Wednesday, August 14, 2013

Down to the Bones

Four days have passed since I found the dead song sparrow fledgling in our backyard. In that short time, the body has been reduced to a sticky pile of bones and feathers — not by beetles or flies, but by slugs and, primarily, ants.

Yesterday, I was able to get a pretty good view of the puncture through the top of the bird's skull. Whether it was by beak or canine, the predator had little trouble piercing the fledgling's thin, delicate bone.

Today, the ants were still numerous, and busied themselves with picking away at every bit of food possible. One of the sparrow's legs had been separated from the rest of its body, and one ant in particular was making quite the show of gnawing away at it:

It was really quite fascinating to watch this individual working away at the leg. All but one of the toes had already been removed.

 

Also interesting to see was the interaction and communication between various ants.

I don't know an awful lot about ant hierarchy, but it was pretty obvious which ones were dominant. Physical communication comprised of jaw- and antennae-touching, pushing, and chasing. I was lucky to get a few of these confrontations on video:

 


I made one other unexpected observation this afternoon: while taking another look at what remained of the sparrow, I saw the soil beneath it suddenly start to heave. This could only mean one thing: burying beetles! I looked beneath the carcass, and sure enough, there was a lone burying beetle (crawling with mites, of course) — likely Nicrophorus tomentosus, as its thorax was covered in yellow hair. This was a different burying beetle species for our yard, as previously I've only seen Nicrophorus orbicollis.

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