I was out at the San Joaquin National Wildlife Refuge this afternoon, checking on what migrant birds are still hanging around as we approach spring. I noticed some sun dogs in the western sky, and snapped a shot or two, but the bright sun was causing lens flares that were messing up the shots. It finally occurred to me to put my hand in front of the sun and suddenly I saw something I've never seen or noticed before: a 22° ice halo around the sun.
The sun dogs (also called mock suns or phantom suns; scientists call them parahelia) are caused by the refraction of sunlight through hexagonal ice crystals in the upper atmosphere. The rainbow colors in the sun dogs themselves happen because of the prisming effect of the crystals.
Either that, or I have summoned forth the twin solhundes (sun wolves) of Norse mythology...
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...
I must admit that an exploration of the valley can be a bit monotonous. Traveling Highway 99 or Interstate 5 involves hundreds of miles of featureless fields and orchards, interrupted now and then by towns whose cultural attractions consist of gas stations and fast food restaurants (don't get me wrong, some of our towns have fascinating cultures, but you may have to work to find them at times).
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.
What has enriched my life in recent years is seeing the valley the way our migrant birds see it: a series of "wilderness" islands that allow me to imagine the valley as it once was, America's version of the Serengeti Plains. The prairies and wetlands once supported millions of grazing animals and migrating bird species (along with the year-round resident species). Most of these "islands" are part of the National Wildlife Refuge system, while others are preserves administered by a variety of federal, state and private organizations. These refuges allow the preservation and survival of the remnants of the incredible ecosystem that once existed here. It took a long time to recognize what we were doing to these animals as we took away more and more of their habitat to grow our food, but now there is a movement towards rehabilitating some of the wetland environments. We are trying to undo the damage we've caused over the last century and a half.
I was reminded of these efforts this afternoon when I drove over to a viewing area at the San Joaquin National Wildlife Refuge, one of the main centers of the efforts to rebuild the wetlands (something like 400,000 trees have been planted in riparian habitats that had been converted to farmlands, later abandoned). I saw an astounding sight.
There were perhaps tens of thousands of Aleutian Cackling Geese (Branta hutchinsii leucopareia) gathered in a plowed cornfield (planted by the refuge employees to provide food for the birds). The birds are closely related to the Canada Goose, but are considered a separate species based on DNA analysis. The species had gone into a steep decline due to hunting, the introduction of foxes on the island where they bred, and loss of winter habitat in the Central Valley. They were actually thought to be extinct for twenty four years, as none were seen after 1938, but a group of several hundred were found on some isolated islands in 1962. They were listed officially as an endangered species in 1967.
Aggressive efforts began to protect the birds from extinction, and in fifty years, the results have been successful enough that the bird has been removed from endangered status. From a population of less than 1,000 birds, there are now more than 120,000. And I was looking at a large percentage of the entire population of these birds at the San Joaquin National Wildlife Refuge this afternoon. It was stunning.
The birds certainly still face problems. They are crowded onto relatively limited lands, and drought years can limit the amount of maize and wheat that can be planted on their behalf. The drought also limits that available wetlands that they prefer for roosting. But still for a few moments this afternoon, I was reminded how the valley used to support millions of geese and cranes. It may still do so again. It's possible to share the bounty of our valley with the original inhabitants.
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!
Isolation brings about evolutionary change, and the Canada Goose clan has been doing some changing over the last few thousand years, especially in Hawaii, but also here in California. Today's blog is cross-posted from my new birding blog, Geotripper's California Birds.
If you've ever been accosted by a Canada Goose at the local park, pictures like these might give you the shivers. If one of them can deliver a nasty bite, just imagine what a few thousand of them can do. But take heart, these scenes are no nightmare. They aren't even Canada Geese. The birds occupying this field in the San Joaquin National Wildlife Refuge west of Modesto are Aleutian Cackling Geese (Branta hutchinsii). It's true, though, that before 2005 they were Canada Geese. Allow me to explain.
The Canada Goose lives in many environments, and in some cases particular flocks broke away and colonized different islands or territories (see yesterday's post for an extreme example). The presence or lack of food sources or differences in the nature of predators favored certain traits (size and behavior, for instance) in the young. The geese who summered on the Aleutian Islands were long recognized as a smaller subspecies of the Canada Goose, but recent DNA analysis has led researchers to consider these birds an entirely different species. And so these birds are not Canada Geese, they are the much smaller Aleutian Cackling Geese, which are genetically distinct from the Canada Goose.
The Cackling Geese winter by the tens of thousands in the wildlife refuge a few miles west of my home. It is a stunning sight to see so many of the birds in one place. From the observation deck on Beckwith Road, one can see and hear thousands of birds taking off and landing, and in general making a racket (cackling, as it were). They have been encouraged to stay here instead of nearby agricultural fields through the planting of corn and other food plants. In April they will pick up and leave, headed north to breed in the Arctic.
The refuge is also home to thousands of lesser Sandhill Cranes. We could just make out a flock of them in the far distance. Snow Geese also winter in the area. There were five of them among the thousands of Cackling Geese yesterday, looking mildly confused. They usually arrive in large numbers in late November or early December.
"George, are you SURE this is the right place? Shouldn't you have asked directions in Oregon?"
As we were standing and watching the flocks there was a tremendous BOOM, and thousands of the geese immediately took flight. A huge dust plume over to the west revealed where the explosion had come from. And why.
It was a huge net. Several dozen of the birds had been trapped and for the next few minutes we could see Fish and Wildlife employees tagging them.
As usual, the picture quality from YouTube sucks (the compression process I suppose), but you can get a sense of the cacophony of sound from the flying geese from the short video below.
