Why are we out flipping cardboard in the forest?

Ordinarily, if you were out for a walk in a park and saw people leaving cardboard behind, you might have something to say. It might not be good, understandably. But Habitat Acquisition Trust has a reason for you to think twice about removing or disturbing some very particular cardboard you might come across in the woods.

bgt Kristiina ovaska

In the quest to better assess the habitat needs of the elusive and endangered Blue-grey Taildropper Slug (Prophysaon coeruleum, photo right by Kristiina Ovaska) with permission from local parks and private landowners HAT has been intentionally placing small squares of cardboard on the ground in places where these slugs are suspected to live. Believe or not, these pieces of cardboard, referred to as Artificial Cover Objects or ACOs, provide a kind of shelter that slugs and snails will use. This makes regularly spaced ACOs a great way to research an area's gastropod populations. You can tell that these pieces are for research and not garbage because they are marked with numbers and spaced evenly.

So, if you're out for a stroll in the forest and come across some of us flipping soggy cardboard, you might have something to say after all: "Find any Blue-grey Taildropper Slugs?"

If you would like to help out with gastropod surveys, please send a message to This email address is being protected from spambots. You need JavaScript enabled to view it.

If you or your friends and family are free Sat. Nov 19th from 10:30 - 1:30, RSVP to This email address is being protected from spambots. You need JavaScript enabled to view it. to join us for a day of removing invasive species to imporve Blue-grey Taildropper Slug habitat at Thetis Lake. RSVP for details!

Over the next several weeks HATters will be especially vigilant for the blue beauties. If you've found a Blue-grey Taildropper (BGT) be sure to take a picture right away and send it along to This email address is being protected from spambots. You need JavaScript enabled to view it. It's important to snap a shot fast because once disturbed a BGT on the surface is likely to bury into the litter. This small slug is tough enough to spot as is, but once buried beneath the leaf litter and soil, there's not much of a chance of finding them again.


While surveying in public parks can be done easily, to get a full picture of BGT's distribution and habitat needs sightings and surveys on private lands are key.

"We don't know where they are on private lands," remarks Lennart.


HAT Contract Biologist Lennart Sopuck says that you can look for them under mushroom caps. BGTs are mushroom-eating specialists, although it's thought that they exhibit this behaviour more at night. They are also thought to dine on underground fungal parts called hyphae. This tendency to take to the soil, makes these blue jewels of the woods an especially rare find.

Photo right: Mushrooms at the Hunter Conservation Covenant. Potentially good eats for a slug.

On a recent surveying trip, Lennart and HAT Community and Development Coordinator Alanah came across a wide variety of gastropods both native and invasive. Surveying at two HAT conservation covenants and two parks, however they were unable to find their target species, the BGT. Lennart remarked that although a moist day is ideal, the BGTs prefer to come out at colder temperatures when there's almost frost on the ground. From now until November however, is prime time to observe one of these unique tentacled creatures.

At the Hunter Covenant near Prospect Lake, Lennart and Alanah came across the shellof the provincially blue-listed Pacific Sideband Snail (Monadenia fidelis). Though nobody was home, it was a delightful find amongst the common Banana Slugs (Ariolimax columbianus). Lennart recalled surveying at another site where there were over a hundreds of the Pacific Sideband Snails, the largest native snail in BC. He says that they do well on outcrops and rocky areas with a moist eastern-facing slope in habitat with maple trees. Live Monadenia photo below.


At the Ruby Creek Conservation Covenant in Metchosin, the duo encountered a taildropper species, but not a blue one. They came across the native Reticulate Taildropper (Prophysaon andersoni - photos below). A bit larger and of a duller olive-brown, andersoni do have charming dark stripes along either side of their mantle.

prophysaon andersoni

The native Northwest Hesperian (Vespericola columbianus - photo below) snail was commonly found at each site. This medium-sized snail, has tiny hairs on its shell as an identifying feature. Other than looking at size, juveniles can be differentiated from adults by their lack of a flaring aperture around their shell opening.


The Robust Lancetooth Snail (Haplotrema vancouverense) was another regular native species encountered. With its murky greenish shell, you might be able to spot one while you're out exploring in nature yourself. 

lennart hunters

Some of our native snails are only a few millimeters wide and require careful examination. One of these small but lovely snails is the Western Glass-snail (Vitrina pellucida). With its transparent shell, Glass-snail is an apt name for this tiny bead-like animal.

Among the many exotic slugs commonly observed were the Hedgehog Arion (Arion intermedius), Longneck Fieldslug (Deroceras panormitanum) and Leopard Slug (Limax maximus). The Hedgehog is identifiable by its stippled back end, while the others can be a little trickier, as the Leopard-like markings are quite variable, as is the colour of the Fieldslug.

Photo right: Lennart makes notes on gastropods found under ACO at Hunter Conservation Covenant.

So while Lennart and Alanah did not spot the rare and intriguing Blue-grey Taildropper, they did get the opportunity to examine an interesting cross-section of gastropods found locallyand collect important information. Lennart suspects the next round of surveys will be more fruitful for those hoping to encounter a BGT.

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