@misc{Witkowski_Józef_Population_1983,
 author={Witkowski, Józef},
 editor={Polska Akademia Nauk. Instytut Zoologii},
 copyright={Creative Commons Attribution BY 3.0 PL license},
 address={Warszawa},
 howpublished={online},
 year={1983},
 language={eng},
 language={rus},
 language={pol},
 abstract={This study was performed during the period 1972 to 1977. The goose population numbered 280-312 pairs. A similar number was reported before World War II and then after 1960. Between these dates there occurred a sudden drop (of approx. 75%) caused by a sharp increase in the exploitation of geese by man. The population study was performed on 122-154 paire of goose breeding in one of the fish-pond complexes. The geese nested exclusively on ponds. The time of start of egg laying coincided with the disappearance of ice cover, which could be explained in terms of antipredatory behaviour. The clutch size per breeding female ranged from 2 to 10 (12?) eggs, the mean value in different seasons being 4.9 to 5.6 eggs. No relationship was noted between mean clutch size and time of commencement of the nesting period. The mean clutch size decreased from 6. 7 to 3.5 as the season passed. Almost all of the clutches with more than 10 eggs were laid by two females. 44.2 % of nests ended in a failure. The main causes were predation by the hooded crow and abandonment of nests, in similar proportions. Other causes accounted for only 0.9 %. In successful clutches the rate of hatching success was 90.4%. Mortality of the young (till fledging) was 27.4 %. The mean production of young per breeding pair in one season was 2 young. The ratio of actual to potential production was 38%. This was sufficient to ensure stability of the goose population.},
 type={Text},
 title={Population studies of the grey-lag goose Anser anser breeding in the Barycz valley, Poland},
 URL={http://rcin.org.pl/Content/71227/PDF/WA058_38373_P257-T19_Acta-Ornith-Nr-8.pdf},
 volume={19},
 number={1-6},
 journal={Acta Ornithologica},
 publisher={Państwowe Wydawnictwo Naukowe},
 keywords={Graylag Goose, ecology, breeding birds, Poland, Barycz River Valley, populations, Greylag Goose, Grey-lag Goose, birds, Anser anser, Anatidae, Aves},
}