Seed tracking season is in full swing here on BCI. And the seeds are moving amazing amounts.
Agoutis burry seeds to give themselves a storehouse of food for later in the year, when very few trees have ripe fruit. The trees are happy about this, because it puts their seeds in a good place to germinate – underground. We are studying how far agoutis move these seeds and what determines their fate, questions important both from the plant perspective (forest regeneration, species diversity) and from the animal’s perspective (surviving the lean season).
To test our hypotheses, we need an agouti of known identity to cache a seed, which we then follow long-term with a small radio-transmitter. Earlier this year we trapped a bunch of agoutis and marked them, now we are using camera traps to record which agouti initially takes the seed away and buries it. We are aiming for at least 200 seeds cached by known agoutis, and so far we are up to 35, a pretty good start.
You would think that tracking 35 seeds wouldn’t be that hard, how often can one seed move? Turns out, some seeds are moving almost every day. At least in the first week we have seven seeds that have moved five or more times. But is it the same agouti managing its own caches, or massive thievery?
To address this question we are following a subset of our tracked seeds with camera traps. When a known agouti buries a seed we use the radio-tag to find it, and then put a camera trap nearby to record what happens next. These results are just starting to come in, but its already obvious that these early seed movements are largely due to thievery.
Here is a video of a thief. This seed was originally cached by Shelia, a radio-collared agouti, but then it is stolen by Sharpee, an agouti with ear tags and a white tuft of hair on its side.
We have even had a reciprocal theft. Some other agouti stole a seed that Shelia cached, moved it 12m away and reached it. Then 2 days later Shelia found it, dug it up, and moved it 70 m away. We’ve moved the camera nearby and will keep tracking these seeds until they germinate into a new baby tree, or get munched by a hungry agouti.
Bonus footage: another cache thievery