timothy

Perennial grass (Phleum pratense) of the family Poaceae (or Gramineae), native to Europe and widely cultivated as a hay and pasture grass in North America. The stems grow in large clumps, are 1.5–3 ft (0.5–1 m) tall, and have swollen, bulblike bases. The flower clusters are long, dense, and cylindrical. Alpine, or mountain, timothy (P. alpinum) is about half as tall and occurs in wet areas from Greenland to Alaska, and at high altitudes in many other parts of North America and Europe.

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(born July 17, 1745, Salem, Mass.—died Jan. 29, 1829, Salem, Mass., U.S.) U.S. politician. He joined the militia in 1766 and served in the American Revolution under George Washington, becoming adjutant general (1777–78) and quartermaster general (1780–85). He later served as U.S. postmaster general (1791–95), secretary of war (1795), and secretary of state (1795–1800). He served in the U.S. Senate from 1803 to 1811 and in the House of Representatives from 1813 to 1817. A leader of the Federalist Party, he was a member of the Essex Junto, and he opposed the War of 1812. After retiring from politics, he turned to experimental farming and education.

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(born May 17, 1855, Bantry, County Cork, Ire.—died March 26, 1931, Dublin) Irish political leader. Soon after he entered Parliament in 1880, the “Healy Clause” of the Land Act of 1881, protecting tenant farmers' agrarian improvements from rent increases, made him popular in Ireland. Long associated with Charles Stewart Parnell, he broke with him in 1886. He grew dissatisfied with both the Liberals and the Irish Nationalists in the wake of the 1916 Easter Rising, and after 1917 he supported Sinn Féin. He was supported by both the British and Irish ministries as governor-general (1922–28) of the new Irish Free State.

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(born July 17, 1745, Salem, Mass.—died Jan. 29, 1829, Salem, Mass., U.S.) U.S. politician. He joined the militia in 1766 and served in the American Revolution under George Washington, becoming adjutant general (1777–78) and quartermaster general (1780–85). He later served as U.S. postmaster general (1791–95), secretary of war (1795), and secretary of state (1795–1800). He served in the U.S. Senate from 1803 to 1811 and in the House of Representatives from 1813 to 1817. A leader of the Federalist Party, he was a member of the Essex Junto, and he opposed the War of 1812. After retiring from politics, he turned to experimental farming and education.

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A herd is a large group of animals. The term is usually applied to mammals, particularly ungulates. Other terms are used for similar phenomena in other types of animal. For example, a large group of birds is usually called a flock (this may also refer to certain mammals as well) and a large group of carnivores is usually called a pack. In addition, special collective nouns may be used for particular taxa: for example a flock of geese, if not in flight, is sometimes called a gaggle. However, in theoretical discussions in behavioural ecology, the generic term "herd" is used for all these kinds of assemblage. A herd may also refer to one that tends and cares for such groups (i.e. shepherds tend to sheep, and goatherds tend to goats, etc.).

When an association of animals (or, by extension, people) is described as a "herd", the implication is that the group tends to act together (for example, all moving in the same direction at a given time), but that this does not occur as a result of planning or co-ordination. Rather, each individual is choosing behaviour that corresponds to that of the majority of other members, possibly through imitation or possibly because all are responding to the same external circumstances. A herd can be contrasted with a co-ordinated group where individuals have distinct roles. Many human groupings, such as an army detachments or sports teams, show such co-ordination and differentiation of roles, but so do some animal groupings such as those of eusocial insects, which are co-ordinated through pheromones and other forms of animal communication. Conversely, some human groupings may behave more like herds.

Why do animals herd?

The question of why animals group together is one of the most fundamental in sociobiology and behavioural ecology. As noted above, the term "herd" is most commonly used of grazing animals such as ungulates, and in these cases it is believed that the strongest selective pressure leading to herding rather than a solitary existence is protection against predators. There is clearly a tradeoff involved, since on the one hand a predator may hesitate to attack a large group of animals, while on the other a large group offers an easily detected target. It is generally believed that the most important protective factor is risk dilution - even if a predator attacks the herd, the risk for any individual that it will be the victim is greatly reduced. In the case of predators, it is often unclear whether the term "herd" is appropriate, since there may be some degree of co-ordination or role differentiation in group hunting. Predator groups are commonly smaller than grazing groups, since although a pack may be more effective at pulling down prey than a single animal, the prey then has to be shared between all members, so that the weaker animals will often be better off hunting smaller prey on their own.

The structure and size of herds

A herd is by definition relatively unstructured. However, there may be one or a few animals which tend to be imitated by the rest of the members of the herd more than others. An animal taking this role is called a "control animal", since its behaviour will predict that of the herd as a whole. It cannot be assumed, however, that the control animal is deliberately taking a leadership role. Control animals are not necessarily, or even usually, those that are socially dominant in conflict situations, though they frequently are. Group size is an important characterestic of the social environment of gregarious species.

Domestic herds

Domestic animal herds are assembled by humans for practicality in raising them and controlling them. Their behaviour may be quite different from that of wild herds of the same or related species, since both their composition (in terms of the distribution of age and sex within the herd) and their history (in terms of when and how the individuals joined the herd) are likely to be very different.

Human parallels

The term herd is also applied metaphorically to human beings in social psychology, with the concept of herd behaviour. However both the term and concepts that underlie its use are controversial.

The term has acquired a semi-technical usage in behavioral finance to describe the largest group of market investors or market speculators who tend to 'move with the market,' or 'follow the general market trend.' This is at least a plausible example of genuine herding, though according to some researchers it results from rational decisions through processes such as information cascade and rational expectations. Other researchers, however, ascribe it to non-rational process such as mimicry, fear and greed contagion. "Contrarians" or contrarian investors are those who deliberately choose to invest or speculate counter to the "herd".

See also

• Flocking in computer simulations
• Gaggle
• Herding
• Herd behavior
• Herder
• A list of animal names featuring their collective nouns
• Solitary
• Swarming