Having spent a week in Assynt and touring up to Cape Wrath and around lochgilphead, we (daughter and I) noticed the difference in bird behaviour. For instance every time we saw a Buzzard it was hovering for ages. Conclusion that with the geology being so diferent - mainly rocky mountains and the land that is in the valleys(glens) being mainly heather and boggy wet and a mass of wee locans and only occasional raised dryish raised bits, the Buzzards have to hover to find any food. Where as down here they only have to sit around all day on trees, poles and fence posts, which is why I thought they were very lazy birds.
As for the smaller birds, you don't see them till they rise a bit above the heather and low growing shrub, there are very few trees or very short ones. So the birds just have to hop about under cover. The only places you get to see them is where people have in the past planted some around their crofts, or near and around the towns and settlements (there is a bit of forestry and they do seem to be doing a lot of planting of trees in certain areas).
We were surprised at the lack of sea birds we saw, probably due to the migrants not arriving yet, did see a few skeens of Greylags, Some Common Gulls, some ducks only saw two Herons and a few Oyster Catchers. did see quite a few Wagtails on the beaches. We were joined by a couple of Common Gulls, who obviously liked us and they joined us and hunkered down next to us - maybe they were as cold as we were?
I've noticed the birds in our garden are much more complacent than ones out in woodland or open fields. The sparrows especially spend more time squabbling and just hanging about, (in the morning the hedge is full of them waiting for me to come out and replenish the feeder) while the 'wild' ones are much more timid, and more cautious.
When we were at the reserve last week, the finches were exceptionally flighty- the first sign of movement and they were off. Our finches sit swinging on the feeder until the last possible second if I go out to top up their nyjer seeds- then they'll fly into the nearest tree and sit whittering impatiently as though to tell me to hurry up and get on with it!
I suppose since they are relatively protected on all four sides, with good-sized trees and an over-sized hedge nearby they've adapted to being town birds... and they've become more accustomed to humans being about most of the time, too.