What is the fine-grained topic of the following text: Black-crowned Night Heron is an uncommon migrant to most areas of Saudi Arabia but in the Riyadh area is a common spring and autumn passage migrant passing early February to early June and again from late July to early November and rarely as late as December with birds now regularly breeding in the area. Only return the topic.
Migration and breeding patterns of Black-crowned Night Heron in Riyadh, Saudi Arabia