Directed dispersal of mistletoe (Plicosepalus acaciae) by Yellow-vented Bulbuls (Pycnonotus xanthopygos)

Abstract

We studied avian dispersal of seeds from the hemiparasitic mistletoe Plicosepalus acaciae (Loranthaceae) to its tree hosts Acacia raddiana and A. tortilis in the Syrian–African Rift (Arava) valley, Israel. The Yellow-vented Bulbul (Pycnonotus xanthopygos) was the sole avian visitor observed feeding on mistletoe fruits. Bulbuls consumed mistletoe fruits whenever they were available, but the fruits only constituted a significant portion of the diet (71% of foraging attempts) when they were most abundant. These birds are potentially good dispersal vectors of P. acaciae because they swallowed the fruit whole and defecated viable seeds that were covered in a viscid pulp, which allowed the seeds to adhere to substrates when voided. In addition, bulbuls spent a large proportion (66–93%) of total observation time perched in Acacia trees, allowing for directed dispersal. Ephemeral river valleys (wadis) with high mistletoe infection were adjacent to those containing no infections, demonstrating that mistletoe dispersal is common within, but not among wadis. This is consistent with the flight behaviour in bulbuls, which do not typically move among wadis. We combined data on bulbul movements between Acacia trees with transit times of mistletoe seeds to create a hypothetical seed shadow as a function of distance from the parent mistletoe plant. Because they are directed dispersers, the movement patterns of bulbuls may explain the current distribution of P. acaciae in the Arava valley.

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References

  1. Aukema JE, Martínez del Rio C (2002) Where does a fruit-eating bird deposit mistletoe seeds? Seed deposition patterns and an experiment. Ecology 83:3489–3496

    Article  Google Scholar 

  2. Bowie M, Ward D (2004) Water and nutrient status of the mistletoe Plicosepalus acaciae parasitic on isolated Negev Desert populations of Acacia raddiana differing in level of mortality. J Arid Environ 56:487–508. doi:10.1016/S0140-1963(03)00067-3

    Article  Google Scholar 

  3. Denslow JS, Levey DJ, Moermond TC, Wentworth BC (1987) A synthetic diet for fruit-eating birds. Wilson Bull 99:131–134

    Google Scholar 

  4. Halevy G, Orshan G (1972) Ecological studies on Acacia species in the Negev and Sinai: I. Distribution of Acacia raddiana, A. tortilis and A. gerrardii ssp. negevensis as related to environmental factors. Isr J Bot 21:197–208

    Google Scholar 

  5. Howe HF, Smallwood J (1982) Ecology of seed dispersal. Annu Rev Ecol Syst 13:201–228. doi:10.1146/annurev.es.13.110182.001221

    Article  Google Scholar 

  6. Ladley JJ, Kelly D (1996) Dispersal, germination and survival of New Zealand mistletoes (Loranthaceae): dependence on birds. NZ J Ecol 20:69–79

    Google Scholar 

  7. López de Buen L, Ornelas JF (1999) Frugivorous birds, host selection, and the mistletoe Psittacanthus schiedeanus, in central Veracruz, Mexico. J Trop Ecol 15:329–340. doi:10.1017/S0266467499000851

    Article  Google Scholar 

  8. Martínez del Rio C, Silva A, Medel R, Hourdequin M (1996) Seed dispersers as disease vectors: bird transmission of mistletoe seeds to plant hosts. Ecology 77:912–921. doi:10.2307/2265511

    Article  Google Scholar 

  9. Murray GK (1988) Avian seed dispersal of three neotropical gap-dependent plants. Ecol Monogr 58:271–298. doi:10.2307/1942541

    Article  Google Scholar 

  10. O’Donnell CFJ, Dilks PJ (1994) Foods and foraging of forest birds in temperate rainforest, South Westland, New Zealand. NZ J Ecol 18:87–107

    Google Scholar 

  11. Overton JM (1994) Dispersal and infection in mistletoe metapopulations. J Ecol 82:711–723. doi:10.2307/2261437

    Article  Google Scholar 

  12. Paz U (1987) The birds of Israel. Ministry of Defense, Tel-Aviv

    Google Scholar 

  13. Reid N (1989) Dispersal of mistletoes by honeyeaters and flowerpeckers: components of seed dispersal quality. Ecology 70:137–145. doi:10.2307/1938420

    Article  Google Scholar 

  14. Reid N (1991) Coevolution of mistletoes and frugivorous birds. Aust J Ecol 16:457–469. doi:10.1111/j.1442-9993.1991.tb01075.x

    Article  Google Scholar 

  15. Reid N, Stafford-Smith M (2000) Population dynamics of an arid zone mistletoe (Amyema preissii, Loranthaceae) and its host Acacia victoriae (Mimosaceae). Aust J Bot 48:45–58. doi:10.1071/BT97076

    Article  Google Scholar 

  16. Robertson AW, Trass A, Ladley JJ, Kelly D (2006) Assessing the benefits of frugivory for seed germination: the importance of the deinhibition effect. Funct Ecol 20:58–66. doi:10.1111/j.1365-2435.2005.01057.x

    Article  Google Scholar 

  17. Rödl T, Ward D (2002) Host recognition in a desert mistletoe: early stages of development are influenced by substrate and host origin. Funct Ecol 16:128–134. doi:10.1046/j.0269-8463.2001.00592.x

    Article  Google Scholar 

  18. Shirihai H (1996) The birds of Israel. Academic, London

    Google Scholar 

  19. Shrestha MK, Golan-Goldhirsh A, Ward D (2002) Population genetic structure and the conservation of isolated populations of Acacia raddiana in the Negev desert. Biol Conserv 108:119–127. doi:10.1016/S0006-3207(02)00100-3

    Article  Google Scholar 

  20. Todt H, Breckle S-W, Veste M (2000) The mistletoe Loranthus acaciae (Loranthaceae) on halophytic and non-halophytic hosts in the southern Arava-Valley (Israel). In: Breckle S-W (ed) I Schimper symposium—Ergebnisse weltweiter Forschung. Verlag Gunter Heimbach, Stuttgart, pp 475–480

    Google Scholar 

  21. Vaknin Y, Yom Tov Y, Eisikowitch D (1996) Flowering seasonality and flower characteristics of Loranthus acaciae Zucc. (Loranthaceae): implications for advertisement and bird-pollination. Sex Plant Reprod 9:279–285. doi:10.1007/BF02152703

    Article  Google Scholar 

  22. Ward D, Shrestha MK, Musli I (2006) Are invasive mistletoes killing Ziziphus spina-christi? Isr J Plant Sci 54:113–117. doi:10.1560/IJPS_54_2_113

    Article  Google Scholar 

  23. Watson DM (2001) Mistletoe—a keystone resource in forests and woodlands worldwide. Annu Rev Ecol Syst 32:219–249. doi:10.1146/annurev.ecolsys.32.081501.114024

    Article  Google Scholar 

  24. Wenny DG (2001) Advantages of seed dispersal: a re-evaluation of directed dispersal. Evol Ecol Res 3:51–74

    Google Scholar 

  25. Wheelwright NT, Orians GH (1982) Seed dispersal by animals: contrasts with pollen dispersal, problems of terminology, and constraints on coevolution. Am Nat 119:402–413. doi:10.1086/283918

    Article  Google Scholar 

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Acknowledgements

We thank Thomas Rödl and Iris Musli for assistance with many aspects of this research and Berry Pinshow for the use of his laboratory. Financial assistance came from Keren Keyemet L’Israel and DISUM grant 00046A from the German Ministry of Environmental Affairs and the Israeli Ministry of Science to D. Ward, Sigma Xi and NSF pre-doctoral fellowships to A.K. Green, and a Claude Leon Foundation postdoctoral fellowship to M.E. Griffiths.

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Correspondence to Adam K. Green.

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Communicated by T. Friedl.

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Green, A.K., Ward, D. & Griffiths, M.E. Directed dispersal of mistletoe (Plicosepalus acaciae) by Yellow-vented Bulbuls (Pycnonotus xanthopygos). J Ornithol 150, 167–173 (2009). https://doi.org/10.1007/s10336-008-0331-9

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Keywords

  • Directed dispersal
  • Foraging behaviour
  • Frugivory
  • Negev desert
  • Seed shadow
  • Transit time