Define pollination and also what is it called when a bird is a pollinator?

Hint: Pollination is the transfer of pollen grains from the male anther to the female stigma. This transfer is carried by various agents such as insects, animals and birds. Pollination of flowers by different agents has got different names. This pollination is done by the agent who can fly high in the sky.

Complete answer:
Ornithophily is the pollination of flowering plants done by the birds as a pollinator. Pollination occurs in the plants bearing colourful flowers and the reproductive parts stigma and stamen are arranged in such a way that pollinators can easily pollinate the flowers. Ornithophily is mainly done by those birds who are involved in the collection of nectars that means those birds who are good nectarivores. Ornithophily mainly occurs in tropical regions where food crops including bananas, papayas, and nutmeg are pollinated.
-The nectarivore birds have special features like brushy tongue and long beak which help them in collecting nectars from the flowers. For example, hummingbirds bear these specialised features.
-Bird pollination is a curse in those plants which are mostly red in colour and their flowers with long tubular structures holding a lot of ample nectar.
-The nectar found in plants are of two types: dilute and concentrated nectar. The dilute nectar is found in plants with generalized pollinators whereas concentrated nectar is found in plants with specialised pollinators.
-The sugar composition of nectar is different in different plants. For example, the nectar collected by the insect is rich in sucrose content.
-For the purpose of pollination plants also have different adaptations. For example, some plants with bird pollinators may have explosive flowers, for example, plants of the family Loranthaceae and also some flowers may explode after the actions of the bird, for example, some species of Banksia.
-Some specialized nectar-feeding birds are hummingbirds, honeyeaters, honeycreepers, sunbirds, etc.
-The red coral tree, silk cotton, and bottle brush are some examples of Ornithophilous plants.

Note:
-The nectarivore birds are having special features like brushy tongue and long beak which help them in collecting nectars
-The nectar found in plants are of two types: dilute and concentrated nectar.
-For energy, the hummingbirds rely completely on nectar, and in order to reproduce the ornithophilous flowers need hummingbirds’ assistance with pollination.
-The evolution of ornithophily has been favoured by those ecosystems in dry regions or isolated islands and also high altitude ecosystems that lack insect pollinators.