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Analysis of mallard’s (Anas platyrhynchos) behavior depending on phenology period and the size of the flock on water basins in Szczecin

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Wojcieszak H. , Wysocki D. , Kaliciuk J.

Zeszyty Naukowe. Acta Biologica. Uniwersytet Szczeciński

2013

tom 20

The subject of the study is the behaviour of Mallard’s Anas platyrhynchos and was carried out in the city of Szczecin (Poland) in 2009–2010. We compared frequency of fights, rapes, courtships, copulations and whistles on a water basins within both big and small flocks, and in different phenology periods. The study shows significant relationship between season, number of ducks on a pond and frequency of fights, as well as between whistles and fights, whistles and season and courtships and season. The results show that the most active period for ducks are the autumn and winter months (pairing period), while more aggressive behaviours can be observed when the population density is high.

Przedmiotem badań były zachowania kaczki krzyżówki Anas platyrhynchos . Badania zostały przeprowadzone w Szczecinie w latach 2009–2010. Porównano częstość występowania walk, kopulacji wymuszonych (gwałtów), zalotów, standardowych kopulacji oraz wydawanych przez samce gwizdów w dużych i małych stadach ptaków oraz podczas różnych pór roku. Badania wykazują znaczącą zależność między sezonem i liczbą kaczek na zbiorniku wodnym a częstotliwością walk, a także między gwizdami i walkami, gwizdami i sezonem oraz zalotami i sezonem fenologicznym. Wykazano, że okres największej aktywności ptaków przypada na jesień i zimę (czas tworzenia się par). Najwięcej zachowań agresywnych można zaobserwować natomiast przy wysokim zagęszczeniu populacji.

Strong potential for endozoochory by waterfowl in a rare, ephemeral wetland plant species, Astragalus contortuplicatus (Fabaceae)

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Lovas-Kiss A. , Sonkoly J. , Vincze O. , Green A. J. , Takacs A. , Molnar A. V.

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It was proposed previously that passive dispersal by migratory aquatic birds explain the widespread distribution of many wetland organisms. Several experimental studies have shown that many widespread wetland plant species can be readily dispersed within the guts of Anatidae. However, it is unclear whether plants with a more restricted distribution are able to disperse via waterbirds. This paper addresses the dispersal ability and germination ecology of the little-known Hungarian milkvetch Astragalus contortuplicatus, which occurs on banks of continental rivers and has a limited and unpredictable distribution. To test whether limited capacity for endozoochory by waterfowl could explain the sporadic appearance of this species, we force-fed ten captive mallards (Anas platyrhynchos) with 100 milkvetch seeds each. Droppings were collected for up to 45 h after feeding. Intact and viable seeds were found in the droppings of each mallard, and altogether 24.7% of seeds fed were recovered intact. The proportion of retrieved seeds that germinated (27.0%) was significantly higher than that of untreated control seeds (0.5%), but significantly lower than that of mechanically scarified seeds (96.0%). Retrieved seeds that germinated developed into healthy mature plants. Given the average flight velocity of mallards, seeds of A. contortuplicatus may travel up to 1600 km inside the digestive tract of migrating individuals. Our results suggest that avian vectors may be more important for the dispersal of rare higher plants (especially those with a hard seed-coat) than hitherto considered. Moreover, they suggest that rarity does not necessarily indicate limited dispersal ability, and may instead be explained by specific habitat requirements.