By Samantha Johnson
Leafy spurge is an invasive alien plant that expands rapidly to blanket cover areas.
The stems grow to a metre tall and are arranged in clumps. According to http://www.natureconservancy.ca, the plant is “native to central and southern Europe, leafy spurge is believed to have been transported to North America in the early 19th century, then spread across western Canada. The plant was first recorded in Alberta in 1933 and in Saskatchewan shortly thereafter.” The greenish-yellow flowers can eject seeds up to 5m when they explode, with seeds able to remain dormant for 8 years in the soil. It contains a milky liquid in the stems and flowers that is an irritant to most livestock and may cause severe skin rashes or irritation to humans.
One animal that does eat it and is able to destroy the seeds are goats. Three years ago, the City of Medicine Hat contracted the Creekside Goat Company, based about 5 miles south of Magrath, AB, to come into Police Point Park twice a year for a total of five years to help deal with the leafy spurge problem. Looking around the park, all the visible yellow flowers right now are leafy spurge.
The program has been effective, according to Ian Langill, Assistant Chief Interpreter but, “typically it takes the five years to really make an impact, but we have noticed that it hasn’t been as bad as it was the first year they (Creekside Goats) came. Even if the plants go into seed, the goats can break it down. The way they chew it, they break the seeds as opposed to other animals who will swallow the seeds whole.”
The goats remain in the park for about a week each time, early July and back again in August. The goats have been trained to eat leafy spurge but also eat some choke cherries, helping to clear up the underbrush, along with thistles and many other plants.
“The plants (leafy spurge) are all in flower,” explained Langill, “and they’ve put lots of energy into creating those flowers. When the goats eat them, they (the plants) lose all the energy they put into growing and flowering. The leafy spurge will try again, the goats will come again and eat it up and they’ve used up lots of energy that year. By doing that over and over, it depletes the energy they can put into producing and the plants start to die.”
Trent Cahoon, shepherd, and his dog, Zack, take care of the 200 strong herd of goats and move them around the park to the areas where leafy spurge is abundant. Goats don’t graze an entire area down to the ground but like to keep moving, so Cahoon and Zack will come back to one area multiple times.
Zack, formerly a sheep herding dog, has been with Creekside Goat Company the longest of all the working dogs, about five years. Cahoon has been with the operation for three years. “The goats are a mix between a South African Boer breed and Spanish breed. This is a good breed because they are sturdy, resistant to disease and they don’t need much water. That’s one great thing about goats, as opposed to sheep and cows who need lots of water, goats don’t and are made for arid regions,” said Cahoon.
The goats spend six to seven months of the year grazing, mostly in parks, and take the winter off. The herd at Police Point is composed of all female goats, adults and last year’s kids. The super herd, as Cahoon called them, a herd 400 strong with this year’s kids, were at the Blood Reserve in Cardston working on the leafy spurge problem there.
“The great thing about goats,” explained Cahoon, “is once the spurge has gone through their system, it won’t sprout again. Sheep, horses, cattle eat and spread the seeds to sprout again but with goats there is something caustic about their digestive system and how they can grind it up so well.”
The goats typically graze for five to six hours in the morning and another five hours in the afternoon. Neither the goats nor Zack like heavy rain or thunderstorms, so they head back to the base by the Interpretive Centre at those times. The herd can be easily spooked, “especially when they are entering into a new area, they hear something, maybe a bunny rabbit, and they are out of there,” stated Cahoon.
There are more signs this year at entrances, both paved and dirt, into the park warning visitors the goats are onsite and to keep dogs on leash. There was an incident last year where an unleashed dog got hold of a goat’s leg. “That was one of the reasons we had lots more signage out this year, because of the dog coming and biting the leg of one of the goats, so we want to ensure people are keeping their dogs on leash this year,” said Langill.
There are also signs in the park warning that leafy spurge can be an irritant to humans. However, walking by or among leafy spurge doesn’t usually create a problem, it’s when the stems or leaves break releasing the waxy, milky liquid. While leafy spurge is an invasive species, there are other spurge-based plants, such as cushion spurge, planted in gardens that are different. “Not all spurges are the same,” explained Langill, “but you do have to be careful when going to a garden centre and look up the plant to see if it is something that could be invasive. Wildflower seed packets don’t contain native wildflowers for this area. They contain wildflowers for Canada but not for Medicine Hat and area.” Thus, thinking it is a good thing to plant wildflower seeds, could inadvertently spread one or more invasive species into this area.