Probably the bird that's most likely to grab your attention is the wheatear. The wheatear is a striking bird and is often seen in flight showing off it's white rump with a black 'T' on it's tail, sometimes giving it's characteristic 'chat' call. The wheatear is often quite approachable and tends to perch upright on rocks making it relatively easy to observe. It's song is a quite pleasant warble mixed in with creaks and rattles which regularly incorporates mimicry. It tends to nest in a crevice or hole in amongst boulders. The wheatear is an Amber Listed species being catergorised as a Species of European Conservation Concern.
Next up is the ring ouzel. A close relative of the blackbird though slightly smaller and slimmer, the male can be easily recognised by its white bib. It's call is a 'tac-tac-tac' reminiscent of the blackbird, and it's song is similar to that of other thrush species. It tends to breed in ghylls, scree and other rocky areas.The ring ouzel has suffered recent population declines (over 50% in the past 25 years) and is a Red List species and of highest conservation priority.
Male ring ouzel
Possibly the most common bird up on the fells is the meadow pipit. It's very similar to many of the other pipits (being small brown and streaky) but once you get on to the fell tops it's very unlikely that you'll see any other pipit species. It nests on the ground in dense vegetation and can often be heard by it's 'sreep' call or by it's song 'tsee-tsee tseek tseek tsee-er tsee-er'. The meadow pipit is also on the Amber List as it's population has declined between 25% and 50%.
Finally the skylark. The skylark could possibly be confused with the meadow pipit though it is chunkier with a thicker bill and has a crest that may be raised, it is also much less common. It is famously known for it's display flight, when the male rises vertically into the air where it sings melodiously often for several minutes. It may also be heard by it's liquid 'chirrup' call. Another ground nester, the skylark has also suffered dramatic population declines (over 50% in the last 25 years) and is therefore another Red List species.
Of course there are many other birds to be found on the fells, such as the chaffinch or wren, but the few highlighted above would not be found in your average garden, and with a little effort should also be relatively easy to identify.