Something like a passive infra-red (PIR) sensor can trigger a recording device, but unfortunately the XR160E has no inputs of any kind to connect one to.
I'd imagine that, even if you did buy a remotely-controllable handycam, you would need to rig up some kind of customised connection between the PIR and the remote control handset in order to trigger the 'record' action.
If you want to look at options beyond using your current camera, let me know
I am interested in other options besides using the current camera.
I want to record birds feeding their chicks at the nestbox for research purposes. I want to know how often the bird visits the nest in a day and I need to identify the food items.
Therefore I need a reasonable quality, which is either a HD camera on tripod at a distance or a small camera attached to the nestbox. I also would like it to record only when the adult bird is at the nest (motion detection).
What you're looking to do isn't difficult with the right equipment and a little care setting it up. What's not quite so easy is finding the equipment... there seems quite a range of PIR-activated, photography-related gear in the US, but not so much here. This, for example, is exactly what you need to remote-trigger a handycam when movement and/or heat is detected: http://www.trailmaster.com/tm700v.php - but you'd have to mail order it, or search for something similar over here.
The good news is this sort of product has been made to fit Sony camcorders for years, connecting to the cam's D-shaped LANC socket, often marked 'AV/R' on the housing. Here's a list of suitably-equipped cams: