Hen Harriers and brood management, where should we go from here?

Male Hen harrier in flight (C) Pete Morris (rspb-images.com)

Today's blog is written by Mike Shurmer, Head of Species for RSPB England. He reflects on the learning from the brood management trial.

In spring in the English uplands, male Hen Harriers are flying high, performing a series of swoops, somersaults and tumbles, showing amazing aerial agility to attract a female and encourage her to breed. They are skydancing, one of the UK’s most impressive wildlife spectacles, exhilarating to watch and an intrinsic part of our uplands. If these males are successful, the females will go on to lay eggs, usually four to five, in their nest on the ground in the heather.

In recent years some of these nests have been destined to become part of the brood management trial, one of the six actions under Defra’s Joint Hen Harrier Action Plan (HHAP). Under brood management, eggs or chicks are removed from some Hen Harrier nests on areas managed for grouse shooting, with the chicks reared in captivity and the fledged young returned to the wild. The five-year trial was launched in 2018, with the first broods managed in 2019, though the trial has now extended to the end of the 2024 breeding season. So far, the trial has seen the removal of broods from 15 Hen Harrier nests, with 58 fledged young subsequently released.

Satellite tagged Hen harrier chick (c) Ben Andrews rspb-images.com

Brood management has been compared by some to other conservation interventions such as headstarting, an intervention to help young birds make it through the vulnerable nest and chick-rearing stage. Headstarting has been done with threatened birds like Spoon-billed Sandpiper in Russia, Black-tailed Godwit in the Fens and increasingly with Curlew in southern England. But whilst the technique is similar, the rationale behind it is very different. Headstarting is seen as an emergency intervention, a short-term fix whilst other conservation measures are put in place. It is buying time whilst issues limiting these populations, such as unsustainable levels of predation or significant habitat loss, are tackled. For Hen Harriers brood management is done for a very different reason – because whilst these birds prey on a variety of small birds and mammals, their diet includes Red Grouse, and for this reason they have been illegally killed for decades.

The RSPB has previously made its objections to brood management very clear and we remain steadfast in our view that the only way to see meaningful Hen Harrier recovery is the ending of illegal persecution. We believe that ethically brood management comes from completely the wrong place. It is about Hen Harriers fitting in around the unsustainable management of driven grouse moors, rather than driven grouse moor management adapting to coexist with Hen Harriers. But how have we got to the situation where removing Hen Harrier eggs and chicks from wild nests, often from within Special Protection Areas (SPAs) purposely designated for their protection, is seen as the route to their recovery?

Hen Harriers have been in a parlous state for decades, as recently as 2013 there were no chicks at all fledged in England. Illegal persecution has taken an awful toll, limiting their numbers and continuing to hold back any chance of meaningful recovery. Brood management has been seen by some as part of the solution. Essentially, the principle of brood management is that by controlling the density of nesting Hen Harriers on grouse moors, predation pressure on grouse will decrease and this will lead to a change in attitudes with grouse moor owners and managers becoming more welcoming and tolerant of this magnificent bird of prey, and as a result they will not be illegally killed.

As of November 2023, we are approaching the last year of the trial, and it is important to reflect on what has been learned. The key questions are: does brood management work, has it changed attitude, and what role, if any, should brood management have in the future of Hen Harrier conservation? To help answer these questions, Natural England are leading an evaluation of the trial on behalf of the Brood Management Partnership. We are calling for this to be a transparent, robust and independent evaluation, that allows us to understand and assess whether brood management can meaningfully contribute to improving Hen Harrier survival, changing attitudes and reducing illegal persecution.

Satellite tagged female Hen harrier (c) Lee O'Dwyer rspb-images

Since their low point in 2013, Hen Harrier breeding numbers have increased in England. Natural England’s reported 54 Hen Harrier breeding attempts in 2023, although their population remains far below the 323-340 pairs that an independent government report found should be present in the English uplands. The trial evaluation will need to understand how brood management, as one of the six actions under the HHAP, has contributed to this increase. But a key objective of brood management is to change attitudes, hearts and minds, and reduce the likelihood of Hen Harriers being illegally killed, and sadly, this illegal killing continues unabated.

In fact, 2022 was the worst year on record for confirmed incidents of Hen Harrier persecution in England, epitomised by the fates of Free and Susie, two Hen Harriers satellite-tagged by Natural England. In April 2022 Free’s head was twisted and ripped off whilst he was still alive, and in June 2022 Susie’s three chicks were brutally stamped to death in their nest.

Initial analysis of brood managed young has shown improved first year survival compared to wild-reared young and it will be important for the review to investigate the mechanisms underlying this pattern, particularly in the context of the brood management theoretical framework stating that survival rates of all Hen Harriers should improve. However, we also know that being the product of a brood managed nest does not prevent the fledged young being subsequently illegally killed. Despite being fitted with satellite-tags an increasing number of brood managed young are going missing or have been proven to have been persecuted in the last two years. Indeed, of the 39 proven persecuted or suspiciously vanished Hen Harriers across the UK since January 2022, 14 of these are brood managed birds that are or have been subject to police investigation.

We know that these 39 birds are only the tip of the iceberg, only representing a small proportion of the wild UK population. The scientific evidence base is growing: a peer-reviewed paper published by the RSPB Centre for Conservation Science this year (Ewing et al., 2023), found that the annual survival of Hen Harriers in the UK is unusually low, with illegal killing accounting for 27-43% of birds under one year of age, and 75% of Hen Harriers aged between one and two years old. Mortality – due to illegal persecution – was found to be higher in areas managed for grouse shooting. A previous Natural England study (Murgatroyd et al., 2019) revealed that Hen Harriers are ten times more likely to die or disappear within areas predominantly covered by grouse moor compared to those that were not managed for grouse. It also concluded that at least 72% of the tagged Hen Harriers in the study were either confirmed to have been illegally killed or disappeared suddenly with no evidence of a satellite tag malfunction.

Diversionary feeding (c) Mark Thomas rspb-images.com

There is an alternative method to reducing harrier predation of grouse during the chick rearing phase – diversionary feeding. This technique provides breeding pairs with an alternative (human provided) food source during chick rearing to minimise predation of grouse. The highly effective method was rigorously tested and refined through the Langholm Moor Demonstration Project, a partnership including game management interests. It is cost effective too – the HHAP estimates a cost of £1,150 to diversionary feed a Hen Harrier brood, compared to an estimated cost of £875,000 for the initial five-year brood management trial. Crucially, diversionary feeding enables Hen Harriers to nest where they choose, and for any impacts on grouse stocks to be minimised.

After seven years it is time for brood management to stop. It is time for the illegal killing of Hen Harriers to stop. It is time to end the use of toxic lead ammunition, the burning of our precious peatlands, and the unsustainable use of veterinary medicines such as medicated grit. It is time to licence driven grouse shooting. It is Time for Change.