Hen Harrier brood meddling on trial (3)

Hen Harrier checks. Photo: Gordon Yates

Assessing the success or failure of brood meddling for Hen Harriers cannot adequately be measured by looking 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 plenty of potential reasons why captive-reared chicks might fail to survive well after they are released. They haven’t had a ‘normal Hen Harrier childhood’ and that may affect their ability to survive in fututre. They have not seen their mother tearing up prey species at the nest, they haven’t watched their parents hunting nearby, they haven’t been taken to good hunting grounds by their parents, there is no prospect of them being taught to hunt in any way by their parents nor taken to safe roosting sites. Who knows what impact the lack of parental care might have. And although the captive-reared birds are released alive, who knows what mineral deficiencies, minor injuries or diseases they may have acquired in captivity or in being transported from moors and back again? It would be rash to assume that all is well with these young birds as they are released into the big wide world.

So, it would be mildly interesting to look at the survival of released birds say to their first birthdays (or beyond) and compare them with similar but wild birds from real nests, brought up by real Hen Harriers.

In 2019 there were five captive-reared Hen Harrier chicks released and all were satellite-tagged by Natural England. We know their fates and that of other satellite-tagged Hen Harriers from the occasionally-updated database (see here). There were 12 Hen Harriers tagged by Natural England in 2019 in the database – five broodmeddled chicks and seven wild birds (see rows 12-23 inclusive). In passing it is worth noting that the brood-meddled chicks were tagged a good two weeks later than the wild birds – another example of comparability issues perhaps (but perhaps not).

Perhaps the most striking thing about these 12 birds was that only one reached its first birthday (and that was one of the seven wild-reared birds). All the captive-reared birds went missing as did several of the wild birds, although some of the wild birds were found and inspection suggested that they had died of natural causes.

The disappearance dates of the six wild birds were; July 2019, August 2019, October 2019, October 2019, January 2020 and March 2020.

The disappearance dates of the five brood-meddled chicks were: September 2019, September 2019, April 2020, May 2020 and May 2020.

I guess the most striking thing about survival of Hen Harrier chicks is that under these circumstances, where only one in 12 gets to see its first birthday, the survival of captive-reared chicks while in captivity is all a bit trivial. I wonder whether anyone warned Natural England that illegal killing rates were very high post-fledging…? I have a feeling we did, but also there is that paper published in March 2019 which nails the massively high disappearance rates associated with flying over driven grouse moors (see here). Who knew? Everyone!

How about the 2020 cohort then? Well, the reason that I describe the Hen Harrier satellite tag database as being occasionally updated is that it hasn’t been updated since September. However, luckily, although luck had nothing to do with it, my friend and colleague Dr Ruth Tingay, the Queen of FoI requests, has got some of these data out of Natural England and shared them with me (eg see here and here).

So far, and we are only talking about December 2020 so far, eight out of 15 wild satellite-tagged Hen Harrier chicks from 2020 are known to be alive, and six of the eight captive-reared Hen Harrier chicks were known to be alive. There’s a long way to go before the birds’ first birthdays – how many will get there? We’ll have to wait and see, but in the 2019 cohort just under half of the disappearances/deaths occurred in the period ahead of us so it’s certainly too early to tell.

None of this is the subject of our appeal on Wednesday and Thursday this week – the courts don’t do biology.

But as a scientist and conservationist, I still can’t understand how Natural England can go ahead with brood meddling in good faith. It’s a pretty poor ‘experiment’ and so far it is showing us what we already know – illegal persecution is massive for these birds on grouse moors, and that should be the focus of all serious efforts to conserve this bird.

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5 Replies to “Hen Harrier brood meddling on trial (3)”

  1. Totally, totally, right Mark in your last summing up paragraph above.The issue is the persecution of Hen harriers by the shooting industry especially on grouse moors and the issue is to stop this persecution. Clearly after years and years of persuasion the shooters that kill our wildlife for fun have not responded in the slightest to this persuasion.
    The Scottish Government to their credit are now trying to do something about the general abuses of moorland and wildlife that are perpetrated by the grouse shooting industry. The Westminster Government, on the other hand, are doing absolutely nothing about these abuses at all.
    Trying to brood meddle Hen Harrier chicle is a total farce. It is not tackling the real problem of persecution and is just “fiddling while Rome burns” . No wonder the call for banning driven grouse shooting altogether is becoming louder and louder every day, and rightly so.
    What a rotten lot this Westminster Government is.

  2. I know this isn’t a new point. But it has got to be the case that when they are released they will feel a more comfortable around humans than wild birds, and less cautious. They won’t get as spooked by human shapes approaching, by voices, by vehicle engines, etc,etc. In my estimation this must partly account for why they get done in so quickly after being set free. Like undoing evolution. Probably if they do get through a few months or so and have perhaps been shot at once or twice – may even have took a few pellets without critical injury, then they will be a little harder to get close to thereafter.

  3. As a shooter and conservationist I take exception to the repeated accusations on very public platforms that the shooting community is responsible for the killing of raptors. While I don’t try to deny that raptors were ruthlessly killed in the past,times and attitudes have changed and no respectable shooting estate would condone or participate in such action nowadays, that is not to say that some irresponsible individuals aren’t still killing raptors. There have been reports to BASC of several incidents of gamekeepers being verbally abused by members of the public while carrying out their work, this has been brought about by the media broadcasting negative and unjustified opinions about shooting and gamekeeping in general. The keepers job is to protect ground nesting birds,in doing so he not only provides the protection of the Gamebirds he’s responsible for but all ground nesting birds in his area and should be respected for his work.
    The accusations of hen harriers being killed by the shooting community are relentless but how many actual witness accounts are there? How many prosecutions?
    It is not inconceivable that militant anti shooting groups could be responsible for the killings. The well publicised fact
    Rthat most hen harriers die on grouse moors is hardly surprising as that’s where they tend to live..
    The game shooting community does more for conservation than any other group and should be respected for it.

    1. Jonny – thank you for your first comment here. You might like to widen your reading a little. You could start here https://markavery.info/2019/03/19/long-awaited-scientific-paper-nails-grouse-moor-crimes/ The paper explained there shows that Hen Harriers are ten times more likely to die on grouse moors per unit of time than on other habitats. That deals with your erroneous ‘that’s where they live’ pont.

      Gamekeepers are wonderful aren’t they? Of 181 people convicted of crimes against birds of prey between 1990 and 2019 67.4% of them were gamekeepers (and another 6.6% of them were involved in game management and shooting in other ways). the National Gamekeepers’ Organisation say that 3000 people are full time gamekeepers in UK (I guess they should know – certainly better than I). So 67% of the crime comes from 0.005% of the population unless I’ve done my sums wrong.

      I welcome more comments from you here but do try to raise the standard a bit please.

    2. Hi Jonny, I’m not having a go at you but I would be interested to know what shooting circles / region of the country you mix in. It is just not possible to be a long-term friend to / associate of / beater or helper within the shooting scene around the grouse moors and not know fine well that raptor persecution is continuing and is as bad as it has ever been for decades.

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