Jarosław K. Nowakowski

Soil and preen waxes influence the expression of carotenoid-based plumage coloration.

The signaling function of carotenoid-based plumage is mainly determined by the concentration of pigments in feathers. For this reason, most studies of the proximate control of coloration focus on processes during and preceding moult. In great tits Parus major, past research demonstrates that carotenoid-based plumage coloration honestly indicates male quality and, thus, may be a sexually selected signal. In this study, we investigate how dirt and preen oil influence the coloration of carotenoid-based feathers in the great tit. We collected six feathers from each individual bird; three feathers served as controls while the remaining three feathers were washed with a chloroform/methanol mixture to remove soil and preen waxes. We assessed plumage coloration using digital photography. This cleaning procedure slightly enhanced ornamentation; the experimentally cleaned feathers expressed hues shifted towards shorter wavelengths and expressed brighter overall coloration than control feathers. This is the first experimental study conducted on wild birds demonstrating that, in addition to pigment concentration, the presence of preen waxes and soils on feathers may contribute to variation in coloration.

Synchronisation of the autumn mass migration of passerines: a case of Robins Erithacus rubecula

Abstract. The pattern of autumn migration of the Robin was studied through an analysis of daily dynamics for the birds caught in the years 1984–1997 at four ringing stations (two on the Baltic coast and two in inland Poland). In a given year, migration dynamics was found to be distinctly similar at all stations. It showed conspicuous consistence (± 2 days) in the dates with peak numbers. This could be explained by assuming that Robins take off at the same time across a large breeding ground, and arrive almost simultaneously at stopover sites located over extensive areas. Moreover, migration dynamics from year to year at a given station was also remarkably similar, though this phenomenon was more distinct at the inland stations than at the coastal ones. Day-to-day fluctuations in numbers were on an average the highest at the coastal station most exposed to variable weather, the lowest at the inland stations, and intermediate at the more “sheltered” of the coastal station. The paper discusses the extent to which such results can reflect the influence of weather conditions on passage, or else a precise internal (physiological and genetic) mechanism responsible for the timing of migration.

Saluga and Ghazal Ringing Station - a new ringing station in Egypt

Saluga and Ghazal Ringing Station - a new ringing station in Egypt On 28 August 2003 under the auspices of the SE European Bird Migration Network (SEEN) a new Egyptian Ringing Station - Saluga and Ghazal began to operate. The paper provides information about the location of the station, its habitat, methods of work and species composition of caught birds.

Does mist-netting provide reliable data to determine the sex and age ratios of migrating birds? A case study involving the Great Tit (Parus major) and the Blue Tit (Cyanistes caeruleus)

Abstract Nowakowski J.K., Chruściel J., Muś K.: Does mist-netting provide reliable data to determine the sex and age ratios of migrating birds? A case study involving the Great Tit (Parus major) and the Blue Tit (Cyanistes caeruleus). Ekologia (Bratislava), Vol. 32, No. 2, p. 173-185 , 2013. Ringing results of tits caught at two stations on the Polish Baltic coast were used to check if mistnetting could be successfully used to analyse the composition of sex and age classes of migrating birds. Four hypotheses are discussed, describing the distribution of age and sex classes during migration, and the consequences these distributions might have for the catching results. We analysed records of 59 000 Blue Tits and more than 84 000 Great Tits that were caught and we found a similarity in the results of catches at stations 188 km apart, and a higher similarity among catching sites 0.5-16 km apart. These results proved that mist-netting provides reliable data on the sex and age structure of migrating flocks, and that these data can generally be interpreted as representative for at least the area in a radius of more than 10 km. The results also showed a migratory divide through the central part of the Polish Baltic coastline between irruptive Blue Tits in the west and regular partial migrants in the east. Great Tits showed no tendency for irruptions anywhere in the study area. A high correspondence in the age and sex ratio was found for Great Tits and Blue Tits, in particular where both species are regular migrants. We found that the ratios of females and immatures did not differ by more than 1% over many years of study in these areas.

ANY CHANGE IN THE METHODOLOGY OF FIELD STUDIES ON BIRD MIGRATION? A COMPARISON OF METHODS USED IN 1994-2003 AND A QUARTER CENTURY EARLIER

Any change in the Methodology of field studies on bird Migration? A comparison of methods used in 1994-2003 and a Quarter Century earlier The holistic approach to the study of bird migration observed in the past decades and the huge advancement in technology should be seen in the numbers and types of methods used in field studies for this phenomenon. To check this assumption, we compared field methods used in the studies on bird migration published in international journals in 1994-2003 (N = 570 papers) and in 1967-1976 (N = 394 papers). We noted an increase in the mean number of methods per a single paper (from 1.49 in the former of these decades to 1.98 in the latter) and a change in the frequency of each method. In recent years, methods such as satellite telemetry, DNA or isotope proportions analyses have been developed. An increase in the mean number of methods as well as changes of the most frequently used methods were more apparent in journals indexed on the ISI Master Journal List in 2003 than in other current journals, where the methods were often found to be similar to those applied a quarter century earlier, which surprised us.