Humans aren’t the only ones to suffer pandemics. Trichomonosis is an illness of doves and cage birds; in 2005, it jumped to wild finches. Spread by parasites in birdbaths and feeders, within a year, half a million UK greenfinches were dead. Since then, the species has steadily declined to a current population a third of pre-disease levels. Experts fear that it may disappear from Britain entirely. Which is why I’m so excited to report that as I write these words, I’m listening to a greenfinch singing in the garden for the first time in years.