Spring is when Clear Lake comes alive with nesting water birds. Without question the most abundant water bird on Clear Lake is the majestic Western Grebe and this spring there are thousands of grebes out on the lake.
Few birds can match the Western Grebe’s courtship dance. It’s not only breathtaking, it is probably the most photographed event among wildlife photographers. But it’s not just their mating dance the makes the grebe one of the most popular water birds. Their other behavioral traits are just as interesting.
Both the male and female build the nest and raise the young. They use tule stalks to make a floating mat and then build the nest on the mat. The female lays from one to four eggs and it takes 23 days for the eggs to hatch. The young leave the nest soon after being hatched and often ride on the backs of their parents. This allows the chicks to rest and to escape danger.
Grebes can live as a long as 15 years but most live only eight to 10 years. Even though very few people have seen a Western Grebe fly, they do migrate and it’s mostly at night.
The grebe is most at home in the water. In fact, with the exception of seeing grebes on their nests, few people have ever seen a grebe on land. Actually, their legs are positioned so far back to aid in swimming that they would fall over if they attempted to walk.
Without question the grebe is the world’s fastest diver. Even bass boats roaring across the lake at speeds in excess of 60 mph rarely hit a grebe. At the last second, just when you think the boat is going to hit the grebe, it dives and escapes unscathed.
The Western Grebe has a close cousin called the Clark’s Grebe. Both grebes are common at Clear Lake. Whereas the Western Grebe has a dull yellow or olive-colored bill and red eyes surrounded by the dark head crown, the Clark’s Grebe has white surrounding the eye and a bill that is bright yellow to orange-yellow.
The sounds made by the two birds are also different. The Western Grebe makes a single sharp kreet whereas the Clark’s Grebe makes two kreets.
Both Western and Clark’s grebes eat mostly insects and fish. They also eat clams and crayfish. They are the ultimate fishermen and can chase down the smallest minnows and pick them off one by one like popcorn. Their primary food source at Clear Lake is the threadfin shad and this year the shad are in the lake by the tens of thousands.
Grebes can be found at just about any location around the lake. During the spring and early summer months they nest back in the tules. Other times they can be seen in the middle of the lake. Grebes are classified as a migratory bird but there is a stable population of Western Grebes at Clear Lake all year. However, the population can double or even triple during the spring nesting season.
Food is also the criteria for how many grebes will be on a lake. In 1990 when the threadfin shad population was at it peak on Clear Lake there was an estimated 50,000 grebes here. At that time it was considered the largest population of grebes anywhere in the world. Of course, once the shad disappeared most of the grebes left for other lakes. The past three years have seen the grebes return to Clear Lake by the thousands because of the abundant food supply.
It’s their courtship dance in the spring that draws most of the attention. 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 their necks arched in perfect unison. Their final act is to dive exactly at the same time. This maneuver is called “rushing” and the birds actually swim so fast they hydroplane.
Clear Lake grebes are also a favorite water bird for federal biologists who are looking for mercury in the birds. The mercury comes from the fish they eat. Biologists take blood samples of birds and then scan them for mercury. The method the biologists use to obtain the blood sample is to trap the grebes at night. They then insert a needle into the heart of the grebe. Surprisingly the procedure doesn’t harm the grebe and they are released.
At one time the Western Grebe nearly disappeared from the lake and the West. Sixty years ago, DDT was sprayed on the water to control mosquitoes and gnats. The pesticide was ingested along with the fish that the grebes ate, which resulted in thin egg shells. As a result, the eggs wouldn’t hatch. However, since the banning of the DDT, the grebes have made a dramatic comeback.
Like all the other shore birds on Clear Lake, grebes are an important part of the ecosystem. They are also an excellent tourist attraction. Tourists from throughout the country come to Clear Lake just to photograph the birds. It’s just another reason that Clear Lake is such a special place.
