What are some adjectives that describe penguins and begin with the letter U?

Here are some quotes from the book. The adjectives are in bold.

• He had never seen those great shining white expanses of ice and snow. How he wished that he had been a scientist, instead of a house painter in Stillwater, so that he might have joined some of the great Polar expeditions.
• Down the hall it went and into the bedrooms, with its strange, pompous little strut.
• In the pleasant little city of Stillwater, Mr. Popper, the house painter was going home from work.