Then, after watching a male Marsh Harrier and revelling in the chinkling of dozens of Calandra Lark, I finally spotted two Stone-Curlew in the field right next to me.

My worries that the local shepherd, who was approaching with his flock, would scare them away disappeared when I saw about fifty Spanish yellow Wagtail skipping in and out of their footsteps. Closer examination revealed races from Britain, central Europe, and an extremely rare and beautiful black-headed form from Russia, superciliaris.

A careful search in a riparian copse, before settling down for lunch, may yield Golden Oriole, Red-necked Nightjar, Penduline Tit, Great Spotted Cuckoo and even the much sought-after Lesser Grey Shrike.

Little Owl, Lesser Kestrel, Crows, Buntings and Wheatears may marshall the outbound tracks as we make our way to the day's final destination, a late afternoon visit to Los Monegros.

Although technically just outside Catalonia, it's worth the trip as we settle and wait for the incoming flocks of Black-bellied Sandgrouse and Great Bustard eager to take advantage - just like us - of the last moments of daylight.

As I was leaving a female Montagu's Harrier, immediately joined by a hauntingly grey male, decided to float around my head for a while. I was hypnotised.

The problem is, as anyone who's ever visited the huge area around Lleida knows, that its rarely this easy, with frustratingly small populations of birds like Lesser Kestrel, Lesser Grey Shrike, Dupont's Lark and Black-bellied and Pin-tailed Sandgrouse.

So, if you want to track down migrating Dotterel, tick off the complete list of Larks, or work your way through Golden Oriole, Southern Grey Shrike, Penduline Tit and Red-billed Chough (title photo), there's no option but to get to know how the birds move and live on a transient land that, over the course of many seasons, changes from fallow to plough to crop to stubble and back again.