Can a species become extinct independent of a mass extinction event? How many species have to go extinct for it to qualify as a mass extinction?

What is the "great pacific garbage patch"? a large area of marine debris concentrated by rotating ocean currents a large area around the pacific rim where debris collects from natural disasters such as tsunamis an area in the pacific ocean where trash is intentionally dumped due to lack of landfill availability a large trash dump located in hawaii

What environmental cues and landmarks do the geese use to determine the timing and direction of their migration over the mountains? how do they find their way?

Can someone i have no idea of how to do this.