The turtle dove (<em>Streptopelia turtur</em>) in Midelt plain, Morocco: nesting preferences and breeding success <em>versus</em> the impact of predation and agricultural practices

Diversity of feeding habitats and diet composition in the turtle doves Streptopelia turtur to buffer loss and modification of natural habitats during breeding season

Habitats, agricultural practices, and population dynamics of a threatened species: The European turtle dove in France

Simple SummaryThe European turtle dove (Streptopelia turtur) is a migratory species that overwinters in sub-Saharan Africa, migrating to Europe each spring to breed. Over the past four decades, turtle dove populations have declined by as much as 79%, making the species vulnerable to extinction. A major threat to the species is illegal killing (poaching) during its spring migration through the Mediterranean coasts of Europe. According to the international action plan for the conservation of the species, eradicating this threat is key for reversing the European turtle dove population declines by 2028. In this study, we used a network of acoustic sensors to record the gun hunting pressure at known hunting sites in the Ionian Islands, Greece—a known poaching hot-spot—over four spring migrations (2019–2022). Based on the number of gunshots recorded, we estimate that up to 57,095 turtle doves were killed or injured across the region in 2021. We anticipate that these findings will generate the resolve needed among responsible authorities to eradicate the spring migration in the Ionian Islands, and propose the roll out acoustic monitoring grids in additional poaching hot-spots along the migration routes of the turtle dove.The European turtle dove (Streptopelia turtur) is an Afro-Palearctic migrant whose populations have declined by 79% from 1980 to 2014. In 2018, the International Single Species Action Plan for the Turtle Dove (ISSAP) was developed with the goal of enabling, by 2028, an increase in turtle dove numbers along each of the three migration flyways (western, central, eastern). To achieve this, the illegal killing of turtle doves, a critical threat to the species, has to be eradicated. The Ionian Islands off the west coast of Greece lie on the eastern flyway and are considered a major turtle dove poaching hot-spot during spring migration. Quantifying wildlife crime, however, is challenging. In the absence of a reliable protocol for monitoring spring poaching levels, the agencies tasked with tackling the problem have no means of assessing the effectiveness of the anti-poaching measures and adapting them if required. Using passive acoustic monitoring (PAM) methods, we recorded gun hunting intensity at known turtle dove poaching sites during the 2019–2022 spring migrations (2–10 sites/season) with unprecedented spatial and temporal resolution. Based on published gunshot to killed/injured bird ratio for similar species (corroborated with discussions with local hunters) and an estimate of the proportion of hunting sites monitored by our PAM grid (using gunshot detection range estimates from control gunshots), we estimated that in 2021, up to 57,095 turtle doves were killed or injured across five Ionian Islands (Zakynthos, Paxi, Antipaxi, Othoni, and Mathraki). The 2022 estimate was almost half, but it is unclear as to whether the change is due to a decline in poachers or turtle doves. We propose ways of improving confidence in future estimates, and call for a temporary moratorium of autumn turtle dove hunting in Greece—as per ISSAP recommendation—until spring poaching is eradicated and the eastern flyway population shows signs of a full recovery. Finally, we hope our findings will pave the way for the development of PAM grids at turtle dove poaching hot-spots across all migration flyways, contributing to the global conservation of the species.

Capsule Although subject to human disturbance Turtle Doves do nest successfully in these olive and orange orchards. Aim To investigate the breeding ecology of Turtle Doves in a man‐made agricultural habitat in central Morocco. Methods Turtle Dove nests were monitored in orange and olive orchards over three years (2006, 2007 and 2008). Nest abundance, nest location, egg‐laying chronology, clutch size, nest survival rates and breeding success were determined and compared between orchard types. Results The Moroccan population of Turtle Doves start breeding earlier than European populations. Clutch size, nest survival rates and breeding success were similar in orange and olive orchards. Nest location differed between orange and olive trees. Nest densities were 16 nests/ha in olive orchards and 45 nests/ha in orange orchards. Nest success rate averaged 48%. Daily nest survival rates did not vary according to orchard types, year and date. In the two orchards, no nest position variables were significant predictors of nesting success. Conclusion Although highly frequented by people, fruit orchards seem to be suitable breeding habitats for Turtle Doves in this region.

The migratory European Turtle Dove Streptopelia turtur has undergone a 69% decline in population size and a 25% contraction in breeding range in Britain over the last 30 years. An investigation of the breeding ecology of this summer visitor was undertaken in 1998–2000 at two study sites in East Anglia, England. The only previous study of Turtle Dove reproduction in Britain provided pre‐decline data for comparison with the current situation in a modern agricultural environment. Territory sizes ranged from 1.91 to 3.08 ha, were established in areas with scrub, hedges and woodland and contained less cropped land than expected from its availability. The majority of nests were sited 1–3 m above ground level within thorny bushes, particularly Hawthorn Crataegus monogyna. Nests found by radiotelemetry were significantly higher above ground level and were found in greater numbers than expected in woodland and coniferous trees than those found by cold searching, which were lower and found predominantly in hedges and thorny bushes. Turtle Dove nest success rate averaged 53% during incubation and 65% during the nestling stage, so that only 35% of nests successfully produced young. A comparison with data collected during the 1960s showed that Turtle Doves today have a shorter breeding season and consequently produce about half the number of clutches and young per pair than formerly. A simple simulation model suggested that the reduction in productivity alone would lead to a population decline of 17% per annum. This study suggests that the recovery of Turtle Doves in Britain is dependent upon the provision and sympathetic management of nesting and foraging habitats. The current arrangements for set‐aside and agri‐environmental schemes provide the framework for delivering these requirements.

BackgroundThe turtle dove is a migratory species that has suffered a rapid decline principally across its Northern ranges, despite pronounced conservation measures. Consequently, it has been categorized as ‘Near Threatened’ in Europe. Degradation of breeding habitats and a decrease in food resources are listed as principal causes of this decline. Despite its importance, the productivity of the North African population is widely unknown. Here we present the first estimation of the density of the breeding population and the superior reproductively of Streptopelia turtur arenicola in Morocco and entire North Africa.MethodsThis study was carried out for two seasons 2018–2019 in the Saïss plain, central Morocco. Based on previous data, doves were monitored weekly, from early March to late August, in aquatic ecosystems (two dams and one river) and farmlands (cereals and orchards). The breeding population was censused using the “point-count” method, following a walked transect of 5 km in orchards, 7 km in cereal fields, and 3 km along the river. Equally, nests were searched in natural habitats counting riparian trees, forests, and ornamental trees, and in orchards based on the Common Birds Census (CBC) methodology, in which the singing doves, mating pairs, nesting, and/or feeding behavior were the most monitored signs to discover nests. In orchards, nests were searched line-by-line based on the rows of fruit trees. For each recorded nest, we note the breeding chronology, clutch size and incubation period, success and failure factors, dimensions, and vertical placement on trees. To evaluate the predictors of doves’ occurrence, we noted at each site the presence of cereals, water, human disturbance, presence of nesting trees, and predators.Results and DiscussionIn total, 3,580 turtle doves (22.37 birds/ha), including 240 breeding pairs, were documented. Nesting occurred mainly in olive groves, cereals were used for forage, and aquatic ecosystems for water sources. The nesting period lasted from late April to July (last fledglings). All nests were located on olive trees at a height of 225.30 ± 48.87 cm. The clutch size was 1.98 ± 0.13 (laid eggs/built nests), the incubation period lasted 14.16 ± 1.32 days, and the rearing period lasted 16.54 ± 1.76 days. The breeding success among the 240 monitored nests accounted for 73.84% during the nesting phase and 87.42% during the incubation phase; 71.5%% of nestlings have fledged, which is the highest success rate for turtle doves in Europe and Northwest Africa. Clutches were aborted mostly due to predation from snakes (7.5% of nests, 16.12% of eggs, and 5.63% of chicks), nest desertion (9.16% of nests and 5.37% of eggs), and marginally by the destruction of nests through farming activities. These findings are important for conservation plans, to restore turtle doves’ habitats in Europe, where the species is widely declining.

SummaryPost-fledging survival plays a vital role in the dynamics of bird populations and yet is the least-studied avian life-stage. Habitat requirements post-fledging may have important implications for behaviour and survival, especially for declining populations in landscapes that have undergone wide-scale anthropogenic modification, resulting in an altered distribution and composition of habitats. The European Turtle Dove is a widespread but rapidly declining species both within the UK and across Europe. Reduced seed food availability is thought to influence breeding success of this species, but it is not known whether post-fledging survival may also be influenced by seed availability. Here, we use leg-ring radio-tag attachments to monitor post-fledging survival and movements in 15 Turtle Dove nestlings from eight nests monitored during 2014 as part of a wider autecological study. Fledglings remained in close proximity to their nest for three weeks post-tagging, spending more than half their time in the immediate vicinity (within ∼20 m) of the nest. 95% of foraging trips during this period were within 329 m of the nest and fledglings selected seed-rich habitat (semi-natural grassland, low-intensity grazing, fallow and quarries). Fledglings that were heavier and in better body condition at seven days old were more likely to survive for 30 days post-fledging, and the proportion of available seed-rich habitat was a strong predictor of nestling weight and condition at seven days old. Whilst our sample size is modest, this study highlights the crucial role of food availability in juvenile survival, both while adults are feeding nestlings, and to recently fledged young, and the potential for agri-environment schemes providing foraging and nesting habitats in close proximity to provide important benefits.

Studies incorporating the nesting behavior and ecology of parasite disease in the European turtle dove during breeding periods are rare. This research examined nest features and nesting materials in Turtle doves to characterize nest dimensions, build, and incorporate vegetation, mainly aromatic and medicinal plants. In parallel, we estimated the ectoparasite load on chicks to verify an eventual relation between odorant plants and pathogen loads. The study was carried in apple orchards at Okhaja Ait Ayach, Midelt province Morocco, during 2015 and 2016. The obtained results demonstrate that the Turtle dove constructs a medium nest, compared to its body size, using several plant species, including medicinal and aromatic species known for their toxicity against pathogens. The inhibition capacity of nesting materials is reflected in parasite loads since only 8% of chicks were infested with Columbicola columbae and Dermanyssus gallinae. Repellent materials in nests are a successful behavioral strategy for this declining game to protect nestlings against pathogens.

SummaryConservation measures providing food-rich habitats through agri-environment schemes (AES) have the potential to affect the demography and local abundance of species limited by food availability. The European Turtle Dove Streptopelia turtur is one of Europe’s fastest declining birds, with breeding season dietary changes coincident with a reduction in reproductive output suggesting food limitation during breeding. In this study we provided seed-rich habitats at six intervention sites over a 4-year period and tested for impacts of the intervention on breeding success, ranging behaviour and the local abundance of territorial turtle doves. Nesting success and chick biometrics were unrelated to the local availability of seed-rich habitat or to the proximity of intervention plots. Nestling weight was higher close to human habitation consistent with an influence of anthropogenic supplementary food provision. Small home ranges were associated with a high proportion of non-farmed habitats, while large home ranges were more likely to contain seed-rich habitat suggesting that breeding doves were willing to travel further to utilize such habitat where available. Extensively managed grassland and intervention plot fields were selected by foraging turtle doves. A slower temporal decline in the abundance of breeding males on intervention sites probably reflects enhanced habitat suitability during territory settlement. Refining techniques to deliver sources of sown, natural, and supplementary seed that are plentiful, accessible, and parasite-free is likely to be crucial for the conservation of turtle doves.

Simple SummaryThe European turtle dove (Streptopelia turtur) is an important gamebird in south-western Europe, and in some areas a significant proportion of hunting grounds conduct targeted management aiming to increase its breeding densities and hunting opportunities, mainly through food provision. Using harvest data from managed grounds, we estimated the productivity (juvenile/adult ratio), the harvesting levels and the local turtle dove abundance before the hunting season, the latter being compared to the number of birds observed by hunters in food plots. Our research found high values of productivity and significant differences between the estimated abundance and the number of birds observed by hunters, which suggests that in a high proportion of grounds, the latter method may have led to bird overestimation and overharvesting. As managed grounds for the turtle dove may increase the productivity and recruitment of the species, it is crucial to ensure sustainable harvesting through (1) bird monitoring based on transects to calculate abundance and (2) promoting regulations to adjust the number of hunting days.In some regions of Spain, hunting grounds conduct management targeting the European turtle dove (Streptopelia turtur), a commonly hunted species, and unsustainable harvesting levels at these sites have been identified as one of the factors responsible for the species’ decline across its range. In hunting grounds where food was provided, we estimated the local turtle dove abundance before the hunting season, productivity (juvenile/adult ratio) and harvesting levels using harvest data from managed grounds over 4 years (2009, 2015, 2019 and 2020). Compared to previous research, a higher productivity value was found (median 1.67, range 1.24–4.15) in grounds providing more food for a longer period. We calculated that the harvesting rate should not exceed 37% of the estimated turtle dove population size (35–45%). Significant differences were found between the estimated local turtle dove abundance using a removal sampling protocol and the number of birds observed by hunters before the hunting season, which suggests that in a high proportion of grounds, the latter method may have led to bird overestimation and overharvesting. Our research supports the current European Union’s harvest management plan to promote sustainable hunting in grounds where targeted management is conducted.

Trichomonas gallinae is an emerging avian pathogen in the UK and across Europe, leading to population declines in songbirds (especially greenfinches Carduelis chloris) where prevalence is high (Robinson et al., 2010). The parasite is present worldwide, and elsewhere it is typically a pathogen of columbiformes, where it can have population limiting effects (Bunbury et al., 2008). Recent work has shown a high prevalence in UK columbiformes, with the highest rates of infection (86%) in the migratory European Turtle Dove Streptopelia turtur (Lennon et al., 2013). Infected individuals do not necessarily exhibit clinical signs, and carriers without clinical signs may transfer disease organisms between sites during migration (e.g. Rappole et al., 2000) and exhibit reduced survival (Bunbury et al., 2008). European Turtle Doves breeding in the UK are thought to have a non-breeding range spanning much of the Sahel in West Africa, coinciding with the range of several species of Afro-tropical columbids. T. gallinae may be transmitted between infected individuals at shared food and water sources, with this being of particular concern at those sites utilised by large numbers of birds. Such events may be frequent in the Sahel, where birds congregate at scarce water sources in an otherwise arid environment. This leads to concerns that intra- and interspecies transmission rates may be high during the non-breeding period.

Many farmland birds have difficulties finding sufficient food in intensely managed agricultural ecosystems, and in more extensively worked landscapes they are often attracted to human–induced dietary sources. European turtle doves Streptopelia turtur feed on seeds collected on the ground, and are readily attracted to supplementary provided grain at feeding stations. Supplementary feeding is a common management practice on hunting estates around the world. This study was conducted in 40 hunting estates located in central west Spain: 20 sites where supplementary food was provided to attract turtle doves and 20 control sites without feeding stations. At sites with supplemental feeding, the field age ratio was 20% higher and the hunted age ratio was 33% higher than at control sites, indicating a positive effect of the food supplementation of the breeding success around supplemented sites. Both the amount of food provided per day and the amount of time where supplemental food was given (20–120 days) were positively correlated with the field age ratio and, less strongly, with the hunted age ratio. These data suggest that providing extra food can increase the breeding success of this species when the amount provided is sufficiently large and when supplementary food is provided early in the breeding season. However, hunting pressure was also higher at supplemented sites. Future studies should therefore closely monitor the positive and negative effects in order to ascertain which management practices will ensure the viability of these important European turtle dove populations.

A total of 364 Turtle Dove ( Streptopelia turtur) nests were found in the Tadla irrigated area during the 2006–2009 breeding seasons. Of these, 135 were located in orange orchards, 178 in olive orchards and 51 in olive hedgerows. Gaussian generalised linear modelling was used to model the nest height and the nest–trunk distance according to the characteristics of olive and orange trees in the orchards and hedgerows. Tree height and type of plantings had the strongest effects on both nest height ( R2 = 0.67) and nest–trunk distance ( R2 = 0.48). Overall, the same pattern of Turtle Dove nest height was recorded in the three types of plantings, whereas different patterns were noted for the nest–trunk distance. The results provide evidence of non-random patterns of nest placement in olive and orange agro-ecosystems. This game species exhibits adaptive behavioural plasticity in nest placement and appears to be well-adapted to the olive and orange grove conditions in this region. This high adaptability is beneficial to maintaining the species in these artificial habitats. Additional quantitative studies are needed to improve our understanding on the mechanisms driving the choice of nest placement by Turtle Doves in this agricultural man-made environment.

The European Turtle Dove (turtle dove) is globally threatened after undergoing a sustained and generalised decline across its breeding range, with habitat loss suggested as the main driver. Here, we reviewed the scientific literature on habitat associations across its European breeding range, in relation to distribution, breeding numbers, nesting substrates, food and foraging habitats, to identify optimal habitat management measures. Large-scale distribution seemed related to the availability, but not dominance, of woodland landscapes; abundance was generally higher in woodland than on farmland. However, abundance in woodland increased with additional structural diversity and proximity to farmland, and abundance on farmland increased with greater availability of non-farmland features. Nesting occurred most frequently on trees (secondarily on bushes) but we found geographical differences in the type of nesting substrate, with thorny bushes being used more frequently in the north, and open canopy trees in the south. Turtle doves fed on a wide spectrum of seeds with a predominance of wild, particularly early-flowering, plants; but we could not identify a single plant species whose abundance determined turtle dove numbers. Across the distribution range, a shift from wild to cultivated seeds occurred as the season progressed. However, interventions should favour the availability and access to wild seeds. Efficient management interventions depend on the dominant habitat; overall, interventions should seek to augment landscape heterogeneity by increasing the mixing of farmland and woodland. Combined forestry and agricultural policies must provide the right conditions for ecotone species like the Turtle dove.

Although avian nesting success is much studied, little is known about the relative importance of the factors that contribute to annual reproductive success and population limitation, especially for long‐distance migratory songbird species. We combined a field experiment limiting access to nests by mammalian predators with modeling of long‐term field data of American redstarts (Parulidae:Setophaga ruticilla) to assess the effects of multiple environmental variables on breeding success and population limitation. Experimental treatment (baffles placed around tree boles beneath active nests; n = 71) increased nesting success of this single‐brooded species significantly (77 vs 50% in controls; n = 343), demonstrating that scansorial mammals, primarily red squirrelsTamiasciurus hudsonicusand eastern chipmunksTamias striatus, reduced reproductive success. Based on unbaffled nests (n = 466), daily nest survival varied annually, and was positively influenced by May temperature and negatively by sciurid nest predator abundance. Daily nest survival was also influenced positively by June rainfall, and declined with nest age but not with calendar date. Since nest failure was overwhelmingly caused by nest predation, these significant climate and nest‐age effects in our models are indirect, likely influencing nest predator and/or nesting bird behaviors that in turn influenced nest predation. Redstart population density had no effect on nesting success, after accounting for other factors. Annual reproductive success accounted for 34% of the variability in annual population change in redstarts in our study area. Our findings document 1) breeding season population limitation in this species, 2) a link between tree masting and bird population dynamics via mammal population fluctuations, 3) the independent contributions of summer versus winter population processes in a migratory species, and 4) the potential complexity of climate‐biotic interactions.