Tried to get on earlier, Richard but something was wrong then I saw why. The server changeover.I see there's no 'Underline' option now.. Bold,Italics Text size/colour but no 'U'.
I wasn't actually aware of the process involved about how birds are ringed so I had to check on that. Having said that, thinking about it, I vaguely recall watching birds being trapped in a section of mist net of a TV documentary..like Countryfile or maybe the Spring-Autumn-Winter Watch programme . On an organised wildlife trip to Scotland years ago (Mull included) the group I was with were taken to an old-timer in the middle of nowhere..out in the hills and he looked after barn owls and showed us how he rings the youngsters. We were told that only those licensed can do it.... after training.
Here's what I found. The findings, by the author,Erica Spotswood, were published in 2011. It was the first research carried out into the the activity.
Here's how she came to carry out her research
Spotswood first discovered the lack of research into mist-netting while applying to study the Grey-green Fruit Dove in French Polynesia. When concerned officials denied her permit and questioned the safety of capturing birds with mist-nets, Spotswood realised that no comprehensive study quantifying the frequency of bird injuries during mist-netting existed.
She said...
."I was very surprised to find that no study of this kind existed, because mist-netting has been around since the 1950s and is an extremely widely used and common technique for monitoring bird populations"
The research, led by Erica Spotswood, from the University of California at Berkeley, used data from organisations across the United States and Canada to assess the risk factors which could increase rates of injury or mortality including bird size, age, frequency of capture and the role of predators.
The results revealed that birds are rarely injured or killed by mist nets. Of 620,997 captures the percentage of incidents of injury amounting to 0.59% while only 0.23% of captures resulted in mortality. The authors then began to analyse risk factors which could lead to increased incidents.
Finally the team found that birds which were released with an injury were just as likely to be recaptured as birds without, meaning that injured birds continue to survive in similar numbers to uninjured birds, meaning the long term impact of mist netting is minimal.
Another source:
Mist netting is widely used as a method for the capture of birds (Figure 1). In recent years, for example, around a million birds annually have been captured for ringing in Britain and Ireland; most of these (85%–90%) are passerines caught in mist nets and, additionally, there are usually over 200,000 recaptures of ringed individuals (Robinson, Leech, & Clark, 2017). Mist netting is considered among researchers and bird‐ringing organizations to be safe and effective when carried out by trained and experienced individuals who follow published guidelines (e.g., Busse & Meissner, 2015 Gustafson, Hildenbrand, & Metras, 1997; Redfern & Clark, 2001)
I've used bold type to highlight particualr data..it's not shouting at you as bold lettering can come sometimes across as.
A third source stated:
Incidents of mortality occur before handling. We recommend that all Ringing Schemes should collate and make available data on capture‐related mortality. Overall rates of mortality associated with capture were low and support the use of mist netting as a safe capture technique, without undue bias from mortality, when used by appropriately trained individuals.
Ringing allows us to study how many young birds leave the nest and survive to become adults, as well as how many adults survive the stresses of breeding, migration and severe weather. Changes in survival rates and other aspects of birds' biology help us to understand the causes of population declines. Alongside other surveys and data, helps us to build up a picture of each population and whether they're struggling or thriving.
Data collected over the last few decades indicates a severe population decline of many UK bird species.
Understanding which threatened species we need to support and protect, as well as the underlying causes behind their decline, has never been more important.
I also read that most deaths inside the netting are caused by predators in the form of raptors so recommendations were made on how to reduce this along with other recommendations to reduce injury or mortality.
We use this data in our practical conservation work, helping to create the habitats and circumstances that will help these bird populations recover, and hopefully thrive once again.
It seems to me that, weighed up against the data collected, not only for gaining knowledge of the habits of birds but putting that knowledge to use in conservation measures for particular species in the form of intervention be it here in the UK or wherever a species migrates to outweighs the minimal loss of life caused at the time of capture with mist netting. So..there's my answer to your question,Richard.