Interpreting surveys to estimate the size of the monarch butterfly population: Pitfalls and prospects.

ABSTRACT: To assess the change in the size of the eastern North American monarch butterfly summer population, studies have used long-term data sets of counts of adult butterflies or eggs per milkweed stem. Despite the observed decline in the monarch population as measured at overwintering sites in Mexico, these studies found no decline in summer counts in the Midwest, the core of the summer breeding range, leading to a suggestion that the cause of the monarch population decline is not the loss of Midwest agricultural milkweeds but increased mortality during the fall migration. Using these counts to estimate population size, however, does not account for the shift of monarch activity from agricultural fields to non-agricultural sites over the past 20 years, as a result of the loss of agricultural mil

SUBMITTER: Pleasants JM 

PROVIDER: S-EPMC5510856 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature