Document Detail

Fruit tracking, frugivore satiation, and their consequences for seed dispersal.
MedLine Citation:
PMID:  18270742     Owner:  NLM     Status:  MEDLINE    
Vertebrate frugivore communities are easily satiated by abundant fruit supplies and, contrary to abiotic dispersal agents, typically disperse only part of the available seed pool. This frugivore satiation is likely to be a widespread phenomenon and should be an influential predictor of plants' ability to disperse their offspring to suitable establishment sites; yet it has never been systematically quantified. Here I investigate patterns of fruit abundance, frugivore activity and frugivore satiation, and their consequences for seed dispersal in the fleshy-fruited tree Frangula alnus. Based on constant-effort seed trapping conducted over 3 years, I assess densities of total and frugivore-consumed seedfall across two spatial (within/between populations) and two temporal (within/between ripening seasons) scales. Furthermore, I examine relationships between fruit abundance and the amount of seeds that are actually dispersed away from fruiting trees. Frugivore activity tightly matched fruit abundance, although some differences existed between scales. This marked fruit tracking did not prevent a significant frugivore satiation, however, and only 53% of the available fruit crops were actually consumed. The extent of satiation varied most at the within-population level, likely due to the territorial behaviour of important frugivore species. In contrast, levels of satiation remained remarkably invariable through time, suggesting that frugivores behave as opportunists and closely adjust the composition of their diet to the available food supply. Overall, greater fruit abundance resulted in a higher proportion of seeds falling beneath fruiting trees, but it also helped increase the (absolute) number of seeds dispersed. This study shows that frugivore satiation can be an important phenomenon even when frugivores tightly track fruit abundance. Its negative effects on recruitment may be attenuated, however, if greater fruit crops help increase population-wide frugivore activity and the amount of seeds being dispersed to suitable establishment sites.
Arndt Hampe
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-02-13
Journal Detail:
Title:  Oecologia     Volume:  156     ISSN:  0029-8549     ISO Abbreviation:  Oecologia     Publication Date:  2008 May 
Date Detail:
Created Date:  2008-04-16     Completed Date:  2008-09-23     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0150372     Medline TA:  Oecologia     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  137-45     Citation Subset:  IM    
INRA, UMR 1202 Biodiversity, Genes and Communities (BIOGECO), 69 Route d'Arcachon, 33612 Cestas Cedex, France.
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MeSH Terms
Birds / physiology*
Feeding Behavior
Frangula / physiology*

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