Grazing (behaviour)

File:Green Sea Turtle grazing seagrass.jpg grazing on seagrass]]

Many small selective herbivores follow larger grazers which skim off the highest, tough growth of grasses, exposing tender shoots. For terrestrial animals, grazing is normally distinguished from browsing in that grazing is eating grass or forbs, whereas browsing is eating woody twigs and leaves from trees and shrubs.{{cite book |chapter=Browsing is a specialized form of grazing. "Graze, verb: 2. Eat growing grass." "Browse, verb: 1. Feed on, crop, (leaves, twigs, scanty vegetation)." |title=Concise Oxford Dictionary |year=1976 |edition=6 |isbn=0-19-861122-6 |author1=Fowler |publisher=Oxford University Press, Incorporated }} Grazing differs from predation because the organism being grazed upon may not be killed. It differs from parasitism because the two organisms live together in a constant state of physical externality (i.e., low intimacy).{{cite book |last1=Stiling |first1=Peter |title=Ecology: theories and applications |date=1999 |publisher=Prentice Hall |location=Upper Saddle River, NJ |isbn=0139156534 |edition=3rd |url-access=registration |url=https://archive.org/details/ecologytheoriesa00stil }}{{page needed|date=April 2017}} Water animals that feed by rasping algae and other micro-organisms from stones are called grazers–scrapers.{{cite book |author1=Begon, M. |author2=Townsend C. |author3=Harper, J. |year=1990 |title=Ecology |edition=2 |publisher=Blackwell Science, London |isbn=0-86542-111-0}}

{{main|Graminivore}}

Graminivory is a form of grazing involving feeding primarily on grass{{cite web |url=http://www.merriam-webster.com/dictionary/graminivorous |title=Definition of GRAMINIVOROUS |website=www.merriam-webster.com}} (specifically "true" grasses in the Poaceae). Horses, cattle, capybara, hippopotamuses, grasshoppers, geese, and giant pandas are graminivores. Giant pandas (Ailuropoda melanoleuca) are obligate bamboo grazers, 99% of their diet consisting of sub-alpine bamboo species.{{cite journal |author=ZHOU, Shiqiang |title=Effects of wildness training giant pandas? Grazing and artificial harvesting on clone population biomass of umbrella bamboo (Fargesia robusta) |journal=Chinese Journal of Applied Environmental Biology |volume=18 |issue=1 |year=2012 |pages=1–8 |url=http://en.cnki.com.cn/Article_en/CJFDTOTAL-YYHS201201001.htm |display-authors=etal |doi=10.3724/sp.j.1145.2012.00001 |access-date=2019-10-01 |archive-date=2019-02-12 |archive-url=https://web.archive.org/web/20190212130923/http://en.cnki.com.cn/Article_en/CJFDTOTAL-YYHS201201001.htm |url-status=dead |url-access=subscription }}

{{further|Cecotrophy}}

File:Capibara 1.jpg is one of several herbivores that practice cecotrophy.]]

For lagomorphs (rabbits, hares, pikas), easily digestible food is processed in the gastrointestinal tract & expelled as regular feces. But to get nutrients out of hard-to-digest fiber, lagomorphs ferment fiber in the cecum (in the GI tract) and then expel the contents as cecotropes, which are reingested (cecotrophy). The cecotropes are then absorbed in the small intestine to utilize the nutrients. This process is different from cows chewing their cud but with similar results.{{cite web |url=http://www.oaktreevet.co.uk/Pages/leaflets/rabbit%20general.htm |title=Information for Rabbit Owners — Oak Tree Veterinary Centre |publisher=Oaktreevet.co.uk |access-date=2010-08-30 |url-status=dead |archive-url=https://web.archive.org/web/20120623015452/http://www.oaktreevet.co.uk/Pages/leaflets/rabbit%20general.htm |archive-date=2012-06-23 }}

Capybara (Hydrochoerus hydrochaeris) are herbivores that graze mainly on grasses and aquatic plants,[https://web.archive.org/web/20050930231549/http://nationalzoo.si.edu/Animals/Amazonia/Facts/capybarafacts.cfm Capybara Facts.] Smithsonian National Zoological Park. Retrieved on December 16, 2007.{{cite journal |vauthors=Forero-Montana J, Betancur J, Cavelier J|url=http://www.scielo.sa.cr/scielo.php?script=sci_arttext&pid=S0034-77442003000200029&lng=es&nrm=iso |title=Dieta del capibara Hydrochaeris hydrochaeris (cavia: Hydrochaeridae) en Caño Limón, Arauca, Colombia |journal=Revista de Biología Tropical |year=2003 |volume=51 |issue=2 |pages=571–578|pmid=15162749}} [https://web.archive.org/web/20090325001404/http://rbt.biologia.ucr.ac.cr/revistas/F51-2%20%5B2003%5D.pdf/29-Forero-Dieta.pdf PDF] as well as fruit and tree bark.[https://web.archive.org/web/20100620162726/http://palmbeachzoo.org/animals/capybara.html Capybara.] Palm Beach Zoo. Retrieved on December 17, 2007. As with other grazers, they can be very selective,{{cite journal |author=Quintana, R.D., S. Monge, A.I. Malvárez |year=1998 |title=Feeding patterns of capybara Hydrochaeris hypdrochaeris (Rodentia, Hydrochaeridae) and cattle in the non-insular area of the Lower Delta of the Parana River, Argentina |journal=Mammalia |volume=62 |issue=1 |pages=37–52 |doi=10.1515/mamm.1998.62.1.37|s2cid=83976640 }} feeding on the leaves of one species and disregarding other species surrounding it. They eat a greater variety of plants during the dry season, as fewer plants are available. While they eat grass during the wet season, they have to switch to more abundant reeds during the dry season.{{cite journal |title=Foraging patterns of capybaras in a seasonally flooded savanna of Venezuela| jstor=2559868 |doi=10.1017/S0266467498000078 |year=1998 |last1=Barreto |first1=Guillermo R. |last2=Herrera |first2=Emilio A. |journal=Journal of Tropical Ecology |volume=14 | issue=1 | pages=87–98 | s2cid=84982123 }} The capybara's jaw hinge is not perpendicular; hence, it chews food by grinding back-and-forth rather than side-to-side.[https://web.archive.org/web/20070614005832/http://www.sfzoo.org/cgi-bin/animals.py?ID=90 Capybara. Hydrochaeris hydrochaeris]. San Francisco Zoo

Like lagomorphs, capybara create, expel & eat cecotropes (cecotrophy) to get more nutrition from their food.

They may also regurgitate food to masticate again, similar to cud-chewing by a cow.{{cite journal |author=Lord-Rexford, D. |year=1994 |title=A descriptive account of capybara behaviour |journal=Studies on Neotropical Fauna and Environment |volume=29 |issue=1 |pages=11–22 |doi=10.1080/01650529409360912|bibcode=1994SNFE...29...11L }} As with other rodents, the front teeth of capybara grow continually to compensate for the constant wear from eating grasses.[http://www.bristolzoo.org.uk/learning/animals/mammals/capybara Bristol Zoo Gardens (UK) Capybara] {{webarchive |url=https://web.archive.org/web/20070918183854/http://www.bristolzoo.org.uk/learning/animals/mammals/capybara |date=2007-09-18}}. Bristolzoo.org.uk. Retrieved on 2011-12-07. Their cheek teeth also grow continuously.

{{main|Pseudoruminant}}

The hippopotamus is a large, semi-aquatic mammal inhabiting rivers, lakes, and mangrove swamps. During the day, they remain cool by staying in the water or mud; reproduction and childbirth occur in water. They emerge at dusk to graze on grasses. While hippopotamuses rest near each other in the water, grazing is solitary. Their incisors can be as long as {{convert|40|cm|in|abbr=on}} and the canines (tusks) up to {{convert|50|cm|in|abbr=on}};{{cite book |title=The Behavior Guide to African Mammals: Including Hoofed Mammals, Carnivores, Primates |author=Estes, R. |publisher=University of California Press |pages=[https://archive.org/details/isbn_0520080858/page/222 222–26] |year=1992 |isbn=0-520-08085-8 |url=https://archive.org/details/isbn_0520080858/page/222 }} however, the canines and incisors are used for combat, and play no role in feeding. Hippos rely on their broad, horny lips to grasp and pull grasses which are then ground by the molars.{{cite book |author=Kingdon, J. |year=1988 |title=East African Mammals: An Atlas of Evolution in Africa, Volume 3, Part B: Large Mammals |pages=256–77 |publisher=University Of Chicago Press |isbn=0-226-43722-1}} The hippo is considered to be a pseudoruminant; it has a complex three- or four-chambered stomach but does not "chew cud".{{cite book |last=Eltringham |first=S.K. |title= The Hippos|year=1999 |publisher=Academic Press |isbn=0-85661-131-X |series= Poyser Natural History Series}}

Although grazing is typically associated with mammals feeding on grasslands, ecologists sometimes use the word in a broader sense to include any organism that feeds on any other species without ending the life of the prey organism.{{cite book |author=Begon, M., Townsend, C. and Harper, J. |year=1996 |title=Ecology |edition=3 |publisher=Blackwell Science, London}}{{page needed|date=January 2018}} Use of the term "grazing" varies further; for example, a marine biologist may describe herbivorous sea urchins that feed on kelp as grazers, even when they kill the organism by cutting the plant at the base. Malacologists sometimes apply the word to aquatic snails that feed by consuming the microscopic film of algae, diatoms and detritus—a biofilm—that covers the substrate and other surfaces underwater.{{cn|date=October 2019}} In marine ecosystems, grazing by mesograzers such as some crustaceans maintains habitat structure by preventing algal overgrowth, especially in coral reefs.{{cite journal |last1=Pearson |first1=Ryan M. |last2=Jinks |first2=Kristin I. |last3=Brown |first3=Christopher J. |last4=Schlacher |first4=Thomas A. |last5=Connolly |first5=Rod M. |date=2018 |title=Functional changes in reef systems in warmer seas: Asymmetrical effects of altered grazing by a widespread crustacean mesograzer |journal=Science of the Total Environment |volume=644 |pages=976–981 |doi=10.1016/j.scitotenv.2018.07.051 |pmid=30743894 |issn=0048-9697 |bibcode=2018ScTEn.644..976P |hdl=10072/382266 |s2cid=53074768 |hdl-access=free }}

File:Cattle at Velika Planina, Slovenia.jpg, Slovenia]]

Grazer urine and feces "recycle nitrogen, phosphorus, potassium and other plant nutrients and return them to the soil".[http://www.nativehabitat.org/grazing.html "Benefits of Grazing Cattle on the Prairie". Native Habitat Organization. Retrieved 1 Dec 2008] {{webarchive |url=https://web.archive.org/web/20070306235850/http://www.nativehabitat.org/grazing.html |date=2007-03-06}} Grazing can allow for the accumulation of organic matter which may help to combat soil erosion.[http://intensivegrazing.tamu.edu/benefits.htm Dalrymple, R.L.. "Fringe Benefits of Rotational Stocking". Intensive Grazing Benefits. Noble Foundation. Retrieved 1 Dec 2008] {{webarchive |url=https://web.archive.org/web/20080820082932/http://intensivegrazing.tamu.edu/benefits.htm |date=2008-08-20}} This acts as nutrition for insects and organisms found within the soil. These organisms "aid in carbon sequestration and water filtration".

When grass is grazed, dead litter grass is reduced which is advantageous for birds such as waterfowl.{{cite web |url=http://www.fergusfallsjournal.com/news/2008/feb/21/waterfowl-area-grazing-benefits-birds-cattle/ |title=Waterfowl area grazing benefits birds, cattle - The Fergus Falls Daily Journal |date=21 February 2008 |publisher= |access-date=1 October 2019 |archive-date=16 June 2009 |archive-url=https://web.archive.org/web/20090616043130/http://www.fergusfallsjournal.com/news/2008/feb/21/waterfowl-area-grazing-benefits-birds-cattle/ |url-status=dead }} Grazing can increase biodiversity. Without grazing, many of the same grasses grow, for example brome and bluegrass, consequently producing a monoculture.

{{blockquote|In North American tallgrass prairies, diversity and productivity are controlled to a large extent by nitrogen availability{{nbsp}}... Nitrogen availability in prairies was driven by interactions between frequency of fires and grazing by large herbivores{{nbsp}}... Spring fires enhance growth of certain grasses, and herbivores such as bison preferentially graze these grasses, keeping a system of checks and balances working properly, and allowing many plant species to flourish.{{cite web |url=http://news.bio-medicine.org/biology-news-2/Bison-Grazing-Increases-Biodiversity-In-Grasslands-14701-1/ |title=Bison Grazing Increases Biodiversity In ...(Grazing by herbivorous mammals like b...) |website=news.bio-medicine.org |access-date=2019-10-01 |archive-date=2021-04-27 |archive-url=https://web.archive.org/web/20210427120239/http://news.bio-medicine.org/biology-news-2/Bison-Grazing-Increases-Biodiversity-In-Grasslands-14701-1/ |url-status=dead }}}}

{{Reflist|30em}}

{{Wiktionary|grazing|grazer}}

{{Feeding}}

{{Ethology}}

{{Authority control}}

Category:Ethology

Category:Herbivory

Category:Land use