On August 4th, a team that consisted of Shari Forbes, a few Calgary Police Services Canine Unit officers and me, put out four pig carcasses in the wilds outside of Calgary so that we may see what scavenged upon them and eventually — hopefully — scattered the pigs’ remains.
On September 2nd, we returned, with some help from Edmonton Police Services members and a Lethbridge member, to see what, if anything had happened.
Shari had set-up cameras at each carcass so that we could remotely monitor any big events. But the actual dispersal of remains, if it existed, would be unknown until we revisited each site and performed a search.
September 2nd was the search day.
We didn’t know what to expect.
This is the fourth of four posts outlining what we found at each of the four sites.
As mentioned with the previous site, a farmer owned some land northwest of Calgary and agreed to let us place two carcasses there. We dressed two pig carcasses in human clothing and placed each carcass at least 100 metres apart from the other to discourage cross-dispersal of scavenged and scattered remains. Each carcass was placed in either an ‘open’ or ‘forested’ environmental context. At this site, the carcass was placed in a ‘forested’ context.
This location was about 80 kilometres NW of Calgary, and characterized by farmland with patches of aspen, pine, and spruce trees in gently rolling to undulating topography.
We identified a patch of trees and bush about 100 m by 300m adjacent to a gravel road and otherwise surrounded by cultivated farmland. At the south end of this treed patch, we’d placed a pig carcass as our ‘open’ context (see Pt III) and at the north end, we placed a carcass as our ‘forested’ context.
Like the ‘open’ site just to the south, not much happened at this site in the beginning. However, the location of one of the cameras afforded an excellent view of the pig carcass as it was devoured by maggots.
People often ask me how long it takes a carcass to decompose. My answer is: that depends. It’s not a great answer, but it is accurate, especially in a cold climate like Canada’s.
The other thing here, too, is that, often when people say ‘decompose’, they’re really asking is how long it takes a carcass to be reduced to bones. There are more things than just decomposition occurring when a carcass is being reduced to bone. One of these things is insect activity. And often, it can be difficult to separate the affects of insect activity on a carcass from the act of decomposition.
Insect activity can greatly increase the speed at which a carcass is reduced to bones.
Case in point: I created a little video of the pig carcass at our ‘forested’ site to demonstrate how quickly a carcass can be reduced by insect activity. This video shows the pig carcass on August 7, 2021 at 09:23. The temperature then (by way of the camera’s reading) was 10 degrees Celsius. The carcass already had substantial maggot mounds. By August 9, 2021 at 13:29, the carcass had essentially been reduced to bones and skin. The temperature didn’t rise above 18 degrees Celsius during the day and dipped to a low of no less than 4 degree Celsius at night.
I invite you to also note the clothing on the pig carcass. At the beginning, see how the shorts are riding on the pig’s hips and the shirt is pulled over the pig’s torso? Now look at the clothing at the end. The shorts and shirt ‘appear’ to have been pulled down and up, respectively. It appears as if the pig had been undressed.
This is important because, if we hadn’t had a camera on this carcass, one might think that someone had come along and pulled down the shorts and pulled up the shirt. This movement of clothing mimics the same movement of clothing seen on victims of sexual assault. My former supervisor, Dr. Owen Beattie, observed this phenomenon and wrote a paper on it. And in this video, you can see how this clothing was moved and could easily be mistaken for sexual interference.
Pretty neat, huh?
Did any scavengers show up here? Yup. But not until August 20, three weeks after we’d placed the carcass. A bear appeared on August 20. A coyote appeared on August 27 and stayed a while. A fox showed up on August 28. Then the (a) coyote appeared and actively scavenged and moved the carcass on August 29 (I may make yet another video 😉 ). This coyote was joined by another on August 31 and continued scavenging the carcass.
A skunk strolled by on September 1, but didn’t interact with the carcass.
A coyote, a bear, and a fox visited this pig carcass after the carcass had been reduced to nearly skin and bones by maggots.
A coyote on August 29 actively scavenging and moving the pig carcass. This coyote (?) was joined by another a couple days later to continue scavenging.
When we arrived to search the area on September 2, we found some remains at the Original Deposition Point (ODP), and a directional dispersal of other remains.
At the ODP, we found:
- body staining
- vertebrae, articulated and disarticulated
A trail of dispersed remains, including:
- 2 articulated limbs
- scat (likely coyote)
The trail of dispersal extended about 10 metres from the ODP. However, we also found an articulated section of ribs and vertebrae about 17 metres from the ODP and outside the forested area. Huh!
What did we learn from this site?
- Insect activity can reduce a carcass to “skin and bones” in under 48 hours.
- Coyotes seem to like carcasses in later stages of decomposition. Yum.
- Coyotes may not always drag their scavenged resources further into the forest and into cover.
We’ll be revisiting this site and its neighbour, the ‘open’ site to the south, again on October 8. Stay tuned for updates.
We are performing a search of a couple Edmonton area sites on October 5. What will we find? Stay tuned!