What scientific evidence is there that monarchs are at risk? Provide two examples, at least one of which involves quantitative data. This is NOT asking WHY the monarchs are in trouble but how we know they are in trouble. A lack of milkweed explains why they are endangered, not how we know they are endangered. (Note: Scientific evidence can include qualitative observations (see, hear, feel, taste, smell) or quantitative data. The word "quantitative" means numerical data.)

Question

What scientific evidence is there that monarchs are at risk? Provide two examples, at least one of which involves quantitative data. This is NOT asking WHY the monarchs are in trouble but how we know they are in trouble. A lack of milkweed explains why they are endangered, not how we know they are endangered.  (Note: Scientific evidence can include qualitative observations (see, hear, feel, taste, smell) or quantitative data.   The word "quantitative" means numerical data.)