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Nine things I have learned about predation


One of the longest experiments I have done recently was recording the decomposition and predation of a fresh dead roe deer. I began it back at the start of December, then moved my trail camera away at the end of spring. In between, I recorded hours and hours of videos of what happened to the body as it was left in the wood. For the first month, the answer was not very much - but the next two months made up for that !

One warning at the start: I know a lot of children read this blog, so be prepared that this post shows a lot of images of decomposition. None of them are too bad (well, one is a bit), but just be warned before you click on any videos...

I first wrote about finding the roe deer body here after the first month. It died on about the 4th December. A few weeks later I blogged about it again.

After I found the body, Iwent back to get the trail camera and set it up in a prime position for watching the body. The body was wedged under a fallen down tree. There was very little action on it for around a month, until a fox opened it up, just above the back leg. 

And this is it now....it is hard to notice it unless you knew it was there !

So what did I learn ?

1. It was younger than I thought

When I first blogged about it, I said "it looks like a young female, maybe 18 months old." Because all roe deer are almost always born in May/June, an animal that died in December would always be x years and six months old - so either six months, 18 months, 30 months, 42 months, and so on.

I guessed this because it seemed younger than a full adult, but still larger than a juvenile, but I was wrong. Teeth are the best guide to aging:

The ways I knew that it was this young was from the teeth (only three were through and the 4th was just emerging - roe deer over about a year will have all six teeth) and also from the endings of the femur and humorous, where the end of the bones were not fused because it was so young. This evidence agrees the deer was 5-8 months old.

2. The pine marten wasn't interested

I secretly hoped that if I ever found a fresh body like this, it would attract pine marten so they could be filmed - especially after filming pine marten almost non-stop for the year before !

But the local pine marten was not interested in the slightest by the roe body, even though it was on its route through the wood.. This is really weird because this could have been a feast to them because they are carnivorous !

3. Neither was the fox really !

The fox did some important work. It opened up the carcass (after a month !), dragged the body out into the open, allowing the others to feed on the body.

But after that, it hardly came back, even though I think it was responsible for the next bit:

4. Dead bodies can disappear

Also: trail cameras sometimes forget to work.

I never found out what moved the body, but it almost certainly had to be the fox, and it would have taken a while. Whatever it was it, it had to drag the body over a large fallen tree trunk. It ended up only about ten feet away, but it confused me for a bit. I don't know why the trail camera didn't trip.

5. This was mainly the buzzards' show

Most of the predation came from at least two buzzards, possibly more. One buzzard came the the site almost everyday about mid morning, and fed at the deer for around half an hour straight each time. This one minute video just shows that buzzard slowly picking apart the body. It started at the groin area, and gradually worked upwards , putting its head inside the carcass, and pulling back the skin as needed.

Buzzards are nervous feeders. They land by the body and spend a few minutes making sure no-one else is about before landing. When feeding, they keep looking all around them .

The buzzard also spent a lot of time pulling out the fur. Now I know that if I see scattered fur around a body that it is a sign of raptor predation:

6. Three months on, the meat was still edible

Warning: next video is the grossest !

Even though the buzzard was feeding almost every day,  three months after death and the buzzard was still feeding on the torso of the deer. I have seen roe deer that die in the summer  be skeletonised within a few weeks, but this deer took much longer, mainly because of the winter temperatures.

In the video above, the buzzard pulls out an organ from the body. I thought originally it was the heart, but now I think it may be the liver or a part of the lungs.

7. Claws can do a lot of damage

Towards the end of this video, you can see it tearing the joints by gripping the femur with its claws, and flapping its wings, pulling the femur up.

It did the same with the rib cage as well, which broke some of the ribs close to the spine. Whenever I have found bodies with broken ribs before I have assumed that it was done by a fox. Now I know it could have also been done by a buzzard.

8. Robins: nature's hidden carnivores

The first time I saw a robin near the body I thought, live everyone does, that robins are cute little birds that would only eat small grubs and worms. After a while I realised the robin was eating the deer the same as the buzzard. Robins are not only carnivorous, but that they will also fight each other to the death for food.

9. Magpies are great to watch

You don't see as many magpies round here as the other corvids, like crows, rooks and jackdaws.

Literally the first thing the magpie did when it first found the body was to peck the eyes - corvids are well known for this. They would feed on the meat, even though they don't have a hooked beak to tear open a body, which is why you often see them feeding on roadkill which is already opened up. The two above scrapped over feeding above,  but in the video below, it shows the magpies sitting side by side as they ate, which surprised me because I always thought that magpies were really territorial. I think the incomer stretches its neck up to show the other one it is bigger, and after that they are fine together:

And one was even cheeky enough to steal from the buzzard !

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Jo said...

Fantastically interesting, Jake. Really good original research, especially the observation of the buzzard breaking the ribs.

sedruff said...

This is quite an interesting post, although I couldn't get any of the videos to play.
But studying the deer as it decomposed was a great idea for an experiment!

Jake said...

If you click on the "Youtube" logo at the bottom right of each video, it'll link to the videos on Youtube themselves, and they should play there, if all else fails.

Bessie said...

This is really interesting i have got half a broken deer rib perhaps this is what happened to it great post.

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