Raptors can be effective seed dispersers

21 Apr 2016 - 11:10 -- Eduardo de Juana

On the oceanic island of Fuerteventura in the Canary Islands, an examination of 300 and 319 pellets, respectively, of two native predatory birds, the Eurasian Buzzard (Buteo buteo) and the Common Kestrel (Falco tinnunculus), found up to 11,000 weed seeds from a total of 39 and 62 different plant species, respectively#R. Both raptors consumed invasive mammals: rabbits (Oryctolagus cuniculus) and ground squirrels (Atlantoxerus getulus), that carried these seeds in their guts. Despite the time interval between pellet collection and germination experiments, almost 10% of planted seeds germinated, even after passing through two digestive processes, one inside a mammal and another inside a raptor. Mesembryanthemum nodiflorum and Aizoon canariense were the two plant species appearing with the greatest frequency in both raptor pellets. Raptors are not usually considered as important seed dispersers but this study suggests that they may have an important ecological role as seed dispersers of weeds, since the extents of their home-ranges may far exceed those of the primary dispersers.

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Eurasian Buzzard (Buteo buteo)

Taxonomy:

Falco Buteo

Linnaeus, 1758, Sweden.

Has sometimes been considered conspecific with B. oreophilus, B. trizonatus and also B. brachypterus, and until recently...

Descriptive notes: 40–52 cm; male 427–1180 g, female 486–1360 g; wingspan 109–136 cm. Extremely variable. Generally dark brown above and on most of underbody and underwing coverts; from below, wingtip and trailing edge of...
figure, drawing, illustration of Eurasian Buzzard (Buteo buteo)

Common Kestrel (Falco tinnunculus)

Taxonomy:

Falco Tinnunculus

Linnaeus, 1758, Sweden.

May form a species-group with F. newtoni, F. punctatus and F. araeus, probably including also F. moluccensis and F....

Descriptive notes: 27–35 cm; male 136–252 g, female 154–314 g (nominate race); wingspan 57–79 cm. Head and tail grey, with subterminal black band on tail; outer half of upperwing dark; rest of upperwing and back...
figure, drawing, illustration of Common Kestrel (Falco tinnunculus)