|A White-faced Ibis (Plegadis chihi) at the Merced National Wildlife Refuge|
|A Black Phoebe (Sayornis nigricans) at the Merced National Wildlife Refuge|
So I've started blogging bird pictures on occasion, such as here, here, and here (click on the words for the link). Is there a geological link in observing birds? I've decided there is, especially in California's Great Valley. The science of the Earth is eclectic, drawing on many different disciplines, including chemistry, physics, astronomy, oceanography, meteorology, and on occasion, biology (think especially of paleontology). Sometimes there is a direct connection, such as when overgrazing or removal of beavers changes the pattern of stream erosion. And land-use issues are one of those areas where geologists can provide an important perspective.
|Artificially flooded ancestral wetlands at the Merced National Wildlife Refuge. These are reclaimed farmlands.|
One of the most important land-use issues in the Great Valley involves agricultural and urban development and the conflict it causes with the natural habitat that existed prior to the arrival of European settlers. Some 95% of the valley has been plowed over, and all the major (and most of the minor) rivers have been dammed, diverted, or otherwise changed in the service of agriculture. In more recent years, urban growth has paved over prime agricultural acreage, creating a conflict within a conflict. The ramifications of these conflicts extend far beyond the Great Valley. They reach from the northernmost Arctic wastes to the equator, and into South America. The Great Valley, as it turns out, is one of the most critical stops on the migratory flyway for myriads of bird species. Our choices in the valley determine the health of ecosystems thousands of miles away. And most of the wetlands that made the valley such an important flyway stop were drained and plowed decades ago.
|Black-necked Stilt (Himantopus mexicanus) at the Merced National Wildlife Refuge|
That is why I am kind of thrilled to be writing today about the bird species of my home turf. I have driven by a couple of wildlife refuges for two decades without stopping (what can I say? I live next to the Sierra Nevada and the California Coast; they are a huge distraction). In the last few months, we've been stopping and having a look, and yesterday at the Merced National Wildlife Refuge I saw an incredible thing.
|Great Egret (Ardea alba) at the Merced National Wildlife Refuge|
The first thing to realize is that the destruction of wetlands has been recognized for many decades, and for years some visionaries have worked to establish protected wetlands. In some cases they have reclaimed former agricultural acreage in a concerted effort to reconstruct some of the original environment that once characterized the valley. There is now a mosaic of wildlife refuges surrounding my community, lined up like islands in a sea of farms and ranches reaching from one end of the valley to the other (a 400 mile stretch). We can never fully recover what was, and will never see the spectacle of millions upon millions of birds descending on the valley floor, but we can see the tens of thousands of the survivors.
|Sandhill Cranes (Grus canadensis) at the Merced Refuge|
That's what I saw yesterday. I'm admitting my own stupid ignorance here, but I had no idea that we had an American version of the Serengeti Plains a short way from my house. We've probably all seen television documentaries and footage of vast flocks of birds flying and flocking, but I'd never seen such a thing for myself. We headed out to the Merced National Wildlife Refuge because we'd heard they had flooded the wetlands, and that some Sandhill Cranes might be seen. We saw some cranes, but that's not what I found stunning. It was the Ross's (or maybe Snow) Geese.
|Ross's Geese (Chen rossii) and Coots at the Merced Refuge|
The Ross's Geese spend their summers in the far northern islands of Canada, and spend their winters in California. As we drove the loop road through the refuge, we could see vast flocks off in the distance, and from more than a mile away we could hear their noise. As we drew closer, we could see that there were thousands of them, maybe tens of thousands (some sources mention 60,000 geese). They were chattering and honking, and it was almost deafening. Then the extraordinary thing happened. There was a hush that made us look up, and then a sound like a jet engine began to roar. The ground actually seemed to tremble. Every single one of the ten thousand or so geese was taking flight at once. In less than 20 seconds they were all airborne. I have no idea what set them off, but it was like nothing I've ever seen in my life.
|Ross's Geese taking flight|
I got a good video of the event, but the compression process during uploading removes the high definition and makes it hard to easily visualize what was happening. I can only say to try and imagine what this piddly movie is showing, and then someday give yourself the opportunity to visit the wildlife refuge during the winter and see it happening for yourself. It's free!