Premier Presentation: The status of North America’s butterflies: Are once-common species in trouble?

It is hard to know how many butterflies in the North America are truly imperiled. Data from NatureServe suggested that over 17 percent of butterfly species are at risk of extinction. But this data has a limitation; it shows whether a species is at risk of extinction, not if it is in decline. Indeed, most of the butterflies listed as imperiled by NatureServe are rare endemics – those species that have discrete habitat patches. What this data misses is the decline in broadly distributed once common species.  There is compelling evidence that widespread butterfly species are becoming less common. Data from overwintering sites in Mexico clearly shows that monarch butterflies (Danaus plexippus) have declined over 80 percent.  Other common butterflies may have also suffered marked declines but they have been happening generally unnoticed. Many scientists are expressing concern that species we once took for granted may be in trouble and some long term data sets provide some evidence for this trend.  This talk will explore what information we have on common species and their decline and discuss why populations may be declining, what research is needed to better understand this phenomenon and how we can start to address the conservation needs of these important insects.