From all indications this will be another year when there is no nesting or hatching of western grebes at Clear Lake. Last year not a single active nest or baby grebe was seen on the lake. It”s a far cry from five years ago when an estimated 100,000 grebes were on the lake and primary nesting areas such as Long Tule Point were literally awash with baby grebes.
Most of the experts blame the lack of nests and baby grebes on a shortage of food. The threadfin shad are all but gone and even the silverside minnows are in short supply. These baitfish are the primary food for the grebes on Clear Lake.
There are about a thousand grebes scattered around the lake but none are successfully nesting. About the only reason that can be given for the lack of nesting is the absence of food required for the female to produce eggs and then feed the chicks. It”s the old story of Mother Nature saying if the food supply isn”t there for the young, then there will be no reproduction.
This is a repeat of what happened last year. A team of scientists from the University of California at Davis spent several weeks studying the grebes and they told me that they found no active nests or any young chicks after traveling completely around the lake.
Of course, that doesn”t mean you can”t enjoy observing one of Clear Lake”s most fascinating water birds. They are still doing their mating rituals, which includes running across the water and head bobbing. Plus there are enough grebes on the lake to observe without any trouble.
Western grebes feed mostly on minnows but they will also eat clams and crayfish. They are the ultimate fishermen. I have seen them chase down the small silverside minnows and pick them off one by one like popcorn. Studies have shown that grebes capture most of their prey by stabbing them through the middle with their long and sharp beaks. However, on smaller fish, such as the silverside minnow, they grab them with their beaks. Most of the time they swallow their food underwater. Scientists believe they do this because it prevents other grebes from stealing their food. However, it”s common for a grebe to surface with a minnow in its mouth and offer it to its mate or to the chicks.
The stomach of a western grebe is lined with downy-types of feathers that are formed into a ball. It is believed the purpose for the feathery ball is to prevent sharp fish bones from penetrating the stomach lining.
Extensive studies done at Clear Lake in 1950 showed the primary prey for western grebes were bluegill minnows. Very few bass were found in their stomachs. Of course, that was before threadfin shad or silverside minnows were introduced into the lake.
It is the grebes” mating dance that draws most of the attention from bird watchers. The male approaches the female and does a series of dips with his head. She responds with like dips and then they ran across the surface of the water with they necks arched in perfect unison. Their final act is to dive exactly at the same time.
Western grebes also perform what is called the “weed ceremony,” which occurs after the grebes have paired up and just before they start building nests. The male and female will dive and bring up weeds in their bills. They face each other and do a spiral dance.
Of course, just about everyone knows that the chicks ride on the mother”s back, but how they climb up there is also unusual. The mother extends her foot as a platform for the chick to climb up on and then onto her back. I didn”t believe that at first until one day I had the opportunity to observe a pair of chicks climb up on their mother”s back several times over a period of about 30 minutes. Every time they used her foot as a platform.
Whether or not the western grebes are in trouble in others areas is unknown, but it would be a golden opportunity for biologists from the U.S. Fish and Wildlife Service and the Department of Fish and Game to study the existing grebes at Clear Lake to see what their health status is. They could check body fat and see if the female is generating any egg growth. But I don”t see that happening. Neither agency has any money for research.
