Looks too big for a mouse and gophers tend to have short tails. And are also not very evident above ground during daylight hours. I'd suspect a rat.

As it's on the ground presumably going after seeds and looks to have the same general appearance probably Rattus norvegicus. Try using a mix birds don't flick out of the feeder such as one that is sunflower seed only. Or making other arrangements so that there is not a constant layer of uneaten bird seed on the lawn beneath. Including maybe discontinuing feeding entirely if necessary. Otherwise you can end up with a significant rat infestation, might have one already.

He seems awfully bold and fat. Do you have neighbors with kids nearby? He could be an escaped pet.

Is there any chance it's a vole?

Initially I thought he may be either a pet or a vole as apposed to a rat, doesn't seem big enough

Luke, what is your general location and what is your best estimate regarding the size of this animal? It certainly has a vole-like appearance.

Seems overly large for a vole, but then the scale is hard to judge. And I'd be very surprised to see voles wandering about in broad daylight. They also tend to be more nocturnal in their activities and are seldom seen above ground in daylight - too vulnerable to predators.

But to be honest, it does look more like a vole than a rat - just appears to be larger than voles in my area (I only see dead ones, delivered for my admiration by my cat :-))

btw, I have never seen a skinny vole - with a diet so plentiful and diverse as theirs, it's not hard to stay plump!!

My area is in the East Midlands in the UK it was approximately the size of a beer can (for lack of better reference)

Voles are tiny and have no eyes to speak of because they live underground and eat plant roots. What you have is a big rat.

It's a "water vole"

http://britishwildlife.wikia.com/wiki/Water_Vole 

That's what "Rat" of the Wind in the Willows really was. Not a rat, a water vole.

I think lazy's got it!! Sure looks like the same creature!

"Voles are tiny and have no eyes to speak of"

That's a bit of an over-generalization!! There are about 150 different species of voles, some tiny; some quite large (9"). And they all have eyes that function and are very visible, just as mice and rats do. They may live underground but they do venture up to the surface and roam around during darkness wreaking plant havoc. And they eat a whole lot more than roots.......:-)

Voles in my garden in NY have no eyes. I trap a lot all year. Funny how a common name like "voles" can apply to so many different animals in so many different parts of the world, much like common names for plants. In my part of the world, the photo above is a big rat. Common name. Lol.

One asked about does have the small-looking ears - too small for Norway Rat - and contrasting black tail of the Water Vole.