, Volume 153, Issue 4, pp 903–911 | Cite as

Acorn dispersal estimated by radio-tracking

  • Josep Pons
  • Juli G. PausasEmail author
Plant Animal Interactions


Bird-dispersed seeds are difficult to track, especially in the case of long-distance dispersal events. To estimate the oak dispersal distance and the seed shadow generated by the European jay (Garrulus glandarius), we inserted radio-transmitters in 239 acorns, placed them in bird-feeders and then located them by radio-tracking. Using this methodology we located the exact caching site of 94 Quercus ilex and 54 Q. suber acorns and determined the caching habitat characteristics (vegetation type, distance, spatial distribution). The results show that: (1) there is no differences in the dispersal distance distribution between the different acorn species or sizes, (2) dispersal distances range from approximately 3 m up to approximately 550 m (mean = 68.6 m; median = 49.2 m), (3) recently abandoned fields and forest tracks were the sites preferred by jays to cache acorns, whereas fields and shrublands were avoided and (4) seed shadows showed acorn aggregation zones (i.e. clusters of caches) close to the feeder as well as isolated caches at longer distances. The results also suggest that radio-transmitters are a cheap and reliable way to determine seed shadows and quantify both seed dispersal and post-dispersal seed predation for medium to large seeds.


Cork oak Dispersal shadow European jay (Garrulus glandariusHolm oak Quercus ilex Quercus suber Seed radio-tracking 



We thank P. Jordano for helpful comments on a draft version of this paper, Aina Blasco for her kind contribution to the fieldwork and J. Cortina for lending us part of the radio-tracking material. Comments from the three anonymous referees helped to improve the paper. This work has been financed by the EU project CREOAK (QLRT-2001-01594) and the Spanish project VARQUS (CGL2004-04325/BOS). The CEAM is funded by Generalitat Valenciana and Bancaixa.


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Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  1. 1.CEAM Fundación Centro de Estudios Ambientales del MediterráneoPaternaSpain
  2. 2.Departament d’EcologiaUniversitat d’AlacantAlacantSpain

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