The Mottled Duskywing (Erynnis martialis) has historically been known to occur in southeastern Manitoba, southern Ontario and southwestern Quebec. It prefers dry sandy areas or limestone alvars where its hostplant, New Jersey Tea (Ceano­thus sp.), is found. Records from the past 20 years indicate that populations of Mottled Duskywing are declining across their Canadian range and have disap­peared altogether from some previously known localities. This trend has been observed not only in Canada, but throughout the rest of this species’ eastern North American range

The Mottled Duskywing has not been seen in Quebec since the mid-1990s, and habitat loss due to intense development pressures is likely to blame. Succes­sional pressures on this species’ hostplant have also resulted in habitat loss in several localities where the overstorey has grown and flled in areas where the low-growing New Jersey Tea once fourished. In other localities, aerial spraying for the destructive Gypsy Moth (Lymantria dispar) may have wiped out small lo­cal populations which were unable to recolonize as more common species have.

This butterfy is now represented by only very small, extremely localized popula­tions in southern Ontario and southwestern Manitoba. Although suitable habitat remains abundant throughout its previously recorded range, the Mottled Dusky-wing has been unable to adapt to habitat loss and alterations at a local scale.

The Committee for the Status of Endangered Wildlife in Canada (COSEWIC) has retained Natural Resource Solutions Inc. to prepare a status report on the Mot­tled Duskywing.  However, long-term monitoring of disturbed and undisturbed locations is needed to understand more about the Mottled Duskywing’s habitat preferences, resilience to disturbance, and specifc reasons for its decline.

Jessica Grealey, Natural Resources Solutions Inc., Waterloo, ON. 

 

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