Having just travelled through the East Riding, I find it not surprising that many bird species are in decline. There isn't any secret to it that needs the pretence of intensively written reports.
Mile after mile of farmland hedgerows were being tractor strimmed to neat garden-type hedges. All the growth that young birds would have just discovered to be 'home' was being hacked away. But worst of all was the squandering of the hawthorn berries and many, many elder fruits--rich black luscious hanging bunches. Now all gathering mud and squashed on the road.