The Helpful Gardener: Rats Aid Pollination and Seed Dispersal

By Haleydolton @haleydolton

Rats do not always provoke the best reaction from people, but hopefully, due to recent research, people may look upon them more favorably and get past their ‘creepy’ hairy tail and feet.

Historically, rats have been transported all around the world mainly by exploring travellers, making rats an invasive species across the majority of the globe. Some rat populations have played a major role in carrying diseases to new countries and devastating native flora and fauna species. However, new investigations into the role played by invasive rats in an ecosystem have been conducted and it turns out, they are not all that bad.

Recent declines in pollinating invertebrates such as bees, has resulted in pollination of flowering plants declining. This has a negative impact on food crops and the natural flora and fauna found in the wild. Insect pollination is approximately worth £141 billion per year, making a resolution to this problem not only ecologically important, but also financially beneficial.

Fortunately, other species can pollinate flowers such as bats, birds, mammals and reptiles. Dr. David Wilcove and his team have found the invasive rat (Rattus rattus) in New Zealand acting as a pollinator on the main Island. Unfortunately, this may only be because they have preyed upon the majority of endemic pollinators.

Although this research is somewhat of a double – edged sword, it was unexpected to find rats acting as pollinator for native plant species which may otherwise have suffered a major population deficit. Dr. Wilcove has suggested the rats make a successful substitute for pollinators in this instance because the plants studied do not rely on a specialist to pollinate them.

In another study, Dr. Pierre-Michel Forget and his team have discovered for the first time that the species, Kivu giant pouched rat (Cricetomys kivuensis) is helping flora seed dispersal in Africa.

Rodents in temperate climates are well known to disperse seeds far from a parent tree. For example, we have all seen a squirrel hiding their nuts for winter! Conversely, it was long thought that rodents living in tropical conditions in Africa only stored seeds deep in burrows, leaving no chance for them to germinate.

However, Dr. Forget established the Kivu giant pouched rat also scatter-hoarded large seeds, leaving any forgotten hidden seeds the chance to germinate. This not only benefits the ecosystem as whole, but also the rat directly as food will continue to be provided from new plants in years to come.

These two studies highlight the importance invasive species may be playing in certain ecosystems, which is vital to consider in future pest control schemes.