During the winter months, we suspend our monthly river swim to avoid disturbing the spawning Atlantic salmon and brown trout, which deposit their eggs in redds – shallow, bowl-like depressions excavated in the chalk streambed. Though the breeding season typically ends in February, we’re mindful that there may still be newly hatched alevins hidden in the gravel. At some points during the year, the water level drops so low that it’s knee-scrapingly shallow in places but this morning the river is running high and fast after several days of heavy rain, so there’s no chance of any accidental contact. The sky is overcast and the mature trees flanking the river are still bare, their branches adorned with orbs of mistletoe, some a metre or more in diameter. But the air carries the faint fragrance of spring awakening – the sweet marzipan scent of blackthorn bursting into flower. Goat willows dip gracefully towards the water, smothered in yellow, pollen-laden catkins. They have attracted several red-tailed bumblebees, while a rotund buff-tailed queen is ping-ponging between a clump of spring snowflakes and a swathe of daffodils. As we head upstream towards our entry point – the furthest of two sets of wooden “dog dip” steps installed to prevent riverbank erosion – the ground softens underfoot, water lapping over the bank. I peer into the depths and glimpse a shoal of trout fry navigating the swirling eddies as they seek shelter beneath a tangle of vegetative debris snagged by overhanging branches. Further along, the river has burst its banks, swallowing the path, and by the time we reach the submerged steps, we’re wading shin-deep. We slip into the water, serenaded by duetting wrens and lone chiffchaff – my first of the year. But there’s no opportunity to pause and enjoy this joyful harbinger of spring, as I’m immediately swept along with the current. One of my companions calls over her shoulder, asking if I can identify an orange-breasted bird she’s seen lurking in the riverside scrub. “Too big to be a robin,” she exclaims. As I glide past, I spot it perched amid a froth of blackthorn blossom – a plump, coral-plumaged male bullfinch greedily nipping off unopened buds with its stubby black bill.