W latach 2005–2007 przeprowadzono liczenie gniazd w koloniach lęgowych gawrona Corvus frugilegus na terenie Gniezna. Wykazano obecność odpowiednio 180, 160 i 138 zasiedlonych gniazd, zlokalizowanych w dziewięciu miejscach. Były to małe kolonie liczące 4–40 gniazd. Stwierdzono wyższe zagęszczenie par lęgowych (4,34 par/km2 w 2005 r., 3,90 par/km2 w 2006 r., 3,36 par/km2 w 2007 r.) niż przeciętnie dla całej Wielkopolski (1,02–1,15 par/km2)
In a group of sound females in the age from 21 - 40 years and in the adolescents 16 - 20 years hair analysis was conducted. In the younger group magnesium and zinc levels were higher than the Polish reference values (IEK- WAT-Warsaw). The levels of calcium and zinc with pregriant females were higher and the level of copper was lower than the norm. No deviations were found with adnimis- trative workers.
In a group of sound man in the age from 21 - 40 years hair analysis was conducted. The levels of lead and chromium were higher then the reference values. The levels of cadmium and lesd in blood serum were in norm in other groups. The calcium level was lower then the Polish norm in general.