Preen oil chemical composition in herring gull Larus argentatus,common gull Larus canus and black-headed gull Chroicocephalus ridibundus confirms their status as two separate genera

Fatty acid and alcohol components of preen oil were determined in three gull species that belong to two systematic genera: herring gull Larus argentatus, common gull Larus canus and black-headed gull Chroicocephalus ridibundus. All gulls were captured in winter, in Gdańsk, Poland. All gulls produced monoesters composed of C₇–C₁₆ saturated fatty acids and C₁₁–C₂₀ saturated alcohols, with n-octanoic acid and n-hexadecanol as the major fatty acid and alcohol, respectively. Preen oils of black-headed gull had higher content of trimethyl fatty acids, 2,8-dimethylundecanoic acid, 2,6-dimethylundecanoic acid and 2,6-dimethylnonanoic acid, and lower content of 2-methyl fatty acids than oils of herring gull and common gull. Preen oils produced by black-headed gull also had lower content of 2-methyl alcohols. The relative contents of n-octanoic acid and n-hexadecanol did not differ among species. The differences among species are probably not a result of different diet, as all gulls fed mainly on household refuse. Hence, preen oil analysis confirmed the taxonomic relations among these gull species, that recently were placed into two different genera.     

Agonistic display and spacing in the black-headed gull, Larus ridibundus

Black-headed gulls nesting on islands in a marsh habitat had a higher breeding success than those nesting on the periphery of the colony. Island birds maintained close inter-nest distances whereas peripheral nests were spaced further apart as predation of eggs increased. These changes in spacing corresponded with changes in the response distances of agonistic displays. There was no change during incubation for island birds but peripheral birds displayed to intruders at much greater distances than during pair formation. Island birds were more likely to attack and display more frequently to intruders than peripheral birds. However, in one season the peripheral birds were more aggressive during pair formation because of an increase in intrusions by unpaired females.     

Energy dissipation in the elastic recoil of leg tendons of Larus ridibundus

Cycles of tension and recoil were given to different tendons of black-headed gull (Larus ridibundus) in an Instron universal testing machine. It is shown that a large proportion of the energy elastically stored in straining is released upon recoil, ranging the energy lost (dissipation energy) between 8 and 13%. These results are in complete agreement with those published in the literature on mammals and birds that can be considered as the most accurate.     

Craniogenesis in the laughing gull (Larus ridibundus L.). The reconstruction of the basic plan of the bird

To contribute to the knowledge of the cranium of older bird embryos, the chondrocranium and osteocranium of the Black-headed Gull (Larus ridibundus) are described. The chondrocranium of the Black-headed Gull is compared with the chondrocranium of other bird species with special consideration of functional and phylogenetic aspects. As a result a "grundplan" of the bird chondrocranium is reconstructed. Most of the chondrocranial autapomorphies of birds are connected with the enlargement of the eyes, the development of a beak and a prokinetic skull, and the reduction of the olfactory system.     

Isolation, purification and characterization of spleen ferritin of Gallus domesticus L

The ferritin from the spleen of the chickens has been isolated by a method of salt fractionation and by a pH change followed by purification in sephadex G-200. 2. The identification of the protein was carried out by acrylamide gel electrophoresis showing a single band. 3. The characterization of ferritin has been made by determination of molecular weight, amino acids analysis and the number of iron atoms (4520) which bound the ferritin. 4. The ferritin from the spleen of chicken is compared with the ferritin from the liver of pigeon.