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Lack of synchrony between breeding in two neighbouring starling (Sturnus vulgaris L.) populations in New Zealand : evidence of no regional effect of the ENSO?

Flux J., Bull P., Zduniak P., Tryjanowski P.

Polish Journal of Ecology

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2009

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Vol. 57, nr 2

363-369

EN

Weather and climatic conditions may impact on many aspects of bird populations, including population size, the timing of breeding and synchrony between these variables in local populations. We examined synchrony in population size and the laying date of two starling Sturnus vulgaris populations 25 km apart, at Ohau and Belmont, in New Zealand. Data were collected in nest-boxes in both study plots from 1970 to 2003. Additionally we investigated possible relationships with a large geographical climate index, the El Nino Southern Oscillation (ENSO). Starlings at Ohau bred significantly earlier than at Belmont. The difference in the median of year median date of laying the first egg was 3 days. Simultaneously, the percent of nest boxes used by birds was much higher in Ohau (86%, SE = 4.1) than in Belmont (52%, SE = 2.9). However, we did not find a significant relationship between median dates of laying and the percent of nest boxes used by birds in each breeding season in the two populations. Furthermore, we found no influence of ENSO on (potential) synchrony in starlings. breeding parameters. We suggest that lack of synchrony between two close local populations, both in percentage of occupied nest boxes and time of laying, is due to starlings responding to very local conditions, like food availability. We urge future studies to take advantage of spatially close populations.

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Autumn sexual display in Tree Sparrows (Passer montanus L.) as a component of the winter survival strategy

Pinowski J., Pinowska B., Zduniak P., Tryjanowski P., Jerzak L., Romanowski J.

Polish Journal of Ecology

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2009

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Vol. 57, nr 1

159-169

EN

The evolution of organisms leads to the elimination of behaviors that are costly in terms of energy. One of such behaviors in the Tree Sparrow Passer montanus is the autumn display during which these birds construct nests. The purpose of this paper is to find out if this behavior is a part of the strategy for winter survival. The study of Tree Sparrows was conducted near Warsaw, Central Poland. During the breeding season, nest boxes were checked to record the presence of Tree Sparrow nests. Before the autumn display, breeding nests were dyed in order to identify nest material added in the period of autumn display. Nestlings in nest boxes, juveniles, and adults captured in mist-nets were banded with different combinations of color bands to identify their age during visual observations in the period of autumn sexual display. Juveniles and adults caught in mist-nets were classified as molted or not molted birds. In winter, nest boxes were checked to catch the birds roosting in them at night. Autumnal sexual display in Tree Sparrows is similar to the spring display. Both adults and juveniles leave the breeding colony in August and return after molt. They form pairs, copulate and build nests in fall. The autumn display is continued from the first ten days of September to early November. The number of Tree Sparrows participating in the autumn display increases with the percentage of the birds that completed molt in the population. In the first half of September, 16% of the population completed molt, while 99% in mid-October. On the average, adult birds formed pairs on 11 September (SD: 7.7 days), and juveniles on 17 September (SD: 8.0 days). Nest construction was started, on the average, 14.2 [plus or minus]8.7 days after pairing. The advance in nest building was dependent on the time of pair formation. Intensive nest building took place in the last 10-days period of September and in October. Early in November, nest building ceased with the onset of cool weather. The last birds to pair did not construct complete autumn nests and in winter they roosted in shrubs or in tree crowns. The building of autumn nest as a consequence of the autumn display, serving as a roosting place in winter, can be a consequence of natural selection promoting this behaviour.

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Intrapopulation variation of egg size in the White Stork (Ciconia ciconia) in Southern Poland

Profus P., Tryjanowski P., Tworek S., Zduniak P.

Polish Journal of Ecology

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2004

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Vol. 52, nr 1

75-78

EN

White Stork (Ciconia ciconia) eggs were studied in Upper Silesia, Southern Poland. The measurements of eggs - their length, breadth, volume and elongation index were collected for 95 nests in years 1974-2002, and repeatability of these measurements was computed. Mean clutch size was 4.05 [plus-minus] 0.82. Mean egg measurements were: 72.10 [plus-minus] 2.18 mm, 52.19 [plus-minus] 1.47 mm, 100.49 [plus-minus] 6.92 cm^3 and 1.38 [plus-minus] 0.05, for length, breadth volume and elongation index, respectively. Coefficients of variation for clutch means ranged from 1.68 (breadth) to 4.37 (volume). Mean repeatability estimates were 0.53, 0.68, 0.63, 0.58 for length, breadth, volume and elongation index, respectively. The results obtained suggest that one should expect relatively low or intermediate heritability of egg dimensions in population studied.

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Effect of distance between host trees and leaf litter removal on population density of Cameraria ohridella Deschka & Dimic, 1986 (Lepidoptera, Gracillariidae) - pest of chestnut (Aesculus sp.) trees

Baraniak E., Walczak U., Tryjanowski P., Zduniak P.

Polish Journal of Ecology

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2004

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Vol. 52, nr 4

569-574

EN

The influence of distance between host trees and leaf litter removal on population density of Cameraria ohridella have been for the first time examined in an isolated population of horse chestnut (Aesculus hippocastanum L.) trees. The observation was performed in the small town (area 13,58 km^2) in Wielkopolska region (West Poland) on the total number of 49 trees: 31 (11 clumps) of them with autumnal leaves removal (controlled sites), and 18 (5 clumps) without this procedure (uncontrolled sites). The main factors determining the extent of the leaf destruction by larvae were the leaf litter removal and the number of subsequent generations on a given tree. The effect of mean distance between trees on the infestation level was statistically significant only for the third generation larvae, when analyzing all sites. There was no significant correlation when checking the impact of mean and short distance on the leaves infestation between controlled and uncontrolled sites. The abundance of the first generation of the larvae of raked sites is possibly a result of low number of in situ overwintering individuals and the number of immigrants from uncontrolled areas. Assuming the random choice of direction of the migration, the effect of the immigrants on the trees which leaves have been disposed of is not as high as it should be expected. Additionally, the moths can be blown away by the wind in a random direction. Consequently, the noted increase in the leaves infestation by the third generation larvae can be result of the rate of population increase innate for the species and only partly a result of immigration from refuge areas.