Releasing captive-bred Turtle Doves as a conservation measure - YES or NO?

In September 2025, Operation Turtle Dove (OTD) and its partners issued a statement regarding the release of captive-bred Turtle Doves as a conservation measure. OTD stated that they do not support such releases because:

• They do not meet IUCN guidelines or DEFRA’s code for species reintroductions.

• In the UK, the primary factor in their decline is the availability of seed food and nesting

habitat during the breeding season.

• The UK population is considered part of a recovering western Europe population.

• The risks associated with disease transmission and genetic contamination outweigh the

potential benefits.

• A non-migratory resident population could form, presenting an unwarranted level of risk.

We feel that this statement represents a single point of view which has not been discussed; and that the captive breeding and release of Turtle Doves could be a useful tool to support the species’ wider recovery, which should be understood at a time when the species is still

undergoing a significant national decline.

There is an emerging body of evidence that the well-managed release of captive-bred Turtle

Doves can aid population recovery without an “unwarranted level of risk”. The following sections address OTD’s main concerns and outline why the controlled release of captive-bred birds may be both necessary and beneficial.

The reintroduction work currently underway has been criticised for allegedly failing to meet the International Union for Conservation of Nature (IUCN) guidelines for species reintroductions (2013). Broadly, these guidelines require that any reintroduction demonstrates a clear conservation benefit, is based on appropriate founder genetics and behaviour, and is supported by comprehensive risk assessments, welfare and disease management standards, and compliance with both ecological and social feasibility criteria. These projects must be led by a multidisciplinary team with competencies in species ecology, genetics, disease management, habitat restoration, risk assessment, and stakeholder engagement. In practice, these standards have been fully considered and met by the projects involved. Moreover, no specific licence is required to reintroduce Turtle Doves to the UK. Having adhered to the principles outlined in the IUCN guidelines, there is therefore no statutory requirement to obtain a licence under Defra’s Code for Species Reintroductions.

Population Trends and Recovery Potential

The UK population of turtle doves has shown no signs of recovery despite the Western European population rising by 40% between 2021 and 2024 following a temporary hunting ban (RSPB 2025; Carboneras et al., 2025). Data from the British Trust of Ornithology’s (BTO) Breeding Bird Survey (BBS) shows a decline from 3,214 territories in 2006, to 2,092 territories in 2021(Stanbury et al., 2021; Raven et al., 2007). The latest survey (2024) reports a 98% decline since 1995, with “no signs of recovery” in the British population despite “signs of recovery along the Western European Flyway” (Heywood et al,. 2025). This data indicates that the UK population warrants separate consideration from the continental population, a distinction that the OTD statement does not

identify.

Given that releases of captive bred birds have been ongoing since 2020, and that detailed records of marked birds from these populations reflect a clear trend of disappearance from Septemberand emergence in May (T. Lay, communication, Oct 7th, 2025). It may be that the ‘wild’ population reflected in the figures above is in part at least partially supported by the release of captive bred birds.

Given this context, the UK population is at high risk of being significantly lower than the minimum viable population (MVP) thresholds. Factors such as habitat quality, food availability and genetic diversity all influence this risk. The species’ high site fidelity may further exacerbate population fragmentation and increase the risk of genetic bottlenecking. Supplementing the UK population with unrelated bloodstock in quantity could mitigate these risks, strengthen genetic diversity, link fragmented subpopulations and restore the population to areas of the English landscape where it formerly occurred but is currently absent with no evidence of recolonisation being observed.

For a long-distance migratory species with high mortality rates, such supplementation may be critical to ensure its long-term viability in the UK.

Integrating Habitat Restoration and Supplementary Releases

Whilst the availability of high-quality habitat remains a limiting factor in Turtle Dove recovery, an approach that combines the restoration of nesting scrub habitat with food strip provision to the guidelines outlined by OTD; the reinstatement of naturally seed rich environments and a wider use of pigs specifically to improve landscapes for nature will otherwise form mosaics of suitable breeding and foraging areas for Turtle Doves. Where the species no longer exists or is otherwise very rare, these environments could simply remain unoccupied. The release of captive-bred Turtle Doves into restored, ecologically suitable sites could therefore facilitate recolonisation whilst strengthening local populations.

The European Commission’s announcement (April 2025) to resume limited hunting of Turtle

Doves in Western Europe further underscores the urgency of the above. Hunting is a major driver of the species’ decline, yet despite a population increase of 40%, this unwelcome adjustment of policy will now put the species under pressure again. Although the hunting quota is capped at 1.5% of the population (approximately 132,000 birds), weak enforcement could well result in this rising to past historical levels of at least one million birds being killed annually (Vickery et al., 2014). Renewed pressure of this sort would slow the recovery rate of the species’ core population in Spain, limit any growth into northern Europe and thus negatively impact any likelihood of rising natural immigration to the UK.

Relying solely on the forgoing to provide a process of genetic rescue and population increase as a sole strategy could therefore prove very risky.

Addressing Health and Genetic Concerns

OTD’s concerns regarding disease transmission and genetic integrity are valid but can be

effectively mitigated through rigorous management protocols. All participating captive-breeding sites have conducted independent veterinary-led Disease Risk Analyses (DRA) to ensure that biosecurity standards meet or exceed best practice. All birds involved in these projects are housed separately from other species, both captive and wild, with strict quarantine procedures applied to any transferred individuals. Aviaries are vermin-proof, regularly sanitised, and require antiviral foot-dip use before and after entry to maintain biosecurity and minimise pathogen transmission.

Released birds are bred from high-quality, UK-origin stock, with no hybridisation risk from other dove species. They are reared under conditions that promote natural behaviours such as foraging, nest building, and chick rearing. Prior to release, birds are overwintered in controlled environments, ensuring they attain peak physical condition in the year following their hatch to reduce the high levels of juvenile mortality associated with migration. Released flocks have widely demonstrated successful breeding in subsequent seasons and by doing so have contributed directly to local population recruitment. It is hoped that at least some of these birds will return to their overwintering locations in the Southwest of England in years to come in order to reestablish their presence in landscapes where they no longer exist.

Evidence for Migration Among Captive-Bred Birds

The assertion that captive-bred Turtle Doves do not migrate is not supported by current evidence but presumably based rather on the assumption that any migratory instincts have been bred out of captive bred birds or compromised by overwintering birds in their first year. Tracking data from multiple releases since 2020 indicate that captive-bred individuals exhibit natural migratory behaviour consistent with their wild counterparts (T. Lay, communication, Oct 7th, 2025). As of September 2025, one of the satellite-tagged birds from the 2025 release is currently migrating through France and into Northern Spain along the Western European flyway (Sept 2025, ring 1306). These findings demonstrate that migratory behaviour is retained in captive-bred stock regardless of their first winter location or ex-situ ancestry. We acknowledge the need to strengthen this body of

evidence; therefore, a broader satellite-tagging program is planned for future release cohorts to obtain more comprehensive migration data.

Captive-bred Turtle Doves in the UK exhibit consistent pre-migratory behaviour, typically

gathering in small flocks during late summer and early autumn before departing from early

October and remaining absent until the following spring. Reintroduction initiatives have never sought to establish a non-migratory UK population. However, it is important to recognise that overwintering individuals have been recorded in the UK for many decades prior to the release of any captive-bred birds. For example, Payn (1962) documented Turtle Doves spending the winter in Ipswich, Suffolk. Any current understanding of UK Turtle Dove migration is derived from a limited sample of approximately twelve satellite-tracked individuals - representing only 0.57% of the current estimated national population. Whilst this work has provided valuable insights into migration routes and timing, the evidence base remains narrow and cannot be considered representative of the wider population. Historical records demonstrate that behavioural flexibility, including occasional overwintering, is not a recent development but a natural aspect of the species’ ecology. Consequently, conservation conclusions should integrate both recent tracking data and historical context to ensure a balanced and evidence-based understanding of the species’ migratory behaviour.

Conclusions and Recommendations

It is clear over the past thirteen years that Operation Turtle Dove (OTD) has made commendable progress to reverse the decline of Turtle Doves in the UK through the restoration of high-quality breeding habitats and the enhancement of seed availability within these areas. Despite these sustained efforts, national monitoring data indicates that the population continues to decline at an estimated rate of approximately 15% per year. Habitat restoration alone, whilst essential, has not reversed this downward trend. Given the species’ precarious status, the controlled release of healthy captive-bred individuals, combined with habitat management, offers a practical and evidence-based solution to supplement the wild population. As with every reintroduction project that is flexibly managed and responsive to events, this process as it develops further will become

more effective.

To secure the long-term future of Turtle Doves in the UK, conservation strategies must adopt an integrated approach that combines habitat restoration, biosecurity, genetic management andcontrolled releases. Only through these coordinated and collaborative efforts can the UK population be successfully directed towards successful recovery.

As a footnote to the foregoing, it is important to consider that, much like the White Stork Project at Knepp Castle, the public and media response to Turtle Dove reintroduction initiatives - particularly those conducted at Sandringham and in the southwest of England - has been overwhelmingly positive and supportive. Many people have expressed genuine enthusiasm and delight at the return of these birds and the revival of their once-familiar calls across the countryside. While it is recognised that definitive evidence of long-term success for captive breeding and reintroduction in this species is not yet available, such projects undoubtedly represent a valuable conservation tool. They should continue to be developed, monitored, and refined, without prejudice, until their full potential and utility are comprehensively understood.

References

Carboneras, C., Rubio, B., Cruz-Flores, M., Guillemain, M. & Arroyo, B. (2025). Turtle Dove AHMM

Management Scenarios and Technical Recommendation: TFRB 25-03-02, March 2025 Annual

Review (Western and Central-Eastern Flyways). European Turtle Dove Adaptive Harvest

Management Mechanism, European Commission / AEWA Technical Framework. Available

at: https://www.operationturtledove.org/wp-content/uploads/2025/03/TFRB-25-03-02-

Technical-recommendation-2025.pdf (Accessed: 2 November 2025).

RSPB “Hope for Turtle Doves continues to grow”, posted Friday 4th April 2025,

https://www.rspb.org.uk/whats-happening/news/turtle-dove-numbers-start-to-soar

Stanbury, A., Balmer, D., Eaton, M., Grice, P., Khan, N., Orchard, M. & Wotton, S., 2023. The status

of the UK breeding European Turtle Dove Streptopelia turtur population in 2021. Bird Study, 70(1),

pp.1–12.

Raven, M.J., Noble, D.G. & Baillie, S.R., 2007. The Breeding Bird Survey 2006. BTO Research

Report 471. Thetford: British Trust for Ornithology.

Heywood, J.J.N., Massimino, D., Baker, L., Balmer, D.E., Brighton, C.H., Gillings, S., Kelly, L.,

Noble, D.G., Pearce-Higgins, J.W., White, D.M., Woodcock, P., Workman, E. & Wotton, S. 2025.

The Breeding Bird Survey 2024. BTO Research Report 787 British Trust for Ornithology, Thetford

Vickery, J.A., Ewing, S.R., Smith, K.W., Pain, D.J., Bairlein, F., Škorpilová, J. & Gregory, R.D., 2014.

The decline of Afro-Palaearctic migrants and an assessment of potential causes. Ibis, 156(1),

pp.1–22.

Payn, W.H., Birds of Suffolk, 1962.