Synzoochoryczne rozsiewanie żołędzi przez sójki Garrulus glandarius na powierzchniach zrębowych oraz pod drzewostanem

The aim of this study was to analyse the preferences of jays in terms of oak acorn deposition in accordance to availability of some types of habitat. Investigations were carried out in forested areas of the Olsztyn Lakeland (NE Poland) with Scots pine forests domination. In autumn of 2014 and 2015 122 acorns of Quercus robur with concealed Telenax transmitters were served in four locations and then dispersed by jays Garrulus glandarius. Acorns with transmitters were radio tracked and localized after dispersion in different types of habitats. We distinguished three types of habitat: forest stands >40 years old, young forests <25 years old as well as clear−cuts and other open areas. The availability of habitats were estimated by 144 random points (36 per each location). Obtained availability/utilisation data were analyzed with chi square test ( =0.05). Results showed that majority (76.4%) of dispersed acorns were deposited under canopy of Scots pine stands, while only 8.2% were deposited on clear−cuts and other open areas. It seems that jays avoid to scatter its caches among clear−cuts and other open areas when availability of these types of environment is compared. Jays preferred to scatter the acorns under canopy of older (>40 years old) stands. It proves that the regeneration of oaks in clear−cuts is with low probability of success. The results suggest that density and high quality of regeneration that occurred on some of the clear−cuts seem to be a synchronization relic of oaks' mast crop and Scots pine fellings. In these circumstances the best solution to obtain oak regeneration is to synchronize the harvest with mast crops and carry it out immediately after acorn production to make an oak regeneration success guaranteed.