Declining monarchs:
Habitat not climate is
your Achilles’ heel.
Understanding why a species is declining is a large part of establishing a suitable conservation approach. In North America the monarch butterfly population has sharply declined in recent decades, yet the reasons for this were unclear until now.
Thogmartin et al (2017) investigated monarch butterfly populations and found that the decline is largely down to habitat loss from herbicide use and the loss of overwinter forest, as well as insecticides. Whilst climate impacts on yearly population size, this is not enough to explain the decreases in monarch butterfly population recorded over recent decades.
Original Research : https://doi.org/10.1098/rsos.170760