A pollinator is an animal that moves pollen from the male parts of flowers to the female parts of the same or different flowers of the same species. This enables plants to produce seeds and fruit, thereby allowing them to reproduce and sustain healthy ecosystems.
Pollination also occurs through self-pollination, wind and water. Which of these systems is used depends on the plant species, but it can also be influenced by local weather conditions and the availability of pollinators. While the vast majority of fruit tree and colorful flower species are heavily dependent on pollinators, edible grains and other species of grasses rely entirely on the wind.
Pollinators include insects, birds, reptiles, bats and some small mammals. Among these, insects are the most important and diverse group. Bees are the most efficient and specialized pollinators for many crop species and wild flowering plants. Butterflies and moths contribute to pollination across a wide range of habitats, often visiting multiple plant species as they move. Beetles, flies and thrips also play crucial but sometimes less targeted roles.
Several hundred species of reptiles, mostly lizards but also geckos and skinks, are also pollinators. The only known amphibian pollinator is an endangered tree frog in coastal Brazil.
Whereas bees rule daytime pollination, bats dominate the night. These essential keystone pollinators serve as the primary or sole reproductive lifeline for more than 500 plant species in 67 families. Without them, major desert and tropical ecosystems would face collapse, and global agriculture would lose billions of dollars in commercial fruit industries.
Birds are just as important for pollination as bats, and their overall footprint spans a significantly broader geographical range. While roughly 50 specialized bat species serve nocturnal plants through specialized relationships, more than 900 bird species act as pollinators, reaching a far greater variety of plant species and dominating daytime vertebrate pollination.
Non-flying mammals have a much smaller role, but serve as vital pollinators for at least 85 plant species. They are typically small, nocturnal and highly agile tree dwellers that are attracted to big, tough, bowl-shaped flowers that produce large amounts of sugary nectar and can withstand the rough handling of furry faces.
Among them is the honey possum of Southwestern Australia, which is the world's only flightless mammal that obtains all of its food from flowers. The Black-and-White Ruffed Lemur in Madagascar, the world's largest pollinator, is strong enough to rip open the bracts (colorful protective structures) which surround some tropical flowers. Some wild mice, rats and shrews are highly effective nocturnal pollinators.
Pollinators also have another important role: they serve as major food sources for other species. For example, many songbirds time their egg hatching with the emergence of pollinating insect populations.
While the threat of extinction is widespread and growing for numerous species, the threat is particularly severe for pollinators. This is a result of the compounding effects of land use change, climate change, pollution and invasive species. For example, insects are particularly vulnerable to pesticides and artificial lighting, which attracts them away from flowers and makes them more exposed to predators. Migratory bats are particularly vulnerable to gaps in their long migration corridors.
Among the most endangered pollinators are wild native bees, including specialized solitary bees and bumblebees. Managed honeybees, despite receiving the most media attention, are considered a domesticated agricultural species not at risk of extinction. Roughly 16 to 20 percent of butterfly and moth species are facing high extinction risks, alongside nectar-feeding bats, which are the most endangered vertebrate pollinators.
Losing even a seemingly minor pollinator species can trigger an ecological domino effect that collapses an entire ecosystem. While dominant general pollinators handle the highest volume of plants, minor and specialized pollinators play critical, irreplaceable roles in ecological networks.
The continued loss of pollinators will ultimately have severe effects for humans. Although it will not likely lead to widespread famine, because wheat, rice, corn and other grains are wind- or self-pollinated, it will diminish the supply of micronutrient-rich foods such as fruits, vegetables and nuts, making diets less varied and less healthy. This shortage will make global diets less balanced and exacerbate malnutrition and diet-related chronic illnesses, particularly in vulnerable regions and households.