12. Chickadee Notes

Maritime Ringlet in New Brunswick 

Status

Maritime RingletThe Maritime Ringlet, Coenonympha inornata nipisiquit, is one of only two butterflies in Canada that live exclusively in salt marsh habitat. This insect has an extremely restricted distribution that covers an area of less than three square kilometer. For this reason, the Maritime Ringlet has been proposed for endangered species status under the Endangered Species Act of New Brunswick. Only four colonies are known, three of which are found in New Brunswick salt marshes in the immediate vicinity of Bathurst, at Daly Point and Carron Point, and near Beresford at the mouth of the Peters River. A fourth population occupies a salt marsh near Miguasha, Quebec on the Gaspé Peninsula.

Natural History

The Maritime Ringlet is one of two subspecies of Ringlets found in New Brunswick. The other subspecies, the Inornate Ringlet, Coenonympha inornata inornata, is more widespread and common. It is found in a variety of open grassy habitats, including fields adjacent to the salt marshes inhabited by the Maritime Ringlet, but it rarely ventures into the salt marsh. Although the adults of these two subspecies are very similar in appearance, they differ in their biology and ecology. Each subspecies occupies a different habitat, uses different larval host plants and has different adult flight periods. The Inornate Ringlet adults fly only during June and early July while the Maritime Ringlet adults appear during late July and August. Any Ringlets observed outside the salt marsh during June and early July will be the Inornate Ringlet. Since the two subspecies overlap in distribution and are reproductively isolated, it has been suggested that they should be considered separate species.

The Maritime Ringlet... is one of only two butterflies in Canada that live exclusively in salt marsh habitat.

Like all butterflies and moths, the Maritime Ringlet has an egg, caterpillar, pupal, and adult stage during its life cycle. As the caterpillars grow they moult several times. The Maritime Ringlet caterpillars moult five times and pass through five larval stages called instars. Once the caterpillar becomes full grown it moults into the pupal stage. During the pupal stage the larval structures are reorganized into adult structures. When the transformation is completed the last moult occurs and the full-grown adult emerges from the pupal shell.

The Maritime Ringlet adult is tan- coloured with an eye spot on the underside of the front wing. It is a relatively small butterfly with a wing span between 3.2 and 3.6 cm. Adult Maritime Ringlets fly in the salt marshes for about three weeks between late July and mid- August, where they can be relatively numerous within their limited habitat. Individual adults probably live less than one week. Males usually emerge first and are easily observed as they patrol the salt marsh searching for unmated females. Females usually fly only after they have mated. Females spend most of their time laying eggs, and are usually observed only when they are taking nectar from the flowers of sea lavender, along with males, bumble bees, and other insects.

Once the females mate they begin to lay eggs on their caterpillar host plant which is salt meadow grass, Spartina patens. The eggs are usually laid near the tips of dead blades of the host plant at its base. After about ten days the eggs hatch into 3 mm long caterpillars. Initially the caterpillars feed on the tip of the dead blades of grass the eggs were laid on and later feed on the new shoots. The caterpillars moult to the second instar in early to mid-September and continue to feed until late September. At this time the caterpillars, which are about 6 mm long, stop feeding, crawl into the leaf litter at the base of the salt grass, and enter diapause, a resting stage. The caterpillars pass the winter in the leaf litter and must withstand a combination of freezing temperatures as low as -20s C and occasional flooding by salt water during high storm tides.

...only four populations of this butterfly are known.

During May the caterpillars resume feeding on the new grass shoots. The caterpillars are green with longitudinal yellowish stripes and are well camouflaged on the salt meadow grass. The larvae become full grown by mid to late July and reach a length of about 2.2 to 2.3 cm. When mature, the caterpillars stop feeding and seek out a pupation site, usually near the base of grass stems. The cryptically-coloured blue-green, and black striped pupae are attached by a silk pad to the stems of the grass. The pupal stage lasts about ten days and then the adult emerges and the cycle begins anew.

During much of the larval feeding period the caterpillars are subject to flooding by salt water during high storm tides and by fresh water during spring flooding. Unfortunately, there are no data available on the frequency and duration of flooding in these salt marshes. Examination of the decayed vegetation at the edges of the marshes suggest that the marsh is sometimes covered to a depth of 60 cm or more. Flooding is probably most frequent during the fall, spring and early summer. The caterpillars must be able to withstand immersion in salt or fresh water for at least several hours at a time.

The Maritime Ringlet is most common in sections of the marshes dominated by salt meadow grass, sea lavender, and seaside goldenrod, and rarely ventures beyond the edge of this habitat. Although the presence of the host is necessary for the existence of the butterfly, the Maritime Ringlet is not found in all sections of the marshes dominated by this plant. Where species such as sedges, associated with fresh water habitats, infiltrate the salt meadow grass stands, the butterfly becomes increasingly rare. This suggests that salinity of the water is critical for maintaining the microhabitat required for the survival of the butterfly. Although suitable salt marsh habitat appears to be common along the shores of the Chaleur Bay only four populations of this butterfly are known. It is probable that this butterfly was more widespread in former times. However, it is also possible that the microhabitat requirements of this insect have greatly limited the type of salt marsh that it can survive in.

Helping Out

The Maritime Ringlet is entirely dependent on salt marsh habitat and therefore protecting the salt marshes occupied by this butterfly is essential for its survival. Two populations, those at Carron Point and Daly Point are now protected in reserves administered by New Brunswick Department of Natural Resources and Energy and Brunswick Mines and Smelting. Unfortunately, the largest population, near Beresford, is not protected and the salt marsh is being encroached on by housing. Steps should be taken to protect this site.

...protecting the salt marshes occupied by this butterfly is essential for its survival.

Even where salt marshes are protected Maritime Ringlet populations may be at risk. Polluted fresh or saltwater from outlying regions, perhaps contaminated with oils or detergents, can pose a threat to Maritime Ringlet larvae or pupae. Physical changes to water courses that influence the flow of water to and from the salt marshes could damage the microhabitats supporting this butterfly. It is vital that the estuary systems feeding these marshes not be altered or polluted if the Maritime Ringlet is to survive.

If you are fortunate enough to live near, or visit, one of the marsh sites of this rare butterfly be certain to treat the habitat with respect. We can all help conserve marine and coastal species, such as the Maritime Ringlet, by supporting efforts to control and reduce pollution along New Brunswick coasts.

Little was known about the biology and ecology of the Maritime Ringlet until recently. Much of the information presented here is the result of studies conducted in 1993 and funded by World Wildlife Fund Canada and the New Brunswick Department of Natural Resources & Energy, Fish, and Wildlife Branch. Although our knowledge of the biology of this butterfly has increased considerably a result of these studies, additional research is required to ensure that effective conservation and management policies for the Maritime Ringlet can be formulated.

Further Reading:

Clayden, S.R., D.F. McAlpine, and C. Guidry. 1984. Rare and vulnerable Species in New Brunswick. New Brunswick Museum Publications in Natural Science 2: 95 pp.

Christie, D.S. 1970. Bathurst's butter- flies. New Brunswick Museum Memo 2: 9-11.

Pyle, R., M. Bentzien, and P. Opler. 1981. Insect conservation. Annual Review of Entomology 26:233-258.