Sunday 20 July 2014

Giant Petrels

The giant petrels, commonly known as 'geeps', are one of my key study species. They're split into two species – the Northern and Southern, differentiated by the colour of their bill tip. Red for Northern and green for Southern. The sexes are basically the same, with the males being marginally bulkier and with longer beaks.
Northern Giant Petrel. Check out that lovely eye and the impressive beak - the salt gland on top to enable filtration of sea water and the huge pointed tip for ripping through carcasses.
The geeps get a bit of a raw deal. The only time you'll see them in any sort of nature documentary is when they're scavenging dead seals or waiting patiently for defenceless young pups and penguins. They'll be fighting with each other for rights to the kill, then shoving their heads right inside these big dead seals, pulling out covered in blood.

No waste on Bird Island. A recently deceased Fur Seal will quickly be reduced to a pile of bones and the geeps are the first ones in there.
They're not as eye-catching as the penguins or as elegant as the albatrosses, but once you start spending some time with them you get captivated by their charisma.

Describing them is a bit like describing a Frankingstein. They're the largest of the procelleria family of petrels and prions. Normally when you think of these birds you'd think of petite Storm Petrels or the elegant shearwaters soaring over the waves, perfectly adapted for a life at sea but a little ungainly on land. Unlike the smaller members of the family the geeps have strong legs that enable them to stalk the beach like dinosaurs. When they fight over food their tails are up, like turkeys, and their wings outstretched as they run at each other, shrieking like banshees.

A beach-master pose as this geep challenges anyone else to try taking his food away from him.
Like most wildlife, it's when you see them with their partners and young that you really warm to them. Giant Petrels are monogamous with long-term pair bonds and often nest in the same place, frequently the same area they were born, year after year. Many of them hang around, with their partners, through the winter.

A pair circling and calling together.
They're amongst the earliest nesters on Bird Island as the Northerns start laying eggs in mid-September with the Southerns about a month later. The nest can be a simple scrape on the ground but is usually a turret built from mud, moss and tussac grass. An ambitious pair may try to use an old Wandering Albatross nest.

The pair will take turns sitting on the egg for around a week at a time while their partner is off feeding. The egg takes about two months to incubate and during this time the birds have to put up with whatever the weather throws at them – wind, rain and snow. There's no ground-based predators here, no rats or cats or mice (which is one of the reasons Bird Island is so important), so there's little threat to the geeps from other life. With a bill like that they're not worth messing with, although there's the occasional territorial squabble between adults.

Geep scrap. These two males were fighting over a nest. The female sat by passively and then left with the loser. Like with most animals the fights are mainly posturing, establishing who is bigger, but then can lead to the interlocking of beaks and with those very sharp tips it's not unlikely that some blood will be spilt. This usually seems to signal the end of the fight.
Each of the approximately 500 nests in my study area gets a number and I'll take a GPS reference so I can plot them on a map later. The majority of the birds here carry rings and darvics. I'll take the numbers down and enter them onto an existing database, from that we'll know whether each individual has stuck with the same partner, changed location, been seen before and many other things. Throughout the season I'll visit about once a week to check on the progress of the egg and chick, ultimately recording whether the pair have bred successfully or not.

Writing down nest number, location and ring numbers of a particularly unconcerned pair. (Hannah's photo).
This is all part of an ongoing, long-term study collecting data on these species to find out all sorts of things like population and population changes, breeding success and survival rates.

Giant Petrels are scavengers as well as predators and can often be seen following boats in the south seas, waiting for any scraps.
Amongst the Southern geep population there's the occasional all-white individual. It's not an albino, it's just a morphological difference. They interbreed with the more usual coloured birds. There's two females like this in my study population of approximately 300 Southern Giant Petrels.

A white morph chick, pretty much full grown and ready for departure.
Two months after being laid a little white chick pokes its way out the egg with this big clunking beak. It's parents stay with it, continuing their regular change-overs for another few weeks, after which time it is left alone. Like most birds of it's kind it defends itself with a snapping bill and the threat of regurgitation – viscous vomit that could ruin an assailant's plumage, fur or jacket.

A week-old geep chick getting it's first rays of sunshine, yawning or calling for food.
As they get older the young birds lose their downy fluff and grow a layer of sleek, black adult feathers. They start to wander away from the nest, but not too far as you never know when a parent will return with food.

Half way through chick development, when they've grown to a decent size but are still covered with down, keeping them warm as the adult feathers develop beneath.
By March the Northern chicks are three to four months old. I'll head round the study area and take weight and bill-length measurements from all of them, also giving them a unique ring so they can be identified in the future. All that remains then is for them to lose their remaining chick feathers, stretch out their wings and head off to sea. By mid-April they'll all be gone with the Southern geeps about a month behind them.

Ready to go. This was the first egg laid last season, in mid-September. By mid-March she was looking beautifully slick and smart and was soon to depart.
They're long-lived birds. I've not seen any figures for ages but there's ones here breeding that are older than me and it wouldn't surprise me if they can get to double that age. Many of these chicks will return to the same areas of their birth to breed, but it'll be a few years before that happens. I was finding apparent first-time breeders this season that were ringed here as chicks in 2005 and 2006. Ongoing experiments using tiny geolocator devices are trying to work out where the young birds go during their teenage years. Ringing recoveries have shown that within a few months of leaving these young birds can be found as far away as Australia. Similar such work has shown a difference in feeding strategies, with females more likely to feed out at sea while males patrol the beaches. As with all good science, the answers are sure to throw up many more questions.

Southern Giant Petrel. Their presence on the island during the winter is one of the highlights of going for a walk.

Tuesday 1 July 2014

Midwinter part 2

The second half of midwinter week has been full of games, fun and relaxation.

The blood-red sky one morning over base and La Roche.

 With a week off and a big snow drift in front of base what was the most obvious thing to do? Cian and Jess were half way through building a snowman, or snowmaiden, when I went out to help them. She was meant to be a female companion for Jess, although Cian seemed to be making early moves on her. I was shovelling more snow for them when I realised it was coming out in large, compact blocks... would it be possible to build an igloo?

Cian and his Ice Bride

 Starting out with low expectations, I was half way through before putting some real thought and effort into it, hence the with problems with the final result. I managed to get a roof on it but it was very cramped – every time I moved I risked dropping more snow on myself. The other problem was the low entrance that meant crawling in dragged in more snow.

The interior roof of my igloo - pretty and more secure than it looks.

Despite these problems I decided to try and sleep there that night. I stayed up late reading indoors and taking photos in the dark until feeling tired enough I crawled in, trying not to drop snow into my sleeping bag.

Sitting outside my igloo, waiting for bedtime. A carefree sleep wasn't helped by the presence of the weeping angel just outside.

Lying there I was comfortable (so long as I didn't move) and warm enough but the problem was I just wasn't tired. It took over an hour of listening to the sea, the occasional distant seal and the worryingly close scavenging sheathbills but I did eventually drift off. All too soon after that I rolled over and woke up with a face-full of snow. By this point I needed to get up and do a wee. After the rigmarole of getting out my bag and crawling through the icy entrance I was once again wide awake. I'm afraid the temptation of going indoors for a hot drink and a comfy duvet was too much and I slept the rest of the night in my own bed.

The illuminated igloo.

One of the big traditions of Bird Island midwinter is the highland games. All suitably dressed we gathered outside where Cian and I had set up a few events; caber tossing, welly wanging, throwing the ball in the snow-hole, triple jump, obstacle frisbee and the free-for-all that was the potato and spoon slalom.

Rob holding his caber.

Cian having a good toss.

Jess giving a welly a good wanging.

We finished off the Highland Games with a ceremonial smashing of the snow-maiden and the igloo.

We rounded off the week with a long day out exploring. Over the hill to Johnson Beach then around to Burton Cove to investigate the cave there. Some of these are spots we can't go in the summer, either because of too much work or because the density of Fur Seals puts the shore out of bounds. Although there are seals about at the moment they are easily bypassed.

Johnson Beach, once pristine white snow, now a Jackson Pollock mess in a limited colour scheme depending on what the Gentoos have been eating.

The big but not deep cave at Burton Cove.

Before returning to base we did a quick check on one of the Wandering Albatross areas, making sure the chicks are doing okay. They are really big and fluffy at the moment, as they need to be what with sitting here all through the winter. Happily they have survived their most vulnerable stage – when they are first left alone by the parents – and through these months there are very few failures.

Wandering Albatross chick in front of Tonk and the cloud rolling in.

Greeting a friendly Wandering Albatross chick. We go past this one every time we walk up the hill and it has got quite used to me sitting beside it and chatting. It is yet to respond though, which I find a bit rude. Jess's photo.

The final part of a great day was a slow walk back along the beaches. While keeping an eye out for Leopard Seals I was held up by a group of Gentoo Penguins who consistently come out of the water at the gentle, sandy slope at one end of the beach then walk all the way along past the rocks to their congregation areas at the far end. The sharp claws on the end of their feet are good for walking up frozen streams, but not so good for cutting across or going down the thin sheets of ice now stretching across parts of the shore and seeing them regularly slip and slide makes me feel better about my own stability inadequacies.
  
Gentoo Penguins heading home across a frozen stream.