A dawn chorus rings out as tens of thousands of pink-footed geese circle the Angus sky on a cold October morning.

Every autumn these birds descend on the Montrose Basin in their tens of thousands. This year is no different.

The geese hail from the cooler climes of Greenland and Iceland.

This year they've arrived slightly earlier than usual, as snow in Iceland has spurred them into heading south ahead of schedule.

You can hear them before you see them, their unmistakable honking echoing around the basin.

There are 50,000 geese at this nature reserve already, with many more due to flock here in the coming weeks.

"The geese come here overnight for a safe haven, and they feed out in the arable fields around during the day," said Anna Cowie, Montrose Basin ranger with the Scottish Wildlife Trust.

"Often they're not too keen to take off at very first light. But dawn is definitely the optimum time to see them.

"This is the main site in Scotland for pink-footed geese, we think the majority of them pass through here.

"Traditionally they would have fed on the salt marsh around the basin. But as arable crops have intensified over the years, they now feed in the surrounding fields."

When the birds take to the sky en masse, it's quite a spectacle.

Birdwatcher Donald Miller from Moray got up at the crack of dawn to go and see them.

"It's just incredible to see that number of geese in one place," he said.

"And this time in the morning, when they're starting to lift-off - it's a wonderful sight."

Members of the public can book viewings at dawn or dusk.

But if you're interested, you'll have to be quick - by November, most of the birds will start leaving Scottish shores for the wetlands of eastern England.