Skomer shearwater chicks putting on weight

Chicks from the world's largest colony of Manx shearwaters will start fledging from the end of this month.

The young birds will be making their first flight - 7,000 miles from Skomer Island off Pembrokeshire to South America.

Scientists weigh around 100 chicks every day for more than two months as part of their studies into the health of the population.

The chicks are often bigger than their parents by the time the adults leave the island for the winter.

The youngsters will then lose a little weight, put on muscle and have fed enough to sustain them to follow their parents south.

There are an estimated 300,000 breeding pairs of shearwater on the island, which is a nature reserve run by the Wildlife Trust of South and West Wales.

Natasha Gillies, part of the Oxford Navigation project team, shows the process of weighing.