Storks are being reestablished in Sussex right now.. The migrants will already be crossing to Gibraltar.
No mile walk there. Either sit out on a comfy bench at Europa Point, a short walk from the bus stop and cafe, or, even better, take a seat at Cafe Solo in Casemates Square, with a decent meal, and watch storks and raptors soar overhead.
Storks, harriers, accipiters, Bonelli's and Booted eagles, lots of short-toed (snake) eagles, spotless starlings, yellow-legged gulls, Sardinian (and many other) warblers...