Monarch butterflies are a keystone species, meaning they play a massive role in their native ecosystems. Think you know ...

The number of monarch butterflies spending the winter in the western United States has dropped to its second-lowest mark in nearly three decades as pesticides, diminishing habitat and climate ...

For the past three years, more than 200,000 western monarch butterflies spent their winters along the California coast — huddling together in tall tree groves, finding respite from the wind from ...

Fewer-than-usual monarch butterflies migrated through San Luis ... creating difficult conditions for the monarchs to survive in. In fact, California set new heat records every July during the ...