Summary
With a decline exceeding 30% over three generations, the once-common European Turtle-dove is now considered globally threatened by IUCN. As a legal game species in 10 European countries, the recent International Single Species Action Plan for this species highlighted the need to carry out an assessment of the sustainability of current levels of hunting. In 2013–2014, the Western European population was estimated at 1.3–2.1 million pairs, and the hunting bag in the same region to be 1.1 million birds. Using the Demographic Invariant Method, we assessed whether current levels of hunting harvest within Europe constitute overexploitation of the western flyway European Turtle-dove population. We calculated the maximum growth rate λmax that a population might achieve in the absence of any additive mortality. Then we estimated the potential maximum harvestable population fraction (P) allowed by excess population growth. We explored a wide range of plausible scenarios relating to assumed demographic rates, geographic scope of the flyway and management objectives. λmax was estimated to lie between 1.551 and 1.869. Current levels of hunting along the western flyway are more than double the sustainable fraction (P) under all suitably conservative scenarios, and only fall below this threshold under the most restrictive assumptions. We conclude that current levels of legal hunting along the western flyway are unlikely to be sustainable. Reducing uncertainty associated with assessments of the sustainability of turtle dove hunting will require improved information on (in order of decreasing importance) current levels of hunting, adult survival, age structure and population size.
AimTo describe the population trend for European turtle doves in Spain. To identify favourable and unfavourable areas for the species and to test whether favourability or land use explain spatial variation in abundance change.LocationMainland Spain.MethodsWe used generalized linear models with extensive abundance data to describe population change for the European turtle dove across Spain. We used breeding distribution (presence/absence) data at 100 km2 resolution to model environmental favourability in relation to topo‐climatic and land use variables. Finally, we tested whether land use and favourability explained spatial variation in abundance trends.ResultsThe large Spanish turtle dove population declined by 37% between 1996 and 2018. Favourability was highest in the south, east and north–west of Spain and lowest in the north and at higher altitudes. Abundance trends were more negative in areas of lower environmental favourability and in localities dominated by arboreal habitats such as forests, “dehesas” (open agro‐forestry landscapes with scattered Quercus trees), transitional woodland shrubs or sclerophyllous vegetation (a mixture of sclerophyllous shrubs with some scattered trees). Trends were more positive in localities dominated by complex cultivation (small parcels of mixed crop types, including woody permanent crops like olive, or almond trees or vineyards).Main conclusionsOur study highlights a substantial recent decline in the numerically important turtle dove breeding population in Spain. Declines in abundance were more strongly associated with arboreal (forest and shrub areas) rather than agricultural habitats, highlighting an urgent need for further research into the ecology of this important quarry species in arboreal breeding habitats in southern Europe.
Behaviour has direct links to wing morphology in bird species. Many studies have postulated migration to be one of the most important forces of selection acting on wing morphology, particularly in relation to wing pointedness. Studies in passerines have found that adults have longer and more pointed wings than juveniles, especially in migratory species. We analysed differences in wing morphology between age groups of the European Turtle Dove, a non‐passerine migratory species that benefits from rounded wings during their daily activity, due to its ground‐feeding behaviour and acrobatic flight style. Our results show that adults of this species have longer but more rounded wings than juveniles. This suggests that in this species wing morphology in juveniles is selected to facilitate the first migration, whereas other selection forces (e.g. flight manoeuvrability) are more important after the first moult. These data also explain why juveniles are not as adept at escaping from predators or hunters as adults.
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.
There is a strong relationship between bird wing morphology and flight style. wing shapes are related to manoeuvrability, flight speed, energetic costs during flight and takeoff speed. wing shape differences among species have been frequently studied but differences can also be found within species, between sexes and age groups. Many studies have assessed differences in wing shape between juveniles and adults in different passerine species but little is known about such differences in other bird orders. Performing a Size Constrained Components Analysis (SCCA) and a graphical approximation, we analysed the wing shape of juveniles and adults of eight species, including four passerines and four non-passerines of three different orders. According to a graphical approximation, we observed that wing shape differences between age groups differ among species. In the non-passerine species considered, juveniles have more pointed and concave wings than adults. In contrast, in the four passerine species, juveniles have more rounded wings than adults. However, the results for the C2 axis of SCCA
SummarySurveys based on abundance indices may still be the most cost-efficient method for monitoring programmes that aim to be extensive in time or space, but it is important to take into account differences in activity patterns when combining data collected at different times or from different areas. The European Turtle-dove Streptopelia turtur is a migratory game species that has declined in recent decades and for which identifying efficient and easy-to-apply monitoring schemes to assess changes in abundance is critical for adaptive management. We describe variation in cooing activity to help optimising Turtle Dove abundance monitoring schemes based on point-counts of cooing males. Cooing activity (number of minutes during a ten-minute sampling period when each Turtle Dove was cooing) declined markedly and linearly throughout the morning; in addition, it increased slightly from May to late June, and declined abruptly in the second half of July. The number of different turtle doves detected per ten-minute period significantly declined with time since dawn and was markedly lower after mid-July. Predicted abundance per observation point at dawn on 25 June (from a GLM per region including time and a quadratic relationship with date), correlated tightly (r = 0.95) with the average number of turtle doves detected at each point over multiple visits during the breeding season. Correlation of the latter with the number of birds observed in a single visit during the breeding period was weaker (0.68 ± 0.02). Estimated abundance per point was higher the longer the monitoring bout duration, but five-minute periods allowed detecting c. 80% of birds detected during ten-minute periods. To optimize Turtle Dove abundance monitoring schemes based on abundance indices, we suggest implementing five-minute samplings from mid-May to mid-July during the first three hours after dawn, and transforming the observed values into predicted values considering the date and time at which surveys were made, to obtain comparable results across observation points and years.—Arroyo, B., Moreno-Zarate, L., Fernández-Tizón, M., Sardà-Palomera, F., Bota, G. & Mougeot, F. (2023). Temporal patterns of cooing activity of the European Turtle-dove Streptopelia turtur: optimising monitoring schemes based on abundance indices. Ardeola, 70: 151-168.
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