Hummingbirds and plants have a very close and important relationship. Hummingbirds rely on certain flowers as a food source, while those flowers depend on hummingbirds for pollination. This mutually beneficial relationship has evolved over millennia and allows both hummingbirds and plants to thrive. In this article, we will explore the specifics of the hummingbird-plant relationship, including the types of plants that attract hummingbirds, the role of hummingbirds in pollination, and how each species depends on the other. Understanding these connections can help us appreciate the natural world and why preserving biodiversity is so crucial.
What types of plants do hummingbirds visit?
Hummingbirds are attracted to flowers that provide nectar, their primary food source. The most common hummingbird-pollinated plants include:
– Trumpet creeper: These woody vines produce bright orange trumpet-shaped flowers that appeal to hummingbirds. Trumpet creepers grow well throughout the eastern United States.
– Cardinal flower: With bright red blooms, cardinal flowers advertise to hummingbirds with their color. These wildflowers thrive along streams and ponds in the eastern and central United States.
– Fuchsia: These popular ornamental shrubs feature hanging red and purple flowers. Both native and hybrid fuchsia varieties attract hummingbirds to feeders throughout North and South America.
– Salvia: With over 900 species, salvia is a diverse group of plants. Many salvias produce the tube-shaped flowers favored by hummingbirds, in colors like red, purple, pink, orange, and white.
– Columbine: The spurred flowers of these woodland plants hold ample nectar for hummingbirds. Different columbine species occur across North America.
– Penstemon: Also called beardtongue, penstemon species have bell or tube-shaped flowers that appeal to hummingbirds. They grow wild across much of North America.
– Pineapple sage: With bright red flowers and a sweet pineapple scent, this herb is a magnet for hummingbirds in the southwestern United States. It blooms in fall when other food sources start fading.
Why are hummingbirds and certain flowers a good match?
Hummingbirds and tubular flowers like those above have coevolved to be an ideal match in many ways:
– **Flower shape** – Tubular and trumpet-shaped flowers perfectly accommodate the long, slender beaks of hummingbirds. This allows hummingbirds easy access to the nectar tucked inside these flowers.
– **Color** – Bright red, orange, and pink flowers attract hummingbirds and allow these birds to spot the flowers from a distance. Contrasting flower centers also serve as targets, guiding the birds straight to the nectar.
– **Nectar** – The sucrose-rich nectar within hummingbird flowers provides these fast-flying birds with the high-energy food they require. This sweet liquid is the ideal fuel to power hummingbirds’ wings.
– **Abundant nectar** – Flowers adapted to hummingbirds produce relatively large amounts of nectar, delivering more reward per visit compared to the flowers of insect-pollinated plants. This helps offset the high metabolic demands of hummingbirds.
– **Flower orientation** – Many hummingbird flowers, like fuchsias, hang upside down. Gravity causes the nectar to pool at the base, which perfectly positions the nectar right at the tip of a feeding hummingbird’s beak.
How do hummingbirds assist with plant pollination?
As hummingbirds visit their preferred flowers in search of nectar, they deliver an invaluable service to plants through pollination. Here’s an overview of how hummingbirds pollinate flowers:
– Bees collect nectar and pollen from a wide variety of plants. Hummingbirds, in contrast, sip nectar from specialized tubular or trumpet-shaped flowers adapted to match their anatomy.
– When a hummingbird inserts its beak inside one of these flowers, pollen grains from the flower’s anthers stick to the bird’s head and beak.
– As the hummingbird flies to the next flower of the same species, some of this pollen rubs off inside the second flower’s stigma.
– Pollen deposited on the stigma then travels down the flower’s style. This enables fertilization and fruit production.
– A hummingbird may visit hundreds of flowers per day. Each time it transfers pollen, it facilitates cross-pollination between different individual plants.
– Without hummingbirds to transport pollen, many specialized flowers would fail to be adequately pollinated. Researchers have found hummingbird-pollinated plants produce up to 60% fewer seeds when hummingbirds are excluded.
Why are hummingbirds so well-suited to pollinate certain plants?
Hummingbirds have several unique adaptations that allow them to pollinate specialized flowers more effectively than many other animals can:
– **Narrow beaks** – A hummingbird’s slender, pointed beak reaches deep inside tubular flowers to sip the nectar within. As the beak probes the flower, it efficiently contacts both anthers and stigma to transfer pollen.
– **Thigmotaxis** – Hummingbirds exhibit a behavior called thigmotaxis where they prod around confined spaces. This instinct causes them to repeatedly insert their beaks inside flowers, increasing pollen transfer.
– **Hovering ability** – Hummingbirds can hover in place while feeding. This allows them to carefully probe every inch of a flower for nectar while also promoting thorough pollination. In contrast, larger birds must repeatedly land and take off.
– **High metabolism** – Hummingbirds have extremely high metabolisms and require frequent feeding. This brings them back to the same plants repeatedly, which is key for effective pollination.
– **Good memory** – Individual hummingbirds remember favorable feeding locations and return to them. Remembering flower locations promotes fidelity to particular plants, again boosting pollination.
– **Small size** – These tiny birds can access tubular blooms and reach nectar that no other pollinators can. Their petite size also allows them to exploit hanging flowers.
Examples of co-evolved hummingbird flowers
Many plants and hummingbird species have tightly coevolved to form highly specialized pollination relationships. Here are some examples:
– **Giant heliconia and hermit hummingbird** – Endemic to the rainforests of Central America, the hermit hummingbird has an extra-long, strongly curved beak perfectly matched to the hugely elongated flowers of the giant heliconia. As the bird’s beak extends deep into these flowers, its head and bill pick up pollen for transfer.
– **Torch ginger and mangrove hummingbird** – Found across the tropics globally, torch ginger produces flowers with tubular red bracts (modified leaves) that hold abundant nectar. The mangrove hummingbird’s curved bill allows it to access this nectar and pollinate the flowers.
– **Puya raimondii and oasis hummingbird** – This giant bromeliad is pollinated solely by the oasis hummingbird as it feeds on nectar held in Puya’s down-facing blooms. Both species are found only in the Andes Mountains.
– **Scarlet gilia and Allen’s hummingbird** – With its slender bill that matches the long tubular shape of scarlet gilia flowers, Allen’s hummingbird is a key pollinator of this plant in California. Scarlet gilia in turn depends on this one hummingbird species for pollination.
– **Bearded heliconia and long-billed hermit** – This heliconia’s flowers match perfectly with the extremely elongated bill of the long-billed hermit in Central America. As it feeds on nectar, pollen covers up to a third of the bird’s bill length.
Do hummingbirds remember and return to the same plants?
Research shows hummingbirds rely on both sight and memory to relocate rewarding flowers. This flower fidelity benefits plants by promoting cross-pollination between separate individuals. Here’s some of the evidence:
– In lab experiments, hummingbirds presented with artificial flowers remembered flower locations after waiting periods of up to eight hours. This memory allowed them to return to productive feeding sites.
– Hummingbirds closely inspect flowers and have good vision that allows them to associate a flower’s colors, shape and location with a nectar reward. These cues likely help spark their memory to return.
– Scientists have clocked hummingbirds visiting the same clumps of flowers or feeders several times per hour and returning to them day after day. Such repetition maximizes pollination.
– Some hummingbirds strongly prefer flowers of one color. Individuals returning repeatedly to their favored color will transfer pollen most efficiently between same-color blooms of the same plant species.
– Male hummingbirds are especially motivated to remember flower locations. They use this knowledge to establish feeding territories, which brings them back repeatedly to the same groups of flowers.
– Hummingbirds deprived of nectar will visit a wider array of flower species. However, adequately fed birds prefer to stick with tried and true nectar sources. This flower fidelity benefits the plants they rely on most.
How did these specialized plant-hummingbird relationships evolve?
The evolution of hummingbird flowers and associated pollination relationships required coevolution – a process whereby two species reciprocally affect each other’s evolution. Here is how scientists think it happened:
– Existing nectar-rich bee flowers provided an initial food source for early hummingbirds between 22 and 40 million years ago. Foraging on these flowers allowed hummingbird traits like hover-feeding to develop.
– Random genetic mutations produced flowers with a more tubular shape and greater nectar volume that were better suited to hummingbirds. These adaptations attracted more hummingbird visits.
– Hummingbirds with slight beak variations allowing them to access the new flower shapes were more successful. They visited the adapted flowers more frequently, driving more pronounced beak evolution.
– Preferences emerged, with certain hummingbirds specializing on particular flower shapes and colors. This drove even stronger reciprocal adaptations in each species.
– As hummingbirds became the primary pollinators of some flowers, the flowers evolved to perfectly match hummingbird anatomy and behavior, resulting in the highly specialized relationships seen today.
What ecological roles do hummingbirds fill?
As frequent flower visitors and pollinators, hummingbirds fill some important ecological roles:
– **Pollination** – By transferring pollen from flower to flower, hummingbirds facilitate plant reproduction in many ecosystems. The plants they visit often depend on them fully for pollination.
– **Seed dispersal** – Hummingbirds play a minor role dispersing seeds of certain berries and fruit after eating the pulp. Manzanita shrubs, for one, rely partly on hummingbirds dispersing seeds.
– **Flower evolution** – By exerting selective pressure and causing specialized adaptations, hummingbirds drive ongoing evolution of many flowering plants.
– **Food web support** – Nectar-feeding bats, insects, and other flower visitors all rely on the same flowers that hummingbirds use, though they access different floral resources. Hummingbird pollination keeps these food sources available.
– **Nutrient cycling** – Hummingbirds excrete nitrogen-rich waste after feeding on nectar. This returns nitrogen from ocean-derived food sources (nectar) back to terrestrial ecosystems.
– **Pest control** – To obtain protein for reproduction, hummingbirds feed heavily on insects. This provides natural pest control services to plants and gardens.
How do hummingbirds and plants impact each other’s reproduction?
Hummingbirds and their favored plants help each other immensely when it comes to reproduction by facilitating pollination:
– As hummingbirds move pollen from flower to flower, they allow plants to produce seeds and propagate future generations. Plants visited mainly by hummingbirds would reproduce far less without them.
– In return, the nectar these plants offer fuels hummingbird reproduction. Female hummingbirds need lots of energy from nectar to produce eggs. Males also require nectar to maintain energy and court females.
– Some co-evolved flowers time their bloom periods to precisely match hummingbird nesting. For example, puya plants in Chile bloom when hummingbird females are building nests and have peak energy needs.
– Abundant nectar also supports hummingbird migration and winter survival. Hummingbirds migrating north each spring rely on a sequence of plants flowering from south to north to fuel this journey.
– Plants produce extra dilute nectar lacking sugars during the hummingbird nesting season. This provides a high-energy boost to females and chicks without overtaxing their kidneys.
– In colder climates, late-blooming flowers like pineapple sage extend the time hummingbirds can breed by fueling migration and pre-hibernation weight gain.
How could climate change impact hummingbird-plant interactions?
Climate change poses some serious threats to the mutualistic relationships between hummingbirds and their host plants:
– Rising temperatures cause many flowers and hummingbirds to breed and migrate earlier. However, some species are shifting faster than others, disrupting perfect timing between migration and nectar availability.
– Climate extremes like droughts can kill flowers and nectar plants. This leaves migrating hummingbirds starved for fuel.
– Warming benefits generalist hummingbird species that will take over territories of extinction-prone specialists. Loss of these specialized birds could reduce pollination of the plants they co-evolved with.
– Northern expansion of southern generalists like the ruby-throated hummingbird may outcompete native species. Mismatching of bills and flower shapes could negatively impact pollination.
– Hotter summers and lack of water stress plants, reducing nectar production. Less food availability negatively affects hummingbird reproduction and survival.
– Some areas may see an increased number of hummingbird species while others lose species diversity. Altered community compositions could disrupt plant pollination.
How can providing hummingbird gardens and feeders support wild populations?
Here are some ways backyard gardeners can support hummingbird conservation through thoughtful habitat gardening:
– Plant a diversity of native plants selected for continuous bloom from spring through fall. This provides essential food from migration through breeding.
– Include late-season bloomers to fuel migration and pre-hibernation weight gain. Good choices are sages, asters, and trumpets.
– Choose flowers with red, orange, and pink tubular blooms preferred by hummingbirds. Select a mix of flower shapes to attract diverse species.
– Avoid modern hybrid flowers. Opt for old-fashioned varieties with more accessible nectar.
– Allow some weeds like thistles, jewelweed, and hedge nettle to grow. These supplement garden flowers with extra nectar.
– Only use chemical pesticides and herbicides when absolutely necessary. Limit use to protect hummingbird safety.
– Set up feeders with fresh sugar-water (1 part sugar to 4 parts water) in early spring and keep them clean and filled through fall.
– Include perches for hummingbirds to rest. Make sure feeders are in the shade to slow sugar water spoilage.
– Provide water sources like misters, fountains, and small ponds for drinking and bathing.
Conclusion
The relationship between hummingbirds and the plants they pollinate provides an excellent example of coevolution and mutualism where both parties benefit. Plants adapted to match hummingbird anatomy and behavior rely completely on visits by these tiny energetic birds to reproduce. In turn, hummingbirds get the high-energy nectar they require from their co-evolved partner plants. This reciprocal relationship spans both New and Old World ecosystems, with over 100 specialized plant-hummingbird partnerships cataloged. Looking ahead, both sides of these essential bonds face threats from habitat loss and climate change that call for increased conservation awareness and habitat protection. Thoughtful gardening choices can help preserve these beautiful pollination mutualisms in our own backyards.
