Do you have any sensible stats for that expectation? For what it's worth, now into my 7th year of free ranging, the birds that get or are assumed predated here these days (and there are not many) are youngsters, not the older birds. Averages can be very misleading.
No, only my experiences. I agree in general.
Inexperienced birds - which youngsters are by definition - are more likely to get predated than experienced ones, and this is not sufficiently recognized in most studies I've seen. Most experiments I've come across are far too short term, and often incapable by design of giving realistic results. A chick hatched in an incubator and raised by machines in a sterile environment does not behave like a chick raised by a broody free-ranging from hatch.
Completely agree.
Anyone who starts free-ranging experiences losses from predation. Some keepers respond by promptly bringing their birds back into the protection of captivity, and assume that the losses they suffered are typical and that they would continue at that rate until all birds are gone. Many posters on BYC are exemplars of that. I lost my first 6 birds to the foxes within the year.
Yup. Sad but true.
But keepers who persevere, and who analyse the losses - letting the chickens roost in trees was my mistake - and fix the issue(s) identified - make them sleep in the coops in my case, together with some research on foxes and methods of their deterrence - find that, with experience, the birds get better at predator detection and evasion, just as they get better at foraging and other natural behaviours. And they pass this knowledge from experience on to the chicks raised amongst them.
As you know, this is what I did. It's hard going and very few people here on BYC are prepared to take the longer term view. Many of the posters are relatively new to chicken keeping and what they call free ranging may just be a small area in a backyard with inadequate cover and high predator load. Others haven't even thought very much about a long term keeping strategy and others are young and won't be the person responsible for the chickens once the attractions/demands of adult life take up their interest and time.
But...
I had most of the common predators in Catalonia but I had one in particular, the Goshawk that killed very experienced birds, male and female. In fact, the Goshawk was responsible for the majority of the senior birds I lost to predation. This needs to be taken into account. Not all predators are equally dangerous for a number of reasons. The weasel struck a lot but only killed one adult bird to the best of my knowledge. The foxes were dusk to dawn hunters and I didn't lose a single chicken to a fox in daylight hours. I did lose a couple from outside nest while sitting on eggs.
Martens tended to try the jump from tree if out in daylight and the chickens usually saw them and grouped together for defense. Didn't lose a chicken to Martens. I've had a Mink make a try in daylight but it was sick, close to dying and the dogs saw it off.
Falcons, buzzards and the various other hawks were either too small to take down a full sized bird, or in the case of the buzzard, too slow and clumbsy.
Chicks and juveniles before they learnt to keep with the tribe were routinely predated.
When I started we were losing a chicken a month. When I finished ten years later maybe one healthy adult a year. Chicks went from 60% to 30ish percent.
Limiting the number in a clutch helped a lot. Too many chicks, staggered hatches, plus the occasional nutter, were the common reasons for many of the chick losses.
A proper study of the life expectancy of free-range versus confined chickens should compare the data of a long-established multi-generational free ranging flock - not one of identical clones put together ex nihilo for the purpose of the experiment - with those from a variety of confined type flocks. I don't bet, but I'd wager the losses from disease among the latter would outnumber the losses from predation among the former. And there may be some very old birds among the latter, but I'd wager the general health of the flock was better among the former. Further, it might not happen during the experiment, but it does happen in real life, that some flocks in confinement face catastrophic losses when a predator gets into their 'secure' coop. Perhaps an actuary's approach would be appropriate?
I agree, but there are not that many here on BYC with that many years of experience at chicken keeping, let alone free range/ranging chickens with roosters and broody hens to breed in for the loses.