Assessing the success or failure of brood meddling for Hen Harriers can’t adequately be measured by taking a look at survival of chicks in captivity even if this were to be compared with correctly comparable nests in the wild.
How about post-release survival too? There are many potential explanation why captive-reared chicks may fail to outlive effectively after they’re launched. They haven’t had a ‘regular Hen Harrier childhood’ and which will have an effect on their skill to outlive in fututre. They haven’t seen their mom tearing up prey species on the nest, they haven’t watched their dad and mom searching close by, they haven’t been taken to good searching grounds by their dad and mom, there is no such thing as a prospect of them being taught to hunt in any manner by their dad and mom nor taken to secure roosting websites. Who is aware of what affect the dearth of parental care might need. And though the captive-reared birds are launched alive, who is aware of what mineral deficiencies, minor accidents or ailments they could have acquired in captivity or in being transported from moors and again once more? It could be rash to imagine that each one is effectively with these younger birds as they’re launched into the large vast world.
So, it might be mildly fascinating to have a look at the survival of launched birds say to their first birthdays (or past) and examine them with comparable however wild birds from actual nests, introduced up by actual Hen Harriers.
In 2019 there have been 5 captive-reared Hen Harrier chicks launched and all have been satellite-tagged by Pure England. We all know their fates and that of different satellite-tagged Hen Harriers from the occasionally-updated database (see here). There have been 12 Hen Harriers tagged by Pure England in 2019 within the database – 5 broodmeddled chicks and 7 wild birds (see rows 12-23 inclusive). In passing it’s value noting that the brood-meddled chicks have been tagged a superb two weeks later than the wild birds – one other instance of comparability points maybe (however maybe not).
Maybe essentially the most hanging factor about these 12 birds was that just one reached its first birthday (and that was one of many seven wild-reared birds). All of the captive-reared birds went lacking as did a number of of the wild birds, though a number of the wild birds have been discovered and inspection recommended that they’d died of pure causes.
The disappearance dates of the six wild birds have been; July 2019, August 2019, October 2019, October 2019, January 2020 and March 2020.
The disappearance dates of the 5 brood-meddled chicks have been: September 2019, September 2019, April 2020, Could 2020 and Could 2020.
I suppose essentially the most hanging factor about survival of Hen Harrier chicks is that underneath these circumstances, the place just one in 12 will get to see its first birthday, the survival of captive-reared chicks whereas in captivity is all a bit trivial. I ponder whether anybody warned Pure England that unlawful killing charges have been very excessive post-fledging…? I’ve a sense we did, but in addition there’s that paper printed in March 2019 which nails the massively excessive disappearance charges related to flying over pushed grouse moors (see here). Who knew? Everybody!
How concerning the 2020 cohort then? Effectively, the explanation that I describe the Hen Harrier satellite tv for pc tag database as being sometimes up to date is that it hasn’t been up to date since September. Nevertheless, fortunately, though luck had nothing to do with it, my good friend and colleague Dr Ruth Tingay, the Queen of FoI requests, has bought a few of these knowledge out of Pure England and shared them with me (eg see here and here).
Up to now, and we’re solely speaking about December 2020 to date, eight out of 15 wild satellite-tagged Hen Harrier chicks from 2020 are identified to be alive, and 6 of the eight captive-reared Hen Harrier chicks have been identified to be alive. There’s a protracted method to go earlier than the birds’ first birthdays – what number of will get there? We’ll have to attend and see, however within the 2019 cohort just below half of the disappearances/deaths occurred within the interval forward of us so it’s definitely too early to inform.
None of that is the topic of our attraction on Wednesday and Thursday this week – the courts don’t do biology.
However as a scientist and conservationist, I nonetheless can’t perceive how Pure England can go forward with brood meddling in good religion. It’s a fairly poor ‘experiment’ and to date it’s exhibiting us what we already know – unlawful persecution is huge for these birds on grouse moors, and that ought to be the main focus of all severe efforts to preserve this chook.