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A Monarch butterfly rests on the forehead of a man, at the Amanalco de Becerra sanctuary, on the mountains near the extinct Nevado de Toluca volcano, in Mexico, Thursday, February 14, 2019. The monarch butterfly population, like that of other insects, fluctuates widely depending on a variety of factors, but scientists say the recoveries after each big dip tend to be smaller, suggesting an overall declining trend. (Photo by Marco Ugarte/AP Photo)
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