ORNIS SVECICA 15: 113–118, 2005 https://doi.org/10.34080/os.v15.22743 Seasonal changes in the number of the Grey Heron Ardea cinerea occurring on Kolut fishponds in northern Serbia Säsongsförändringar av antalet gråhägrar Ardea cinerea vid Kolut fiskdammar i norra Serbien MARKO TUCAKOV Abstract The number of Grey Herons Ardea cinerea occurring at tumn (August to December) than in spring (January to different times of the year on Kolut fishponds in north- April). There was no significant difference between the ern Serbia was monitored between 1998 and 2003. With spring months in the number of herons while there was data pooled over the years, the number of birds occur- significantly more herons occurring in November than ring in the the non-breeding period, August to April, in the other autumn months. The number of Grey Her- varied significantly between months. The number of ons correlated with the number of Great White Egrets overwintering herons was low and then increased sig- Egretta alba, meaning that also the number of Great nificantly to reach a spring peak in March. In April the White Egrets increased when the number of herons did number decreased before breeding, probably because so. migrating individuals left the area. In autumn there was an even higher peak in November compared to the Marko Tucakov, Marka Oreškoviça 9, 25275 Backi Breg, spring peak. Significantly more herons occurred in au- Serbia and Montenegro; e-mail:
[email protected] Received 3 January 2005, Accepted 25 February, Editor: A. Brodin be the most important type of stopover site, with Introduction numerous flocks of herons present at many loca- In Europe, the Grey Heron is a migratory, partially tions outside the breeding season (Šoti & Dimitri- migratory and dispersive species.