Lajos Sasvári

Observational learning in great, blue and marsh tits.

Great tits (Parus major L.), blue tits (P. caeruleus) and marsh tits (P. palustris) were compared with respect to their ability to learn food finding from other individuals. The great tits were more successful than the other two species. This seems to be related to difference in adaptability in the wild, where the great tit is the most successful of the three species in urban environments.

Great tits benefit from feeding in mixed-species flocks: a field experiment

Abstract Patch depletion, food intake and aggressive interactions were studied in flocks of great tits, Parus major , and in mixed-species flocks of great tits and marsh tits, P. palustris , exploiting one or two patches. Both male and female great tits had a higher feeding rate in mixed-species flocks than in single-species flocks. Food was depleted more quickly and aggression was lower in mixed flocks. The difference in intake rates between males and females was lower when they were feeding over two patches than on one patch because of the dispersion and consequent reduction in aggressive interactions in the group. Marsh tits and female great tits were more likely than male great tits to be attracted to a neighbouring food patch by another individual. Marsh tits outside the flock were a greater attraction to individuals from the group than were great tits. Individuals appeared to feed less efficiently in two patches as they spent longer there than in one patch of the same size and food density.

Keypeck conditioning with reinforcements in two different locations in thrush, tit and sparrow species.

Twenty-one individuals each of the species great tits (Parus major), blue tits (Parus caeruleus), marsh tits (Parus palustris), blackbirds (Turdus merula), songthrushes (Turdus philomelos), tree sparrows (Passer montanus) and house sparrows (Passer domesticus) were conditioned to a keypeck response by means of food reinforcement. The site where the reward was given was then changed. The number of reinforcements were then counted until the keypeck response followed immediately (within 10 seconds) on three successive occasions, and a comparison was made between species. Of the species studied the blackbird needed significantly fewer instances of reinforcement in order to re-establish an immediate keypeck response. A significant difference was also seen between the performance of the great tit and marsh tit, as well as between the blue tit and the marsh tit. No significant difference was found between the performance of the house sparrow and the tree sparrow.

Bird predation by tawny owls (Strix aluco L.) and its effect on the reproductive performance of tits

Abstract The density of great tit Parus major L. and blue tit Parus caeruleus L. was artificially increased by placing nest-box colonies for these species in the vicinity of the nests of breeding tawny owls during 1993–1997. Bird prey composition in the owl nests, the proportion of parents disappearing from the breeding tit populations and the reproductive performance of the widowed parents were analysed. The frequency of predation on tits by tawny owls was greater in areas where tit density had been artificially increased. Owls preyed more on tits during the feeding period of owlets than during the incubation period and more in years when snow covered the ground during the incubation period than when it did not. Mortality due to predation was male biased and more females lost their mates in populations breeding near tawny owl nests. Reproductive performance of the widowed parents was lower and their body weights were lighter at the end of the nestling period than those found in birds rearing youngs with their mates. Predation by owls increased the between-year turnover in the breeding tit population: widowed parents did not return to the nesting site for the next breeding season.

The influence of parental age and weather on testosterone concentration and offspring survival in broods of tawny owl Strix aluco

Previous research has suggested that parental condition may affect offspring mortality patterns by affecting offspring testosterone levels. Accordingly, we hypothesized that there is a relationship between offspring testosterone concentration and survival during the early nestling period, and that both are influenced by parent age/experience and by prey availability. We tested our hypothesis on tawny owls Strix aluco in their first and third known breeding seasons, when they bred either in adverse or mild weather conditions, in Duna-Ipoly National Park, Hungary. Plasma testosterone concentrations of the nestlings were analyzed and related to parental condition, hatching order and nestling mortality. Inexperienced parents breeding in all weather conditions and experienced parents breeding in adverse conditions were both in poor condition compared to experienced parents breeding in mild conditions. Parents in poor condition produced broods with large between-sibling differences in testosterone concentrations and their later-hatched nestlings (which had low testosterone levels) died during the early nestling period, whereas parents in good condition produced broods with lower variation in offspring testosterone concentrations and all offspring survived the early nestling period. We discuss environmental influences on the amount of testosterone deposited in eggs, and also how maternal testosterone might induce those mechanisms producing testosterone in the nestlings.

Predation Risk of Tawny Owl Strix aluco Nests in Relation to Altitude, Breeding Experience, Breeding Density and Weather Conditions

Nest predation was studied in a population of Tawny Owls Strix aluco in the Duna-Ipoly National Park, Hungary during the period 1992–2009, and related to the choice of nesting sites at different altitudes, the breeding experience of males, and weather conditions. The use of nesting sites at high elevations reduced the risk of nest predation in comparison to lower elevations, where breeding territories occur at a higher density. Also, the risk of nest predation decreased as the local breeding experience of males increased. Adverse weather conditions, i.e. long-lasting snow cover, increasing breeding density, and later laying dates enhanced the probability of breeding failure by nest predation. Broods were depredated in the nestling period rather than during incubation.

Different responsiveness of Indian and European Great Tit(Parus major mahrattarum; P. m. major) to acoustic stimuli

The song and the anxiety churring of the Indian Great Tit(Parus major mahrattarum) were played back to the European Great Tit(P. m. major) near Budapest and the song and the anxiety churring of the European Great Tit were played back to the Indian Great Tit in the Thekkady National Park, South India. The anxiety churrings of the two subspecies were similar, their songs were conspicuously different. The European subspecies responded significantly more to the sounds of the Indian subspecies than did the Indian to the sounds of the European subspecies. This phenomenon can be explained by the higher acoustic responsiveness of the European Great Tit. The increased acoustic responsiveness together with the increased social tendency could have promoted the adaptability of the European Great Tit. Der Gesang und der Alarmruf der indischen Kohlmeise wurde europäischen Kohlmeisen in der Umgebung von Budapest vorgespielt und umgekehrt der Gesang und der Alarmruf der europäischen den indischen Kohlmeisen im Nationalpark Thekkady (Kerala). Der Alarmruf beider Unterarten ist ähnlich, der Gesang jedoch verschieden. Die europäische Unterart reagierte signifikant öfter auf den Gesang und den Alarmruf der indischen Unterart als die indische Unterart auf die Lautäußerungen der europäischen. Diese Erscheinung ist mit der größeren akustischen Reaktionsfähigkeit der europäischen Kohlmeise zu erklären. Eine ausgeprägtere akustische Sensibilität weist auf eine stärkere soziale Tendenz hin und diese führte möglicherweise zu größerer Anpassungsfähigkeit der europäischen Kohlmeise.