King Silverbirch had a great obsession with silver and when it was mentioned, he could not get enough of it. In his pursuit for more silver on the island, King Silverbirch treated his subjects mercilessly as he searched for it in the mines.
He often had fits of anger in which he signed someone's death decree or something else that he would greatly regret later on.
In Urchin and the Heartstone, he sends Lord Treeth, Bronze, Trail, and Scatter to Mistmantle Isle to kidnap Urchin, "The Marked Squirrel", with the hopes that Urchin could find more silver. Despite the protests of Smokewreath, King Silverbirch was very welcoming to Urchin, giving him food, water, and a nicely furnished room. Later, in a fit, he told Smokewreath that he could have Urchin when the first snowflake falls, and stripped Urchin's room. He also gave most of "the Freak's" care to Commander Cedar, which was a mistake because they could, and did, plot together.
After Urchin, Juniper, and Cedar fled Silverbirch's tower, the maniacal king sent guards, led by Granite, to catch them, and Urchin sacrificed himself to Smokewreath so they could go free. After Juniper freed them, there was an earthquake, which made the fortress collapse in on itself, killing Silverbirch and everyone else in the tower.