Foraging

Foraging is searching for wild food resources. It affects an animal's fitness because it plays an important role in an animal's ability to survive and reproduce.[1] Foraging theory is a branch of behavioral ecology that studies the foraging behavior of animals in response to the environment where the animal lives.

Behavioral ecologists use economic models to understand foraging; many of these models are a type of optimal model. Thus foraging theory is discussed in terms of optimizing a payoff from a foraging decision. The payoff for many of these models is the amount of energy an animal receives per unit time, more specifically, the highest ratio of energetic gain to cost while foraging.[2] Foraging theory predicts that the decisions that maximize energy per unit time and thus deliver the highest payoff will be selected for and persist. Key words used to describe foraging behavior include resources, the elements necessary for survival and reproduction which have a limited supply, predator, any organism that consumes others, and prey, an organism that is eaten in part or whole by another.[1]

Behavioral ecologists first tackled this topic in the 1960s and 1970s. Their goal was to quantify and formalize a set of models to test their null hypothesis that animals forage randomly. Important contributions to foraging theory have been made by:

Grizzly Bear foraging
Grizzly bear (Ursus arctos horribilis) mother and cubs foraging in Denali National Park, Alaska.

Factors influencing foraging behavior

Troop of Olive Baboons
A troop of olive baboons (Papio anubis) foraging in Laikipia, Kenya. Young primates learn from elders in their group about proper foraging.

Several factors affect an animal's ability to forage and acquire profitable resources.

Learning

Learning is defined as an adaptive change or modification of a behavior based on a previous experience.[3] Since an animal's environment is constantly changing, the ability to adjust foraging behavior is essential for maximization of fitness. Studies in social insects have shown that there is a significant correlation between learning and foraging performance.[3]

In nonhuman primates, young individuals learn foraging behavior from their peers and elders by watching other group members forage and by copying their behavior.[4] Observing and learning from other members of the group ensure that the younger members of the group learn what is safe to eat and become proficient foragers.

One measure of learning is 'foraging innovation'—an animal consuming new food, or using a new foraging technique in response to their dynamic living environment.[5] Foraging innovation is considered learning because it involves behavioral plasticity on the animal's part. The animal recognizes the need to come up with a new foraging strategy and introduce something it has never used before to maximize his or her fitness (survival). Forebrain size has been associated with learning behavior. Animals with larger brain sizes are expected to learn better.[5] A higher ability to innovate has been linked to larger forebrain sizes in North American and British Isle birds according to Lefebvre et al. (1997).[6] In this study, bird orders that contained individuals with larger forebrain sizes displayed a higher amount of foraging innovation. Examples of innovations recorded in birds include following tractors and eating frogs or other insects killed by it and using swaying trees to catch their prey.[5]

Another measure of learning is spatio-temporal learning (also called time-place learning), which refers to an individual's ability to associate the time of an event with the place of that event.[7] This type of learning has been documented in the foraging behaviors of individuals of the stingless bee species Trigona fulviventris.[7] Studies showed that T. fulviventris individuals learned the locations and times of feeding events, and arrived to those locations up to thirty minutes before the feeding event in anticipation of the food reward.[7]

Genetics

European honey bee extracts nectar
A European honey bee extracts nectar. According to Hunt (2007), two genes have been associated with the sugar concentration of the nectar honey bees collect.

Foraging behavior can also be influenced by genetics. The genes associated with foraging behavior have been widely studied in honeybees with reference to the following; onset of foraging behavior, task division between foragers and workers, and bias in foraging for either pollen or nectar.[5][8] Honey bee foraging activity occurs both inside and outside the hive for either pollen or nectar. Similar behavior is seen in many social wasps, such as the species Apoica flavissima. Studies using quantitative trait loci (QTL) mapping have associated the following loci with the matched functions; Pln-1 and Pln-4 with onset of foraging age, Pln-1 and 2 with the size of the pollen loads collected by workers, and Pln-2 and pln-3 were shown to influence the sugar concentration of the nectar collected.[8]

Presence of predators

The presence of predators while a (prey) animal is foraging affects its behaviour. In general, foragers balance the risk of predation with their needs, thus deviating from the foraging behaviour that would be expected in the absence of predators.[9] An example of this balanced risk can be observed in the foraging behavior of A. longimana.[10]

Parasitism

Similarly, parasitism can affect the way in which animals forage. Parasitism can affect foraging at several levels. Animals might simply avoid food items that increase their risk of being parasitized, as when the prey items are intermediate hosts of parasites. Animals might also avoid areas that would expose them to a high risk of parasitism. Finally, animals might effectively self-medicate, either prophylactically or therapeutically.

Types of foraging

Foraging can be categorized into two main types. The first is solitary foraging, when animals forage by themselves. The second is group foraging. Group foraging includes when animals can be seen foraging together when it is beneficial for them to do so (called an aggregation economy) and when it is detrimental for them to do so (called a dispersion economy).

Solitary foraging

Solitary foraging the variety of foraging in which animals find, capture and consume their prey alone. Individuals can manually exploit patches or they can use tools to exploit their prey. Animals may choose to forage on their own when the resources are abundant, which can occur when the habitat is rich or when the number of conspecifics foraging are few. In these cases there may be no need for group foraging.[11] In addition, foraging alone can result in less interaction with other foragers, which can decrease the amount of competition and dominance interactions an animal deals with. It will also ensure that a solitary forager is less conspicuous to predators.[12] Solitary foraging strategies characterize many of the phocids (the true seals) such as the elephant and harbor seals. An example of an exclusive solitary forager is the South American species of the harvester ant, Pogonomyrmex vermiculatus.[13]

Tool use in solitary foraging

BonoboFishing04.jpeg
A bonobo fishing for termites with a tool, a prepared stick

Some examples of tool use include dolphins using sponges to feed on fish that bury themselves in the sediment,[14] New Caledonian crows that use sticks to get larvae out of trees,[15] and chimpanzees that similarly use sticks to capture and consume termites.[16]

Solitary foraging and optimal foraging theory

The theory scientists use to understand solitary foraging is called optimal foraging theory. Optimal foraging theory (OFT) was first proposed in 1966, in two papers published independently, by Robert MacArthur and Eric Pianka,[17] and by J. Merritt Emlen.[18] This theory argues that because of the key importance of successful foraging to an individual's survival, it should be possible to predict foraging behavior by using decision theory to determine the behavior that an "optimal forager" would exhibit. Such a forager has perfect knowledge of what to do to maximize usable food intake. While the behavior of real animals inevitably departs from that of the optimal forager, optimal foraging theory has proved very useful in developing hypotheses for describing real foraging behavior. Departures from optimality often help to identify constraints either in the animal's behavioral or cognitive repertoire, or in the environment, that had not previously been suspected. With those constraints identified, foraging behavior often does approach the optimal pattern even if it is not identical to it. In other words, we know from optimal foraging theory that animals are not foraging randomly even if their behavior doesn't perfectly match what is predicted by OFT.

There are many versions of optimal foraging theory that are relevant to different foraging situations. These models generally possess the following components according to Stephens et al. 2007;

  • Currency: an objective function, what we want to maximize,[19] in this case energy over time as a currency of fitness
  • Decision: set of choices under the organism's control,[19] or the decisions that the organism exhibits
  • Constraints: "an organism's choices are constrained by genetics, physiology neurology, morphology and the laws of chemistry and physics"[19]

Some of these versions include:

The optimal diet model, which analyzes the behavior of a forager that encounters different types of prey and must choose which to attack. This model is also known as the prey model or the attack model. In this model the predator encounters different prey items and decides whether to spend time handling or eating the prey. It predicts that foragers should ignore low profitability prey items when more profitable items are present and abundant.[19] The objective of this model is to identify the choice that will maximize fitness. How profitable a prey item is depends on ecological variables such as the time required to find, capture, and consume the prey in addition to the energy it provides. It is likely that an individual will settle for a trade off between maximizing the intake rate while eating and minimising the search interval between prey.[1]

Patch selection theory, which describes the behavior of a forager whose prey is concentrated in small areas known as patches with a significant travel time between them. The model seeks to find out how much time an individual will spend on one patch before deciding to move to the next patch. To understand whether an animal should stay at a patch or move to a new one, think of a bear in a patch of berry bushes. The longer a bear stays at the patch of berry bushes the less berries there are for that bear to eat. The bear must decide how long to stay and thus when to leave that patch and move to a new patch. Movement depends on the travel time between patches and the energy gained from one patch versus another.[19] This is based on the marginal value theorem.

Central place foraging theory is a version of the patch model. This model describes the behavior of a forager that must return to a particular place to consume food, or perhaps to hoard food or feed it to a mate or offspring. Chipmunks are a good example of this model. As travel time between the patch and their hiding place increased, the chipmunks stayed longer at the patch.

In recent decades, optimal foraging theory has often been applied to the foraging behavior of human hunter-gatherers. Although this is controversial, coming under some of the same kinds of attack as the application of sociobiological theory to human behavior, it does represent a convergence of ideas from human ecology and economic anthropology that has proved fruitful and interesting.

Group foraging

Group foraging is when animals find, capture and consume prey in the presence of other individuals. In other words, it is foraging when success depends not only on your own foraging behaviors but the behaviors of others as well.[19] An important note here is that group foraging can emerge in two types of situations. The first situation is frequently thought of and occurs when foraging in a group is beneficial and brings greater rewards known as an aggregation economy.[1] The second situation occurs when a group of animals forage together but it may not be in an animal's best interest to do so known as a dispersion economy. Think of a cardinal at a bird feeder for the dispersion economy. We might see a group of birds foraging at that bird feeder but it is not in the best interest of the cardinal for any of the other birds to be there too. The amount of food the cardinal can get from that bird feeder depends on how much it can take from the bird feeder but also depends on how much the other birds take as well.

Male Northern Cardinal At Feeder
A male northern cardinal at a bird feeder. Birds feeding at a bird feeder is an example of a dispersion economy. This is when it may not be in an animal's best interest to forage in a group.

In red harvester ants, the foraging process is divided between three different types of workers: nest patrollers, trail patrollers, and foragers. These workers can utilize many different methods of communicating while foraging in a group, such as guiding flights, scent paths, and "jostling runs", as seen in the eusocial bee Melipona scutellaris.[20]

Tai chimpanzee's also engage in foraging for meats when they can, which is achieved through group foraging. Where the positive correlation has been found between the success of the hunt and the size of the foraging group. The chimps have also been observed implying rules with their foraging, where there is a benefit to becoming involved in the through allowing hunter first access to the fresh kills.[21][22][23]

Cost and benefits of group foraging

Lioness and cub
Female lions make foraging decisions and more specifically decisions about hunting group size with protection of their cubs and territory defense in mind.[24]

As already mentioned, group foraging brings both costs and benefits to the members of that group. Some of the benefits of group foraging include being able to capture larger prey,[24] being able to create aggregations of prey,[25] being able to capture prey that are difficult or dangerous and most importantly reduction of predation threat.[19] With regard to costs, however, group foraging results in competition for available resources by other group members. Competition for resources can be characterized by either scramble competition whereby each individual strives to get a portion of the shared resource, or by interference competition whereby the presence of competitors prevents a forager's accessibility to resources.[1] Group foraging can thus reduce an animal's foraging payoff.[19]

Group foraging may be influenced by the size of a group. In some species like lions and wild dogs, foraging success increases with an increase in group size then declines once the optimal size is exceeded. A myriad number of factors affect the group sizes in different species. For example, lionesses (female lions) do not make decisions about foraging in a vacuum. They make decisions that reflect a balance between obtaining food, defending their territory and protecting their young. In fact, we see that lion foraging behavior does not maximize their energy gain. They are not behaving optimally with respect to foraging because they have to defend their territory and protect young so they hunt in small groups to reduce the risk of being caught alone.[24] Another factor that may influence group size is the cost of hunting. To understand the behavior of wild dogs and the average group size we must incorporate the distance the dogs run.[26]

Theorizing on hominid foraging during the Aurignacian Blades et al (2001) defined the forager performing the activity to the optimal efficiency when the individual is having considered the balance of costs for search and pursuit of prey in considerations of prey selection. Also in selecting an area to work within the individual would have had to decide the correct time to move to another location corresponding to perception of yield remaining and potential yields of any given area available. [27]

Group foraging and the ideal free distribution

The theory scientists use to understand group foraging is called the Ideal free distribution. This is the null model for thinking about what would draw animals into groups to forage and how they would behave in the process. This model predicts that animals will make an instantaneous decision about where to forage based on the quality (prey availability) of the patches available at that time and will choose the most profitable patch, the one that maximizes their energy intake. This quality depends on the starting quality of the patch and the number of predators already there consuming the prey.

See also

References

  1. ^ a b c d e Danchin, E.; Giraldeau, L. & Cezilly, F. (2008). Behavioural Ecology. New York: Oxford University Press. ISBN 978-0-19-920629-2.
  2. ^ Hughes, Roger N, ed. (1989), Behavioural Mechanisms of Food Selection, London & New York: Springer-Verlag, p. v, ISBN 978-0-387-51762-9
  3. ^ a b Raine, N.E.; Chittka, L. (2008). "The correlation of learning speed and natural foraging success in bumble-bees'". Proceedings of the Royal Society B: Biological Sciences. 275 (1636): 803–808. doi:10.1098/rspb.2007.1652. PMC 2596909. PMID 18198141.
  4. ^ Rapaport, L.G.; Brown, G.R. (2008). "Social influences on foraging behavior in young nonhuman primates:learning what, where and how to eat". Evolutionary Anthropology: Issues, News, and Reviews. 17 (4): 189–201. doi:10.1002/evan.20180.
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  11. ^ Riedman, Marianne (1990). The pinnipeds: seals, sea lions, and walruses. Berkeley: University of California Press. ISBN 978-0-520-06497-3.
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  13. ^ Torres-Contreras, Hugo; Ruby Olivares-Donoso; Hermann M. Niemeyer (2007). "Solitary Foraging in the Ancestral South American Ant, Pogonomyrmex vermiculatus. Is it Due to Constraints in the Production or Perception of Trail Pheromones?". Journal of Chemical Ecology. 33 (2): 435–440. doi:10.1007/s10886-006-9240-7. PMID 17187299.
  14. ^ Patterson, E.M.; Mann, J. (2011). "The Ecological Conditions That Favor Tool Use and Innovation in Wild Bottlenose Dolphins (Tursiops sp.)". PLOS One. 6 (7): e22243. doi:10.1371/journal.pone.0022243. PMC 3140497. PMID 21799801.
  15. ^ Rutz, C.; et al. (2010). "The ecological significance of tool use in New Caledonian Crows". Science. 329 (5998): 1523–1526. doi:10.1126/science.1192053. PMID 20847272.
  16. ^ Goodall, Jane (1964). "Tool-using and aimed throwing in a community of free-living chimpanzees". Nature. 201 (4926): 1264–1266. doi:10.1038/2011264a0. PMID 14151401.
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External links

Africanized bee

The Africanized bee, also known as the Africanised honey bee, and known colloquially as the "killer bee", is a hybrid of the western honey bee species (Apis mellifera), produced originally by cross-breeding of the East African lowland honey bee (A. m. scutellata) with various European honey bees such as the Italian honey bee A. m. ligustica and the Iberian honey bee A. m. iberiensis.

The Africanized honey bee was first introduced to Brazil in 1956 in an effort to increase honey production, but 26 swarms escaped quarantine in 1957. Since then, the hybrid has spread throughout South America and arrived in North America in 1985. Hives were found in south Texas in the United States in 1990.Africanized bees are typically much more defensive than other varieties of honey bee, and react to disturbances faster than European honey bees. They can chase a person a quarter of a mile (400 m); they have killed some 1,000 humans, with victims receiving ten times more stings than from European honey bees. They have also killed horses and other animals.

American white ibis

The American white ibis (Eudocimus albus) is a species of bird in the ibis family, Threskiornithidae. It is found from Virginia via the Gulf Coast of the United States south through most of the coastal New World tropics. This particular ibis is a medium-sized bird with an overall white plumage, bright red-orange down-curved bill and long legs, and black wing tips that are usually only visible in flight. Males are larger and have longer bills than females. The breeding range runs along the Gulf and Atlantic Coast, and the coasts of Mexico and Central America. Outside the breeding period, the range extends further inland in North America and also includes the Caribbean. It is also found along the northwestern South American coastline in Colombia and Venezuela. Populations in central Venezuela overlap and interbreed with the scarlet ibis. The two have been classified by some authorities as a single species.

Their diet consists primarily of small aquatic prey, such as insects and small fishes. Crayfish are its preferred food in most regions, but it can adjust its diet according to the habitat and prey abundance. Its main foraging behavior is probing with its beak at the bottom of shallow water to feel for and capture its prey. It does not see the prey.

During the breeding season, the American white ibis gathers in huge colonies near water. Pairs are predominantly monogamous and both parents care for the young, although males tend to engage in extra-pair copulation with other females to increase their reproductive success. Males have also been found to pirate food from unmated females and juveniles during the breeding season.

Human pollution has affected the behavior of the American white ibis via an increase in the concentrations of methylmercury, which is released into the environment from untreated waste. Exposure to methylmercury alters the hormone levels of American white ibis, affecting their mating and nesting behavior and leading to lower reproduction rates.

Autonomous robot

An autonomous robot, or automatic robot, is a robot that performs behaviors or tasks with a high degree of autonomy. Autonomous robotics is usually considered to be a subfield of artificial intelligence, robotics, and information engineering. Early versions were proposed and demonstrated by author/inventor David L. Heiserman.Autonomous robots are particularly desirable in fields such as spaceflight, household maintenance (such as cleaning), waste water treatment, and delivering goods and services.

Some modern factory robots are "autonomous" within the strict confines of their direct environment. It may not be that every degree of freedom exists in their surrounding environment, but the factory robot's workplace is challenging and can often contain chaotic, unpredicted variables. The exact orientation and position of the next object of work and (in the more advanced factories) even the type of object and the required task must be determined. This can vary unpredictably (at least from the robot's point of view).

One important area of robotics research is to enable the robot to cope with its environment whether this be on land, underwater, in the air, underground, or in space.

A fully autonomous robot can:

Gain information about the environment

Work for an extended period without human intervention

Move either all or part of itself throughout its operating environment without human assistance

Avoid situations that are harmful to people, property, or itself unless those are part of its design specificationsAn autonomous robot may also learn or gain new knowledge like adjusting for new methods of accomplishing its tasks or adapting to changing surroundings.

Like other machines, autonomous robots still require regular maintenance.

Aye-aye

The aye-aye (Daubentonia madagascariensis) is a long-fingered lemur, a strepsirrhine primate native to Madagascar that combines rodent-like teeth that perpetually grow and a special thin middle finger.

It is the world's largest nocturnal primate. It is characterized by its unusual method of finding food: it taps on trees to find grubs, then gnaws holes in the wood using its forward-slanting incisors to create a small hole in which it inserts its narrow middle finger to pull the grubs out. This foraging method is called percussive foraging, and takes up 5–41% of foraging time. The only other animal species known to find food in this way is the striped possum. From an ecological point of view, the aye-aye fills the niche of a woodpecker, as it is capable of penetrating wood to extract the invertebrates within.The aye-aye is the only extant member of the genus Daubentonia and family Daubentoniidae. It is currently classified as Endangered by the IUCN; and a second species, Daubentonia robusta, appears to have become extinct at some point within the last 1000 years.

Bombus terrestris

Bombus terrestris, the buff-tailed bumblebee or large earth bumblebee, is one of the most numerous bumblebee species in Europe. It is one of the main species used in greenhouse pollination, and so can be found in many countries and areas where it is not native, such as Tasmania. Moreover, it is a eusocial insect with an overlap of generations, a division of labor, and cooperative brood care. The queen is monandrous which means she mates with only one male. B. terrestris workers learn flower colors and forage efficiently.

Cannibalism

Cannibalism involves consuming all or part of another individual of the same species as food. To consume the same species, or show cannibalistic behavior, is a common ecological interaction in the animal kingdom, and has been recorded in more than 1,500 species. Human cannibalism is well-documented, both in ancient and in recent times.The rate of cannibalism increases in nutritionally-poor environments as individuals turn to conspecifics as an additional food-source. Cannibalism regulates population numbers, whereby resources such as food, shelter and territory become more readily available with the decrease of potential competition. Although it may benefit the individual, it has been shown that the presence of cannibalism decreases the expected survival rate of the whole population and increases the risk of consuming a relative. Other negative effects may include the increased risk of pathogen transmission as the encounter rate of hosts increases. Cannibalism, however, does not—as once believed—occur only as a result of extreme food shortage or of artificial/unnatural conditions, but may also occur under natural conditions in a variety of species.Cannibalism seems especially prevalent in aquatic ecosystems, in which up to approximately 90% of the organisms engage in cannibalistic activity at some point in their life-cycle. Cannibalism is not restricted to carnivorous species: it also occurs in herbivores and in detritivores. Sexual cannibalism normally involves the consumption of the male by the female individual before, during or after copulation. Other forms of cannibalism include size-structured cannibalism and intrauterine cannibalism.

Behavioural, physiological and morphological adaptations have evolved to decrease the rate of cannibalism in individual species.

Flock (birds)

A flock is a gathering of a group of same species animals in order to forage or travel with one another. In avians flocks are typically seen in association with migration. While this is true it can also be seen that flocking is important in safety from predation and foraging benefits. However it is also important to note that living in a flock can also come at a cost to the birds living within it.The definition of flock is narrow, only focusing on a single species existing within a flock. However the existence of mixed flocks are also present in the environment and consist of at least two or more species. In avians the species that tend to flock together are typically similar in taxonomy as well as morphological characters such as size and shape. By having a flock with multiple species present, the defence against predation increases. Defence against predators is particularly important in closed habitats such as forests where early warning calls play a vital importance in the early recognition of danger. The result is the formation of many mixed-species feeding flocks.

Freeganism

Freeganism is a practice and ideology of limited participation in the conventional economy and minimal consumption of resources, particularly through recovering wasted goods like food. The word "freegan" is a portmanteau of "free" and "vegan". While vegans might avoid buying animal products as an act of protest against animal exploitation, freegans—at least in theory—avoid buying anything as an act of protest against the food system in general.

Freeganism is often presented as synonymous with "dumpster diving" for discarded food, although freegans are distinguished by their association with an anti-consumerist and anti-capitalist ideology and their engagement in a wider range of alternative living strategies, such as voluntary unemployment, squatting in abandoned buildings, and "guerrilla gardening" in unoccupied city parks.

Hummingbird

Hummingbirds are birds native to the Americas and constitute the biological family Trochilidae. They are among the smallest of birds, most species measuring 7.5–13 cm (3–5 in) in length. The smallest extant bird species is a hummingbird, the 5 cm (2.0 in) bee hummingbird, which weighs less than 2.0 g (0.07 oz).

They are known as hummingbirds because of the humming sound created by their beating wings which flap at high frequencies audible to humans. They hover in mid-air at rapid wing-flapping rates, which vary from around 12 beats per second in the largest species, to in excess of 80 in some of the smallest. Of those species that have been measured in wind tunnels, their top speed exceeds 15 m/s (54 km/h; 34 mph) and some species can dive at speeds in excess of 22 m/s (79 km/h; 49 mph).Hummingbirds have the greatest mass-specific metabolic rate of any homeothermic animal. To conserve energy when food is scarce, and nightly when not foraging, they can go into torpor, a state similar to hibernation, slowing metabolic rate to 1/15th of its normal rate.

Hunter-gatherer

A hunter-gatherer is a human living in a society in which most or all food is obtained by foraging (collecting wild plants and pursuing wild animals). Hunter-gatherer societies stand in contrast to agricultural societies, which rely mainly on domesticated species.

Hunting and gathering was humanity's first and most successful adaptation, occupying at least 90 percent of human history. Following the invention of agriculture, hunter-gatherers who did not change have been displaced or conquered by farming or pastoralist groups in most parts of the world.

In West Eurasia, agriculture led to widespread genetic changes when older hunter-gatherer populations were largely replaced by Middle Eastern farmers during the Neolithic who in turn were overrun by Indo-Europeans during the Bronze Age.Only a few contemporary societies are classified as hunter-gatherers, and many supplement their foraging activity with horticulture or pastoralism.

Ideal free distribution

In ecology, an ideal free distribution is a way in which animals distribute themselves among several patches of resources. The theory states that the number of individual animals that will aggregate in various patches is proportional to the amount of resources available in each. For example, if patch A contains twice as many resources as patch B, there will be twice as many individuals foraging in patch A as in patch B. The ideal free distribution (IFD) theory predicts that the distribution of animals among patches will minimize resource competition and maximize fitness.The term "ideal" implies that animals are aware of each patch's quality, and they choose to forage in the patch with the highest quality. The term "free" implies that animals are capable of moving unhindered from one patch to another. Although these assumptions are not always upheld in nature, there are still many experiments that have been performed in support of IFD, even if populations naturally deviate between patches before reaching IFD. IFD theory can still be used to analyze foraging behaviors of animals, whether those behaviors support IFD, or violate it.

Marginal value theorem

The marginal value theorem (MVT) is an optimality model that usually describes the behavior of an optimally foraging individual in a system where resources (often food) are located in discrete patches separated by areas with no resources. Due to the resource-free space, animals must spend time traveling between patches. The MVT can also be applied to other situations in which organisms face diminishing returns.

The MVT was first proposed by Eric Charnov in 1976. In his original formulation: "The predator should leave the patch it is presently in when the marginal capture rate in the patch drops to the average capture rate for the habitat."

Melastomataceae

The family Melastomataceae (alternatively Melastomaceae) is a taxon of dicotyledonous flowering plants found mostly in the tropics (two thirds of the genera are from the New World tropics) comprising c. 165 genera and c. 5115 known species. Melastomes are annual or perennial herbs, shrubs, or small trees.

Mixed-species foraging flock

A mixed-species feeding flock, also termed a mixed-species foraging flock, mixed hunting party or informally bird wave, is a flock of usually insectivorous birds of different species that join each other and move together while foraging. These are different from feeding aggregations, which are congregations of several species of bird at areas of high food availability.

A mixed-species foraging flock typically has "nuclear" species that appear to be central to its formation and movement. Species that trail them are termed "attendants". Attendants tend to join the foraging flock only when the flock enters their territory.How such flocks are initiated is under investigation. In Sri Lanka, for example, vocal mimicry by the greater racket-tailed drongo might have a key role in the initiation of mixed-species foraging flocks, while in parts of the American tropics noisy packs of foraging golden-crowned warblers might play the same role. Forest structure is also believed to be an important factor deciding the propensity to form flocks. In tropical forests, birds that glean food from foliage were the most abundant species in mixed-species flocks.A typical Neotropic mixed feeding flock moves through the forest at about 0.3 kilometers per hour (0.19 mph), with different species foraging in their preferred niches (on the ground, on trunks, in high or low foliage, etc.). Some species follow the flock all day, while others – such as the long-billed gnatwren – join it only as long as it crosses their own territories.

Mushroom hunting

Mushroom hunting, mushrooming, mushroom picking, mushroom foraging, and similar terms describe the activity of gathering mushrooms in the wild, typically for food. This practice is popular throughout most of Europe, Australia, Japan, Korea, parts of the Middle East, and the Indian subcontinent, as well as the temperate regions of Canada and the United States.

Myrtaceae

Myrtaceae or the myrtle family is a family of dicotyledonous plants placed within the order Myrtales. Myrtle, pohutukawa, bay rum tree, clove, guava, acca (feijoa), allspice, and eucalyptus are some notable members of this group. All species are woody, contain essential oils, and have flower parts in multiples of four or five. The leaves are evergreen, alternate to mostly opposite, simple, and usually entire (i.e., without a toothed margin). The flowers have a base number of five petals, though in several genera the petals are minute or absent. The stamens are usually very conspicuous, brightly coloured and numerous.

Optimal foraging theory

Optimal foraging theory (OFT) is a behavioral ecology model that helps predict how an animal behaves when searching for food. Although obtaining food provides the animal with energy, searching for and capturing the food require both energy and time. To maximize fitness, an animal adopts a foraging strategy that provides the most benefit (energy) for the lowest cost, maximizing the net energy gained. OFT helps predict the best strategy that an animal can use to achieve this goal.

OFT is an ecological application of the optimality model. This theory assumes that the most economically advantageous foraging pattern will be selected for in a species through natural selection. When using OFT to model foraging behavior, organisms are said to be maximizing a variable known as the currency, such as the most food per unit time. In addition, the constraints of the environment are other variables that must be considered. Constraints are defined as factors that can limit the forager's ability to maximize the currency. The optimal decision rule, or the organism's best foraging strategy, is defined as the decision that maximizes the currency under the constraints of the environment. Identifying the optimal decision rule is the primary goal of the OFT.

Roadrunner

The roadrunners (genus Geococcyx), also known as chaparral birds or chaparral cocks, are two species of fast-running ground cuckoos with long tails and crests. They are found in the southwestern United States and Mexico, usually in the desert. Some have been clocked at 20 miles per hour (32 km/h) while a few have also been clocked up to 27 miles per hour.

Scaly-breasted munia

The scaly-breasted munia or spotted munia (Lonchura punctulata), known in the pet trade as nutmeg mannikin or spice finch, is a sparrow-sized estrildid finch native to tropical Asia. A species of the genus Lonchura, it was formally described and named by Carl Linnaeus in 1758. Its name is based on the distinct scale-like feather markings on the breast and belly. The adult is brown above and has a dark conical bill. The species has 11 subspecies across their range and differ slightly in size and colour.

This munia eats mainly grass seeds apart from berries and small insects. They forage in flocks and communicate with soft calls and whistles. The species is highly social and may sometimes roost with other species of munias. This species is found in tropical plains and grasslands. Breeding pairs construct dome-shaped nests using grass or bamboo leaves.

The species is endemic to Asia and occurs from India and Sri Lanka east to Indonesia and the Philippines (where it is called mayang pakíng). It has been introduced into many other parts of the world and feral populations have established in Puerto Rico and Hispaniola as well as parts of Australia and the United States of America. The bird is listed as of Least Concern by the International Union for Conservation of Nature (IUCN).

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