page_title: Dispersal vector
section_title: Ornithochory
hierarchical_section_title: Dispersal vector / Animal dispersal / Ornithochory
caption_attribution_description: Owl Pellet
context_page_description: A dispersal vector is an agent of biological dispersal that moves a dispersal unit, or organism, away from its birth population to another location or population in which the individual will reproduce. These dispersal units can range from pollen to seeds to fungi to entire organisms.
  There are two types of dispersal vector, those that are active and those that are passive. Active dispersal involves organisms that are capable of movement under their own energy. In passive dispersal, the organisms have evolved dispersal units, or propagules, that use the kinetic energy of the environment for movement. In plants, some dispersal units have tissue that assists with dispersal and are called diaspores. Some dispersal is self-driven, such as using gravity, and does not rely on external vectors. Other types of dispersal are due to external vectors, which can be biotic vectors, such as animals, or abiotic vectors, such as the wind or water.
  In many cases, organisms will be dispersed by more than one vector before reaching its final destination.
context_section_description: Birds contribute to seed dispersal in several ways that are unique from general vectors. Birds often cache, or store, the seeds of trees and shrubs for later consumption; only some of these seeds are later recovered and eaten, so many of the seeds are able to utilize the behavior of seed caching to allow them to germinate away from the mother tree.
  Long-distance dispersal, which is rare for a parent plant to achieve alone, could be mediated by migratory movements of birds. Long-distance dispersal operates over spatial areas that span thousands of kilometers, which allow it to promote rapid range shifts and determine species distributions.
  In seed dispersal, ingestion of seeds that are capable of resisting digestive juices allows the seeds to be scattered in feces and dispersed far from the parent organism. For these seeds, gut passage enhances germination ability when the seeds are ingested by birds and mammals.
  Finally, ingestion of herbivores by carnivorous animals may help disperse seeds by preying on primary seed dispersers such as herbivores or omnivores. When a bird is eaten by a cat or another carnivore, that animal will inadvertently consume the seeds that the prey species consumed. These seeds may then be later deposited in a process called diplochory, where a seed is moved by more than one dispersal vector, which is important for seed dispersal outcomes as carnivores range widely and enhance the genetic connectivity of dispersed populations.
  Birds act as dispersal vectors for non-seed dispersal units as well. Hummingbirds spread pollen on their beaks, and fungal spores may stick to the bottom of birds’ feet. Water birds may also help to disperse aquatic invertebrates, specifically branchiopods, ostracods, and bryozoans.
caption: Barn owl pellets containing pouched mouse remains have been found to contain germinating seeds.[8]
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