Microbial digestion in the herbivorous lizard Uromastyx aegyptius (Agamidae)

The utilization of a diet rich in plant cell walls was studied in a large, desert-dwelling, herbivorous lizard, Uromastyx aegyptius (Agamidae). The diet eaten by U. aegyptius in spring in the 'Arava Valley, Israel, consisted almost entirely of leaves and fruits of short-lived annual plant species. The leaves contained only moderate levels of fibre compared with grasses and tree leaves, but those fruits eaten were markedly higher in fibre and lignin. All items had notably high contents of ash.
Following oral doses of [¹⁴C] cellulose, ¹⁴CO₂ was detected in respired air from U. aegyptius , demonstrating that the cellulose was digested and that the lizards gained oxidative energy from cellulose degradation. The hind gut was the principal site of microbial activity and the apparent digestibility of the cell-wall fraction was 69%. Similarly, the caecum/proximal colon had the highest concentrations of SCFA (76–120 mM).
The mean rate of SCFA production at 40 C in vitro was 31 mmol/1 h^-1. Assuming that this is representative of daily production rate, 69 kJ/kg d^-1 would be made available to the animal. This is 47% of the mean digestible energy intake estimated in free-living animals. Microbial fermentation contributes an important part of the energy budget of U. aegyptius but the effects of variation in body temperature on digestion and fermentation need further consideration.     

Cooperative problem solving in rooks (Corvus frugilegus)

Recent work has shown that captive rooks, like chimpanzees and other primates, develop cooperative alliances with their conspecifics. Furthermore, the pressures hypothesized to have favoured social intelligence in primates also apply to corvids. We tested cooperative problem-solving in rooks to compare their performance and cognition with primates. Without training, eight rooks quickly solved a problem in which two individuals had to pull both ends of a string simultaneously in order to pull in a food platform. Similar to chimpanzees and capuchin monkeys, performance was better when within-dyad tolerance levels were higher. In contrast to chimpanzees, rooks did not delay acting on the apparatus while their partner gained access to the test room. Furthermore, given a choice between an apparatus that could be operated individually over one that required the action of two individuals, four out of six individuals showed no preference. These results may indicate that cooperation in chimpanzees is underpinned by more complex cognitive processes than that in rooks. Such a difference may arise from the fact that while both chimpanzees and rooks form cooperative alliances, chimpanzees, but not rooks, live in a variable social network made up of competitive and cooperative relationships.     

Effects of temperature and hypercapnia on ventilation and breathing pattern in the lizard Uromastyx aegyptius microlepis

In most reptiles, the ventilatory response to hypercapnia consists of large increases in tidal volume (V(T)), whereas the effects on breathing frequency (f(R)) are more variable. The increased V(T) seems to arise from direct inhibition of pulmonary stretch receptors. Most reptiles also exhibit a transitory increase in ventilation upon removal of CO(2) and this post-hypercapnic hyperpnea may consist of changes in both V(T) and f(R). While it is well established that increased body temperature augments the ventilatory response to hypercapnia, the effects of temperature on the post-hypercapnic hyperpnea is less described. In the present study, we characterise the ventilatory response of the agamid lizard Uromastyx aegyptius to hypercapnia and upon the return to air at 25 and 35 degrees C. At both temperatures, hypercapnia caused large increases in V(T) and small reductions in f(R), that were most pronounced at the higher temperature. The post-hypercapnic hyperpnea, which mainly consisted of increased f(R), was numerically larger at 35 compared to 25 degrees C. However, when expressed as a proportion of the levels of ventilation reached during steady-state hypercapnia, the post-hypercapnic hyperpnea was largest at 25 degrees C. Some individuals exhibited buccal pumping where each expiratory thoracic breath was followed by numerous small forced inhalations caused by contractions of the buccal cavity. This breathing pattern was most pronounced during severe hypercapnia and particularly evident during the post-hypercapnic hyperpnea.     

Occurrence of the Brown-necked Raven,Corvus ruficollis,at Cizre in Eastern Turkey

An adult male of Maynard's Longnose Sand Snake (Lytorhynchus maynardi) was collected on 24 July 2009 from the east of Sistan and Baluchistan Province in south-eastern Iran. The new locality is the westernmost record of this species in western Asia, and the first record for 42 years from Iran. Information on the geographic distribution of the genus Lytorhynchus Peters, 1863 in Iran, comparative morphology and some ecological data are presented here.     

Social dominance in captive jackdaws (Corvus monedula)

Social hierarchy was studied in two flocks (14 and 10 individuals, respectively) of captive jackdaws. Parent birds acquired high-ranking positions during the nesting period. Outside the breeding season the hierarchy seemed to be stable. Males generally dominated females. When the top-ranking male arrived at the feeding place it tended to supplant one of the feeding birds rather than choose an unoccupied site.     

Ontogeny of heart rate in embryonic and nestling crows (Corvus corone and Corvus macrorhynchos)

The developmental patterns of mean heart rate (MHR) and instantaneous heart rate (IHR) were investigated in embryos and chicks of altricial Corvuscorone and Corvus macrorhynchos. The MHR of embryos increased linearly with time from 250 beats · min⁻¹ at mid-incubation to 290 beats · min⁻¹ in hatchlings. MHR during the pipping period was maximal, but only marginally higher than in hatchlings. MHR was stable at about 290–300 beats · min⁻¹ during the 1st week after hatching. Spontaneous heart rate (HR) decelerations and accelerations were found in embryos and chicks, disturbing the baseline HR with increasing frequency during development. However, the IHR accelerations developed later and were less frequent than in precocial species. IHR and body temperature decreased during mild cold exposure (23–25 °C) and IHR accelerations were reduced in nestlings during the 1st week. We suggest that the development of parasympathetic control of HR in crows occurs at 60% of incubation, similar to precocial embryos, but sympathetic control may be delayed and suppressed in contrast to precocial embryos. Accepted: 3 March 1999     

Interinsular variations in the spring and summer diet of the Raven Corvus corax in the Canary Islands

This paper presents the first data on the diet of the Raven Corvus corax in the Canary Islands, based on analysis of 2315 pellets collected from all of the islands and islets in the archipelago. The Ravens on three groups of island showed differences in diet, but in all cases the diet was clearly omnivorous, both in its qualitative and quantitative composition. It is evident that a broadening of the Raven's trophic niche has occurred in comparison with those living in continental areas. While the diet has a strong plant component on the wetter islands (frequency of occurrence > 87%), an appreciable animal component in the diet (principally vertebrates) is more frequent on the drier islands of the archipelago (frequency of occurrence > 96%). The composition of the plant component of the diet varied markedly from one island to another. Remains of refuse are more commonly found in the Raven's diet on the central and western islands. We concluded that while the animal diet is essential from the bioenergetic point of view, the vegetation diet is only a complementary food source. The Raven plays an important role in seed dispersal among the different habitats within each island.     

Preferential learning from non-affiliated individuals in jackdaws (Corvus monedula)

It has been suggested that affiliated social relations may facilitate information transfer between individuals. We here tested this rarely examined hypothesis with juvenile and adult jackdaws (Corvus monedula) in three stimulus enhancement tasks, both in a non-food context (experiment 1) and in a food context (experiments 2 and 3). We first show that siblings and pair partners maintain stronger bonded social relations than do non-siblings and non-pair partners. We therefore tested individuals in sibling and non-sibling dyads and, later in ontogeny, in pair and non-pair dyads. Jackdaws either did not learn from any other conspecific (experiment 1), or they learned from non-affiliated individuals (non-siblings, non-pair partners in experiments 2 and 3). This may be related to two main characteristics of jackdaws' affiliated relationships. First, affiliates share food at a high rate and may rely on their knowledgeable partners to secure food rather than learning from them. Second, affiliates spend most time in close spatial proximity to each other which increases the probability that they simultaneously experience occurrences in their environment. Hence, spatially more distant individuals, which are more likely to be non-affiliated, face different foraging situations and may therefore provide more relevant information which may lead to selective social learning.     

Effects of Group Size on Approach to Novel Objects in Ravens (Corvus corax)

Neophobia may constrain explorative behaviour, learning and innovation, while social context may facilitate approach to novel objects and acceptance of novel food. We examined the effects of neophobia on the exploration of novel objects in relation to social context in ravens (Corvus corax). Ravens are suitable subjects for studying effects of social context, as they are highly neophobic scavengers that recruit conspecifics to food. We tested two groups of six and 11 hand‐raised birds in three conditions: single‐bird, in dyadic combinations and sibling sub‐groups of three to six birds. Contrary to expectation, individuals of both groups were quicker to approach novel objects when tested alone than when tested with conspecifics. However, they spent more time close to and manipulating the novel objects in the social conditions (dyadic and group) than when being alone. We discuss the possibility that the higher latencies of dyads and groups to approach novel objects may reflect a ‘negotiation’ process in a ‘war of attrition’ between the individuals over risk‐taking.     

Salient eyes deter conspecific nest intruders in wild jackdaws (Corvus monedula)

Animals often respond fearfully when encountering eyes or eye-like shapes. Although gaze aversion has been documented in mammals when avoiding group-member conflict, the importance of eye coloration during interactions between conspecifics has yet to be examined in non-primate species. Jackdaws (Corvus monedula) have near-white irides, which are conspicuous against their dark feathers and visible when seen from outside the cavities where they nest. Because jackdaws compete for nest sites, their conspicuous eyes may act as a warning signal to indicate that a nest is occupied and deter intrusions by conspecifics. We tested whether jackdaws’ pale irides serve as a deterrent to prospecting conspecifics by comparing prospectors’ behaviour towards nest-boxes displaying images with bright eyes (BEs) only, a jackdaw face with natural BEs, or a jackdaw face with dark eyes. The jackdaw face with BEs was most effective in deterring birds from making contact with nest-boxes, whereas both BE conditions reduced the amount of time jackdaws spent in proximity to the image. We suggest BEs in jackdaws may function to prevent conspecific competitors from approaching occupied nest sites.     

Pluviantaenia kassalensis n. g., n. sp. (Davaineidae), a new cestode from the Egyptian plover Pluvianus aegyptius (L.) in the Sudan

Pluviantaenia kassalensis n. g., n. sp. (Davaineidae), from the intestine of Pluvianus aegyptius (Charadriiformes, Glareolidae) in the Kassala area of the Sudan, differs from other davaineid cestodes in having an armed scolex with an inflated pseudorostellum terminating in two fan-shaped lobes, in the absence of suckers, the presence of a very large sucker-like genital atrium provided distally with a powerful sphincter, and the presence of a thin-walled cirrus-sac, smaller than the genital atrium, enclosing a robust, armed cirrus. The genital atrium cirrus-sac complex, but not the female organs, may be duplicated bilaterally and/or additional sets may occur in marginal or submarginal positions.     

Threats and control of the brown necked ravens (Corvus ruficollis) in Egypt

The Suez Canal region is a small fertile area in Egypt that is placed under enormous pressure of existing resources. In these areas, intensive agricultural practices are performed in combination with high population densities. The described problem is that together with agricultural practices and urbanization, Brown necked ravens (Corvus ruficollis) are in huge amounts attracted. The birds are very aggressive and showed to be a serious pest. They spread germs and diseases for human health and food production. Therefore, the birds need to be controlled. Our research focuses on identifying food preferences of raven and on the way raven control is most effective. Ravens are omnivorous birds. From our laboratory study it was seen that most preferable foods were, in descending order: fresh fishes, cow liver, crustacean, watermelons, tomatoes and yoghurt. Under field conditions where stomach content was dissected, animal matters showed to a more preferred food source than plant matters. Observations on olfactory sensitivity showed that ravens could easily locate their food. Biological observations in the field on reproduction of ravens showed that raven females lay two to six eggs. Average number of babies per nest was between one and four. Average number of raven flock before sun rise was more than 100, while it was less than 100 before sun set. The impact of mechanical, biological and chemical control was investigated. Without control, approximately flock numbers of more than 100 ravens were recorded. The average number of raven flock was 60 before mechanical control operation (nests destroyed and using net), while it was 40 after mechanical control. Results of the biological control showed that kestrel (Falco tinnunculus rupicolaeformes) predated raven babies more effective than barn owls (Tyto alba). Within the chemical control experiments, Brodifacoum (0.0005%) was most effective against ravens, followed by Zink phosphide (19%) and Methomyl (90%, carbamate compound).     

Corticosterone excretion patterns and affiliative behavior over development in ravens (Corvus corax)

Averse effects of social stress may be buffered by the presence of social allies, which mainly has been demonstrated in mammals and recently also in birds. However, effects of socio-positive behavior prior to fledging in relation to corticosterone excretion in altricial birds have not been investigated yet. We here monitored corticosterone excretion patterns in three groups of hand raised juvenile ravens (n=5, 6 and 11) in the nest, post-fledging (May-July) and when ravens would be independent from their parents (September-November). We related these corticosterone excretion patterns to socio-positive behavior. Behavioral data were collected via focal sampling in each developmental period considered. We analyzed amounts of excreted immunoreactive corticosterone metabolites (CM) using enzyme immuno assays. We collected fecal samples in each developmental period considered and evaluated the most appropriate assay via an isolation stress experiment. Basal CM was significantly higher during the nestling period than post-fledging or when birds were independent. The time nestlings spent allopreening correlated negatively with mean CM. Post-fledging, individuals with higher CM levels sat close to (distance <50 cm) conspecifics more frequently and tended to preen them longer. When birds were independent and a stable rank hierarchy was established, dominant individuals were preened significantly longer than subordinates. These patterns observed in ravens parallel those described for primates, which could indicate that animal species living in a complex social environment may deal with social problems in a similar way that is not restricted to mammals or primates.     

Prevalence of Listeria sp. in droppings from urban rooks (Corvus frugilegus)

Droppings from 112 urban rooks ( Corvus frugilegus ) were cultured for the presence of Listeria sp. Overall, 46% of rooks sampled harboured one or more Listeria species. Of all birds examined, 33%, 24% and 8%, respectively, were infected with Listeria monocytogenes, Listeria innocua and Listeria seeligeri. Differentiation of L. monocytogenes and L. seeligeri carried out by several phenotypic typing methods proved the diversity of strains and the major role of rooks which widely contribute to spreading this bacteria in our environment. The results also suggest that the ability to recover specific Listeria strains from the same sample is at least partially dependent on the methodology. These findings reinforce the need for strain-specific typing of multiple L. monocytogenes isolates from the same sample.     

Breeding biology of House Crows (Corvus splendens) in Durban,South Africa

Nesting House Crows Corvus splendens were studied in the suburb of Merewent, Durban, South Africa, during the summer breeding season of 1999–2000. The c. 1km² study area supported 52–62 pairs. Breeding dispersal was clumped, suggesting a level of colonial breeding, but pairs were apparently intolerant of conspecifics nesting in the same tree. The two closest simultaneously active nests were 30m apart in adjacent trees. Details of nest locations, trees, heights, structure, dimensions and weights are provided. Egg-laying occurred October–January, mainly mid October to end November. Clutch size, egg dimensions and weights are given. Apparent repeat clutches were found but there was no evidence of double brooding. Details of nestling growth, and fledging and post-fledging dependence periods, are provided. Breeding success was relatively poor. Early breeding attempts were more successful than late breeding attempts. Breeding failure was suspected, or known, to be associated with observer disturbance, egg breakage, failure of eggs to hatch, starvation of chicks, nest collapse and independent control measures.