Hummingbirds and flowers have a very close relationship. Hummingbirds rely on flowers for food in the form of nectar, and flowers rely on hummingbirds for pollination. This mutualistic relationship has evolved over millions of years, with hummingbirds developing adaptations like long beaks and tongues specifically to reach into certain flowers, while flowers have adapted colors, shapes, and nectar chemistry to attract hummingbirds. Understanding this co-evolutionary relationship provides insights into the natural history of both groups.
How do hummingbirds get food from flowers?
Hummingbirds have specially adapted beaks and tongues to sip nectar from flowers. Their long, slender beaks allow them to reach deep into tubular flowers. Their extensile tongues have forked tips that can dart in and out of flowers quickly. As the hummingbird inserts its beak into the flower, its tongue laps up nectar at a rate of 13-17 times per second. The nectar provides a high-energy food source for hummingbirds, containing sugars like sucrose, fructose, and glucose. Flowers have evolved to produce ample nectar during daylight hours when hummingbirds are active.
How do hummingbirds pollinate flowers?
As hummingbirds visit multiple flowers to drink nectar, they inadvertently carry pollen from one flower to another on their head and beak. When they insert their beak into a flower, their head and beak pick up pollen grains. As they fly to the next flower, they deposit some of that pollen onto the second flower’s stigma, the sticky part of the female reproductive organ. This fertilizes the plant so it can form seeds and fruit. A hummingbird may visit hundreds or thousands of flowers per day, making them prolific pollinators. Their wings also beat so fast that it allows for excellent pollen dispersal.
Which flowers do hummingbirds pollinate?
Hummingbirds primarily pollinate flowers that are tubular in shape and colorful, typically red. Some common hummingbird pollinated flowers include:
| Flower | Color | Region |
|---|---|---|
| Cardinal flower | Red | Eastern North America |
| Indian paintbrush | Red | Western North America |
| Salvia | Red | North and South America |
| Fuchsia | Red | North and South America |
| Trumpet vine | Orange, red | North and South America |
| Firecracker plant | Red | Tropical regions |
These tubular flowers perfectly match the long, slender beaks and tongues of hummingbirds. The red color attracts the hummingbirds since they can see red well. In exchange for food, the hummingbirds transfer pollen between plants as they feed, resulting in pollination and reproduction of these flowers.
How have hummingbird-pollinated flowers evolved?
The evolution between hummingbirds and flowering plants is a classic example of co-evolution. As hummingbirds specialized on nectar-feeding, flowers evolved in tandem to attract the hummingbirds. Several evolutionary adaptations occurred in hummingbird-pollinated flowers:
- Tubular corollas to match long beaks
- Red pigments in petals to attract birds
- Nectar with higher sugar concentration
- Greater nectar volumes produced
- Flower orientation for easier access
These adaptations make it easier and more rewarding for hummingbirds to feed, and in return the flowers get pollinated. This mutually beneficial relationship drives the evolution of specialized traits in both groups of organisms.
How have hummingbirds evolved to pollinate flowers?
Hummingbirds have also undergone adaptations as nectar-feeders:
- Slender, pointed beaks to reach into flowers
- Extremely long, forked tongues
- Ability to see red and orange flowers
- Hovering flight to stay suspended while feeding
- High metabolism to power constant feeding
These adaptations allow hummingbirds to specialize on nectivory. Their hovering ability and vision to detect flower colors are unique among birds. The match between beak shape, tongue structure, and flower shape ensures close pollen transfer. Overall, hummingbirds have evolved to become specialized nectar-feeding birds.
How does this relationship help both hummingbirds and flowers?
This co-evolved mutualistic relationship is beneficial for both groups. Hummingbirds get an abundant source of high-energy food to power their metabolically demanding lifestyle. Flowers get the service of pollination so they can reproduce.
Specific benefits include:
For hummingbirds:
- Reliable and efficient source of food energy
- Enhanced breeding and survival by accessing lots of calories
- Co-evolved with diverse flower species across ecosystems
For flowers:
- Increased pollination success by attracting efficient pollinators
- Greater genetic diversity through pollen transfer between plants
- More seeds and fruit produced, aiding reproduction
This mutualistic relationship is a key example of how species can evolve adaptations in tandem to help each other survive. Both hummingbirds and their companion flowers benefit greatly.
What risks exist in this codependent relationship?
While this mutualistic relationship has many benefits, there are also risks associated with codependency between two species. Potential risks include:
- If one species declines, it threatens the other (coextinction risk)
- Specialized relationships are vulnerable if environment changes
- Competing generalist species may displace codependent specialists
- Spread of disease between closely linked species
- Potential for one species to exploit the other and become parasitic
Maintaining diverse networks between interacting species helps provide resilience against these risks. But the intimacy between hummingbirds and their companion flowers means they face threats if the partnership is disrupted.
Examples of co-evolution between hummingbirds and flowers
Here are some specific examples of co-evolution between hummingbird species and flower species:
Broad-tailed hummingbird and Indian paintbrush
The broad-tailed hummingbird has co-evolved with the reddish-orange flowers of Indian paintbrush across the western United States. The flowers provide nectar, and the bird transfers pollen between plants. Indian paintbrush flowers have tube lengths and nectar volumes matched to the long beaks and high energy needs of broad-tailed hummingbirds.
Ruby-throated hummingbird and trumpet creeper vine
The ruby-throated hummingbird is the primary pollinator of the orange-red flowers of the trumpet creeper vine in eastern North America. The birds rely on this vine as a key food source. Trumpet creepers have elongated tubes to match the ruby-throat’s beak and produce enough nectar to meet the bird’s high metabolic requirements.
Andean hillstar hummingbird and giant lobelia
The Andean hillstar hummingbird is the sole pollinator for the red tubular flowers of the giant lobelia in the South American Andes mountains. The extremely long beak and tongue of the hillstar allows it to feed from the deep flowers. This exclusive relationship has driven the dramatic elongation of the hillstar’s beak and the lobelia’s flower tubes.
Calliope hummingbird and Indian rhododendron
The Calliope hummingbird feeds exclusively on the nectar of the bright red Indian rhododendron flowers in the western Himalayas region. These higher-elevation flowers provide vital food for breeding Calliopes. In turn, pollen transfer by Calliopes is critical for rhododendron reproduction in remote mountain areas.
Threats to these coevolved relationships
While mutually beneficial overall, these specialized co-evolutionary relationships are also more vulnerable to disruption. Potential threats include:
- Habitat loss: Deforestation, agriculture, and urbanization destroys specialized ecosystems
- Invasive species: Introduced competitor species can displace native codependent species
- Climate change: Altering of historical climate patterns disrupts timing between species
- Disease: Close contact facilitates spread of pathogens between partnered species
Maintaining intact ecosystems can help protect the intricate links between plants and pollinators like hummingbirds. Targeted conservation practices may be needed where critical mutually beneficial relationships are threatened by environmental changes.
Conclusion
The coevolutionary relationship between hummingbirds and flowering plants is an elegant result of natural selection over millions of years. Specialized adaptations allowing hummingbirds to drink nectar and flowers to be pollinated show the power of mutually beneficial partnerships. While threats exist in the form of habitat loss and climate change, understanding and protecting these important ecological interactions will be key for conservation. This codependent relationship will continue to shape the evolution of both hummingbirds and their partner flowers long into the future.
