A birder spotted more than just wildlife on an excursion in the English countryside last September. As Smithsonian reports, the unnamed British man uncovered a hoard of Celtic coins dating back 2000 years.

The bird-watcher had stopped near a field to observe a buzzard when he noticed something glittering in the dirt. Upon closer inspection, he realized the metal object was a handmade gold coin, and it was one of several in the area.

Fortunately for him, bird-watching isn't his only hobby. After spotting the artifact, he went home to grab the metal detector he uses in amateur treasure hunts. The device produced a strong signal when he brought it back to the site, indicating there was more gold beneath the surface. The birder dug up 18 inches of dirt before uncovering a copper vessel overflowing with treasure.

His sharp eye led to the discovery of roughly 1300 gold pieces—the largest trove of Iron Age Celtic coins found in the UK in over a decade. The artifacts date back to the first century CE, when the Celtic queen Boudica led an assault against the Romans following the death of her husband King Prasutagus. Though her army toppled the capital of Roman Britain and killed up to 80,000 people, the revolution wasn't successful. Historians believe Boudica's people used Celtic gold coins as sacred offerings during times of hardship.

The British bird-watcher handed the coin stash over to the local authorities, who will enlist experts to determine the artifacts' authenticity. If deemed to be treasure, the gold will go to a museum, and the man who discovered it will be eligible to receive a reward.

[h/t Smithsonian]