rooks.org.uk

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The Rook is one of our most familiar and widespread birds. With nearly one million pairs in Britain, it is only absent from upland areas and from treeless islands off the west coast of Scotland, though it has been able to find suitable trees to nest on Shetland and on Lewis in the Western Isles …

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The study was carried out in 2000–2002 around 6 rookeries. Rooks foraged in numbers from 1 to 132 birds (n = 417); flocks of less than 10 individuals were dominant. The type of crop influenced the size of a foraging flock. Most of the rooks were recorded within 0.5–1 km of the rookery, while the greatest distance of a foraging ground from the rookery (x– = 2833.3 m) depended on the size of that rookery. Spring corn, meadows and pastureland were of the greatest significance in the rooks’ foraging area. Winter corn and root crops were avoided, while wasteland areas were visited intermittently.

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In a free living rook (Corvus frugilegus) a well differentiated squamous cell carcinoma without keratinization arising from the oesophageal mucosa was found. This tumour had grown around the right main bronchus and so caused marked respiratory distress.

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Sleep and wake states were monitored polygraphically in the rook Corvus frugilegus, under the natural photoperiod and temperature. The indices of sleep and wake states in the rook were similar to those described previously for birds in general. The appearance of sleep episodes was confined to the dark part of the photoperiod.

Slow wave sleep (SWS) showed a tendency to increase during the course of the night, while paradoxical sleep (PS) showed the opposite trend. The distribution of short SWS episodes were clustered into two groups, one group occurred in the period following the onset of sleep and the other, less prominent group occurred towards the end of sleep. The longest episodes of SWS appeared in the second half of the night, whereas those of PS appeared after onset of sleep.

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The occurrence of avian mycobacteriosis in the rook (C. frugilegus) was investigated in the years 1966-1985. A total of 188 birds captured at three localities of the Czech Republic were subjected to patho-morphological examination and to culture examination. Patho-anatomic lesions were observed in five rooks (2.6%), M. avium was isolated from 10 rooks (5.3%). Positive findings occurred in each examined locality.

Rook sensitivity to M. avium infection was tested by experimental infections. After intramuscular infection with M. avium suspension macroscopic tuberculosis lesions were found out at the place of puncture, histological lesions in liver and spleen at the beginning of the trial (days 12-35). Mycobacteria were isolated from particular organs and tissues, more frequently at the beginning of the trial.

Peroral infection by feed contaminated with liver of tuberculous fowl failed to induce tuberculous lesions, while a proof of M. avium from the organs was the only one after 157 days. The contact of the rook with the tuberculous fowl did not lead to the origin of tuberculous lesions after 238 days nor were the mycobacteria proved in the rook tissues.

In comparison with e.g. the house sparrow, tree sparrow and pheasant, the rook is very resistant to M. avium infection according to the results of experimental infections. A relatively frequent occurrence of tuberculous processes or of mycobacteria in the rook captured in the open area is probably conditioned by a possibility of repeated, frequent contacts of the rook with the contaminated environment during its longer life.

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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.

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Although animals (particularly tool-users) are capable of solving physical tasks in the laboratory , the degree to which they understand them in terms of their underlying physical forces is a matter of contention. Here, using a new paradigm, the two-trap tube task, we report the performance of non-tool-using rooks. In contrast to the low success rates of previous studies using trap-tube problems , seven out of eight rooks solved the initial task, and did so rapidly. Instead of the usual, conceptually flawed control, we used a series of novel transfer tasks to test for understanding.

All seven transferred their solution across a change in stimuli. However, six out of seven were unable to transfer to two further tasks, which did not share any one visual constant. One female was able to solve these further transfer tasks. Her result is suggestive evidence that rooks are capable of sophisticated physical cognition, if not through an understanding of unobservable forces , perhaps through rule abstraction. Our results highlight the need to investigate cognitive mechanisms other than causal understanding in studying animal physical cognition.

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The ultrastructure of liver cells was studied in rooks (Corvus frugilegus) living in radioactive and chemical contamination areas. The ultrastructure of liver cells from rook as well as jackdaw (Corvus monedula) and hooded crow (Corvus cornix) (Corvidae family) from a conventionally clean area was studied as control. Control hepatocytes proved to contain a great number of mitochondria, many of which were swollen and had clear matrix and disorganized cristae. The cristae nearly lacked glycogen and had abundant lipid droplets, which often tightly contacted mitochondria. The cytoplasm of hepatocytes in birds from both ecologically unfavorable areas had numerous mitochondria with the same ultrastructure.

In contrast to control, the hepatocyte cytoplasm:

• contained a lot of glycogen;
• there were many lipid droplets, which directly contacted glycogen granules; and
• had more abundant peroxisomes.

In addition to normal erythrocytes, the sinusoids contained erythrocytes with mitochondria, vesicles, and lipid droplets in their cytoplasm. Analysis of many micrographs of lipid droplets contacting glycogen granules, mitochondria, peroxisomes, and cisterns of smooth endoplasmic reticulum allowed us to propose that glycogen is synthesized via gluconeogenesis from glycerol and products of fatty acid oxidation in the liver cell cytoplasm of rooks from ecologically unfavorable areas as distinct from control.

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