Monday, April 21, 2014

Bison weighing themselves...

Proportion of bison for a given weight. Red is from the field scale. Blue is from the round ups in the fall.

Bison crossings over our field scale have really taken off. We've recorded 400 weights in the past four days. For a herd of just 300, that's pretty good.

We don't have the tag reader in place yet, but I looked at the distribution of weights recorded in the field, vs. what we get in the roundups.

You can see some pretty similar peaks. The first peak are calves. The second peak would be yearlings. The third peak would be adult females.

The adult female peak is shifted ~50 kg lower. Previous work showed that the animals lose about 10% of the body mass over the winter, which we are showing here.

The heaviest animal we had was 738 kg. You can see the tail for roundups extends beyond this. Whoever that was will probably put on 100 kg this year.

The new EID readers show up later this week. Soon, we'll start to track individuals over time.

That's going to be amazing. 

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