Large Mystery

The trouble with planning to spread out several posts is that sometimes exciting things happen in the meantime and derail the schedule. We'll see if I get back to posting about my trip later.

For now I will tell you about some exciting things I saw while doing a transect for the Cascade Wildlife Monitoring Project up on the Snoqualmie Pass. I'm pretty sure we found marten tracks, but they weren't particularly clear tracks and with my lack of familiarity with them I'm not 100% confident of declaring them such without further consultation with someone more knowledgeable. There were also a couple of interesting small rodent mysteries that I may post about another time. But what I'm going to post about now has only become more mysterious for me as I continue to investigate it.

I found this set of tracks - apparently coming from a wooded area, going through a clearing and disappearing as it got to a stream bank. Tracks that large are generally of interest on the transect (and for me personally), so I was excited to check it out with the team. But not having all day to look at the tracks (having already spent a lot of time looking at what we believe to be marten tracks and still having another transect to complete) we took some pictures and measurements, discussed our thoughts and moved on.

There is a pretty clear pairing of tracks except in a few anomalous sets. I didn't think about it too much at the time, but because of the pairing had figured the animal was moving in an overstep trot. When I returned the next day I was a little shocked to realize that was probably not the case - that the anomalous sets suggest that all the other tracks were directly registering. That leaves me questioning which gait the animal was in let alone figuring out what animal it was.

If you have any thoughts or questions please post a comment. I would really like to figure this out as well as possible.

There wasn't much detail in individual tracks, but what there was looked mostly like this:


(the dark rectangle at the right is a ruler that is a bit over 15cm long)

When I measured the individual compressions I measured the whole way across since there was not enough detail to determine a true track. Also consider the likelihood that there were actually two feet landing in each compression. The individual tracks I measured were in part of the trail where the animal was moving somewhat slower then the speeds it later reached.

In the section of the trail where the first picture below was taken, lengths were from 11.8 - 13 cm, width from 12.5 to 14cm and the trail width was 18 - 24cm. The trail narrowed even more where the stride increased (as in the second and third gait pictures).

Most of the trail looked like the first two pictures below with what looked like a side trot or 2x2 direct register gait. However if you look at the third picture (or towards the background of the first two) you can see that sometimes there is an "extra" foot that would seem to rule out a side trot. The tape measure in the pictures is out to 6 feet. I will give some measurements of the tracks and gaits below the pictures.

Looking back the trail

Up the trail

Up the trail

Strides (assuming a 2x2 lope) were 84, 94, and 71cm in the slower section and when it sped up were 109, 112, 127, 109, 102, 105cm. The 112,127,109cm section was where there was an additional foot registering.

Group lengths were 46 and 54cm in the slower section and between 54 and 75cm in the faster section.

One further detail to be considered is that one of the extra feet, presumably a hind since it was the last in the grouping*, broke through and the hole was around 5cm across (I believe the compression in the hole was a bit larger than that though.)



So is it in a 2x2 lope, a direct register walk/trot with an odd pairing of tracks (a limp perhaps?), two animals travelling almost exactly in the same tracks, something else? Why does the track that breaks through not break the top out of the hole when the foot goes forward (perhaps the snow was to firm for the relatively lighter pressure of the exiting foot to break it)? And who was it?

*It is my understanding that oversteps are more likely to occur than understeps for most animals, particularly as the animal goes faster. Additionally there is some obscuring of the front track by the following track suggesting that the second track was made after the first one.