How does Brian measure time?

Brian uses the sun to measure time.

He stood and moved out into the sand and looked up at the sun. It was still high. He didn't know what time it must be. At home it would be one or two if the sun were that high.

Now, he thought. Now I have some food and I can do something about fixing this place up. He glanced at the sun and saw he had some time before dark.

Why was it so difficult for Brian to catch a fool bird at first