Begging in animals

Begging in animals is when an animal solicits being given resources by another animal. This is usually a young animal soliciting food from their parents, brood hosts or other adults. However, the resource is sometimes non-food related or may be solicited by adult animals. Begging behavior is most widely studied in birds, however, mammals, amphibians, and invertebrates perform begging displays. Generally in food solicitation, begging behavior is instinctive, although in some instances it is learned (e.g. pet cats and dogs).

While the ultimate causation for begging is an increase in the animal's individual fitness, several theories have been proposed for how food begging evolved proximate causes including scramble competition, honest signalling of need, and cooperative begging by siblings. Various types of information such as nutritional status or immunocompetence can be transmitted with auditory and visual begging signals and the behavior can be modulated by several factors such as brood size and hormones. Similarly, several costs of begging have been investigated including energetic, growth and predation cost. Begging from humans also occurs under artificial circumstances such as donkeys, elephants and dolphins begging for food from tourists.

In 1950, Tinbergen and Perdeck tested the effects of visual stimuli on begging behavior by gull chicks, elucidating which characteristics of their parent's bills the chicks were reacting to. Using models varying in different characteristics, they tested multiple stimuli and found that gull chicks pecked most at a long, red bill with contrasting white bars at the end. Chicks also pecked at other models; in decreasing order of begging intensity were a two-dimensional cardboard cut-out of the head of a gull with a red spot on its bill, simply a bill with a red spot, and a cut-out of a gull's head with no red spot on the bill. These studies showed the chicks were responding to the red spot stimulus on their parents' bills, an example of imprinting.

1n 1953, Von Haartman first demonstrated that chick begging is a stimulus to parental feeding and that the begging level of the brood increases with deprivation.

Parent–offspring conflict describes the evolutionary conflict arising from differences in optimal fitness of parents and their offspring. While parents tend to maximize the number of offspring, the offspring can increase their fitness by getting a greater share of parental investment often by competing with their siblings. Food distribution by parents among offspring is a key element in the parent-offspring conflict. Young animals are potential competitors and attempt to skew parental food allocation in their favor; this is most often attempted by conspicuous begging displays. Several models have been proposed to explain the evolution of conspicuous offspring solicitation. One model predicts that begging intensity is driven by scramble or sibling competition. A second model is that begging intensity reflects the true condition or need of the individual and that the cost of the signal imposes honesty. A third model predicts that animals respond to the overall signal of the entire brood and that the siblings cooperate to gain the most food.

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