Ark or park: the need to predict relative effectiveness of ex situ and in situ conservation before attempting captive breeding

1. When species face extinction, captive breeding may be appropriate. However, captive breeding may be unsuccessful, while reducing motivation and resources for in situ conservation and impacting wild source populations. Despite such risks, decisions are generally taken without rigorous evaluation. We develop an individual-based, stochastic population model to evaluate the potential effectiveness of captive-breeding and release programmes, illustrated by the Critically Endangered Ardeotis nigriceps Vigors great Indian bustard. 2. The model was parameterized from a comprehensive review of captive breeding and wild demography of large bustards. To handle uncertainty in the standards of captive-breeding performance that may be achieved we explored four scenarios of programme quality: ‘full-range’ (parameters sampled across the observed range), ‘below-average’, ‘above-average’ and ‘best possible’ (performance observed in exemplary breeding programmes). Results are evaluated examining i) the probability of captive population extirpation within 50 years and ii) numbers of adult females subsequently established in the wild following release, compared to an alternative strategy of in situ conservation without attempting captive breeding. 3. Successful implementation of captive breeding, involving permanent retention of 20 breeding females and release of surplus juveniles, required collection of many wild eggs and consistent ‘best possible’ performance across all aspects of the programme. Under ‘full-range’ and ‘above-average’ scenarios captive population extirpation probabilities were 73–88% % and 23‒51%% respectively, depending on egg collection rates. 4. Although most (73‒92%) ‘best possible’ programmes supported releases, re-establishment of free-living adults also required effective in situ conservation. Incremental implementation of effective conservation measures over the initial 10 years resulted in more free-living adults within 35 years if eggs were left in the wild without attempting captive breeding. 5. Synthesis and applications. For the great Indian bustard Ardeotis nigriceps, rapid implementation of in situ conservation offers a better chance to avoid extinction than captive breeding. Demographic modelling should be used to examine whether captive breeding is likely to bring net benefits to conservation programmes

Orientation of native versus translocated juvenile lesser spotted eagles <i>(Clanga pomarina)</i> on the first autumn migration

The ontogeny of migration routines used by wild birds remains unresolved. Here we investigated the migratory orientation of juvenile lesser spotted eagles (LSE; Clanga pomarina) based on translocation and satellite tracking. Between 2004 and 2016, 85 second-hatched juveniles (Abels) were reared in captivity for release into the declining German population, including 50 birds that were translocated 940 km from Latvia. In 2009, we tracked 12 translocated juveniles, as well as eight native juveniles and nine native adults, to determine how inexperienced birds come to use strategic migration routes. Native juveniles departed around the same time as the adults and six of eight used the eastern flyway around the Mediterranean, which was used by all adults. In contrast, translocated juveniles departed on average 6 days before native LSEs, and five travelled southward and died in the central Mediterranean region. Consequently, fewer translocated juveniles (4/12) than native juveniles (7/8) reached Africa. We conclude that juvenile LSEs have a much better chance of learning the strategic southeastern flyway if they leave at an appropriate time to connect with experienced elders upon departure. It is not clear why translocated juveniles departed so early. Regardless, by the end of the year, most juveniles had perished, whether they were translocated (10/12) or not (6/8). The small number of surviving translocated juveniles thus still represents a significant increase in the annual productivity of the German LSE population in 2009

Amphibians in the diet of European Barn Owls

We present a review of the propensity to eat amphibians in the Barn Owl Tyto alba in Europe. Based on the analysis of 596 published studies reporting 3.32 million prey items identified in pellets, 17 869 amphibians (0.54%) were found. An analysis of 9036 amphibians identified to the species level showed that Barn Owls avoid consuming toxic species, and they are able to capture tree frogs (Hylidae) only rarely. The true frogs (Ranidae) are by far the most frequently captured amphibians followed by spadefoot toads (Pelobatidae) and Parsley frogs (Pelodytidae)

Restricted-area culls and red fox abundance: are effects a matter of time and place?

Predators are often culled to benefit prey, but in many cases this conservation goal is not achieved or results remain unknown. The red fox (Vulpes vulpes) is a predator of global significance, and an invasive species in some regions. Red fox culls intended to benefit prey are often restricted to small areas, and effectiveness is rarely sufficiently evaluated. Given the economic, ecological, social, and welfare issues associated with lethal predator control, there is a strong need to assess the effects of spatiotemporal variation in culling intensity on red fox abundance. We surveyed red fox populations in fragmented forests of south‐western Germany and related indices of local fox abundance to culling data, predicted landscape‐scale fox abundance, and other covariates. We tested whether restricted‐area culling was associated with local reductions in fox abundance, and examined how this relationship changed over time. Local fox abundance was temporarily reduced in spring, following winter culls. However, the effect was minor and fox populations had compensated for the reductions at the latest by autumn. Restricted‐area culling therefore likely failed to sustain effects on fox abundance throughout the period most relevant for conservation (i.e., the reproductive period of the target prey species). To be effective as a conservation tool, culling will therefore require explicit spatiotemporal coordination matching the biology of predators and target prey