BAS webdiary

I'll try and post more photos and a post-script when I return to the UK, but with just two weeks left on Bird Island I am busy making the most of my time, packing, and trying not to think about leaving.

I wrote the March web diary for the BAS site that sums up what we have been up to this last month and many of my feelings about leaving. Click here for that.

Jerry

Penguin counting

This has been a busy month with the penguins. Al and I, with plenty of assistance from the others on base, have been out counting and weighing chicks across the whole island.

First up came the gentoos. There are 7 separate colonies containing between 200 and 1500 nests (counted at the end of October). The beauty of counting nests is that they don’t move around, whereas young penguins do. Especially once they’re large enough for their parents to leave them and head off to sea to feed. While awaiting their return the young ones crèche together in large, noisy and smelly (though undeniably cute) groups. The largest of these groups can contain several hundred chicks and require some co-ordination of counters.

We’ll try and position ourselves so we’ve a good view of a group, but also so we’re preventing them from running off or mingling with other groups. Then everyone counts as accurately as they are able. Chicks do move around but you do your best and hope that those missed are made up for by any double-counted. When done everyone calls out their figure, like a chaotic bingo hall, and if close enough we’ll move on to the next group. In most cases we aim to have at least six counts, with no more than 5% variation.

Assembled to count a group of gentoo chicks.

As we know how many occupied nests there were from the October counts we can say how many chicks have survived per nest. Gentoos lay two eggs though of course not all survive. A productivity of 1.2 to 1.5 would indicate a good year.

Stopping for lunch at the edge of the colony, it soon becomes the centre of the colony as the chicks head over to investigate.

Similar counts are carried out with the macaroni penguins, although with only one chick per year their productivity is naturally lower. This may be a product of their different behaviour, specifically foraging further from the colony for food. When entering the smaller colony, Little Mac, penguins cross a gateway that can identify and weigh them. An individual can typically leave the colony in the morning 500g lighter than it arrived the previous night – all food passed on to the chick, not bad for a 4kg bird!

We also weigh the penguin chicks at a specific age each year. Weight is a good indicator of general health and many birds are weighed prior to fledging. For the penguins this requires a team of volunteers willing to get muddy and smelly as the chicks have to be caught in a net, put in a strong bag and weighed on a spring balance. It takes less than a minute before they’re running back into the mass of fluffy compatriots.

Still a bit fluffy, young gentoo chicks taking their first steps into the sea.

The penguin chicks are now starting to leave. The macaronis clear the colony within a week, disappearing off to sea while their parents will return in a week or two to moult their feathers before spending another winter in the ocean. The gentoo chicks spend more time familiarising themselves with the water; wading in and putting their faces below the surface then getting freaked out and running back onto the beach when they get knocked over by a wave. Gradually they get more accomplished and start swimming, though often are too fat to dive underwater properly, needing to lose some weight as they develop their swimming muscles.

Not only are there waves, the young penguins also have to deal with over-playful fur seal pups, themselves just getting used to the water and inquisitive about anything near them.

As they lose their downy feathers and a little fat they become more streamlined and start to look like proper penguins. They spend more time in the water and start heading further from the shore.

Jerry