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Article 4

Birds outnumber insects in visiting Brassica flowers on Ventotene Island (Central Mediterranean)

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J. G. Cecere1,2, L. Cornara3, F. Spina2, S. Imperio4, L. Boitani1
1 Department of Biology and Biotechnology Charles Darwin, University of Rome “La Sapienza”,Viale dell’Università 32, 00185 Roma, Italy
2 Istituto Superiore per la Protezione e la Ricerca Ambientale, Via Cà Fornacetta 9, 40064 Ozzano Emilia (BO), Italy
3 Dipartimento per lo Studio del Territorio e delle sue Risorse (Dip.Te.Ris.), Polo Botanico Hanbury, Corso Dogali 1M, 16136 Genova, Italy
4 RicercaFauna, Via Caio Canuleio 83, 00174 Roma Italy
Corresponding author: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

ABSTRACT. – European warblers migrating across the Mediterranean feed on nectar at stopover sites on islands, thus carrying pollen grains stuck to bills and plumage from one stopover to the next. Plants belonging to a single wild species of the Brassica oleracea group are largely used by songbirds for nectar feeding at Ventotene island and their pollen is commonly found on staging warblers. We studied the potential role of nectar feeding warblers in pollen dispersion of Brassica plants and compared it to that of insects. The study was carried out at Ventotene from the end of March to mid May during the years 2008 and 2009. Direct observations of bird and insect visits to plants showed that the frequency of bird visits was significantly higher than the frequency of flight-feeding insects, while no significant differences were found between the length of bird and insect visits. Plant caging with a 15 mm-mesh net in order to prevent bird visits, but not insect visits, resulted in a significant lowering of fruit production with respect to control plants. In summary, a mutualistic  relationship could be hypothesised between songbirds and Brassica plants on Ventotene Island. Warbler species obtain a nutritional benefit through nectar consumption, and can transport pollen grains and potentially pollinate exploited plants across stopover sites, with possible implications for pollen carry-over from genetically engineered agricultural crop plants.

You are here: Volume 61 (2011) Issue 3 Article 4
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