Using a present, or "nuptial gift", to ensure a sexual engagement is a practice found throughout the animal kingdom …
In many species of insects, birds and mammals, males acquire and donate food to females either before, during, or after copulation (termed mate provisioning, courtship feeding, nuptial gift giving, or meat-for-sex). …Courtship feeding is particularly common among many bird species.
Gift Giving: Many birds perform a ritual known as courtship feeding or gift giving. Usually the female will spread her wings and open her beak, behaving like a young bird begging for food. This ritual not only allows her to build up her strength for the demanding job of laying and incubating the eggs, but it also assures her that the male will be a good provider for the chicks. Instead of food, some species of bird present their partners with nesting material. Herons give their mates large twigs which are offered up with ceremonial bowing. Gift giving is probably a symbolic show of the males nest building abilities.
Nuptial gifts are food items or inedible tokens that are transferred to females during courtship or copulation 1, 2 and 3. Tokens are of no direct value to females, and it is unknown why females require such worthless gifts as a precondition of mating. One hypothesis is that token giving arose in species that gave nutritious gifts and males exploited female preferences for nutritional gifts by substituting more easily obtainable but worthless items . An invasion of such behavior would require that females accept the substitute gift and copulate for a period of time similar to that with genuine gifts. We show that both these prerequisites are met in the dance fly Rhamphomyia sulcata, in which females normally accept a nutritious gift. We removed the gift from copulating pairs and replaced it with either a large or small prey item or inedible token. We found that although pairs copulated longest with a large genuine gift, the tokens resulted in copula durations equivalent to those with a small genuine gift. We also observed that males that returned to the lek with tokens re-paired successfully. These findings suggest that female behavior in genuine gift-giving species is susceptible to the invasion of male cheating on reproductive investment.
Courtship rituals in insect mating include serenades, dances, nuptial gifts, physical touch, and even aphrodisiacs.
"Males with gifts increase the chances to be accepted by females and also prolong copulation duration, males without gifts are normally rejected or obtain short copulations."
Systematic research into courtship processes inside the workplace as well two 10-year studies examining norms in different international settings continue to support a view that courtship is a social process that socialises both sexes into accepting forms of relationship that maximise the chances of successfully raising children.
Courtship does not always run smoothly for the brightly coloured birds. Mr Hamilton James notes that impatient males only wait around 10 minutes before giving up and eating the fish themselves.
"Sometimes the female will beg for fish and the male will ignore her and eat them in front of her," he adds.
…in most of the examples cited in the article, the 'gifts' seem to be laced with pheromones and other scent markers aimed at stimulating the females 'desire'. So perhaps what we are looking at is a predominance of deceptive behaviour in males in order to acquire sex or rather, exclusive mating rights.