Tuesday, September 1, 2009

a day at the coast




Hello, all.

This is the first post from the Slater Museum of Natural History at the University of Puget Sound in Tacoma, Washington, USA.

These posts will be varied, but the theme is Northwest nature, information about natural ecosystems of the Pacific Northwest and their plants and animals. We encourage anyone with interest in this subject to join the blog and contribute to it. We also encourage civility and respect for the opinion of others. As most of our material will consist of facts rather than opinions, that should be easy!

I'm writing about a trip to the outer coast of Washington on 30 August 2009. Netta Smith and I wanted to get out of the house and see how the coastal bird migration was faring. It turned out there wasn't much migration going on, at least at most of the places we visited. We drove to Westport first, all the way at the end of the road around the marina to check out the breadth of Grays Harbor with our spotting scope. Out in the middle there were vast flocks of birds, underscoring the value of coastal estuaries for marine life. There must be a lot of prey out there to support hundreds, maybe thousands, of Brown Pelicans, Double-crested Cormorants, California and Heermann's Gulls, and Common Murres, all fish-eaters. There were also smaller numbers of Western Gulls, Pigeon Guillemots, and Rhinoceros Auklets on the relatively calm waters of the harbor. Heavy cloud cover made for gray sky and water, but visibility was good.

Small numbers of Brandt's and Pelagic Cormorants were roosting on channel markers and rock jetties, perhaps the beginning of the large numbers that arrive from the south each fall. No ducks, loons, or grebes were seen; they are yet to come. The only shorebird present was a welcome one, a juvenile Wandering Tattler (PHOTO) that probed among the rockweed. This bird is a far-journeying species that breeds in the Alaska mountains and winters on islands of the South Pacific, north to Hawaii and California. They pass along the Washington coast in small numbers every spring and fall, enhancing the sound of the ocean breaking on rocky shores with their loud, ringing calls.

Below us on the same rocks were scattered ochre seastars (Pisaster ochraceus), one of the dominant intertidal invertebrates in Pacific Northwest coastal waters. This is a polymorphic species, occurring in orange and purple morphs. We noted that the orange ones were very conspicuous, even below the water, but we didn't see the purple ones until the waves receded, exposing them, and even then we had to look quickly, as they blended with the rocks and algae. Why is the species polymorphic? Why are the purple ones more common here, when the orange ones are more common in Puget Sound? Does it have anything to do with their conspicuous to potential predators? One thing that Mother Nature bestows on us is a never-ending series of master's and doctor's research topics!

We headed for the ocean beach south of Westport. In some areas, driving on the beach is permitted, and that's a great way to see birds. Unfortunately, as our population has increased, too many of us are doing this now. We were shocked to see how many people were scattered along the beach. There were no shorebirds (sandpipers and plovers) at all, but there were roosts of hundreds of gulls of three species (Western [PHOTO], California, Heermann's) all along. As we would approach one of these roosts to try to get some photos and check for rare species, more times than not one or more people would walk right up to the birds, scaring them away. More often, a frolicking dog or two would do the same, and it was obvious that the resting gulls were irresistible to people and dogs alike. "Oh boy, let's go scare up those birds." If this was an opinion blog, I would relate in no uncertain terms what I thought of those people! Sharing the beach is great, but this wasn't sharing. Imagine just sitting down on your favorite couch to relax and digest your dinner, and someone comes running through the living room and says "up, up, up," so you walk around the house three times and then sit down again. Within a minute or two the pest comes again, and the scene is repeated. Some of the flocks were disturbed so often that I wondered, not for the first time, how birds and other wildlife will manage in the long run to coexist with our own species.

After this frustrating experience at several beach-access points, we motored down to Tokeland to look for the large roosting flock of Marbled Godwits and other shorebirds that are often present at the marina. Perhaps for the first time ever, there was not a single bird present. Other birders who we encountered had seen none of them earlier in the morning, and we arrived right around high tide, when the birds should have been roosting. But it was a low high tide, with plenty of mud flats in Willapa Bay still exposed, and why roost when you can feed? Shorebirds in migration feed until they are stuffed, laying down fat deposits all over their bodies, and after a few days of this, taking off on the next stage of their flight, often hundreds or even thousands of miles. They can burn their fat for "food" as they fly, and the longer they fly, the lighter they get!

Shorebirds are the world's best optimizers when it comes to feeding. A sandpiper's bill may actually be probing the substrate as it is coming to a landing, and they never stop probing, as long as there is a bit of room in their stomach. Many species have sensitive nerve bundles called Herbst corpuscles in little pits on their bill tip, and they can feel the wiggle of a worm or the curve of a snail as they probe the sand or mud.

Our final stop of the day was at Bottle Beach State Park on the south side of Grays Harbor, and that's where the migrants were. Flocks of hundreds of Western Sandpipers flew to newly exposed mud flats as the tide receded, and scattered among them were Semipalmated and Black-bellied Plovers, Whimbrels, Greater Yellowlegs, and other species. The sun never came out this day, but there were just enough birds that we headed home with a sense of accomplishment. Of course the birds were the ones accomplishing.

Dennis Paulson

1 comment:

Aleksei Molodtcov said...

Very good started the blog. I'll hope that you will post more articles about jellyfish and what do jellyfish eat