The photograph shows monarch butterflies landing on plants where there are thousands of other monarch butterflies. these butterflies feed on milkweed plants as they travel south for the winter, covering distances of 5,000 km or more each year. however, the population of these butterflies has been steadily declining over the last 20 years. what is the most likely reason the population of these butterflies has been declining?

Based on the observation that only male crickets produce a song, you hypothesize that a male's song is a form of communication to potential mates. you set up a simple experiment to test this hypothesis. in the laboratory, you place a male snowy tree cricket in enclosure a, which is adjacent to enclosureb. in enclosure b, you place other insects, one at a time, and observe their responses to the male's song. the enclosures are designed so that the two insects being tested cannot see or smell each other, but sound is transmitted from enclosure a to enclosureb.