Filming nesting swifts
Ginny Carvisiglia's dream was to record her swifts’ breeding efforts, but her films were more like horror stories.
I’d been aware of the swifts nesting in the eaves of our London flat for about four years – I could hear their unmistakable screaming resonating through the bathroom ceiling – and in 2011 I decided to install cameras to record the lives of one pair.
The results were thrilling: I captured everything, from the laying of the eggs to the fledging of two healthy chicks.
The following year, for a research project, I set up the cameras again, hoping for more of the same.
But things did not pan out as expected: only one of the previous year’s three nesting pairs returned (and then 10 days later than usual), though they did quickly produce a clutch of three Cadbury Mini Egg lookalikes.
The weather was atrocious. June’s gales and relentless rain forced the pair to leave their eggs for extended periods just to garner enough food for themselves; watching their departures each day, I struggled to resist the temptation to shove a fan heater into the attic to keep the eggs warm.
It got worse. The day before the eggs were due to hatch, the female ejected all of them. I watched my footage over and over again on ‘Swiftcam’, feeling like a CSI detective, endlessly analysing the video and trying to work out the reason for this behaviour.
The only explanation that made sense was that the swifts, experiencing the cold, wet summer, somehow knew that the lack of insect food would make it impossible for them to raise a brood.
I decided to take action nonetheless. I crawled into the cramped attic, carefully gathered the unwanted eggs and placed them in an incubator I’d constructed, Heath Robinson-style, from a polystyrene cool box and bedside lamp.
I took to checking the eggs’ temperatures with my cat’s anal thermometer (well, it was all I had) till, a couple of days later, I tracked down an incubator at Vauxhall City Farm and transferred them there.
Over the following week, my family and friends were all on tenterhooks, waiting for news that the eggs had hatched – but there was to be no happy ending. Closer inspection revealed that the eggs contained no embryos: they hadn’t developed at all.
By then the swifts had laid two more eggs, but disaster struck again. Just when the new clutch was due to hatch, the eggs were ejected. I discovered them, smashed in the garden below the nest site; they contained tiny naked swiftlets, almost fully formed.
Next day, the adults departed – they must have realised that they weren’t going to have time to raise a family this year.
I felt frustrated. If I’d been able to foresee this second ejection, I might have tried to hand-rear the chicks; true, it would have been ethically questionable – and besides, I wouldn’t have had much idea what to do with them.
Thankfully, swifts are long-lived birds and can afford to miss a year’s breeding.
But the traumatic events of the year had an upside: the data I gathered has been invaluable for my research, and the bond I’ve formed with the swifts has made me feel as if I’ve become their ambassador.
‘My’ swifts returned in 2013, successfully rearing two very fat, healthy offspring!