Seed Dispersal by Rooks (Corvus frugilegus) - with Focus on Non-Native Species


  • Amalie Slot Sørensen Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark
  • Majken Pagter Department of Chemistry and Bioscience, Aalborg University, 9220 Aalborg, Denmark
  • Sussie Pagh University of Aalborg



vegetation survey, regurgitation pellets, invasive species, zoochory


Seed dispersal is an essential ecological function, and many plants depend on dispersal mediated by animals (zoochory). Zoochory is important for the natural succession and regeneration of plant communities but may also play a role in the dispersal of non-native and invasive species with damaging ecosystem effects. The rook (Corvus frugilegus) is an omnivorous species eating a broad variety of seeds and therefore potential to disperse a wide range of seeds in both natural and urban habitats. In this study seed dispersal by rooks in Central and Northern Jutland, Denmark was examined through examination of regurgitation pellets and vegetation studies. The aim of the study was to investigate i) to what extent rook regurgitation pellets found under rookeries contain seeds; ii) which seed species are found, including whether pellets contain seeds of non-native species; iii) if the plant species found in the regurgitated pellets were found in the vegetation under rookeries. Regurgitation pellets were collected from April to June beneath rookeries. In total 124 seeds representing 8 taxa were found in 153 pellets. Most of the seed species were cereals and other dry-fruited species, mainly weeds and ruderal species. The study showed that Danish rooks canact as seed dispersers. Cereals and other dry-fruited species such as weeds, and ruderal species were the dominant seeds found in rook pellets. No non-native species were found. However, this does not exclude the possibility of the rooks being able to disperse them. The lack of exotic fruit found in the pellets of Danish rooks may be due to waste management in Denmark, not having open waste dumps and open compost heaps with spill overs from the kitchen is not recommended. A vegetation survey under rookeries showed that only Stellaria media was found both in regurgitation pellets and in the vegetation beneath rookeries, suggesting that many dispersed seeds are unable to germinate or survive under the tree canopies at the rookeries.


Bartuszevige AM. Gorchov DL. 2006. Avian seed dispersal of an invasive shrub. Biological Invasions 8(5):1013-1022. DOI:10.1007/s10530-005-3634-2

Benvenuti S. 2007. Weed seed movement and dispersal strategies in the agricultural environment. Weed biology and management 7(3):141-157.

Bitarafan Z. Andreasen C. 2019. Harvest weed seed control: Seed production and retention of Fallopia convolvulus, Sinapis arvensis, Spergula arvensis and Stellaria media at spring oat maturity. Agronomy 10(1):46. DOI:

Borkowska L. Królak E. Kasprzykowski Z. Kaczorowski P. 2015. The influence of Corvus frugilegus nesting on soil parameters and plant composition in poor and fertile habitats. Landscape and Ecological Engineering 11(1):161-167. DOI: 10.1007/s11355-014-0256-9

Czarnecka J. Kitowski I. 2010. Seed dispersal by the rook Corvus frugilegus L. in agricultural landscape–mechanism and ecological importance. Polish Journal of Ecology 58(3):511-523.

Czarnecka J. Kitowski I. 2013. Rook spring seed dispersal in the agricultural landscape–frugivory, granivory or accidental transport? Folia Geobotanica 48(1):55-73. DOI:10.1007/s12224-012-9134-0

Czarnecka J. Kitowski I. Sugier P. Mirski P. Krupin´ski D. et al. 2013. Seed dispersal in urban green space–does the rook Corvus frugilegus L. contribute to urban flora homogenization? Urban forestry & urban greening 12(3):359-366. DOI:10.1007/s12224-012-9134-0

Department of Agroecology at Aarhus University & SEGES Innovation 2022. Planteværn online.

Fog M. 1963. Distribution and food of the Danish rooks. Communication nr. 33. Danish Review of Game Biology.

Fredshavn J. Nielsen KE. Ejrnæs R. Nygaard B. 2022. Tekniske anvisninger til overvågning af terrestriske naturtyper. Technical report, Fagdatacenter for Biodiversitet og Terrestrisk Natur, DCE, Aarhus Universitet, N01. Version 4.1.

Gosper CR. Stansbury CD. Vivian-Smith G. 2005 Seed dispersal of fleshy-fruited invasive plants by birds: contributing factors and management options. Diversity and distributions 11(6):549-558.

Green AJ. Elmberg J. Lovas-Kiss Á. 2019. Beyond scatter-hoarding and frugivory: European corvids as overlooked vectors for a broad range of plants. Frontiers in Ecology and Evolution 7(133). DOI:10.3389/fevo.2019.00133

Gromadzka J. 1980. Food composition and food consumption of the rook Corvus frugilegus in agrocoenoses in Poland. Acta Ornithologica 17.

Groningen Institute of Archaeology & Deutsches Archäologisches Institut 2006. Digital plant atlas.

Holland J. Hutchison M. Smith B. Aebischer N. 2006. A review of invertebrates and seed-bearing plants as food for farmland birds in Europe. Annals of Applied Biology, 148(1):49-71. DOI :

Holmstrup G. Schjelde J. Lundsgaard R. Nygaard T. Ogstrup L. et al (2018). Sådan ligger landet– tal om landbruget 2017. Technical report, Danmarks Naturfredningsforening og Dyrenes Beskyttelse, pp 6-12.

International Seed Morphology Association 2019. Seed identification guide. Accessed 24 April 2022.

Jordano P. 2000. Fruits and frugivory. In: Fenner M (ed) Seeds: The Ecology of Regeneration in Natural Plant Communities. CABI Publishing, Wallingford, pp 125-166.

Kettunen M. Genovesi P. Gollasch S. Pagad S. Starfinger U. et al. 2008. Technical support to EU strategy on invasive alien species (IAS) — Assessment of the impacts of IAS in Europe and the EU (final module report for the European Commission). Technical report, Institute for European Environmental Policy (IEEP), Brussels, Belgium.

Kitowski I. Sandor AD. Czarnecka J. Grzywaczewski G. 2017. Diet of rooks Corvus frugilegus and potential seed dispersal in urban and agricultural habitats of Romania and Poland. North-Western Journal of Zoology 13(1). Diet_of_Rooks_Corvus_frugilegus_and_potential_seed_dispersal_in_urban_and_agricultural_habitats_of_Romania_and_Poland.

Lenda M. Skórka P. Knops JM. Moroń D. Tworek S. et al. 2012. Plant establishment and invasions: an increase in a seed disperser combined with land abandonment causes an invasion of the non-native walnut in Europe. Proceedings of the Royal Society B: Biological Sciences 279(1733):1491-1497. DOI:

Lindman CAM. & Keuck G. 1999. Bilder ur Nordens Flora (1901-1905). Accessed 15 April 2022.

Millennium Ecosystem Assessment 2005. Ecosystems and human well-being: Biodiversity Synthesis. World Resources Institute, Washington, DC. ISBN 1-59726-040-1.

Nogales M. Hernández EC. Valdés F. 1999. Seed dispersal by common ravens Corvus corax among island habitats (Canarian Archipelago). Ecoscience 6(1):56-61. DOI:

Orłowski G. & Czarnecka J. 2009. Granivory of birds and seed dispersal: viable seeds of Amaranthus retroflexus L. recovered from the droppings of the grey partridge Perdix perdix L. Pol. J. Ecol 57(1):191-196.

Padrón B. Nogales M. Traveset A. Vilá M. Martínez-Abraín A. et al. 2011. Integration of invasive Opuntia spp. by native and alien seed dispersers in the Mediterranean area and the Canary Islands. Biological invasions 13(4):831-844. DOI:

Pyšek P. Hulme PE. Simberloff D. Bacher S. Blackburn TM. et al. 2020. Scientists’ warning on invasive alien species. Biological Reviews 95(6):1511-1534. DOI: 10.1016/j.ecolind.2019.106020

Rai PK. Singh J. 2020. Invasive alien plant species: Their impact on environment, ecosystem services and human health. Ecological indicators 111:106020. DOI: 10.1016/j.ecolind.2019.106020

Richardson DM. Allsopp N. D’Antonio CM. Milton SJ. Rejmánek M. 2000. Plant invasions–the role of mutualisms. Biological Reviews 75(1):65-93. DOI: 10.1017/s0006323199005435

Valladares F. Laanisto L. Niinemets Ü. Zavala MA. 2016. Shedding light on shade: ecological perspectives of understorey plant life. Plant Ecology & Diversity 9(3):237-251.

Weir JS. 1969. Importation of nutrients into woodlands by rooks. Nature 221(5179):487-488. DOI:




How to Cite

Sørensen, A. S. ., Pagter, M. ., & Pagh, S. (2023). Seed Dispersal by Rooks (Corvus frugilegus) - with Focus on Non-Native Species . Genetics & Biodiversity Journal, 7(2), 186–194.



Original Article

Most read articles by the same author(s)

1 2 > >>