Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Mark-recapture study and habitat assessment for the northern metalmark butterfly, Calephelis borealis (Lepidoptera: Riodinidae).

Abstract

Background: The northern metalmark (Calephelis borealis), is an exceedingly local, globally rare butterfly that is declining across the Midwestern and Northeastern USA. The two principal stressors driving colony losses include afforestation and invasive plants that crowd out its larval hostplant (Packera ovata) and nectar resources. Aims/methods: To better understand its declines and guide restoration efforts, we (1) performed a mark-recapture study in Connecticut to document population trends where we were actively managing vegetation; (2) conducted a range-wide survey for evidence of phylogeographic structure, using cytochrome oxidase (CO1); (3) investigated abundance determinants of its larval foodplant, Packera ovata; and (4) visited northern metalmark populations across the Northeastern USA to identify common edaphic, structural, and community elements of its colonies. Results: We document that the species is increasing at a managed colony in Connecticut, where we opened the canopy, removed invasive plants, and added nectar resources. Common habitat attributes in the Northeastern USA include limestone soil, eastern redcedar (Juniperus virginiana), and ecotonal woodland structure that allows its shade-loving, larval hostplant (Packera obovata) to be spatially proximate to sun-loving, nectar resources. Nectar limitation is hypothesized to be a driver of colony location and success. Implications for insect conservation: Our results underscore how active plant management (canopy thinning, invasive plant removal, and the addition of nectar plants) was able to rescue an imperiled woodland butterfly, reinforce the increasingly recognized importance of nectar resources in butterfly conservation, and demonstrate how metapopulation structure can buffer against the vagaries of precipitation and other (increasingly variable) climatic factors.