Sunday, May 17, 2009

Midway's For the Birds!

It's been really windy lately, so we haven't been able to go out on the water much since Thursday. We went out briefly yesterday to check spat collectors at the site we call Forbidden Beach, which is off the northwest side of Sand Island (the beach is reserved for the monk seals and other wildlife, so therefore forbidden to people!), which was pretty protected, but the waves were too big to go elsewhere. Unfortunately, May still gets a bit of winter weather, so it's not as predictable as the summer! We've been doing lots of data entry, planning, tile-drilling, etc.

Since I don't have much interesting work to talk about, I'll use this blog to introduce the most famous residents of Midway: its birds!

The most common bird at Midway is, of course, the albatross. We have two species here: the Laysan albatross (Phoebastria immutabilis) and the black-footed albatross (Phoebastria nigripes - pictured left). Once in a while, we get a short-tailed albatross, or a "golden gooney," but I've only seen one once. The albatross generally come back to the island in November and lay their eggs by December. The parents trade off sitting on the nest and feeding thousands of miles away for two months until the single egg hatches in late January to mid-February. The parents regurgitate flying fish eggs and squid oil to the chicks. By now, mid-May, the chicks are quite big and nearly as large as the parents. In about a month, the parents will stop feeding the chicks and the chicks will start trying to fly and moving toward the beaches. The chicks will fledge in late June to July; since Midway hosts over 450,000 breeding pairs of Laysan albatross and over 25,000 breeding pairs of black-footed albatross and only about 65% of chicks survive to fledge, we have lots of dead birds and flies in July, but we also have lots of chicks out on the reef. It's also known as tiger shark season for those of us in the water because the chicks are easy prey!

The juveniles will stay at sea for 3-5 years before returning to Midway to look for a mate, but they frequently don't mate until they are 8-9 years old and then may only have a chick every other year. One of the threats to these birds is the huge amounts of plastic floating on the surface of the North Pacific Ocean; parents will feed pieces of plastic to their chicks, and it's common to see cigarette lighters, toothbrushes, and other myriad pieces of plastic in the gut of dead chicks. Fortunately, albatross chicks spit out their stomach contents in a bolus in order to get rid of squid beaks, and this mechanism also rids the chicks of plastic generally. There are lots of dark boluses of squid beaks and plastic all over the island now.

Another common bird is the white tern (Gygis alba rothschildi), which dart above our heads all the time. They lay their eggs on any available flat surface and don't bother to build a nest, so we find eggs and chicks on window air conditioners, trees, ledges, etc. The parents bring whole small fish and squid to the chick for nearly 4 months! We've observed a white tern pair laying an egg and raising a chick on the exposed reef rim in the northeast part of the atoll (Reef Hotel) for the past three years at the same location . We've seen the chick the last two years, but saw a parent incubating an egg last week there (at right).

One of the more recent additions to Midway's birdlife is the Laysan duck (Anas laysanensis - at left). These endangered ducks have only been found since 1860 at Laysan Island, one of the islands to our southeast, but FWS decided to establish a second population at Midway in 2004 and 2005. Despite an epidemic of botulism last year, the birds have become a com around Midway - I saw 7 of them tonight while biking around town at dusk.

We also see a lot of red-tailed tropic birds, frigate birds, boobies, other tern species, and other seabirds, but I'll save them for another day!

1 comment:

lihsien said...

I'm starting to follow the blog.
The national parks in US could use this kind of blog, too.