Richard Collins: Why nature’s routines and schedules are being disrupted at an alarming rate

Climate change isn’t responsible for all wildlife ills; other human impacts are also implicated.

Song thrush: A bird’s body clock tracks the light, eventually triggering the release of sex
hormones, and the return of singing.

My local song-thrush has lost the run of himself; he started singing during the second week of January. Normally, it’s the mistle-thrush who proclaims the approach of spring and he does so well in advance of his smaller cousin. The large ‘storm-cock’ may hold forth even in the teeth of a late winter’s gale. He usually begins nesting a month earlier than his more melodious relative, making the latter’s early singing all the more odd.

Why is this avian insanity happening? Is climate change responsible? Not directly, it might seem, on the face of it. A songbird’s reproductive organs shrink after the breeding season, rendering it virtually sexless. Daylight length begins to increase from December 21. A bird’s body clock tracks the light, eventually triggering the release of sex hormones. Singing is the overture to mating and nesting; ‘happy days are here again’. Global warming can’t alter the sun’s schedule, but it ‘acts in mysterious ways, its wonders to perform’.