Could plants be hard up, reproductively speaking? A new study found that many plants, particularly in tropical areas, face a growing risk of extinction due to declines in the number of pollinators out there. Pollinators include birds, bees, butterflies, and other insects that take pollen from one plant to another.

Some pollinators, such as hummingbirds, are increasingly stymied by habitat changes over migration routes. Since some plants and their pollinators co-evolved to have highly specific relationships, once a pollinator species declines in number, there is no one left to pollinate the plant. Overall, the study found that worldwide drops in numbers of pollinators left plants competing for reproductive help.

The Canadian-led study found that plants in regions with higher overall biodiversity, such as the tropics, faced more competition for pollinators. This could be because these areas are more at risk for pollinator habitat loss from deforestation.

Previous studies have also concluded we might headed for a pollination crisis. Other threats to pollinators include pesticides, invasive species, and agricultural practices. According to the U.S. Fish and Wildlife Service, 90 percent of all flowering plants and more than 75 percent of food crops rely on pollinators for reproduction.

Photo credit: Fish and Wildlife Service