Behaviour and Its Pattern PART 2 FIXED ACTION

Behaviour and Its Pattern PART 2

• FIXED ACTION PATTERN or INSTINCT • Fixed action patterns consist of a series of actions triggered by a key stimulus. The pattern will go to completion even if the stimulus is removed. • Though a fixed action pattern is more complex than a reflex, it's still automatic and involuntary. Once triggered, it will go on to completion, even if the key stimulus is removed in the meantime.

• However, this fixed action pattern can also occur under circumstances where it is not useful, in other words, where it does not give any benefit like egg rolling and retrival behaviour of the European greylag goose: • If the egg that rolls out of the nest is picked up and taken away, the goose will keep moving her head as though pushing an imaginary egg. • The goose will try to push any egg-shaped object, such as a golf ball, if it is placed near the nest. In fact, she'll even carry out the retrieval pattern in response to a much larger object, such as a volleyball! • .

• A well-studied example of a fixed action pattern occurs in ground-nesting water birds, like greylag geese. If a female greylag goose's egg rolls out of her nest, she will instinctively use her bill to push the egg back into the nest in a series of very stereotyped, predictable, movements. The sight of an egg outside the nest is the stimulus that triggers the retrieval behavior. • It's not too hard to imagine why this hardwired trait would be favored by natural selection. Goose mothers that retrieve their lost eggs are likely to have more surviving offspring, on average, than those that don't.

• This example illustrates the fixed aspect of a fixed action pattern. In the great majority of cases a goose is likely to encounter in nature, the behavior of rolling any egg-like object near the nest back into the nest will be beneficial. However, it's simply a biological program that runs in response to a stimulus and can have unhelpful results under unusual circumstances

• spot-pecking behavior in herring gulls is another example that show fixed action patterns. watch a herring gull caring for its chicks, you may notice a funny ritual around feeding time. The parent gull has a red spot on its beak. When it taps its beak on the ground, the chick will peck at the spot several times. • This pecking triggers a response in the parent: it throws up food for the chick. • The tapping behavior is innate, or genetically preprogrammed. Herring gull chicks will peck at the red dots of their parents' beaks without any prior training. In fact, a baby herring gull can be tricked by a yellow stick adorned with a red dot—it will peck at the stick just as eagerly as it would at a parent's beak.

• Another classic example of a fixed action pattern comes from the three-spined stickleback, a small freshwater fish. During the breeding season, male sticklebacks develop a red belly and display innate aggressive behavior towards other males. • When a male stickleback spots another nearby male, he will launch into a fixed action pattern involving aggressive displays designed to scare off the stranger. The specific stimulus that triggers this fixed action pattern is the red belly coloration pattern characteristic of males during breeding season.

• This is just one example of an innate behavior, or behavior that's genetically hardwired in an organism. Given the right cues, an organism will perform an innate behavior without the need for prior experience or learning. Innate behaviors tend to be very predictable—like the herring gull tapping—and they are often performed in a very similar way by all members of a species.

• MOTIVATION • The term Drive (Urge) was introduced by Woodworth (1918) as motivational concept. Animals experienced drive as biological needs such as eating and drinking and alteration in their behaviour. • Motivation helps animal to achieve some specific goals, such as hunger, thirst, reproductive urge etc. • It also has three aspects: • 1. Driving state within the animal. • 2. The arousal of behaviour. • 3. To achieve the goal.

• HUNGER & THIRST DRIVE • Hunger drive is controlled by lateral hypothalamus and ventro-median nucleus, the former is stimulatory in function while the latter is inhibitory. Glucocorticoids inhibit the hunger drive. Lateral hypothalamus can be stimulated by epinephrine. The hunger and thirst drives depend on hours of deprivation of feeding on dry food. • HOARDING DRIVE • Many mammals such as male gerbil and squirrels possess hoarding drive as the lean season approaches. Low estrogens and testosterone levels stimulate hoarding drive in mammals. Castrated individuals show increased hoarding drive, which can be reduced by giving testosterone treatment.

• HORMONES IN SEXUAL DRIVE • Sexual drive involves courtship behaviour such as singing and dancing in birds, croaking in frogs and fighting in males of many vertebrates. In insects courtship behaviour is stopped if corpora allata are removed. • Hormonal levels increase in breeding season. Castrated males and females do not show sexual behaviour in vertebrates while testosterone injections elicit sexual behaviour. According to Johnson (1976) oestrogen enhances female attractiveness and receptivity and causes oestrous in females. • Hypothalamic Releasing Factor (LH-RF) and ACTH are known to affect copulatory behaviour in many animals.

• AGGRESSION DRIVE • Aggression is controlled by amygdala of the limbic system of brain and posterior hypothalamus is also involved to some extent. In most of the male mammals testosterone causes aggression while in females high oestrogen levels reduce aggression and make the female peaceful. Hydrocortisone also increases aggression while hydroxydione decreases it. In ringed dove implants of testosterone propionate at specific sites of hypothalamus causes aggressiveness.

• TERRITORIAL DRIVE • Many vertebrates mark and defend their territory. Dogs, hyenas and some prosimians mark their territory by their own urine. Monotremes and marsupials have anal glands which they rub on the ground to mark territory. In tigers and cheetahs also there anal glands which spray the secretion on the trees to mark their territory. Gazelles possess orbital glands below the eyes which secrete a tar-like substance that they apply on grasses and bushes. Territorial behaviour is also hormone dependent. Yahr & Thiessen (1972) isolated 11 different hormones that influence territorial behaviour in vertebrates.

• MIGRATORY DRIVE • Migratory drive occurs in fishes and birds and may be seasonal or related to reproduction. Pineal glands, which is affected by day-light hours, affects migration in birds. In warblers pituitary gland influences migratory urge as well as excessive eating to deposit fat energy in the body. In stickleback fish thyroxin injection caused them to migrate. In Salmon and Anguilla, maturation of gonads produces migratory drive, so much so that they stop eating and set out to the course of migration crossing all obstacles on the way. •

• PARENTAL CARE DRIVE • Gonadotropin secretion by pituitary gland cause not only courtship display but also parental care in birds. Progesteron injections made the birds sit on the eggs to incubate within 20 minutes. • In pigeons, secretion of prolactin from pituitary causes enlargement of crop to produce pigeonmilk which is fed to the chicks. Prolactin also acts directly on brain and makes the preoptic nucleus of hypothalamus in birds to respond to chicks calls.