A recent study in Costa Rica revealed some evolutionary secrets of one of nature’s most adorable birds–the hummingbird. Scientists at La Selva Biological Station in Costa Rica wanted to understand feeding habits of the tiny birds and how the relationship between hummingbirds and their favorite flower foods may have developed. Biologists looked at characteristics of several species of hummingbirds and the flowers they munched on over a period of several years, and came up with a few theories to explain the results they found. The scientists measured the length of bird beaks and flower stems, and found a few interesting connections. They found, first of all, that the length of each species’ beak was closely related to the length of the flower corolla on their favorite food. Secondly, they found that the closer the match between bird and flower, the more heavily the species depended on the flower as a primary or significant food source. Additionally, they found that hummingbird species with longer or more curved beaks were more specialized to particular flowers than their shorter-beaked relatives. Closer matches between the beak and flower length also tended to reduce the amount of time the birds spent feeding on each flower. Although the scientists did not measure how much the flowers depended on the birds, they reasoned that the relationship probably goes both ways: if the birds are heavily reliant on specific flowers, those flowers also probably need the hummingbirds to act as pollinators. Therefore, both species need each other in order to survive!
These findings are important for a few reasons. They show clear differentiation between types of hummingbirds, which reduces competition between species, leaving more food to go around. Higher specialization has several positive effects on the birds as well. Close beak matching results in less time at each flower, reducing the energy cost to the tiny birds. It increases their efficiency at feeding and increases resource use efficiency. These flowers and birds have evolved together over millions of years to have a special symbiotic relationship that benefits both types of organisms and influences their development along the way. This study demonstrates some of the clearest evidence for evolutionary biology that we can see outside of the fossil record. If we can understand how organisms evolved and how they relate to one another in the world today, we can better manage our own environment. We can mitigate our impact on the creatures that share the earth with us and set them up for success in the future.
Maglianesi, M. A., Blüthgen, N., Böhning-Gaese, K. and Schleuning, M. (2014). Morphological traits determine specialization and resource use in plant–hummingbird networks in the neotropics. Ecology, 95: 3325–3334. doi:10.1890/13-2261.1