Environmental issues frequently appear in Zindel's thrillers. For instance, the destruction of Australia's natural environment is a prominent issue in Reef of Death, in which unscrupulous corporations despoil the land and coastal waters. In Rats human beings have despoiled much—perhaps most—of the land in and near New York City. The landfill in which the rats live has been placed in a bad spot, right next to a community of homes. Its smell is foul and it is infested with vermin. Zindel contrasts this with the Woodland Bird Sanctuary, a place that represents hope for undoing the destruction that people have wrought on the land.

This environmental theme is nicely worked into the plot of Rats so that it appears to be a natural part of the novel. The rats themselves have adapted to the polluted landscape, becoming creatures who can survive where...