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Global warming compels larger endothermic animals to adapt either physiologically or behaviourally to avoid thermal stress, especially in tropical ecosystems. Their adaptive responses may however be compromised by other constraints, such as predation risk or starvation. Using an exceptional camera-trap dataset spanning 32 protected areas across southern Africa, we find that intermediate-sized herbivores (100–550 kg) switch activity to hotter times of the day when exposed to predation by lions. These herbivores face a tight window for foraging activity being exposed to nocturnal predation and to heat during the day, suggesting a trade-off between predation risk and thermoregulation mediated by body size. These findings stress the importance of incorporating trophic interactions into climate change predictions. Rising temperatures and predator avoidance constrain herbivore activity on the southern African savannas, forcing them into ever-tightening windows of activity, in a ‘timescape of fear’.

International audience; Niche partitioning studies are essential to understand the mechanisms that allow ecologically similar species to coexist. The Rhone streber (Zingel asper) and the European bullhead (Cottus gobio) are both benthic riverine fishes that consume macroinvertebrates. Both species are protected under European legislature. We focused on trophic niche partitioning between these species, as sufficient access to trophic resources is an important requirement for long-term coexistence. We used a combination of faeces metabarcoding dietary data and prey community data to evaluate dietary overlap, trophic niche variation and dietary preferences. Sampling was performed in three sites along the Durance River (France). Both species consumed a wide range of macroinvertebrates but neither C. gobio nor Z. asper selected the most abundant taxa (chironomids and simuliids). Both species selected larger mayfly (Baetis and Ecdyonurus) and caddisfly (Hydropsyche) taxa. Dietary overlap was generally high but declined when large mayflies were rare. Contrasting secondary prey preferences and trophic niche variation may allow these species to exploit the same preferred mayflies in periods of abundance and to avoid competition during resource scarcity. We propose that dietary partitioning may support the coexistence of these two ecologically similar, benthic predators.

Ambarli, Huseyin/0000-0003-4336-9417; Berger, Anne/0000-0001-5765-8039; Hofer, Heribert/0000-0002-2813-7442; Mengulluoglu, Deniz/0000-0001-5203-4147 WOS: 000447756100027 PubMed: 30377514 Intraspecific variation in key traits of widespread species can be hard to predict, if populations have been very little studied in most of the distribution range. Asian populations of the Eurasian lynx (Lynx lynx), one of the most widespread felids worldwide, are such a case in point. We investigated the diet of Eurasian lynx from feces collected Mediterranean, mixed forest-steppe, and subalpine ecosystems of Turkey. We studied prey preferences and functional responses using prey densities obtained from Random Encounter Modelling. Our analysis revealed that the main prey was brown hare (Lepus europaeus) in all three areas (78%-99% of biomass consumed) and lynx showed a strong preference for brown hare (Chesson's selectivity index, =0.90-0.99). Cannibalism contributed at least 5% in two study areas. The type II functional response of lynx populations in Turkey was similar to the Canada lynx (Lynx canadensis) and daily food intake in grams per lynx matched that of Canada lynx and Iberian lynx (Lynx pardinus), both lagomorph specialists, rather than those of Eurasian lynx from Europe. Therefore, lynx in Turkey may be better described as a lagomorph specialist even though it coexists with ungulate prey. We suggest that ungulate-based foraging ecology of Eurasian lynx in Europe may be a recent adjustment to the availability of high densities of ungulates and cannot be representative for other regions like Turkey. The status of lagomorphs should become an essential component of conservation activities targeted at Eurasian lynx or when using this species as a flagship species for landscape preservation. TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [MAM-NCNP 109G016]; Deutscher Akademischer AustauschdienstDeutscher Akademischer Austausch Dienst (DAAD); Nallihan Turizm Gonulluleri Dernegi; Department of Wildlife, General Directory of Nature Conservation and National Parks of Turkey; The Rufford Foundation [RSGF 11447-1]; Kackar Mountains Sustainable Forest Use and Conservation ProjectMinistry of Forestry & Water Affairs - Turkey TUBITAK, Grant/Award Number: MAM-NCNP 109G016; Deutscher Akademischer Austauschdienst, Grant/Award Number: Doctoral Scholarship; Nallihan Turizm Gonulluleri Dernegi; Department of Wildlife, General Directory of Nature Conservation and National Parks of Turkey; The Rufford Foundation, Grant/Award Number: RSGF 11447-1; Kackar Mountains Sustainable Forest Use and Conservation Project

The gray wolf (Canis lupus) is making a comeback in many habitats in central Europe, where it has been once extirpated. Although densities are still low to moderate, this comeback already raises management concerns. In Anatolia, the gray wolf is one of the most common predator species occupying almost all kind of habitats. Although its numbers were reduced in some parts of the country, it has never been extirpated and lived in sympatry with humans. In this study we investigated, for the first time, the winter diet of wolves in north-west Anatolia, where a multispecies wild ungulate community occurs in sympatry with high density livestock. We selected two geographically close but different habitats (steppe and forest) with different wild prey availabilities and compositions. In both areas ungulate contribution to winter diet biomass was more than 90%. Wolf pack size (four to eight wolves) were higher in the study area where livestock numbers and human disturbance were lower and wild prey were more available. In both study areas, wild boar (Sus scrofa) was the main and most preferred food item (Chesson’s α = 0.7 − 0.9) and it occurred at higher density where wolf pack size was smaller. We could not find a high preference (Chesson’s α = 0.3) and high winter predation pressure on the reintroduced Anatolian wild sheep (Ovis gmelinii anatolica) population that occurs in the study area covered by steppe vegetation. Contribution of livestock and food categories other than wild ungulates to wolf diet stayed low. Wolves can help mitigate human-wildlife conflict regulating wild boar numbers, the most common conflict-causing ungulate species in Anatolia. Instead of managing wolf numbers in human dominated landscapes, we recommend reintroduction of wild ungulates to the areas where they became locally extinct and replaced by livestock.

Prey preferences and feeding-related behaviour of a Central European species of Scydmaeninae, Scydmaenus rufus, were studied under laboratory conditions. Results of prey choice experiments involving 22 identified species of mites belonging to 13 families of Oribatida and two families of Mesostigmata (Uropodina) demonstrated that this beetle feeds mostly on oribatid Schelorib­ atidae (60.38% of prey) and Oppiidae (29.75%) and only occasionally on uropodine Urodinychidae (4.42%) and oribatid Mycobatidae (3.39%); species belonging to Trematuridae (Uropodina), Ceratozetidae and Tectocepheidae (Oribatida) were consumed occasionally. The number of mites consumed per beetle per day was 1.42, and when Oppia nitens was the prey, the entire feeding process took 2.93-5.58 h. Observations revealed that mechanisms for overcoming the prey's defences depended on the body form of the mite. When attacking oribatids, with long and spiny legs, the beetles cut off one or two legs before killing the mite by inserting one mandible into its gnathosomal opening. Flattened and short­legged uropodines were killed in the same way but without cutting off their legs. More legs of the prey were removed during feeding, when the mite was already dead; in Oribatida additional damage included removal of genital plates, whereas the genital structures remained intact in Uropodina. Scydmaenus rufus was able to feed on potentially highly toxic Scheloribatidae, which raises questions about the efficiency of chemical defence in Oribatida.

Prey preferences and feeding-related behaviour of a Central European species of Scydmaeninae, Euconnus pubicollis, were studied under laboratory conditions. Results of prey choice experiments involving 50 species of mites belonging to 24 families of Oribatida and one family of Uropodina demonstrated that beetles feed mostly on ptyctimous Phthiracaridae (over 90% of prey) and only occasionally on Achipteriidae, Chamobatidae, Steganacaridae, Oribatellidae, Ceratozetidae, Euphthiracaridae and Galumnidae. The average number of mites consumed per beetle per day was 0.27 ± 0.07, and the entire feeding process took 2.15-33.7 h and showed a clear linear relationship with prey body length. Observations revealed a previously unknown mechanism for capturing prey in Scydmaeninae in which a droplet of liquid that exudes from the mouth onto the dorsal surface of the predator's mouthparts adheres to the mite's cuticle. Morphological adaptations associated with this strategy include the flattened distal parts of the maxillae, whereas the mandibles play a minor role in capturing prey. Mechanisms for overcoming the prey's defences depended on the body form of the mite. When attacking oribatids that adopt the ptychoid defence (encapsulation) Euconnus opened the prodorsum and pressed the anal and genital plates deeply into the idiosoma, whereas it fed on all other mites by entering their bodies through small gnathosomal or/and genital openings, after breaking off mouthparts or/and genital plates. The preferential feeding of a specialized and locally abundant ant-like stone beetle on one family of Oribatida, documented here for the first time, has implications for the population dynamics of the prey and raises questions about predator-prey co-evolution and costs of an unusually prolonged period spent feeding when at risk from competition and attack by larger predators, typical of the habitats where Scydmaeninae occur.

The distribution of weak and strong non-linear feeding interactions (i.e., functional responses) across the links of complex food webs is critically important for their stability. While empirical advances have unravelled constraints on single-prey functional responses, their validity in the context of complex food webs where most predators have multiple prey remain uncertain. In this study, we present conceptual evidence for the invalidity of strictly density-dependent consumption as the null model in multi-prey experiments. Instead, we employ two-prey functional responses parameterised with allometric scaling relationships of the functional response parameters that were derived from a previous single-prey functional response study as novel null models. Our experiments included predators of different sizes from two taxonomical groups (wolf spiders and ground beetles) simultaneously preying on one small and one large prey species. We define compliance with the null model predictions (based on two independent single-prey functional responses) as passive preferences or passive switching, and deviations from the null model as active preferences or active switching. Our results indicate active and passive preferences for the larger prey by predators that are at least twice the size of the larger prey. Moreover, our approach revealed that active preferences increased significantly with the predator-prey body-mass ratio. Together with prior allometric scaling relationships of functional response parameters, this preference allometry may allow estimating the distribution of functional response parameters across the myriads of interactions in natural ecosystems. peerReviewed