Total body electrical conductivity (TOBEC) is the name of a non-invasive method for investigating total body fat (TBF) in vertebrates. The error of measurement depends on body mass (for large animals the relative error is small), body shape and other factors.

The ACAN-2 apparatus operating on the basis of the TOBEC method shows integer numbers (readings) correlated with lean body mass (LBM). From the series of these readings (measurements) TOBEC can be calculated in many ways.

The error for LBM and TBF measurements in Tree Sparrows (of masses 22.5 ± 1.7 g) and House Sparrows (of masses 29.8 ± 2.0 g) was 1.19 g. This error may be reduced by repeating the TOBEC measurement and calculating the arithmetic mean of readings from the apparatus obtained 1 second after the commencement of measurement. Readings making up a single measurement series showed periodic irregular fluctuations of average amplitude 3 units in the case of Tree Sparrows and 5 units for House Sparrows — corresponding to errors of 0.5 g LBM in both species. Given individuals of both species were characterised by similar differences between the first and second TOBEC measurements. The TOBEC value obtained in a measurement during which a bird defecated in the chamber of the apparatus was significantly higher than that for a bird in a clean chamber. The orientation of the head in the chamber did not influence the repeatability of the TOBEC measurement. In Tree Sparrows, the relationship between TOBEC and LBM differed between those captured and held for one night prior to measurement and those measured for TOBEC immediately after capture.

Analysis of stomach contents from 386 Lesser Kestrels Falco naumanni obtained at Bloemfontein, South Africa, during the austral summer over a 12 year period (1984–1996) showed this species to be predominantly insectivorous. Isoptera (Harvester Termite Hodotermes mossambicus), followed by Solifugae and Chilopoda, formed the staple food. Lesser Kestrels consumed large quantities of small-sized prey, mainly Isoptera, early in the austral summer, while larger-sized food items, mostly Acrididae, dominated at the end of the non-breeding season. Results from pit trap sampling suggest that Lesser Kestrels are opportunistic foragers utilising the most abundant prey species.

The occurrence of intestinal parasites was studies in adults and nestlings of Acrocephalus paludicola, A. schoenobaenus, A. palustris, A. scirpaceus and A. arundinaceus. The most common taxa in all these species were Coccidia and Ascaridia, and in some species also Ornithostrongylus and other Nematoda. In A. arundinaceus parasitized males were significantly heavier than nonparasitized ones, whereas in females the opposite was found. Moreover parasite-free males A. schoenobaenus and A. scirpaceus and females A. paludicola tended to be lighter compared to parasitized ones, but the difference was not significant. Infected A. scirpaceus females had significantly larger fat deposits than noninfected ones. Parasite prevalence also varied significantly between the promiscuous A. paludicola and the related monogamous species.

Black-headed Gulls breeding in the central part of the Upper Silesian Industrial Region (Katowice-Szopienice) in Southern Poland were compared with colony from less polluted area (Świerklaniec) situated 23 km away. Heavy metals: Cd, Pb, Zn and Cu — were determined in various organs of nestlings, fledglings and mature birds as well as egg yolks. Resting metabolic rates, hatching success and eggshell thickness were used as biomarkers of environmental exposure to industrial pollutants. The clutch size (2.97 versus 3.61) and hatching success (81.5% versus 87%) were lower in the colony from the more polluted site. The relatively high metal contents in the yolks indicate that off spring are only partially protected from toxic compounds. Gulls were able to regulate body contents of essential metals Zn and Cu, but Pb and Cd accumulated rapidly in the liver, kidneys and lungs of growing birds. Cd also accumulated in the ovaries at the similar levels as in the kidneys. Cd and Pb may have affected earlier stages of development when parents were foraged in a close vicinity of the heavily polluted area but once the young gulls had reached maturity they then foraged in distant areas. During this period they were exposed to pollutants in the same way as the gulls from the less polluted site. There was no growth impairment identified in gulls from the more polluted area, and their resting metabolism (RMR) calculated per unit of body weight was lower, indicating that energetic costs for detoxification were not as high.

4166 measurements of wing length in Reed Warblers were made during 9 breeding and pre-migratory periods in Central Poland. In the studied population there was significant differentiation in the wing length among seasons in adult and juvenile birds. Multiple regression and path analysis showed that weather factors (temperature and precipitation) during the breeding period determine the long-term variation in the wing length in both adult and young birds. Changes in wing length were explained by natural selection and habitat selection. In breeding and pre-migratory periods, temperature and precipitation influence in food availability, and thus affect optimisation of energetic expenses on feeding. It was revealed that long-winged individuals are best adapted to cold and rainy conditions, the short-winged ones, to warm and dry summers. The weather conditions obtaining when the birds arrive at the breeding grounds could be linked to differentiation in availability of optimal places for establishing territories, thereby influencing cempetition for breeding territories and the effectiveness of their occupation by morphometrically different birds.

The study was carried out in 1994-96 in an area of western Poland where field sizes range widely —from < 1 to 50 ha. The spring population density of Partridges was estimated by call counts on 1 km² study plots. The landscape structure was described by the proportion of crops and orchards, the number of arable fields and the length of permanent cover with spontaneous vegetation. Radio-tagged individuals (24 pairs and 6 single males) were tracked during the breeding season. The Partridge density in the study plots ranged from 0 to 7.7 pairs per km², and increased with the number of fields per km² and the proportion of small orchards among the arable fields. Radio-tagged pairs on small fields (< 10 ha) preferred field edges with permanent treeless plant cover and edges without permanent plant cover. On large fields (> 10 ha), a preference was shown for field edges with both wooded and treeless permanent plant cover. Partridges avoided the centres of both types of fields. Preferred nesting sites were in permanent plant cover and orchards; crops were used less frequently than expected. The spring carrying capacity of the field habitat for Partridges was dependent on the availability of field edges, including those devoid of permanent plant cover.

The diet of the Cape Petrel was investigated in two localities of South Shetland Islands, Antarctica, over the period January—February 1996. Stomach contents of adults obtained by flushing and regurgitates of chicks were sampled during the chick-rearing period. During the whole sampling period, euphausiids represented the predominant prey in terms of frequency of occurrence, mass and number at Fildes Peninsula, while at Harmony Point, euphausiids and fish components were found in similar proportions in terms of mass and frequency. Myctophiids fish, in particular Electrona antarctica, formed the bulk of the fish component. The analysis of the diet throughout the breeding season showed significant differences in number and mass of the prey items at Fildes Peninsula, while at Harmony Point, there were significant differences also in the occurrence of preys. Considering both localities, although the occurrence of the prey did not vary significantly during the brooding period, there were significant differences in their number and mass. Similar results were found in the post-brooding period between both localities.

The aim of this study was to provide optimal methodological criteria for the quantitative and qualitative estimates of bird communities inhabiting woodland areas using point counts. Results obtained from counts carried out once or twice during the same breeding season were compared and the optimal duration of each session was assessed. Data obtained in three different woodland areas, from a total of 46 point counts each lasting 20 min. and repeated twice in the breeding season were analyzed in 5-min. blocks. It was concluded that 10-min. sessions repeated twice in a breeding season can provide a good description of the passerine bird community. However, some rarer species of the breeding community under study, including some diurnal raptors, woodpeckers, and scarce passerines, could be underestimated with this duration.

The contents of 30 stomachs of 3 swift species, and 96 stomachs of 9 swallow species were analyzed. Most of the birds were shot during the breeding season in the semi-arid grasslands of South Africa. The swifts fed mainly on termite alates and minute nemathoceran Diptera, while the swallows preyed mainly upon minute Coleoptera. Flying ants were an important food constituent in the diets of both swifts and swallows.

A total of 62 stomach contents of four Merops and three other coraciiform species from South Africa, were analysed. Hymenoptera constituted the bulk of the diet of all four Merops species examined, with Odonata and Coleoptera being supplementary components. Upupa epops and Phoeniculus cyanomelas fed mainly on insect larvae, while Coracias caudata preyed upon Scarabaeidae, Acrididae, Isoptera and Solifugae.

Five bird species (Great, Blue and Coal Tits, Redstart, Tree Sparrow) nested inside vertical metal pipes of fences in Warsaw suburbs (central Poland). It appeared to be the main breeding site for a Great Tit — nearly 80% of the nests of the local population. The preferred diameter of the pipes depended on the size of the species (mainly on the length of the tarsus). It was the widest in Great Tit and the narrowest in Blue Tit. Great Tits built their nests significantly deeper (down to 1.7 m from the top) than the other species. The mean number of fully feathered nestlings per successful nest was lower in pipes than in nest boxes. Such a nest location is a local adaptation of birds living in highly a urbanised area, where natural breeding cavities are scarce.

In some Buzzard nests with nestlings, located in the Kampinoski National Park, surplus food was found — two or more items of small rodents, mainly voles, without traces of damage, stored in nests. Part of the stored prey was in various stages of decay. Surplus prey items were more frequent in farmland nests than in forest nests.

Continuous video camera observations of the Kestrel's nest situated on a building within the city centre showed presence of a surplus prey (mainly untouched sparrows and voles) stored in the nest and its close vicinity. During the first three weeks of the nestling period, chicks were fed this prey, and the frequency of feedings was higher than the frequency of prey delivery. Food storaging was also observed in some other nesting places of Warsaw Kestrels.

Daily pattern of prey deliveries observed in Warsaw did not differ significantly from the available data on Kestrels inhabiting an open landscape.