It’s estimated that more than 90% of the plant species in tropical rainforests rely on animal ingestion to disperse their seeds. Some seeds may even need to be processed by the animals’ digestive tracts to be able to germinate.
You might think that larger creatures would gulp down bigger chunks of food. This idea had long been accepted by scientists studying seed dispersal, leading to the assumption that larger fruit-eating animals generally ingest larger seeds than smaller animals. This idea has been supported by studies of some animals, including fruit-eating birds and bats, but do these positive patterns hold true at a broader scale and across diverse taxa?
We have compiled data from thousands of scientific papers and amassed a worldwide database of 13,135 animal–seed interactions from all vertebrate groups, including 224 species of mammal, 313 species of bird, 42 species of reptile, one species of amphibian and seven species of fish.
The smallest seed-ingesting animal in our dataset was the Chatham Islands skink, which only weighs 3.3 grams. The smallest seed in its diet comes from a type of mountain snowberry. In contrast, the largest seed in the African elephant, which weighs nearly 4 tonnes, comes from an African tropical tree and is 9 cm long.
The South American tapir, which weighs more than 200 kg, transports the greatest number of seed...
