Herald of spring

At the Minoan site of Akrotiri, which was devastated by the Thera eruption in the mid-second millennium BCE, the Minoan ‘Spring Fresco’ (c. 1600 BCE) features blooming lilies and dancing swallows...

Hesiod (c. 700 BCE), one of the earliest Greek poets, believed that swallows proclaimed spring. This drawing, copied from an Attic red figure vase (c. 510 BCE), shows three men looking at a swallow and cheering: "Look, a swallow. It must be spring!"...

The people of Rhodes particularly loved the swallow; you were considered lucky if a swallow nested in your house... Terracotta scent bottle found in Kameiros, Rhodian, c. 610–550 BCE...

Athenaeus of Naucratis (3rd c. CE) writes that in ancient times, after the first swallow was spotted, the Rhodians would hold a festival. The only other festival celebrating the return of the migratory birds (that I know of) is recorded in Macedonia...I talked about this in my post "Leto".

During the festival the Rhodian children would sing:

He comes! He comes! Who loves to hear
Soft sunny hours, and seasons fair:
The swallow hither comes to rest
His sable wing and snowy breast.

The children then ran to different houses and "played the swallow", demanding food...

This Rhodian "obsession" with swallows is interesting. They are also the only Classical Greeks who were "obsessed" with Helios, at the time when "no cultured Greek would worship him"...The Colossus of Rhodes was a statue of Helios...

Helios is usually depicted as a handsome young man crowned with the shining aureole of the Sun, who drove the chariot of the Sun across the sky...Homer described Helios as a god "who gives joy to mortals"...So he was the young sun, the bringer of Spring...

The swallows announced the arrival of Helios, the bringer of spring. Passage from Greek Magical Papyri says of Helios, "the earth flourished when you shone forth and made the plants fruitful when you laughed, and brought to life the living creatures when you permitted."...

Just like in Slavic mythology, where the return of the migratory birds announced the arrival of the young sun Jarilo, the bringer of spring...It is his return from the land of the dead which was celebrated by the spring festivals across Europe...

The word for swallow in Ancient Greek was χελιδών (/kʰhttp://e.liː.dɔ̌ːn/ → /xe.liˈðon/ → /çe.liˈðon/). This was also a name of a constellation, which is today part of the Pisces (fishes)...

This constellation was called swallow: "...in consequence of the entrance of the sun into this constellation, when the swallow appeared in Greece as the herald of Spring..." Pisces: 19 February – 21 March, just before Spring equinox...From: "Astronomia"

At this time, at the beginning of the Spring, the constellation swallow rises at twilight, just before the sun, Helios, to announce his arrival. Very poetic indeed. Interestingly, swallow was in Ancient Greece associated not just with spring but with the time just before dawn...

So here is another example of constellation named after an animal, which marks a significant yearly reoccurring event from this animal's lifecycle. In this case return of swallows. Just like all the animal constellations from the Zodiac. 

More in my posts about zodiac signs.

Slavs also venerated swallows as solar animals. 

You can read about slavic swallow folklore in my post "Swallows". 

There is even a legend that says that if it wasn't for swallow the sun would not be shining in the sky...

You can read more about this in my post "Three suns".

Great web page about the Cultural responses to the migration of the swallows.