Blue grey Taildropper Slug Stewardship

If you are fortunate enough to have Garry Oak meadows or older Douglas-fir/maple forest on your property, please contact us to arrange your free and confidential property visit.  We can show you how to monitor for this endangered slug. 250-995-2428.

About the Blue-grey Taildropper

The Blue-Grey Taildropper is a small slug associated with two endangered ecosystems: Garry oak meadows and mature Douglas-fir forest. Little is known about the slug unfortunately, except that it is extremely rare, and that its habitat is shrinking.This slug is endangered in Canada and on the Red List of species at risk in British Columbia due to its rarity and threats to its habitats from development and other human activities.

Download the  visual identification guide (5MB PDF)

Download the habitat guide (560KB PDF)

Blue-grey Taildropper photo by Kristiina Ovaska

Blue-grey Taildropper - Photo by Kristiina Ovaska

Description

The  Blue-grey Taildropper is a small slender slug about 2–3 cm long when fully extended in movement. As its common name suggests, it ranges in colour from grey to blue, often with some fine, light speckling. The slug can autotomize (drop) its tail if threatened. If you observe the slug very closely, you may be able to see a thin line or groove where the tail would be detached.

How can I tell if the slug I saw is the Taildropper?

Identifying the Blue-grey Taildropper is a challenge if you are not used to looking at slugs.  Dr. Ovaska has prepared a visual ID Guide for HAT, which you can view here. (5MB PDF). You can also take a photo and send it to us at This email address is being protected from spambots. You need JavaScript enabled to view it. . If possible, take a photo both from above and from the right side of the slug to show the position of the breathing hole (pneumostome). The Royal BC Museum offers an an excellent fieldguide to terrestrial molluscs.

Habitat

In Canada, all records of the Blue-grey Taildropper are from moist forests on southern and south-eastern Vancouver Island. Many records are from Garry Oak meadows and their fringes. The slugs also occur in Douglas-fir-dominated forests, especially in small openings with dense shrubs such as Ocean Spray.The slugs are found in moist microsites on the forest floor, such as within leaf litter, under Sword Ferns, within moss, or under decaying logs.

Diet

To learn more about what Blue-grey Taildroppers eat, biologists examine their droppings (yes, that is their poo!).  In Oregon, biologists found fungal spores in 90% of the droppings examined. The spores were mostly from mycorrhizal fungi that form essential symbiotic associations with tree roots.

Why are Blue-grey Taildropper Slugs important?

Mycorrhizal fungi grow on the roots of plants and trees and help them capture nutrients from the soil. This relationship between beneficial fungi and trees is essential for healthy forests. In areas where mycorrhizal fungus/plant relationships have broken down, trees take longer to grow, and are not as healthy. The Blue-grey Taildropper and the few other animals that eat these fungi play a vital role spreading the spores of mycorrhizal fungi, and each time one of these spore-spreading species is lost, the entire forest suffers.

Apart from its ecological role, the Blue-grey Taildropper has intrinsic value as a unique inhabitant of coastal Douglas-fir forests.

What can I do to help?

There are two important things any homeowner can do that will help the Blue-grey Taildropper. 
1. Avoid using slug-baits, especially methaldehyde-based bait!  These slug-baits use toxic chemicals to kill slugs, but they kill all slugs, and other animals too, such as snakes, which can get poisoned when they eat slugs. They can also harm pets and children. Remember that not all slugs are bad.  Most pest slugs in your garden are introduced species, not native forest species.  Contact HAT for alternative slug-management techniques.
2. Preserve a part of your property in an intact state and encourage native plants and shrubs. Even if your property is not a Garry Oak meadow or older Douglas-fir forest, it may still be part of an important corridor for animals and plants travelling between these rare habitats.  Native plantings will help animals like the Blue-grey Taildropper find new homes, which is desperately important for their survival.

Finally, if you are fortunate enough to have Garry Oak meadow or older Douglas-fir forest on your property, contact us to arrange a confidential, free property visit.  We can show you how to search your land for this endangered slug.

For more information

Not much information is available on the Blue-grey Taildropper. You can read the COSEWIC Status report to learn more about the slug and the challenges it faces in Canada.

Other resources include:

Forsyth, R.G. 2004. Land Snails of British Columbia. Royal British Columbia Museum Handbook. Royal British Columbia Museum, Victoria, British Columbia. 188 pp. http://www.mollus.ca/publications/lsbc.htm

Photos at E-Fauna photo archives: http://linnet.geog.ubc.ca/efauna/photoGallery/Gallery.aspx?gr=LandSnails

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