114 INTRODUCTION TO PLANT GEOGRAPHY [CHAP. 



blown out to sea in a gale — or during repeated shorter ' hops ' which 

 sooner or later may amount to considerable traverses. Ridley cites 

 numerous instances of aquatics, etc., being evidently dispersed to 

 isolated ponds and marshes by Water-fowl. Kerner {see the work 

 cited at the end of this chapter), like Darwin, secured ' a sufficiently 

 striking result ' with fertile seeds in ' the mud obtained from the 

 beaks, feet, and feathers of swallows, snipe, wagtails, and jackdaws 

 , . . and when it is remembered that pigeons and cranes traverse 

 from 60 to 70 kilometres in an hour, whilst swallows and peregrine 

 falcons cover as much as 180 kilometres, it is clear that fruits and 

 seeds affixed to these birds may be carried in a very short time over 

 several degrees of latitude '. 



An interesting case in point seems to be furnished by the sub- 

 antarctic Macquarie Island, situated approximately 650 km. from 

 the nearest other land, and supporting thirty-five known species of 

 vascular plants. It has recently been contended that all of these 

 could well have been, and indeed probably were, brought in by Sea- 

 birds since the end of the Pleistocene glaciation. Of these Sea-birds, 

 vast numbers inhabit the island and many are known to make long 

 flights to South America, New Zealand, and to other subantarctic 

 islands. Moreover, many of the habitats on the island, as on 

 mountains and in the Arctic, are conveniently ' open ' for the growth 

 of immigrants. Unidentified seeds, apparently not belonging to 

 any of the local species, have been found on Macquarie Island on 

 Black-browed Albatrosses, adhering to the feet and so coated with 

 regurgitate that they ' could be carried almost indefinitely in flight 

 and could withstand immersion in sea water if the bird alighted to 

 rest, yet on landing the seeds would be easily rubbed off ' (Ecology, 

 ^'oJ- 35. P- 570. October 1954). 



As for endozoic transportation, the effectiveness of this will 

 depend not only on resistance to digestion but also on times of 

 retention within the Bird's body. Sometimes, especially after 

 gorging, seeds may be regurgitated at a distance, without passing 

 through the alimentary canal. Kerner found that whereas many 

 types of Birds have in their excreta ' under ordinary conditions ' no 

 seed capable of germination, some others may void unharmed up 

 to 88 per cent, of the small and smooth seeds or fruits eaten, though 

 retention in such cases is commonly for only some two or three 

 hours. But Ridley quotes a report of Pigeons being shot at Albany, 

 N.Y., ' with green rice in their crops, w^hich it is thought must 

 have been growing, a very few hours before, at a distance of 700 



