Oxycarenus lavaterae is species of Heteroptera and possessing pink blots on corium and distinctive, gleaming membranaceous wings. This appearance could correspond to the definition of a warning color. The design is similar to other coreoid Heteroptera, which live in the Czech Republic; though Oxycarenus lavaterae is a species originating from Mediterranean and quickly spreading north. In Czech Republic it is a new species and predators thus have only short experience with it.The information about chemical protection of Oxycarenus lavaterae is weak and the effect on predators has never been tested. The characteristic behaviour for this species is creating large aggregations, primarily at the time of hibernation. At that time, several thousands of individuals are gathered in apertures or at the surface of tree bark. The aggregation may enhance the warning appearance of this species. The aim of this study was to test the response of bird predators to the adult individuals of Oxycarenus lavaterae. Three species of insectivorous birds differing in the level of foraging and diet specialization was chosen as predator (namely - Great tit (Parus major), Blue tit (Cyanistes caeruleus), Eurasian blackcap (Sylvia atricapilla)). Unmodified individuals of Oxycarenus lavaterae were served to these predators. In the case of the Parus major, the aggregation of Oxycarenus lavaterae (about 100 pieces) was also presented to test the effect of gregarious behavior on the warning signal. This study showed that the Parus major and the Sylvia atricapilla attacked the individual Oxycarenus more often than the Cyanistes caeruleus showing high level of restraint. In experiments with aggregatedOxycarenus lavaterae Parus major attacked them less often than when presented solitarily. However, after eating some Oxycarenus lavaterae, the Parus major showed symptoms of disgust and loss of appetite.

Existing research on the foraging ecology and breeding biology of blue tits (Cyanistes caeruleus) and great tits(Parus major) has mainly concentrated on populations in woodland. However increasing urbanisation means much of the suitable tit habitat is represented by fragmented areas, not large woodlands, and little is known about factors that may affect reproductive success in urban environments. Using General and Generalised Linear Models this study compared reproductive performance in four habitat types with differing levels of habitat modification: the Cambridge University Botanic Garden (CUBG) with an abundance of non-native vegetation and structural fragmentation, two marginal sites with native scrubby vegetation and structural fragmentation and small fragments and large fragments of native woodland. Compositional analysis was used in a study focused on how foraging blue tits used the heterogeneous habitat of the CUBG. Additionally frequency tests were used to compare foraging preferences and foraging behaviours of both species in the CUBG. Productivity was poor in the CUBG compared to all of the other habitats, with great tits appearing to do worse than blue tits, rearing lower quality chicks (significantly lower mean mass than in other habitats). Within the CUBG, positive relationships were found between the abundance of native trees and shrubs and breeding success for both blue tits and great tits. A positive relationship was found between breeding success in blue tits and the abundance of Quercus and Betula. However, habitat and year interactions showed that habitat and reproductive relationships were complicated by annual variation. The two species differed in their foraging preferences in the CUBG; blue tits were observed feeding in native deciduous trees significantly more than in non-native species and had a preference for birch trees over other taxa. Great tits however showed no strong preferences for any of the habitat types. With regards to foraging behaviours, great tits used a wider range of foraging heights and different foraging locations and capture techniques than blue tits. Blue tits were observed‘hanging’ from twigs more frequently, and appeared to be more effective at foraging in the wider variety of plants available in the heterogeneous vegetation of the garden. The data presented in this thesis suggest that blue tits have adopted a better foraging strategy by preferentially choosing native deciduous trees over the abundance of non-natives available in the CUBG. However, despite the apparent better foraging strategy of blue tits, reproductive performance of both species is poor in this urban garden compared to marginal sites and woodland. Urbanisation and the associated loss of optimal tit habitat are likely to continue. It is therefore important to offset urbanisation by the addition of appropriate foraging habitats that are likely to improve reproductive success, such as native trees and shrubs.

Social learning in animals is a frequently studied topic, including birds. Great tits belong to frequently tested passerine species in this context. For this experiment we have chosen another tit species as model birds - adult and juvenile blue tits (Cyanistes caeruleus) and coal tits (Periparus ater). We tested an effect of social information on discrimination learning between palatable and unpalatable prey. Red and green artificial prey items resembling shieldbugs with a mealworm glued underneath were offered to birds. One variant was palatable, the other was unpalatable, soaked in bitter substance. Experimental groups were allowed to observe a pretrained tutor of the same species choosing palatable prey variant and rejecting the unpalatable one. The birds were then subjected to an individual discrimination learning task with simultaneously offered palatable and unpalatable prey items. The control group was not allowed to observe tutor and learned only individually. On the following day, all birds participated in a memory test. We tested if social information has an influence on avoidance learning in juvenile and adult birds of both species. We found that both species of tits were similarly successful in discrimination learning and there was no difference in success in performance between adult...

Avian malaria (Plasmodium spp.) is a popular model system to study the ecology and evolution of parasite-host-vector interactions in the wild. These studies have historically focused mostly on the avian hosts and the malaria parasites. Knowledge regarding the role of vectors is essential to our understanding of these wild systems, but has only very recently started to accumulate. This thesis aimed to contribute to this field by assessing mosquito-malaria-host associations for British mosquitoes and the role of mosquito ecology in shaping these parasite systems in a British woodland study site, using molecular, field ecology and statistical modelling methodologies. From the 12 mosquito species or species groups found, I showed that the Cx.pipiens/torrentium mosquito group is likely to have a major role in avian malaria transmission in Great Britain, while Cs. annulata may be transmitting P. circumflexum. I also demonstrated a positive spatial association between mosquito density per host and avian malaria prevalence, in accordance with theoretical expectations for malaria transmission. Findings here provide evidence that avian malaria transmission in British woodlands is limited mainly to June-August, being preceded by relapse of previous infections or, alternatively, by maintenance of chronic blood parasitaemia through the colder months; this agrees with theoretical expectations and findings elsewhere for temperate climates. This thesis also described local-scale spatial heterogeneity and seasonal variation in adult mosquito abundance within a British woodland where avian malaria is endemic, with differing patterns found between species or species groups. Spatially, variation in adult mosquito abundance was associated with microclimatic and landscape variables such as distances to mosquito breeding sites, microclimate and canopy height; seasonally, variation in mosquito abundance was associated with temperature and rainfall, alongside calendar date. The heterogeneity in mosquito parameters and associations with environmental variables found at a site where avian malaria is endemic highlights the need to anticipate such complexity when trying to understand Plasmodium transmission. By doing so, we further extend the potential of these parasite systems to improve our knowledge regarding the ecology and evolution of parasite-host-vector associations.