A framework for head-starting Eurasian Curlew in Wales

Prepared by the Curlew head-starting Task and Finish Group

V1 April 2025. To be reviewed April 2027

Issue

1.     With any chronic declining population there is an urgent need for species recovery interventions. Here, an emphasis is required on i) an assessment of options and alternatives, ii) techniques for exploring the outcomes of different actions, and iii) how to deal with unintended outcomes through adaptive management. A key test is whether the target population responds to the deployment of conservation interventions. If this is not achieved the scope for recovery will need to be re-evaluated.

2.     Due to the severity of breeding Eurasian Curlew Numenius arquata (“Curlew”) declines in the UK and Ireland there is growing widespread interest in the potential for head-starting as a conservation intervention to aid Curlew recovery. Head-starting is the release into the wild of birds that have been hatched and reared from eggs which were collected from the wild.

3.     With the urgency to address Curlew declines together with pressures of accountability and competing resources it is right to ask whether head-starting is a beneficial intervention to aid Curlew recovery in Wales. On the basis that there is no UK strategy for head-starting Curlew, Gylfinir Cymru requested a small partner Task and Finish Group (“T&F Group”) to explore the need and benefits for Curlew head-starting in Wales (Meeting 16, 21 June 2023). A T&F Group[1] was convened to discuss and determine that need and if appropriate develop a head-starting framework that will be presented to Gylfinir Cymru for endorsement. This paper is the findings of that T&F Group.

Background

4.     The Curlew is a species of urgent conservation concern both in the UK (Stanbury et al., 2021) and Wales (Johnstone et al., 2022). Owing to rapid national declines and the global importance of the UK breeding population, the Curlew is considered to be the most pressing bird conservation priority in the UK (Brown et al., 2015), including Wales (Gylfinir Cymru, 2021). The Curlew is predicted to be on the brink of extinction as a viable breeding species in Wales by 2033 (Taylor et al., 2020).

5.     The population size of any species is driven by two key demographic metrics: productivity and survival. For birds, the three key components of breeding success are the number of eggs which are laid (clutch size), the number of chicks that hatch from those eggs (hatching success) and the number of chicks that fledge (fledging success) from which overall breeding success can be measured. Together with the above metrics, understanding the number of recruits into a population is an important demographic to monitor the health of any bird population in a changing environment.

6.     The Wales Action Plan for the Recovery of Curlew (“The Recovery Plan”) (Gylfinir Cymru 2021) Here identifies the key drivers of Curlew decline in Wales and the outcomes required to achieve a sustainable recovery in the long-term, especially those relating to land management. Currently, the main driver of Curlew declines in the UK and western Europe is low productivity in breeding populations due to the predation/losses of eggs and chicks by meso-predators (Grant et al., 1999; Brown et al., 2015; Douglas et al., 2021) and agricultural management of grasslands (Douglas et al., 2021).

What is head-starting?

7.     Due to the severity of breeding wader declines in the UK (e.g. black-tailed godwit Limosa limosa) and Ireland (e.g. Curlew) and elsewhere (e.g. spoon-billed sandpiper Calidris pygmaea, black stilt Himantopus novaezelandiae) there is growing widespread interest in the potential of head-starting, and related avicultural techniques, to contribute to wader population recovery.

8.     Head-starting is the release into the wild of birds that have been hatched and reared from eggs which were removed from the wild. Head-starting may be used to return captive-reared birds (as opposed to captive-bred) to the population from which eggs were taken or translocated to different sites for release. The objective is to increase productivity by incubating eggs and rearing birds in situations where egg and/or chick mortality in the wild is high. It may also help to secure a breeding population which is otherwise at risk of loss through senescence (old age).

9.     The principal aim of Curlew head-starting, as a contribution to the Recovery Plan, is to ‘buy time’ whilst other conservation interventions, at the landscape scale, are implemented or under consideration. This paper expands on the issues relating to head-starting design highlighted in Annex 1 of the Recovery Plan.

Legislation

10.  The Wildlife and Countryside Act, 1981, (“the Act”) provides the legal framework in Wales for the protection of all wild birds, their eggs and nests and also establishes the legal framework under which NRW may grant licences allowing the killing or taking of wild birds. In Wales, similar to elsewhere in the UK, it is unlawful to take or possess a Curlew egg, chick or adult without an appropriate licence. Curlew is not listed on Schedule 9 of the Act and therefore it is lawful to release Curlew in Wales without a licence.

NRW’s position statement on translocations or reintroductions

11.  In common with the other statutory conservation bodies, NRW has adopted the International Union for Conservation of Nature (IUCN) Guidelines for reintroductions and other conservation translocations - resource | IUCN as the primary tool for assessing species reintroduction and conservation translocation proposals[2]. These guidelines are to help evaluate whether a translocation is appropriate and to understand the associated risks. NRW advises any project that is proposing a conservation reintroduction or translocation within Wales apply the IUCN guidelines and ensure they provide sufficient evidence to allow a proper assessment of their application.

12.  NRW’s assessment of any Curlew head-starting proposal will consider the principles of Sustainable Management of Natural Resources (SMNR) including the impact on resilience of ecosystems and decisions will be based evidence supplied and on the principles of precaution and proportionality.

Approach

Scope

13.  The T&FG considered:

-        Conservation benefits of Curlew head-starting to declining populations.

-        Risks and implications associated with Curlew head-starting.

-        Evidence gaps.

-        The need for a Curlew head-starting framework with clear principles, based upon the best available evidence, to inform all proposed Curlew head-starting projects in Wales.

14.  The T&FG did not consider:

·       Breeding adult Curlews in captivity with the aim of releasing their offspring into the wild.

·       The context of wider pressures and threats on breeding Curlew, though the adoption of any framework should account for these as articulated in the Recovery Plan.

·       Comprehensive consultation outside Wales, though it is expected that the thinking and outputs will be shared with other UK Curlew recovery partnerships and the licensing authorities of Natural England, NatureScot and DAERA.

15.  The T&FG accepted head-starting carries high risk of reputational harm, requires buy-in from rural communities, requires rigorous decision-making, needs to be defendable, requires detailed planning and expert skill set and importantly multi-year funding to both deploy head-starting as a conservation intervention and to monitor its effectiveness. Given this context, the T&F Group addressed two fundamental questions:

Q1   Would head-starting bring a conservation benefit to aid Curlew recovery in Wales?

Q2   If the answer to Q1 is yes, is there a need for a Curlew head-starting framework in Wales?

Would head-starting bring a conservation benefit to aid Curlew recovery in Wales?

16.  In response to Q1 there was broad agreement about the potential conservation benefit, here the following rationale associated with population status and species recovery underpinned that determination:

Population status

• In common with many other countries of the UK and elsewhere in Europe, breeding Curlew in Wales are in significant decline both numerically and spatially, a result of a combination of three significant pressures: habitat loss, unfavourable habitat management and nest/chick loss. At present, while recovery interventions in Wales can be effective in reducing the losses of eggs, these have yet to translate into fledging success at a level sufficient to maintain or increase the population.

• Curlew is predicted to be on the brink of extinction as a viable breeding species in Wales by 2033. Due to the significance of this emergency, Curlew is now considered to be the most pressing bird conservation priority in Wales.

It is accepted that the two bullet points above do not provide evidence that head-starting may benefit Curlew, but they do highlight the urgent need for novel approaches that may be considered beneficial.

Species Recovery

• The Wales Action Plan for the Recovery of Curlew provides a framework for action, of which head-starting is highlighted as a potential action to consider.

• The application of head-starting should be in response to population need, location and vulnerability (e.g. edge of range).

• Welsh head-starting initiatives would facilitate and contribute data / evidence-led outcomes to other UK head-starting pilot studies to improve our understanding and to provide greater scientific rigour to statistical analyses.

• Head-starting provides a means to ‘buy time’ for small populations, keeping them viable until other landscape scale interventions take effect, providing there is a commitment and resources to secure those long-term interventions.

During our assessment to answer Q1 we determined high scientific uncertainty in areas associated with head-starting, since it is a relatively new technique; for example there are no peer-reviewed scientific studies of:

-        survival rates of 1st and 2nd year head-started Curlew in comparison to wild populations, that may indicate whether released birds are equally or more resistant to key pressures and threats;

-        the return rate of head-started Curlew to the recipient (‘beneficiary’) breeding population;

-        the effects of head-starting on population-level genetic diversity where deleterious alleles may spread in the beneficiary breeding population;

-        the of head-started Curlew that go on to successfully rear chicks in comparison to wild bred Curlew;

-        sex ratio among returned head-started birds, is this higher, equal or lower compared to wild chicks, and;

-        the circumstances (i.e. scale and location of releases) where head-started Curlew translate into a positive population-level response.

However, we are aware that some of these evidence gaps may be addressed in the next few years as English Curlew head-starting projects are now accruing sufficient breadth of data to start survival analyses. Furthermore, Ewing et al. (in press) has reviewed Curlew head-starting projects in Europe, this study is expected to be published soon.

17.  In assessing Q1 it was accepted that Curlew head-starting is a relatively high cost and high-risk intervention and lies outside the experience of many conservation organisations. We concluded that this intervention requires specialist skills, is operationally complex, and should only be undertaken as part of a wider conservation programme.

18.  The taking of Curlew eggs or chicks from wild populations to form a captive breeding programme with the aim of releasing their offspring into the wild was out of scope of this paper. However, there was broad consensus this intervention is not recognised under Curlew head-starting.

19.  Crucially when addressing Q1 there was broad agreement that although there are substantial evidence gaps, such is the emergency to address Curlew declines, that sensible and well-thought out conservation interventions should not be delayed on the basis of insufficient peer-reviewed science. This is considered to be analogous to the intervention of predator control, where the scale and required effort of lethal control of meso-predators to give a population-level response is not fully understood but does not negate its deployment as part of a package of measures for Curlew recovery. In both cases, projects should acquire evidence to assess whether it is making a positive difference to breeding productivity.

20.  Due to the paucity of evidence, it is important that any Curlew head-starting proposal is thoroughly planned, rigorously implemented and carefully monitored.

Is there a need for a Curlew head-starting framework in Wales?

21.  We determined that the key test of any conservation intervention or suite of interventions is to improve the conservation status of the target species and thus appraisal and planning must provide the basis for this. In England, there are five head-starting projects covering seven release sites and in the island of Ireland Sanghera et al. (in prep) have looked at the justification and feasibility of Curlew head-starting to aid recovery. In Wales, to date, no such discussion, assessment or decision on the application of Curlew head-starting has taken place. The T&F Group agreed that a realistic and intelligent framework will inform and enable Curlew head-starting in Wales in a balanced manner by:

·       Providing a consistent approach to planning and implementation of head-starting initiatives against a set of clear principles (e.g. licensing, monitoring, knowledge sharing, communication).

·       Facilitating a structured and disciplined approach designed to inform the licensing decision by NRW of proposed head-starting projects in Wales.

·       Articulating the requirements of a head-starting proposal to improve Curlew conservation status (e.g. monitoring plan, performance indicators) with the means to do it (e.g. multi-annual funding, evaluation and adaptive management).

·       Connecting, supporting and underpinning IUCN conservation translocation guidelines.

Guiding principles to determine whether a Curlew head-starting proposal in Wales is appropriate.

22.  The framework will be guided by a set of 12 principles which will be applied when deciding in which situation a Curlew head-starting project is appropriate. Unless all of these principles are satisfied, it would be inappropriate to request a licence to take eggs. If there is considerable uncertainty in the level of risk, a head-starting proposal should not proceed. Applying these principles when deciding on the appropriateness of a Curlew head-starting proposal will require the exercise of judgement based on available evidence and scrutiny.

Principle 1: Curlew are protected by law, and derogations from that legislation may only be granted if there is a demonstrable and genuine need to deploy Curlew head-starting in a given geographical location under licence.

Principle 2: Any donor eggs (especially if derived from breeding Curlew outside Wales) should have a negligible or nil chance of resulting in chicks fledging in the wild.

Principle 3: The release of head-started Curlews can reasonably be expected to contribute to recovery in the context of the Recovery Plan. Even if Principle 1 is satisfied, any head-starting proposal should only be considered where there is reasonable evidence to expect that it will contribute to Curlew recovery within either a geographic location or Wales or both. Here, the intended benefits of head-starting must go beyond simply the preservation of individual birds, benefits must be measurable at a population or ecosystem scale. For example, priority may be given to sites that have the potential for the breeding population to expand and connect with other occupied areas where appropriate habitat and predator control measures are being implemented.

As and when new peer-reviewed evidence emerges it may be necessary to update/review the parameters referenced above.

Principle 4: The proposal will contribute to wider cooperation and synergies to improve both the transfer of technical knowledge and the scientific evidence base. It is imperative that to strengthen capacity-building, development and scientific cooperation there is enhanced collaboration, cooperation, knowledge and data transfer between other UK and European based Curlew head-starting initiatives. This view is commensurate with the ambition to demonstrate how head-starting aids Curlew recovery.

Principle 5: Other methods of resolving insufficient productivity, as practically possible, within an area are in place and have not increased productivity to at least 0.6 fledged young per pair per annum (this is the level of overall breeding success that is considered to prevent further population decline, see Gylfinir Cymru / Curlew Wales, 2021). Should this not be the case or continuing effort is required, action to meet the ecological needs of breeding Curlew (i.e. sufficient suitable habitat, habitat management and predator management) must run continuously with the head-starting project. The proposal should demonstrate how these other interventions will continue to be funded to work at scale, alongside head-starting in the area of release, commensurate with the aim of head-starting ‘buying time’ for the benefits of those interventions to be realised.

Principle 6: All head-starting proposals should follow the IUCN guidelines for reintroductions and other conservation translocations. The IUCN guidelines are designed to be applicable to any conservation translocation and are based on principle rather than example. The guidelines are a response to the present era of accelerating global ecological change and present a logical process from initial concept to design, feasibility, risk assessment, decision making, implementation, monitoring, adjust, evaluation and governance. NRW has adopted the IUCN guidelines when assessing any species translocation proposal (see para 11 above).

Principle 7: Security of funding can be demonstrated, for both head-starting and a parallel package of other interventions. Any proposal requires a demonstration of adequate and accessible financial resources (includes domestic, international, public and private funding sources) with a costed finance plan to cover a minimum of five years (as many Curlew do not breed until their 4th year, this would increase the likelihood of recording the breeding of any head-started birds). A costed work plan will include a contingency and a five-year post-release monitoring plan – see Principle 8.

Principle 8: Ensure a dedicated monitoring programme is built into any proposal. This will include marking/tagging to ensure the movements of released birds can be determined. Such an approach will support Principle 4. It is critical that outcomes are monitored so that lessons can be learned, shared and adaptations made. As a minimum: i) the size and productivity of the recipient population (and the donor population where translocation between sites is involved) should be monitored in order to understand the impact that headstarting is having; ii) released birds should be metal and colour-ringed, field readable colour marks (colour rings, leg flags that are standardised in locals or a national marking scheme) and where possible GPS tagged; iii) the recipient population should be closely monitored in subsequent breeding seasons to determine survival and recruitment rates of head-started birds and their subsequent breeding success compared to wild bred birds and consequently changes in population size; iv) detailed records should be kept of the birds during the rearing process, including hatch date, sex, condition and health, so that the links between rearing and subsequent fitness can be learned. Additionally it will be critical to:

• closely follow birds in the immediate post-release period in order to assess whether they are behaving appropriately and detect any early mortality;

• GPS track a proportion of birds so that their survival and movements can be directly monitored, and lessons learned about the behaviour of that population, and;

• monitor the breeding success of head-started birds relative to that of wild birds, in order to understand their relative fitness for life in the wild.

Principle 9: Any proposal must demonstrate that those involved have the skills and experience to manage disease and biosecurity risk, and to achieve health and welfare standards that maximise the number of Curlews released in good condition.

Principle 10: A Welsh head-starting project may be proposed and considered where donor eggs have been taken under licence in England or Scotland and subsequently hatched, reared and released in Wales, on the provision that Principle 2 is not violated.

Principle 11: The inclusion of a community and landowner engagement plan to encourage and strengthen capacity for societal involvement through education and awareness of the critical measures that are required to safeguard breeding Curlew in Wales. If a proposal involves translocation, a communication plan should cover both the donor and release areas.

Principle 12: An exit strategy will be an integral part of any head-starting proposal. The decision to discontinue maybe defendable if the design includes indicators of measures of success and intolerable limits. In support of Principles 7 and 8 a costed work plan will include a contingency and a minimum five-year post release monitoring plan after the last cohort of released birds.

23.  In summary, this framework sets out the approach, as considered by Gylfinir Cymru, to aid the development of Curlew head-starting proposals in Wales and as a means to facilitate the best outcome for Curlew recovery in Wales.

24.  This framework will inform the mid-term review of the Wales Action Plan for the Recovery of Curlew, the launch of the UK Curlew Action Plan and the review of the AEWA International Single Species Action for Curlew. This framework will also be kept under review as results from Curlew headstarting projects inform collective knowledge and address identified evidence gaps.

Paper adopted by Gylfinir Cymru on 5th March 2025

BASC, Bannau Brycheiniog National Park, Clwydian Range Protected Landscape, Cofnod, Countryside Alliance, Curlew Country, Elan Valley Trust, FUW, GWCT, Gwent Ornithological Society, National Gamekeepers Association, NFU, National Trust, Natural Resources Wales, Parc Cenedlaethol Eryri, RSPB Cymru, Wildlife Trusts Wales, Welsh Ornithological Society

[1] Head-starting Task and Finish Group – Bethan Beech (NRW), Julian Hughes (RSPB Cymru), Patrick Lindley (NRW), Amanda Perkins (Curlew Country)  and Rachel Taylor (BTO Cymru) .

[2] Where we use the term ‘conservation translocations’ we apply the definition from the IUCN Guidelines for Reintroductions and other Conservation Translocations of “Conservation translocation is the deliberate movement of organisms from one site for release to another. It must be intended to yield a measurable conservation benefit at the levels of a populations, species or ecosystem, and not only provide benefit to translocated individuals.”