Phrase "the monarchs have come here in the Fall"

[Ofriendragon]

Monarchs (butterfly) from the western United States travel to a winter home on the California coast. Whole trees in Pacific Grove, California, disappear under a coating of the beautiful sleeping insects. For as long as people can remember, the monarchs have come here in the Fall.

In the Fall obviously refers to a past time, why have come---> a present time tense is used?

And why not
For as long as people can remember, the monarchs come here in the Fall
or
For as long as people can remember, the monarchs came here in the Fall

Many many thanks in advance.

[Jamie (K)]

[Lost_Soul]

Hi, Jamie

In the original sentence the season fall does not refer to any particular season in the past, right? (unlike the fall of 1945)
But we still use the definite article before fall.
My question is - can we omit tre article, e.g. the monarchs have come here in Fall? Does the meaning change after the omission?

Thanks !

[Ofriendragon]

[Jamie (K)]