth sign.)

https://www.angelfire.com/dragon2/leavesandtrees/nature/dragontree.html

This is an imprint I made of one