The Effect of Heterophoria on the Size of Distance and Near Fusion Vergence.

AIMS: To demonstrate changes in distance and near fusional vergence measured with prism bars, while compensating for present heterophoria using current ametropia correction. In addition, to determine the differences in values of the AC/A ratio determined by the heterophoric (calculation) and gradient methods. MATERIAL AND METHODS: The basic sample includes 19 subjects with a mean age of 21.5 ±3.0 years (min. 18, max. 27). We used the Von Graefe technique for examination of distance and near phoria, and prism bars for examination of fusion vergences measured in prism diopters. We divided the basic cohort into six research sets according to the size of distance and near heterophoria. This was a cohort of patients with distance (D OR) and near orthophoria (N OR), a cohort of patients with distance (D EX) and near exophoria (N EX) and a set of patients with distance (D ES) and near esophoria (N ES). RESULTS: In the case of both groups with exophoria (distance, near) we found a statistically significant result only for negative fusion vergence (NFV). There was a statistically significant increase in NFV in the sample with distance and near exophoria (D EX, p = 0.01 and B EX, p = 0.02, respectively). In our study, we also demonstrated a statistically significant difference (p < 0.001) in the values of the AC/A ratio measured by the gradient and heterophoric methods. The values determined by the gradient method are lower (3.0 ±1.1 pD/D versus 5.8 ±0.9 pD/D) than by the heterophoric method. CONCLUSION: By comparing fusion vergence values in patients with exophoria and orthophoria, we demonstrated that in the presence of distance or near exophoria there is an increase in ipsilateral fusion vergence. In the case of an increase in ipsilateral fusion vergence, the finding was statistically significant both distance and near (p = 0.01 and p = 0.02, respectively). By contrast, we were unable to prove this fact in the group of patients with esophoria. In our study, we also demonstrated a statistically significant difference (p < 0.001) in the values of the AC/A ratio measured by the gradient and heterophoric methods. The values determined by the gradient method are lower (3.0 ±1.1 pD/D versus 5.8 ±0.9 pD/D) than by the heterophoric method.

Lifestyle factors associated with age-related macular degeneration: Case-control study.

BACKGROUND: Age-related macular degeneration (AMD) is one of the major causes of vision loss in individuals aged ≥ 65 years in developed countries. This study aimed to determine the associations between modifiable risk factors and AMD. This is the first study describing the relationship between lifestyle factors and AMD in the Czech Republic. METHODS: In this cross-sectional case-control study, 93 AMD cases and 58 controls without AMD and cataract were included. All participants were examined by Optical coherence tomography at the Clinic of Eye Treatment at the University Hospital Brno. Data were collected using a pre-tested self-report questionnaire in a face-to-face interview. RESULTS: We found significant associations between those who were living in the city (OR 95% CI: 2.19 (1.0-4.6); p = 0,039), with a positive family history of AMD (OR 95% CI: 12.75 (1.6-98.6); p = 0,015), exposure to cigarette smoke (OR 95% CI: 2.72 (1.4-5.4); p = 0,004), and daily exposure to passive smoking (OR 95% CI: 2.29 (1.0-5.1); p = 0,045) and AMD. In men, we found significant associations between daily sunlight exposure (OR 95% CI: 2.98 (1.0-8.5); p = 0,041), short or long sleep duration (OR 95% CI: 3.98 (1.2-13.2); p = 0,024) and AMD. Men daily exposed to sunlight were at a 2.98 times higher risk of AMD than men with less than daily sunlight exposure. Men with short or long sleep duration (< 6 and > 8 h) were at a 3.98 times higher risk of AMD than men with recommended sleep duration of 6-8 h. CONCLUSIONS: An increased risk of AMD was observed for living in the city, family history of AMD, exposure to cigarette smoke, and daily exposure to passive smoking. Increased risk of AMD was observed for daily sunlight exposure and short or long sleep duration; however, only in men.

Application of solid-phase microextraction arrows for characterizing volatile organic compounds from 3D printing of acrylonitrile-styrene-acrylate filament.

3D printing is an extensively used manufacturing technique that can pose specific health concerns due to the emission of volatile organic compounds (VOC). Herein, a detailed characterization of 3D printing-related VOC using solid-phase microextraction-gas chromatography/mass spectrometry (SPME-GC/MS) is described for the first time. The VOC were extracted in dynamic mode during the printing from the acrylonitrile-styrene-acrylate filament in an environmental chamber. The effect of extraction time on the extraction efficiency of 16 main VOC was studied for four different commercial SPME arrows. The volatile and semivolatile compounds were the most effectively extracted by carbon wide range-containing and polydimethyl siloxane arrows, respectively. The differences in extraction efficiency between arrows were further correlated to the molecular volume, octanol-water partition coefficient, and vapour pressure of observed VOC. The repeatability of SPME arrows towards the main VOC was assessed from static mode measurements of filament in headspace vials. In addition, we performed a group analysis of 57 VOC classified into 15 categories according to their chemical structure. Divinylbenzene-polydimethyl siloxane arrow turned out to be a good compromise between the total extracted amount and its distribution among tested VOC. Thus, this arrow was used to demonstrate the usefulness of SPME for the qualification of VOC emitted during printing in a real-life environment. A presented methodology can serve as a fast and reliable method for the qualification and semi-quantification of 3D printing-related VOC.

Dietary habits and dietary nutrient intake in patients with age-related macular degeneration: A case-control study.

OBJECTIVES: Age-related macular degeneration (AMD) is the leading cause of irreversible blindness among older adults in developed countries. Although many risk factors are known, the pathogenesis of AMD is still unclear. However, oxidative stress probably plays a vital role in the process of AMD. The increasing prevalence of AMD, risk of vision loss, limited treatment of dry form, expensive treatment of wet form, and decreased quality of life are factors that lead to considering modifiable risk factors of AMD, such as nutrition. This is the first study describing the relationship between dietary habits, dietary nutrient intake and AMD in the Czech Republic. METHODS: In this research, a total of 93 cases with AMD and 58 controls without AMD and cataracts participated. All participants were ophthalmologically examined at the Clinic of Eye Treatments at the University Hospital Brno. Data were collected using a pre-tested self-report questionnaire in a face-to-face interview. Food consumption frequency was assessed by an 18-item semiquantitative food-frequency questionnaire (FFQ). Dietary nutrient intakes were calculated from a 24-hour recall. RESULTS: Patients with AMD compared with controls had significantly higher consumption of legumes and lower consumption of meat products, salt and salty products. In men, we found statistically significant differences in alcohol consumption. The case group consumed alcoholic beverages more frequently (median: 2 times a week) than the control group (median: 1-3 times a month). No differences in alcohol consumption were found in women. In comparison to the case group, the control group had a significantly higher dietary intake of energy (5,783.8 vs. 4,849.3 kJ/day; p = 0.002), proteins (65.3 vs. 52.3 g/day; p = 0.002), fats (57.6 vs. 49.4 g/day; p = 0.046), saturated fatty acids (21.7 vs. 18.9 g/day; p = 0.026), carbohydrates (150.4 vs. 127.1 g/day; p = 0.017), dietary fibre (13.2 vs. 11.3 g/day; p = 0.044), vitamin B2 (1.0 vs. 0.9 mg/day; p = 0.029), vitamin B3 (13.9 vs. 10.0 mg/day; p = 0.011), pantothenic acid (3.5 vs. 2.8 mg/day; p = 0.001), vitamin B6 (1.3 vs. 1.0 mg/day; p = 0.001), potassium (1,656.5 vs. 1,418.0 mg/day; p = 0.022), phosphorus (845.4 vs. 718.7 mg/day; p = 0.020), magnesium (176.5 vs. 143.0 mg/day; p = 0.012), copper (1.0 vs. 0.8 mg/day; p = 0.011), and zinc (7.1 vs. 6.1 mg/day; p = 0.012) counted from a 24-hour recall. CONCLUSIONS: According to FFQ, dietary habits in the patients with AMD and controls were similar. In men from the case group, we found statistically significant higher alcohol consumption. According to a 24-hour recall, the controls achieved recommended dietary intakes rather than cases. In comparison to the case group, the control group had a significantly higher dietary intake of energy, proteins, fats, saturated fatty acids, carbohydrates, dietary fibre, vitamin B2, vitamin B3, pantothenic acid, vitamin B6, potassium, phosphorus, magnesium, copper, and zinc.

Red-backed shrike (Lanius collurio) versus common cuckoo (Cuculus canorus): An example of ineffective cuckoo-hawk mimicry.

The red-backed shrike (Lanius collurio) used to be one of the most common hosts of the common cuckoo (Cuculus canorus). Nevertheless, during the last 30 years, there is increasing evidence from Central Europe that the occurrence of cuckoo chicks in shrike nests has become scarcer, and that in some locations they have disappeared completely. Multiple hypotheses have been suggested to explain this abandonment. Here, we test the hypothesis that shrikes vigorously attack adult cuckoos, potentially resulting in ineffective parasitism. Adult common cuckoos resemble in appearance the Eurasian sparrowhawk (Accipiter nisus), a common predator of small passerines. One hypothesis presumes that the cuckoo has evolved this mimicry to avoid attack by small passerines when searching for their nests. Our results show that shrikes defending their nests attacked cuckoos very vigorously, more often, and more intensively than they did sparrowhawks. In the presence of a sparrowhawk dummy, parent shrikes only produced alarm calls and flew over the dummy. This suggests that cuckoo-hawk mimicry is ineffective in the case of shrikes and that they attack them much more often than they do any other presented intruder. Therefore, this activity could possibly result in the abandonment of shrikes as potential hosts for cuckoos.

Cowards or clever guys: an alternative nest defence strategy employed by shrikes against magpies.

Red-backed shrikes (Lanius collurio) show a substantial variability in their nest defence behaviour, which usually follows the rules of optimal parental behaviour, vigorously attacking egg and chick predators and only passively guarding against harmless animals. Nevertheless, shrikes hesitate to attack the Eurasian magpie (Pica pica), which specializes in plundering passerine nests. Our previous studies have suggested that this behaviour may be the result of an alternative defence strategy, relying on nest crypsis. To test this hypothesis, at the shrike nests, we presented a magpie dummy associated with playbacks drawing the predators' attention to the presence of the nest. We predicted that the presentation of a magpie dummy associated with shrike alarm calls moves the parents to action, causing them to chase the magpie away from the nest. We showed that the presence of a magpie dummy associated with shrike alarm calls elicits a significantly more active response in shrike parents compared to a magpie dummy associated with neutral song. Parents actively moved around the dummy and produced alarm calls; nevertheless, most of the tested pairs hesitated to attack the dummy. We may conclude that the low nest defence activity of shrike parents towards magpie dummy was partly the result of an alternative strategy, which may be cancelled out by alerting the predator to the location of the nest; nevertheless, shrikes seem to be afraid of the magpie and hesitate to attack it physically.

Influence of Flux and Related Factors on Intermetallic Layer Growth within SAC305 Solder Joints.

Flux contained in solder paste significantly affects the process of solder joint creation during reflow soldering, including the creation of an intermetallic layer (IML). This work investigates the dependence of intermetallic layer thickness on ROL0/ROL1 flux classification, glossy or matt solder mask, and OSP/HASL/ENIG soldering pad surface finish. Two original SAC305 solder pastes differing only in the used flux were chosen for the experiment. The influence of multiple reflows was also observed. The intermetallic layer thicknesses were obtained by the image analysis of micro-section images. The flux type proved to have a significant impact on the intermetallic layer thickness. The solder paste with ROL1 caused an increase in IML thickness by up to 40% in comparison to an identical paste with ROL0 flux. Furthermore, doubling the roughness of the solder mask has increased the resulting IML thickness by 37% at HASL surface finish and by an average of 22%.

Mathematical Modelling of Temperature Distribution in Selected Parts of FFF Printer during 3D Printing Process.

This work presented an FEM (finite element method) mathematical model that describes the temperature distribution in different parts of a 3D printer based on additive manufacturing process using filament extrusion during its operation. Variation in properties also originate from inconsistent choices of process parameters employed by individual manufacturers. Therefore, a mathematical model that calculates temperature changes in the filament (and the resulting print) during an FFF (fused filament fabrication) process was deemed useful, as it can estimate otherwise immeasurable properties (such as the internal temperature of the filament during the printing). Two variants of the model (both static and dynamic) were presented in this work. They can provide the user with the material's thermal history during the print. Such knowledge may be used in further analyses of the resulting prints. Thanks to the dynamic model, the cooling of the material on the printing bed can be traced for various printing speeds. Both variants simulate the printing of a PLA (Polylactic acid) filament with the nozzle temperature of 220 °C, bed temperature of 60 °C, and printing speed of 5, 10, and 15 m/s, respectively.

Investigation of Impacts on Printed Circuit Board Laminated Composites Caused by Surface Finish Application.

The purpose of this study was to compare the strength of the bond between resin and glass cloth for various composites (laminates) and its dependence on utilized soldering pad surface finishes. Moreover, the impact of surface finish application on the thermomechanical properties of the composites was evaluated. Three different laminates with various thermal endurances were included in the study. Soldering pads were covered with OSP and HASL surface finishes. The strength of the cohesion of the resin upper layer was examined utilizing a newly established method designed for pulling tests. Experiments studying the bond strength were performed at a selection of laminate temperatures. Changes in thermomechanical behavior were observed by thermomechanical and dynamic mechanical analyses. The results confirmed the influence of the type of laminate and used surface finish on bond strength. In particular, permanent polymer degradation caused by thermal shock during HASL application was observed in the least thermally resistant laminate. A response to thermal shock was detected in thermomechanical properties of other laminates as well, but it does not seem to be permanent.

Predation by avian predators may have initiated the evolution of myrmecomorph spiders.

Myrmecomorphy is a strategy utilized by a variety of species, among which spiders are the most common. It is supposed that myrmecomorphy tends to be selected by predator avoidance of preying on ants rather than by blind ant workers. To date, this hypothesis has been tested mainly on invertebrate predators (mantises and spiders). We are the first to test whether an imperfect myrmecomorph spider (Phrurolithus festivus) gains protection against avian predators (wild adult great tits-Parus major) through its appearance. In a set of preferential trials, we showed that the ant model and the myrmecomorph spider are equally well protected against attack, though the attacked myrmecomorphs are usually eaten. This suggests that the mimicry of the myrmecomorph spiders is effective against avian predators and works in a Batesian manner. In this study, we have provided evidence toward the evolution of myrmecomorphy in response to selective pressure elicited by visually-oriented predators like birds.

Untrained birds' ability to recognise predators with changed body size and colouration in a field experiment.

BACKGROUND: During recognition process, multiple parameters of the encountered stimulus may play a role. Previous studies with wild birds identified the importance of several salient features (e.g., eyes, beak, prominent elements of colouration) which birds use to recognise other bird species, such as predators or nest parasites. In the present study, we observed the responses of passerines visiting winter feeders to stimuli in the form of dummies of Eurasian sparrowhawk which were modified in body size and/or colouration but always carried the salient features of raptors (hooked beak, talons) and one species-specific feature of the sparrowhawk (yellow eyes). In the vicinity of a feeder, we placed a dummy of an unmodified sparrowhawk, life-sized sparrowhawk with pigeon, great tit, or robin colouration, a small, great tit-sized sparrowhawk dummy with unmodified or pigeon colouration, or an unmodified pigeon dummy, which functioned as a harmless control. Then we measured how it affected the number of visits. RESULTS: We found that birds were less afraid of small dummies regardless of their colouration than they were of life-sized raptor dummies or even the pigeon dummy. This contrasts with the results of a previous laboratory experiment where great tits' reaction to small dummies was comparably fearful to their response to life-size dummies. In our experiment, birds were also not afraid of life-sized dummies with modified colouration except for a robin-coloured dummy, which caused an equally significant fear reaction as an unmodified sparrowhawk dummy. It is likely that this dummy resembled the colouration of a male sparrowhawk closely enough to cause this effect. CONCLUSIONS: Based on our observations, we conclude that birds use contextual features to evaluate the size of other birds. Distance and familiar reference points seem to play an important part in this process.

A kestrel without hooked beak and talons is not a kestrel for the red-backed shrike (Lanius collurio).

Birds are strongly motivated to recognize various predators to secure survival and reproductive success. Thus, predator recognition provides a useful tool for the investigation of the process of discrimination and categorization in non-trained animals. The most important role in this process is usually attributed to the prominent unique features shared by all members within the wider category of predators (sharp teeth or beaks, claws, talons and conspicuous eyes). However, birds are also able to discriminate between particular predator species according to their species-specific features (based mainly on colouration). We manipulated general raptor salient features (hooked beak, talons with claws and eyes with supraorbital ridges) and/or species-specific plumage colouration on the dummy of a Eurasian kestrel (Falco tinnunculus) to investigate their importance in the recognition process of the red-backed shrikes (Lanius collurio) during nest defence. We showed that the presence of general raptor salient features is necessary for the recognition of a predator. The kestrel dummy with natural species-specific colouration with altered raptor salient features was treated by shrikes as a harmless bird. Nevertheless, pronounced changes in colouration also prevented successful recognition of the dummy as a kestrel, even when raptor salient features of a raptor were present.

Object categorization by wild-ranging birds in nest defence.

Despite object categorization being an important ability for the survival of wild animals, the principles behind this ability have been only scarcely studied using wild-ranging, untrained animals. Reiterating our previous study undertaken with wild-ranging titmice on winter feeders (Nováková et al. Behav Process 143:7-12, 2017), we aimed to test two hypotheses of object recognition proposed by animal psychology studies: the particulate feature theory and recognition by components in the methodological paradigm of nest defence. We tested whether the parents of the red-backed shrike (Lanius collurio) recognize the dummies of the common kestrel (Falco tinnunculus), which is a potential predator of large chicks or fledglings, as a threat in case when their body parts are scrambled. The kestrel dummy was presented with the head at the top, in the middle, and at the bottom of the body. We showed that the shrikes did not consider dummies of a kestrel with an inappropriately placed head as a threat to the nest and attacked it equally scarcely as the harmless control. These results support the theory of recognition by components, presuming that the mutual position of body parts is essential for appropriate recognition of the object. When the body parts were scrambled, most of shrikes were not able to identify the kestrel in such an object despite all local features (eye, beak, colouration, and claws) being present. Nevertheless, shrikes did not consider the scrambled dummies as completely harmless, because they fed their chicks in their presence significantly less often than in the presence of harmless control.

Haloperidol affects coupling between QT and RR intervals in guinea pig isolated heart.

Prolonged QT interval is an independent risk factor for development of ventricular arrhythmias. Haloperidol is one of the drugs inducing QT prolongation. Previous studies showed that haloperidol affects not only QT duration but also heart rate (RR interval). The present work focused on relationship between QT and RR and its changes under acute and chronic haloperidol administration. The study included 14 male guinea pigs divided into control and haloperidol-treated group. After 21-days administration of haloperidol or vehiculum, electrograms in isolated hearts were recorded. QT/RR and dQT/dRR coupling were calculated. Chronic haloperidol administration significantly decreases the coupling between QT and RR. Acute haloperidol exposure significantly decreases the dQT/dRR coupling in both treated and untreated guinea pig hearts. Flatter QT/RR relationship reveals a lack of QT adaptation to increased heart rate. It should be emphasized that in such situation ECG recording will not show significant QT prolongation evaluated according to clinical rules. However, if QT interval does not adapt to increased heart rate sufficiently, the risk of ventricular arrhythmias may be increased despite practically normal QT interval length. The results are supported by findings in biochemical analyses, which proved eligibility of the used model.

Effect of the exploratory behaviour on a bird's ability to categorize a predator.

Despite the encountering of a predator always being extremely threatening, there is a significant plasticity among individuals in how they cope with such a situation. In laboratory experiments with wild-caught great tits (Parus major), we tested the effect of exploratory behaviour (performance in novel food, object and environment test, startle test) on the ability of individual birds to assess the threat represented by a predator. We presented a wooden dummy of the European sparrowhawk (Accipiter nisus), an extremely dangerous predator, and its visual modifications (chimeras), changing the beak or head to be non-threatening (those of a pigeon - Columba livia f. domestica). We showed that the differences between 'slow' and 'fast explorers' are not very distinct, but that 'slow explorers' generally tended to be more cautious in the presence of an unmodified sparrowhawk dummy, while the 'fast explorers' tended to observe the dummy. On the contrary, 'slow explorers' tended to treat both chimaeras (and the pigeon dummy as well) as less-threatening than 'fast explorers'. Since 'slow explorers' are usually considered to be more sensitive to environmental cues, it came as no surprise that most of them correctly assessed the unmodified sparrowhawk dummy as threatening, while they probably subjected the chimeras to a detailed inspection and were not confused by the presence of sparrowhawk features and assessed them as non-threatening.

Object categorization by wild ranging birds-Winter feeder experiments.

The object categorization is only scarcely studied using untrained wild ranging animals and relevant stimuli. We tested the importance of the spatial position of features salient for categorization of a predator using wild ranging birds (titmice) visiting a winter feeder. As a relevant stimulus we used a dummy of a raptor, the European sparrowhawk (Accipiter nisus), placed at the feeding location. This dummy was designed to be dismantled into three parts and rearranged with the head in the correct position, in the middle or at the bottom of the dummy. When the birds had the option of visiting an alternative feeder with a dummy pigeon, they preferred this option to visiting the feeder with the dummy sparrowhawk with the head in any of the three positions. When the birds had the option of visiting an alternative feeder with an un-rearranged dummy sparrowhawk, they visited both feeders equally often, and very scarcely. This suggests that the titmice considered all of the sparrowhawk modifications as being dangerous, and equally dangerous as the un-rearranged sparrowhawk. The position of the head was not the most important cue for categorization. The presence of the key features was probably sufficient for categorization, and their mutual spatial position was of lower importance.

Ventricular dyssynchrony assessment using ultra-high frequency ECG technique.

PURPOSE: The aim of this proof-of-concept study is to introduce new high-dynamic ECG technique with potential to detect temporal-spatial distribution of ventricular electrical depolarization and to assess the level of ventricular dyssynchrony. METHODS: 5-kHz 12-lead ECG data was collected. The amplitude envelopes of the QRS were computed in an ultra-high frequency band of 500-1000 Hz and were averaged (UHFQRS). UHFQRS V lead maps were compiled, and numerical descriptor identifying ventricular dyssynchrony (UHFDYS) was detected. RESULTS: An electrical UHFQRS maps describe the ventricular dyssynchrony distribution in resolution of milliseconds and correlate with strain rate results obtained by speckle tracking echocardiography. The effect of biventricular stimulation is demonstrated by the UHFQRS morphology and by the UHFDYS descriptor in selected examples. CONCLUSIONS: UHFQRS offers a new and simple technique for assessing electrical activation patterns in ventricular dyssynchrony with a temporal-spatial resolution that cannot be obtained by processing standard surface ECG. The main clinical potential of UHFQRS lies in the identification of differences in electrical activation among CRT candidates and detection of improvements in electrical synchrony in patients with biventricular pacing.

The ability of lizards to identify an artificial Batesian mimic.

Birds are usually considered the main predators shaping the evolution of aposematic signals and mimicry. Nevertheless, some lizards also represent predominately visually oriented predators, so they may also play an important role in the evolution of aposematism. Despite this fact, experimental evidence regarding the responses of lizards to aposematic prey is very poor compared to such evidence in birds. Lizards possess very similar sensory and cognitive abilities to those of birds and their response to aposematic prey may thus be affected by very similar processes. We investigated the reactions of a lizard, the Gran Canaria skink (Chalcides sexlineatus), to an aposematic prey and its artificial Batesian mimic. Further, we attempted to ascertain whether the lizard's food experience has any effect on its ability to recognise an artificial Batesian mimic, by using two groups of predators differing in their prior experience with the prey from which the mimic was fabricated. The red firebug (Pyrrhocoris apterus) was used as an aposematic model, and the Guyana spotted roach (Blaptica dubia) as the palatable prey from which the mimic was fabricated. The appearance of the roach was modified by a paper sticker placed on its back. The skinks showed a strong aversion towards the model firebug. They also avoided attacking the cockroaches with the firebug pattern sticker. This suggests that a visual rather than a chemical signal is responsible for this aversion. The protection provided by the firebug sticker was even effective when the skinks were familiar with unmodified cockroaches (previous food experience).

Do predator energy demands or previous exposure influence protection by aposematic coloration of prey?

Growing evidence exists that aposematic and toxic prey may be included in a predator's diet when the predator experiences physiological stress. The tree sparrow Passer montanus is known to have a significant portion of aposematic and toxic ladybirds in its natural diet. Here, we present experiments testing the attack and eating rate of the tree sparrow toward the invasive aposematic harlequin ladybird Harmonia axyridis. We wondered whether the sparrow's ability to prey on native ladybirds predisposes them to also prey on harlequin ladybirds. We compared the attack and eating rates of tree sparrows of particular age and/or experience classes to test for any changes during ontogeny (hand-reared × young wild-caught ×adult wild-caught) and with differing perceived levels of physiological stress (summer adult × winter adult). Winter adult tree sparrows commonly attacked and ate the offered ladybirds with no evidence of disgust or metabolic difficulties after ingestion. Naïve and wild immature tree sparrows attacked the ladybirds but hesitated to eat them. Adult tree sparrows caught in the summer avoided attacking the ladybirds. These results suggest that tree sparrows are able to cope with chemicals ingested along with the ladybirds. This pre-adaptation enables them to include ladybirds in their diet; though they commonly do this only in times of shortage in insect availability (winter). Young sparrows showed avoidance toward the chemical protection of the ladybirds.

Responses of urban crows to con- and hetero-specific alarm calls in predator and non-predator zoo enclosures.

Urban animals and birds in particular are able to cope with diverse novel threats in a city environment such as avoiding novel, unfamiliar predators. Predator avoidance often includes alarm signals that can be used also by hetero-specifics, which is mainly the case in mixed-species flocks. It can also occur when species do not form flocks but co-occur together. In this study we tested whether urban crows use alarm calls of conspecifics and hetero-specifics (jackdaws, Corvus monedula) differently in a predator and a non-predator context with partly novel and unfamiliar zoo animal species. Birds were tested at the Tiergarten Schönbrunn in the city of Vienna by playing back con- and hetero-specific alarm calls and control stimuli (great tit song and no stimuli) at predator (wolf, polar bear) and non-predator (eland antelope and cranes, peccaries) enclosures. We recorded responses of crows as the percentage of birds flying away after hearing the playback (out of those present before the playback) and as the number of vocalizations given by the present birds. A significantly higher percentage of crows flew away after hearing either con- or hetero-specific alarm calls, but it did not significantly differ between the predator and the non-predator context. Crows treated jackdaw calls just as crow calls, indicating that they make proper use of hetero-specific alarm calls. Responding similarly in both contexts may suggest that the crows were uncertain about the threat a particular zoo animal represents and were generally cautious. In the predator context, however, a high percentage of crows also flew away upon hearing the great tit control song which suggests that they may still evaluate those species which occasionally killed crows as more dangerous and respond to any conspicuous sound.