Estimating mortality rates among passerines caught for ringing with mist-nets using data from previously-ringed birds

1. Mist-netting is the most commonly used method for catching birds for scientific ringing but, despite decades of use, there have been few attempts to quantify the associated potential risks to the individuals caught. Any incidence of mortality through capture and handling, however low, is of potential ethical concern and may also introduce biases into the data. 2. We estimate the mortality rate associated with capture of previously ringed (recaptured) passerines from the British and Irish Ringing Scheme (c. 1.5 million records) caught using mist-nets. The importance of species, age, mass, month, time, previous captures and an index of predator occurrence were tested using generalised linear mixed-effects models. 3. The average mortality rate was 0.0011, most of which was reported to occur before the individuals had been extracted from the nets (c. 70% of incidents). Juveniles appeared to be at higher risk and the incidence of predation from mist-nets was seasonal, with increased risk ...