Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide


Digestion and excretion (pathway cause)



Digestion and excretion (pathway cause)


  • Last modified
  • 04 October 2022
  • Datasheet Type(s)
  • Pathway Cause
  • Preferred Scientific Name
  • Digestion and excretion (pathway cause)
  • Overview
  • The digestion and excretion pathway is probably the single most important means for plant dispersal or spread within an area once introduced, established and naturalized. Livestock are common vectors in managed systems especially grazing land, w...

Don't need the entire report?

Generate a print friendly version containing only the sections you need.

Generate report


Top of page
Digestion and excretion (pathway cause); fresh American black bear scat (Ursus americanus), showing evidence of its feeding on apples (Malus spp.). Note the many seeds embedded within the faecal matrix. Little Pearl Park, Crestone, Colorado, USA. September 2010.
TitleBear scat
CaptionDigestion and excretion (pathway cause); fresh American black bear scat (Ursus americanus), showing evidence of its feeding on apples (Malus spp.). Note the many seeds embedded within the faecal matrix. Little Pearl Park, Crestone, Colorado, USA. September 2010.
Copyright©Fred Bauder/via wikipedia - CC BY-SA 3.0
Digestion and excretion (pathway cause); fresh American black bear scat (Ursus americanus), showing evidence of its feeding on apples (Malus spp.). Note the many seeds embedded within the faecal matrix. Little Pearl Park, Crestone, Colorado, USA. September 2010.
Bear scatDigestion and excretion (pathway cause); fresh American black bear scat (Ursus americanus), showing evidence of its feeding on apples (Malus spp.). Note the many seeds embedded within the faecal matrix. Little Pearl Park, Crestone, Colorado, USA. September 2010.©Fred Bauder/via wikipedia - CC BY-SA 3.0


Top of page

Preferred Scientific Name

  • Digestion and excretion (pathway cause)

International Common Names

  • English: Endochory; Endozoochory
  • Spanish: Digestión/excreción
  • Portuguese: Digestão/excreção


Top of page

The digestion and excretion pathway is probably the single most important means for plant dispersal or spread within an area once introduced, established and naturalized. Livestock are common vectors in managed systems especially grazing land, whereas wild animals, mostly birds and mammals, often play a critical role in natural or semi-natural systems such as forests. However, there are examples where it has been considered as the cause for international introductions, either from the migration of birds or large herbivores, or the long-distance transport of livestock either by ship, or overland.


Top of page

Summary of organism types or species introduced

Concerning the animal vectors themselves, most invasions via endozoochoric pathways are by large herbivores or birds, though not exclusively so. Many plants are also dispersed by a variety of organism types, though some have a specialized mutual relation with one animal species or a single organism type. Snails consume and disperse seeds from a few species; earthworms are dispersal agents for many more. Some fish also eat the fruits/seeds of fruits that fall on the water surface and aid in dispersal. There are specialized terms for dispersal by digestion and excretion by specific organism types, such as mammaliochory (by mammals), ornithochory (by birds), saurochory (by reptiles) and chiropterochory (by bats). Humans could also be responsible, as demonstrated by the introduction of the tomato as an invasive species on some uninhabited islets in the Galapagos, as they may have been excreted by visiting researchers (if they were not merely dropped). 

As for the species introduced and/or spread, there are far too many invasive plants that have digestion and excretion as a pathway to list exhaustively; it is estimated that 64% of all gymnosperm species and 27% of all angiosperms produce fruit that attract animals (Traveset et al., 2007). Endozoochory is a widely studied area, but a thorough review of the current state of knowledge would be beneficial, though this may require dividing into manageable sub-units for thoroughness.

Principal processes

The process is, as described in the pathway title, digestion and excretion. However, in addition to the geographic movement of seed by animals, other processes may be advantageous to the plant. The first occurs during digestion, as chemicals and/or physical action are widely reported to break the dormancy of the seeds of many species (Traveset et al., 2007). For example, with the hard-coated seed of leguminous plants, germination percentages may be many times more than the control. The second occurs during excretion, with the increased chance of the seed being placed in a favourable micro-environment, i.e., near to a water source, and being enclosed in a ready source of plant nutrients. 

Geographical routes and corridors

Long-distance introduction would have followed migratory routes (natural), or trade routes, overland livestock movements following grazing and water, or to a port or railhead (human-induced). Local spread could be considered to be random, though may be more prevalent where animals are likely to collect, such as roosts, sources of drinking water, etc. 

Human-mediated history

The only anthropogenic role in digestion and excretion as a pathway involves the raising and movement of domesticated livestock. Long-distance endozoochory is thought to have been responsible for some plant introductions, in livestock transported by ship or overland. However, this has been mainly responsible for the spread of invasive plants on managed and natural grasslands, and extensive grazing land such as steppes, savannas and other dry areas, even deserts. Significant areas in the Americas were invaded by native legume trees in the late 1850s, e.g. Texas and the southwestern USA, and the Chaco of Argentina and Paraguay, when cattle ranching was introduced, disturbing the ecosystem and providing native trees with an environment where they 'densified' into impenetrable monocultures. Many other examples have since been identified, with cattle being the predominant vector, though sheep, goats and camels are also implicated. 

Man has also been indirectly responsible via the introduction of animals into an environment, and which became feral, or naturalized, and these then became vectors for the spread of invasive plants; such as feral pigs, goats and even rabbits and other small mammals, also birds. The invasion of wild fig trees in Australia, which had a restricted range for many decades, is thought to have been triggered by the introduction of the myna bird, which proved to be a very effective dispersal agent. The spread of the fire tree in Hawaii is also considered to be have been induced, but by multiple triggers. Trees had been naturalized for many years, but were few in number, as were feral pigs: the trigger was the introduction and establishment of European earthworms. The pigs now had a sufficient source of food and multiplied, and the ground disturbance from digging for this food provided a very suitable environment for the spread of the fire tree.

Species Transported by Cause

Top of page
SpeciesNotesLong DistanceLocalReferences
Acacia auriculiformis (northern black wattle)Seeds are dispersed by birds Yes Langeland and Burks
Acacia crassicarpa (northern wattle) Yes
Acacia glauca (wild dividivi) Yes
Acacia hockii Yes Wickens et al. (1995)
Acacia mangium (brown salwood)Seeds hang by orange, fleshy funicles that are then eaten by small birds and dispersed Yes Yes Francis (2010)
Acacia mellifera (blackthorn) Yes
Acacia saligna (coojong)Birds Yes Cronk and Fuller (1995)
Aegilops cylindrica Yes Yes
Albizia chinensis (Chinese albizia) Yes
Alyssum desertorum (desert madwort)Seeds eaten by browsing wild and domestic animals Yes Olliff et al. (2001)
Amaranthus palmeri (Palmer amaranth)Seeds consumed by small mammals and birds Yes EPPO (2019)
Ambrosia confertiflora (burr ragweed) Yes
Ampelopsis arborea (peppervine)Dispersed by bird and mammal droppings Yes Kimbrough (2008); Titus (1991)
Annona glabra (pond apple) Yes Land Protection (2005)
Aphanomyces astaciExperimental Yes Oidtmann et al. (2002)
Ardisia elliptica (shoebutton ardisia) Yes Koop and Horvitz (2005)
Argemone mexicana (Mexican poppy)Seeds found in birds' stomachs Yes Barnés (1946)
Argyreia nervosa (elephant creeper)Seeds dispersed by birds and other animals Yes PIER (2016)
Asparagus asparagoides (bridal creeper)Fruits eaten by birds, rabbits and foxes Yes Graham and Mitchell (1996); Loyn and French (1991); Raymond (1999); Stansbury (1996); Stansbury (2001)
Asparagus densiflorus (asparagus fern)Fruit eaten by birds Yes
Asparagus falcatus (sicklethorn)Dispersed by birds and other animals Yes HEAR (2017)
Atriplex semibaccata (Australian saltbush) Yes
Austrocylindropuntia cylindrica (cane cactus) Yes
Austrocylindropuntia subulata (Eve’s needle cactus) Yes
Axonopus fissifolius Yes
Basella alba (malabar spinach)Dispersed by birds Yes Iplantz (2020)
Bocconia frutescens (plume poppy)Non-native birds frequently consume and disperse seeds within the invaded range Yes Chimera and Drake (2010); Johnson and Nishida (2008)
Bontia daphnoides (white alling)Birds and mammals are cited as possible dispersers Yes Francis (2004)
Brassica rapa (field mustard)Foraged by various animals Yes Encyclopedia of Life (2018)
Brassica tournefortii (African mustard)Rapidly invades disturbed areas. Yes Berry et al. (2014)
Breynia disticha (snowbush)Reported as possibly dispersed by birds Yes Cheek et al. (2013)
Bromus secalinus (rye brome)seeds can pass through animals’ digestive systems Yes
Bunias orientalis (Turkish warty-cabbage) Yes Yes
Butia capitata (coquinho-azedo)Possible animal dispersal as fruits are eaten by birds and mammals Yes De Lima et al. (2011)
Calliandra houstoniana var. calothyrsus (calliandra) Yes
Cananga odorata (ylang-ylang)Species is dispersed by bats, monkeys, birds and squirrels that eat fruit Yes Flora de Nicaragua (2014)
Canna indica (canna lilly) Yes PIER (2008)
Carpobrotus chilensis (sea fig)Eaten and dispersed by mammals Yes Albert et al. (1997)
Cassia fistula (Indian laburnum)Seeds survive digestion Yes Yes PIER (2014)
Cassia grandis (pink shower)Animals consume edible pods and excrete the seeds Yes Yes Janzen (1971)
Castilla elastica (Mexican rubber tree)Frugivores eat fruits but cannot consume the seeds so dispersal is through excretion Yes Richard (2007)
Centaurea melitensis (Maltese starthistle) Yes Fernàndez and Sàiz (2007)
Centaurea solstitialis (yellow starthistle) Yes
Cinnamomum verum (cinnamon)Birds Yes Kueffer et al. (2009)
Cissus quadrangularis (treebine)Fruits eaten and dispersed by birds Yes Yes Staples et al. (2000)
Clerodendrum indicum (Turk's turban)Berries eaten by birds and animals, seeds dispersed after passing through the gut Yes Yes
Clerodendrum speciosissimum (Java glory bower)Birds eat fruits; propagules survive passage through the gut Yes Yes PIER (2014)
Clerodendrum wallichii (Wallich's glorybower)Species produces seed-bearing fruit which are eaten by birds Yes Yes Rueda (1993)
Clidemia hirta (Koster's curse)Mainly birds Yes Mandon-Dalger et al. (2004)
Corbicula fluminea (Asian clam)In the terminal part of the intestine of Pterodoras granulosus, C. fluminea clams are found intact Yes Cantanhêde et al. (2007)
Cornus sericea (redosier dogwood)North America Yes Yes
Cotoneaster horizontalis (wall-spray) Yes Yes
Crassostrea virginica (eastern oyster) Yes Yes
Crataegus monogyna (hawthorn) Yes Bass et al. (2006)
Crescentia cujete (calabash tree)Seeds dispersed in horse and livestock dung Yes Arango-Ulloa et al. (2009)
Crypsis vaginiflora (African pricklegrass)Waterfowl feed on this plant and may transport seeds throughout their wide distribution. Yes Yes Fleskes et al. (2005)
Cuscuta monogyna (eastern dodder)Seeds can pass through the digestive system of ruminants Yes Nazari and Tavakoli (1995)
Daphnia lumholtziEphippial transport, possibly in digestive tract of Nile Perch hypothesized as mode of introduction Yes Havel and Hebert (1993)
Delonix regia (flamboyant) Yes Briones-Salas et al. (2006)
Descurainia sophia (flixweed) Yes Blackshaw and Rode (1991)
Drymaria arenarioides (alfombrilla)Spreading through the faeces of ruminants and rodents Yes Allison (1977)
Elaeagnus angustifolia (Russian olive) Yes Katz and Shafroth (2003)
Elaeagnus pungens (thorny olive) Yes Miller (2003)
Elaeagnus umbellata (autumn olive) Yes Munger (2003)
Elaeis guineensis (African oil palm)Probable, but no supporting refs Yes
Eragrostis lehmanniana (Lehmann lovegrass)Used as a forage grass; seeds excreted by livestock remain largely viable Yes Yes PROTA (2015); Uchytil (1992)
Eragrostis plana (South African lovegrass)Seeds keep viable in cattle digestive tract, being dispersed as animals are moved. Also in horses, lambs and birds Yes Yes Reis (1993); Medeiros et al. (2004)
Eugenia uniflora (Surinam cherry) Yes
Festuca arundinacea (tall fescue)Seeds can be transported in animal dung Yes Campbell and Gibson (2001)
Ficus carica (common fig)Where pollinator wasp is persent, seeds can be dispersed by birds and animals which eat the figs Yes Morton (1987)
Ficus elastica (rubber plant)Birds and animals eat the fruit and disperse seeds Yes Yes PIER (2014)
Ficus microcarpa (Indian laurel tree)Seeds of this species are known to be dispersed by over 200 vertebrate species including birds and b Yes Yes Shanahan et al. (2001); Starr et al. (2003)
Flacourtia indica (governor's plum)Birds Yes Datta and Rawat (2008)
Flemingia strobilifera (wild hops) Yes
Foeniculum vulgare (fennel)Seeds are small and eaten by rodents and birds Yes Cal-IPC (2015)
Globodera pallida (white potato cyst nematode)USA Yes Brodie (1976)
Globodera rostochiensis (yellow potato cyst nematode) Yes
Glycosmis parviflora (flower axistree)Fruits eaten by birds and mammals Yes PROTA (2016)
Halogeton glomeratus (halogeton) Yes
Hedychium coccineum (scarlet ginger lily) Yes Henderson (2003)
Hedychium coronarium (white butterfly ginger lily) Yes
Hedychium gardnerianum (kahili ginger) Yes Yes
Hirschfeldia incana (shortpod mustard) Yes South East Natural Resources Management Board (2009)
Hydrilla verticillata (hydrilla) Yes
Hymenachne amplexicaulis (hymenachne)Seed dispersal by native fish in seasonal wetlands of the Pantanal, Brazil; likely waterfowl Yes Yes Australian Weeds Committee (2012); Silveira and Weiss (2014)
Impatiens glandulifera (Himalayan balsam)by rodents, assumed Yes Beerling and Perrins (1993)
Indigofera tinctoria (true indigo)Said to be eaten by cattle Yes Yes Duke (1981)
Jasminum simplicifolium (Australian wax jasmine)Bird dispersal Yes Yes Bocquet et al. (2007)
Juncus ensifolius (swordleaf rush)Probably transported by waterfowl, deer, livestock Yes Yes Cowan (1945); Koch (1991)
Kigelia africana (sausage tree)Seeds are dispersed by frugivorous vertebrates Yes SANBI (2020)
Kyllinga nemoralis (white kyllinga) Yes MPI (2016)
Lepidium virginicum (Virginian peppercress)Remaining viable in intestinal tract of sea birds. Yes Yes Proctor (1968)
Lespedeza cuneata (sericea lespedeza)Consumed by birds and rodents Yes Daehler (2004)
Leucaena leucocephala (leucaena) Yes
Ligustrum japonicum (Japanese privet)Eaten and dispersed by birds Yes Gilman and Watson (1993); Witmer (1996)
Ligustrum lucidum (broad-leaf privet)Seeds are dispersed by birds Yes Aragón and Groom (2003)
Ligustrum sinense (Chinese privet)Birds eat the fruits Yes
Limnocharis flava (yellow bur-head) Yes
Lonicera morrowii (Morrow’s honeysuckle)Seeds eaten by birds and mammals Yes Yes MA-DACF (2018); Averill et al. (2016)
Macaranga tanarius (parasol leaf tree)Seed dispersed by birds Yes Yes
Meloidogyne incognita (root-knot nematode)Eggs can pass through the intestine. Yes
Morella faya (firetree)Birds and feral pigs Yes PIER (2007)
Mucuna pruriens (velvet bean)Cultivated as a cover crop and fodder/forage crop; ingested by cattle Yes Yes Duke (1981)
Muntingia calabura (Jamaica cherry)Bats and birds disperse the seeds Yes Yes NAS (1980)
Murraya paniculata (orange jessamine)Seeds eaten by birds Yes PIER (2018)
Neonotonia wightii (perennial soybean)Viable seed passed by livestock Yes Gardener et al. (1993a); Gardener et al. (1993b)
Opuntia elatior (red-flower prickly pear) Yes
Opuntia engelmannii (cactus apple) Yes
Opuntia ficus-indica (prickly pear) Yes
Opuntia monacantha (common prickly pear) Yes
Opuntia stricta (erect prickly pear)Wild animals, birds Yes
Pandanus tectorius (screw pine) Yes
Parkia biglobosa (néré) Yes
Parmentiera aculeata (cucumber tree)Fruits are consumed by birds and mammals which disperse the seeds Yes Miceli-Méndez et al. (2008); Queensland Government (2018)
Paspalum millegrana (yerba brava)Seeds consumed/dispersed by birds (especially aquatic birds) Yes Yes Más and Garcia-Molinari (2006)
Paspalum notatum (Bahia grass)Seed dispersed in animal dung Yes Cook et al. (2005)
Paspalum urvillei (Vasey grass)Consumed by animals Yes Powers et al. (1978); Aplet et al. (1991)
Paspalum virgatum (sword grass)Seeds consumed and dispersed by animals Yes Yes Sistachs and Leon (1987)
Pennisetum clandestinum (Kikuyu grass)Seeds can be eaten and spread via dung Yes
Phoenix canariensis (Canary Island date palm) Yes DiTomaso and Healy (2006)
Pimenta dioica (allspice)Fruits are eaten by birds, bats and lizards and seeds excreted locally; migratory birds could cause Yes Rodriguez (1969)
Pimenta racemosa (bay rum tree) Yes
Pinus pinaster (maritime pine)Baboons in South Africa Yes Dean et al. (1986)
Pittosporum undulatum (Australian cheesewood) Yes Goodland and Healey (1996)
Plectranthus amboinicus (Indian borage)Plectranthus species are used for fodder Yes Yes Lukhoba et al. (2006)
Portulaca pilosa (kiss-me-quick) Yes
Potamopyrgus antipodarum (New Zealand mudsnail)Mudsnails are able to survive the pass through the digestive tracts of different fish species Yes Vinson and Baker (2008)
Prosopis glandulosa (honey mesquite)Livestock and wild animals Yes Pasiecznik et al. (2001)
Prosopis juliflora (mesquite)Livestock and wild animals Yes Pasiecznik et al. (2001)
Prunus campanulata (Taiwan cherry)Can be dispersed by birds Yes GISD (2011)
Ptychosperma elegans (solitaire palm)Dispersed by animals Yes PIER (2017)
Pyracantha coccinea (scarlet firethorn)In stomach and droppings of birds. Yes Debussche and Isenmann (1985)
Rhamphicarpa fistulosaPresumably dispersed by free-grazing cattle Yes
Rhus typhina (staghorn sumac) Yes
Rosa rugosa (rugosa rose) Yes Fremstad (1997)
Rottboellia cochinchinensis (itch grass) Yes Thomas and Allison (1974)
Roystonea oleracea (Caribbean royal palm)Birds and bats Yes Staples et al. (2000); Zucaratto and dos Santos Pires (2014)
Rubus argutus (sawtooth blackberry)Seeds germinate after passing through digestive systems (e.g., birds) Yes Motooka and (2003); University of Hawaii Botany Department (2012)
Rubus ellipticus (yellow Himalayan raspberry)Birds etc. Yes Jacobi and Warschauer (1992)
Rubus niveus (Mysore raspberry)Birds, mammals and reptiles Yes Buddenhagen and Jewell (2006)
Rytidostylis carthagenensisFruits consumed by birds and small mammals Yes Delascio-Chitty and López (2007)
Salsola kali (common saltwort) Yes
Salsola paulsenii (barbwire Russian thistle) Yes
Schinus terebinthifolius (Brazilian pepper tree)Birds and other wild animals Yes Ferriter and Clark (1997)
Securigera varia (crown vetch)Deer as local and long distance dispersers of the seeds Yes Yes Encyclopedia of Life (2016)
Senna alata (candle bush)Seeds reported as surviving passage through the gut Yes PIER (2016)
Senna occidentalis (coffee senna)Reported as dispersed in livestock dung Yes PIER (2016)
Senna septemtrionalis (smooth senna)Leaves, seeds and shoots are locally eaten as vegetable, and seeds are used as a coffee substitute Yes Hanelt et al. (2001); Sosef and Maesen (1997)
Sesbania bispinosa (dunchi fibre)As fodder for sheep, cattle and goats. Might aid in scarification needed for germinationZarkawi et al. (2005); Orwa et al. (2009)
Sesbania sericea (silky sesban)Used as fodder Yes Yes Ipor and Oyen (1997)
Solanum capsicoides (cockroach berry)May be dispersed by cows Yes Markle et al. (2014)
Solanum elaeagnifolium (silverleaf nightshade)Benefits from grazing livestock – seed remains viable up to 2 weeks after ingesting Yes Yes EPPO (2007)
Solanum viarum (tropical soda apple) Yes Mullahey et al. (2006)
Sonchus asper (spiny sow-thistle)Seeds consumed and dispersed by birds, small mammals and cattle Yes Yes Hutchinson et al. (1984)
Sporobolus africanus (rat’s tail grass) Yes
Syzygium cumini (black plum) Yes Morton (1987)
Syzygium grande (sea apple)Fruits are eaten by bats, monkeys, and squirrels Yes Ridley (1894); Wyatt Smith (1953)
Ulex europaeus (gorse)Transported by ants, and eaten by quail Yes Chater (1931)
Urtica dioica (stinging nettle) Yes
Vitex parviflora (molave)Seeds are bird dispersed Yes Gonzales et al. (2009)
Ziziphus mauritiana (jujube) Yes Land Protection (2006)


Top of page

Controlling the movement of free-ranging livestock and wild mammals is only feasible with high cost and high maintenance fencing, and may only be practical in small and localized cases such as protected areas. Preventing the movement of birds would, of course, be impossible. Eradication of the animal vector would be effective if possible, but the costs on biodiversity are likely to outweigh any benefits in such circumstances and ethical or moral issues would also need considering. 

Quarantine would be the only possible means of reducing the risks associated with human-mediated animal movement, such as the sale of cattle through town markets, international trade in live animals, or the translocation of wild animals such as rogue bull elephants from one reserve to another. Enforcing a quarantine period would ensure that any previously digested seeds are excreted before they are moved into uninfested areas.


Top of page

6/30/2009 Original text by:

Nick Pasiecznik, Consultant, France