Well they certainly didn't contribute to the population being dead, did they? And it was more than 10 birds that you suggested that died or they wouldn't have been able to arrive at 48% right?
Discount it all you want. People can see for themselves that predation is not a non-existent as some want to portray it. We all know that if the info in this study supported your position, you'd be on here singing it's praises.
And I am NOT saying that is the main reason for the pop decline. IMHO, it the succession of cold and wet springs that we have had.
I was one of those putting the transmitters on those hen turkeys and also one of the people going in to determine the cause of death when one went into mortality mode. So I suspect I have a bit more of a handle on it than some who simply read the final result of the study.
First of all there is a significant stress level put on wildlife when you capture, handle and put bands or a transmitter on it. That especially true with most bird species compared to most mammal species. That stress of being handled alone results in some wildlife dying within a few weeks of being captured.
Then add the fact that the transmitter used on turkeys is a small backpack type devise that is attached by using an elastic band that encircles both wings. I saw turkeys, especially with hens, that were so imbalanced once the transmitter was attached they were unable to fly and had to run away as they left. I suspect they learned to fly again when they became more used to the added weight and possible balance disposition of the new backpack but who knows how it effected them over the long term.
Many of the turkeys that were in mortality mode had been dead for a few days before we got to them. Since the transmitter only gave a location signal for about six hours and only every third day the window for tracking in on it was rather narrow. That meant that often by the time you found the remains you could tell that something had been eating it but it was not always possible to say that what had been eating it actually killed it instead of just scavenged it. I am pretty sure some of the exams got listed as a predation even though it might have been nothing more than a bird that died, perhaps from capture myopathy, and was simply scavenged instead of a predation loss. I also often wondered just how much that backpack might have slowed the turkey's ability to take flight when a predator was closing in on it. Did we set those turkeys up to be more prone to being a victim of predation?
Those are questions without an answer. But, I did notice that most of the predation cases came within the first few weeks of being handled and equipped with the transmitter.
I am not trying to discount the research of the mortality studies. They provide the best information we can get but that doesn't mean there isn't going to be a level of bias in the results sometimes. That is why it is important to redo some projects as better technology becomes available and also why good researchers know that sometimes their data can have a level of uncontrollably bias in the final results.
There was no question that hens became more vulnerable to predation while nesting and that the later into the incubation process the less likely she was to avoid an advancing predator. But, there is also no question, at least in my opinion, that predation was higher on the hens we handled and equipped with transmitters than there is on hens that had never been handled or so equipped.
Dick Bodenhorn