Not once in 30-odd years of bird feeding. We were looking out the window when my wife said, “What’s that yellow bird?” An evening grosbeak sat just metres away, perched on the arm of a feeder.

The yellow-crested helmetshrike (Prionops alberti), also known as King Albert’s helmetshrike, is a small bird that lives in the humid forests of the Albertine Rift mountains in central Africa.

In late winter, after birds had been visiting bird feeders for several months, we captured great tits at sunset and gave them a “fake infection” – injecting them with a small amount of ...