The science behind our pine marten project
Essentially, the pine marten project is what’s known as a ‘presence/absence’ study. We are trying to find out if the pine marten is present here.
Obviously more camera traps means more eyes looking for them. Looking for a rare, mobile, 2ft long mustelid in forests ranging from 2km² to 30km² however is always going to be tough.
Clearly, the more camera traps we have looking for them means a greater chance of snapping a picture.
We can also apply a more rigorous method. We now set the camera traps out in a rough grid after dividing each forest up, with each camera having its own ‘buffer zone’.
This way we cover an even amount of the forest and leave fewer places to hide.
The camera traps are also placed to maximise the capture probability; this means placing them on roads, trails, paths etc and also baiting the camera traps with smelly lures.
More cameras means more data. I always like to describe our camera traps as ‘little workers’. They can be assigned to get a certain picture, or instead to be ‘little scientists’.
Their work means that we gather lots of observations on wildlife in-situ, and those observations can be pooled and analysed.
That means we can begin looking at things like animal activity patterns and distributions for other animals (as well as for any pine marten that show up!).
This graph shows the capture frequencies of roe deer and foxes over a relatively small 30 day monitoring period in Redcap Forest.
Although this data set is small, it suggests that roe deer are more active at dawn and dusk (or crepuscular), and squirrels are more diurnal – all as expected.
We can also use clever software to map the distributions of the species we capture on the cameras. The below image shows the roe deer ‘hotspots’ in one forest; the bigger the red blob, the more captures.
Once we know where a species are most frequent, we can look at why that might be by looking at other data such as environmental variables. This can be done for any and all species we capture on the camera traps.
However, there are some limitations to what we can do. We only have a finite amount of camera traps, so there are always spaces we cannot cover.
Pine marten home ranges can vary wildly – from as little as 1km² up to 33km². The camera traps could simply be in one place while the pine marten is in another…
The variability of the seasons also plays a role. Activity of animals varies depending on the amount of daylight and the weather.
Ideally, we’d monitor every forest identically all at the same time for a long time, but that’s simply not possible with our resources.
All that said, we can still gather good data and start to look at how the animals live their lives in Yorkshire’s forest.