Bird feeder snapper

Hi arduino folks.

A bit of background so you know what I'm looking to achieve:

I just finished a small project to capture birds that land on my bird table outside. It started as a custom android app running on an old phone which did motion detection and then took photos and uploaded them to the internet, however, I added an arduino (with ethernet shield), a bit of custom circuitry and a better quality camera, and got the android phone telling the arduino to control a shutter on the main camera. I've kept the android phone there to give me a bit more control over what I take pictures of (ignoring large birds, ignoring things that been there for too long.etc.), and with the arduino running a little socket server it means I can control the camera from anywhere within the home network (not that I need to, yet..)

Here's a picture of my setup:

I'm getting some great shots from this.

However, I'm looking to start on a new (similar) project.

I want to try to create a system that I can run outside, well away from the house, which can keep itself powered up for as long as possible and take photos of birds of a feeder. The feeder will be very close to the camera. I don't need really high quality images - just clear enough to be able to tell what bird it is. Ideally I want to find the cheapest way possible of doing all of this.

I guess I'm just looking for people to throw a few ideas at me that I could investigate, or at least some people to tell me not to bother pursuing the idea.

My initial thoughts are along the lines of:

1) Dirt dirt cheap digital camera. Something like this 2) Break it open, try to hook into the on switch and the shutter button 3) Maybe some kind of PIR sensor module to detect movement. The bird feeder will be positioned very close to the sensor and camera 4) I guess some way to power the arduino that'll use as little power as possible, maybe with solar panels alongside or something

I guess the most efficient way to use the camera is just to turn it on when needed, and turn it off straight after, hooking into the on/off switch. But as for the arduino.. what would be the best way to get some batteries to last as long as possible? even if I used solar panels, what kind of up-time would I probably get from it? Is there any way I could optimise the power usage without having to manually turn it off overnight?

Sorry - lots and lots of questions, VERY limited electronics knowledge, and only a vague idea of what I'm hoping to achieve. I'm hoping you guys could steer me in the right direction..