This is a reposting of a column at Geotripper
I live in California's Great Valley, also known as the Central Valley. It's one of the most important agricultural regions on Earth, in that it produces around a quarter of the nation's produce. It's an extraordinary geological province, 400 miles of almost perfect flatness. When I moved to the valley nearly thirty years ago, I thought I was moving to a boring place, featureless, and bereft of the kinds of terrain that makes a geologist's heart go pit-a-pat. I was wrong...
The valley environment ranges from oak woodlands in the north through semiarid prairie in the middle reaches to barren desert to the south. The land is actually well-watered, as the adjacent Sierra Nevada feeds numerous rivers that flow into the valley. The rivers have been mostly diverted for use in irrigation, but about 30% of the water continues on to the sea. About 95% of the land surface in the valley has been converted to agricultural and urban development.
I imagine some people would think I was exaggerating a bit when I said there were thousands, maybe tens of thousands of birds at the refuge this afternoon. I certainly couldn't fit them all into a single picture, so I invite you to see a video I took, sweeping across the crowd next to the road. Enjoy!
More on the recovery of the Aleutian Cackling Goose can be read here: http://www2.humboldt.edu/wildlife/faculty/black/pdf/Minietal2011_AleutiansWildfowl.pdf