The droppings of the Grey Partridge Perdix perdix L. wintering on a set-aside field were found to contain 99.3% of Amaranthus retroflexus and 0.7% of Chenopodium album seed coat fragments. A bird consumed on average 3008 (± 95% CL = 2699–3317) weed seeds per 1 g of droppings. The excreted seed coat remnants made up c. 21% of the swallowed seed mass. Approximately 0.3% of the ingested seeds passed undamaged through the gut. The number of undamaged seeds in the droppings was not significantly correlated with the weight of droppings and the amount of the excreted sand grains, seed coat fragments and other plant parts. After over 1.5 years of storage, 3 out of 18 sown undamaged seeds of A. retroflexus germinated. The average germination time of the excreted seeds was 10 days, while for the fresh ones it amounted to 8.5 days. Our results shows that the Gray Partridge is poor seed disperser and it play important role as predator of A. retroflexus seeds.
Montia linearis is a vascular plant originating from western North America. The expansion of this species has been observed for several decades. For the first time M. linearis was found in Europe in 1989. Further six populations were documented by 2004 within the continent: three in Poland, two in Denmark and one in Hungary. Apart from discovering a new population of M. linearis, we confirmed two out of the three previously known localities of the species in Poland. All the currently known populations of M. linearis occupied predominantly meadow habitats, especially intensively managed sites. Some individuals were also found in disturbed sites with bare soil. The studied species inhabited soils of various types with broad range of fertility as well as humidity. Montia linearis populations reached densities up to 87 individuals per 0.04 m2. The number of seeds produced by an individual was between 10 and 55 in 90% of the studied specimens, however much more fertile specimens were also observed. As the previously presented hypothesis of M. linearis dispersal with rail transport seemed not to be well supported, the connection between the M. linearis presence and cattle husbandry is considered. It is possible that the species can be transferred with living animals or manure. The species was able to survive for at least 26 years within once inhabited site. Further spread of M. linearis within Europe is highly probable. The aim of the study is to: (i) describe the current state of populations of M. linearis in Poland, (ii) provide information on habitat preferences and biology of the species, (iii) assess the invasiveness potential of M. linearis in Poland.
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