Birds as pollinators Essay
Pollination, whereby pollen grains (male) are transferred to the ovule (female) of a plant, is an irreplaceable step in the reproduction of seed plants. Most plant fruits are unable to develop without pollination taking place and many beautiful flower varieties would die out if not pollinated. Bees and insects are the most common pollinators, but bats and birds are known to do their share in this vital activity. The agent moving the pollen, whether it is moths, bees, bats, wind or birds, is called the “pollinator” and the plant providing the pollen is called the “polliniser”.
Biotic pollination is the term used when pollination is aided by a pollinator. When this is carried out by birds, the term used is Ornithophily. Hummingbirds, spider hunters, sunbirds, honeycreepers and honeyeaters are the most common pollinator bird species. Plants that make use of pollination by birds commonly have bright red, orange or yellow flowers and very little scent. This is because birds have a keen sense of sight for colour, but generally little or no sense of smell.
Bird pollinated flowers produce copious amounts of nectar to attract and feed the birds that are performing the pollination, as well as having pollen that is usually large and sticky to cling to the feathers of the bird. Hummingbirds are small birds which are found only in the Americas. Their ability to hover in mid-air by flapping their wings up to eighty times per second, plus their long curved beaks and a love for sweet nectar, makes them perfect pollinators.
Hummingbirds burn up a tremendous amount of energy as they dart about from flower to flower and so they are attracted to the flowers that will give them something in return for their pollinating efforts. The flowers they are particularly fond of include shrimp plants, verbenas, bee balm, honeysuckles, fuchsias, hibiscus and bromeliads. Sunbirds and spider hunters feed mainly on nectar, although when feeding young, they often also eat insects. Sunbird species can take nectar while hovering, but usually perch to feed.
Their long curved beaks and brush-tipped tubular tongues make these birds particularly suited to feeding on and pollinating tubular flowers. Honeyeaters resemble hummingbirds in many ways, but are not capable of lengthy hovering flight. Honeyeaters quickly flit from perch to perch, stretching or hanging upside down in order to reach the nectar with their highly developed brush-tipped tongue, while at the same time serving as a pollinator. Birds are not known for pollinating food growing crops, but this does not mean that they are not important.
If it were not for the assistance of our feathered friends, many plant species would be in danger of extinction. Attained from: http://www. birds. com/blog/the-important-role-of-birds-in-pollination/ on 20th Nov, 2012. Globally, bird-pollinated plants can be separated into two groups, one consisting of species pollinated by specialist nectarivores, and the other of plants pollinated by occasional nectarivores. There are marked differences in nectar properties among the two groups, implying that there has been pollinator-mediated selection on these traits.
This raises the possibility that variation in bird assemblages among populations of a plant species could lead to the evolution of intraspecific variation in floral traits. We examined this hypothesis in Kniphofia linearifolia, a common and widespread plant in southern Africa. Although bees are common visitors to flowers of this species, exclusion of birds from inflorescences led to significant reductions in seed set, indicating that the species is primarily bird-pollinated. We showed that bird pollinator assemblages differ markedly between five different populations of K. inearifolia, and that variation in flower morphology and nectar properties between these populations are associated with the dominant guild of bird visitors at each population. We identified two distinct morphotypes, based on corolla length, nectar volume and nectar concentration, which reflect the bird assemblages found in each type.
Further work is needed to establish if a natural geographic mosaic of bird assemblages are the ultimate cause of differentiation in floral traits in this species Authors: Brown, Mark1 [email protected] ac. za Downs, Colleen1 Johnson, Steven1 Source: Plant Systematics & Evolution; Jul2011, Vol. 294 Issue 3/4, p199-206, 8p, 1 Color Photograph, 3 Charts, 3 Graphs, 1 Map Attained from: http://web. ebscohost. com/ehost/detail? sid=1fe8f789-9d74-4021-8fda-9059204eb8a8%40sessionmgr115&vid=1&hid=123&bdata=JnNpdGU9ZWhvc3QtbGl2ZQ%3d%3d# db=a9h&AN=61844127 on 20th Nov, 2012 Birds That Pollinate Flowers Many people in North and South America think of the hummingbird when they think of a bird that pollinates flowers. However, there are over 2,000 species of birds that pollinate flowers, and hummingbird species are just some of the bird pollinators.
Other birds that pollinate flowers include the Hawaiian honeycreeper, certain parrot species in New Guinea, tropical sunbirds and the Australian honeyeater. What Flowers Do Birds Pollinate? Different flowers suit different pollinators. Birds, bees, beetles and butterflies all pollinate flowers, and the flowers and the pollinators suit each other. Flowers that birds can pollinate tend to look similar. They tend to be long, tubular or cup-shaped flowers like honeysuckles. This shape allows a bird to reach into the flower and pollinate it when it places its beak into the flower to look for nectar.
Bird-pollinated flowers are often bright colours like red, yellow or orange. Bright red and pink flowers are particularly attractive to birds. Think of the columbine, many honeysuckles and the fuschia in the hanging planter. These plants are very attractive to bird pollinators. The nectar is deep within the flower so that the bird needs to probe the flower with its beak. While it probes the flower, it collects the pollen on its head and back. Birds look to flowers for nectar, and the pollination is what flowers get out of the deal.
Since birds don’t smell very well, flowers that attract birds do not need to have a scent, although some of them may be scented. Species of Flowers That Attract Birds * If you are creating a flower garden for the birds, what species of flowers should you grow in your garden? Grow honeysuckles on trellises and up existing plants. These plants add a beautiful scent and attract birds with their nectar. Add clematis to the trellis for its large and beautiful flowers that also attract bird pollinators. Place fuschias in planter boxes and hanging baskets.
Grow columbines at the base of trees and shrubs in the partial shade. Impatiens and phloxes also attract birds and create a lovely cottage garden look. Looking for a shrub to plant for the birds? Butterfly bush attracts both bird and butterfly pollinators. Azaleas come in vibrant colours and will also attract avian pollinators. Attained from: Flowers Pollinated by Birds | eHow. com http://www. ehow. com/list_6502456_flowers-pollinated-birds. html#ixzz2ClZEkoi4 on 20th Nov, 2012 Pollination and Plant Families
Some plants, such as pine and grass, are wind-pollinated, so their reproductive strategy is to produce large amounts of pollen in hopes that some makes it to the female. Many other plants depend on animals to spread their pollen. In that case, the animal involved is called a pollinator. Not all animals can pollinate all plants, but certain types of animals such as birds, butterflies, moths, bees, beetles, wasps, bats, and flies, typically pollinate certain types of plants. This is a mutualistic relationship where both the plant and the pollinator(s) benefit each other.
Some plants are very specific with respect to what animal is able to serve as a pollinator, and have special modifications (special shape, etc. ) to attract that pollinator or exclude other would-be pollinators. Others plants are more general and are more attractive to a wider variety of pollinators, but the risk here is that the pollen may not get to the “right” species if the pollinator visits a different type of flower next. | | | | There are special cases where a plant species and a species of pollinator are totally dependent on each other.
These cases are examples of coevolution, the joint evolution of a plant and its animal pollinator. In coevolution, each of the species involved serves as a source of natural selective pressure on the other. A more formal definition for coevolution is “the mutual evolutionary influence between two species. ” One example of this type of coevolution would be the yucca plant and the yucca moth. The female moth lays her eggs in the flowers, simultaneously pollinating the plant, and the caterpillars develop within the seeds in the ovary of the plant.
For the plant, the loss of a few seeds to caterpillars is a price worth paying to insure pollination. The yucca moth is the only animal that is the right size and shape to pollinate yucca flowers. | | In order to make use of animal pollinators, plants must: 1. supply some reward, frequently food, for the pollinator, 2. advertise the presence of this to attract visitors, and 3. Have a way of putting pollen on the pollinator so it is transferred to the next plant/flower. | | The “reward” is not always food (nectar). There is a tropical orchid with a flower that looks and smells like the female of a certain species of wasp.
Males of this species emerge one week before the females, but these orchids are already blooming. The male wasps smell the orchids, “think” they’ve found a female, and try to copulate. The texture of the flowers is such that they “feel” like a female wasp, but the poor males just can’t get it to work, leave to find a more cooperative mate, and end up transferring pollen instead. The adaptations exhibited by any given flower depend on the type of pollinator the flower is designed to attract. Various pollinators have differing adaptations and means of gathering pollen and/or whatever nectar, etc. flower has to offer. | Bees don’t see red, but do see blue, yellow, and ultraviolet. Thus, bee-pollinated flowers are mostly yellow (some blue) with ultraviolet nectar guides or “landing patterns. ” The flowers typically have a delicate, sweet scent, which the bees can smell. Usually the nectar is at the end of some type of small, narrow floral tube which is the right length to fit the tongue of the particular species bee that pollinates that plant. Bee-pollinated flowers typically have a sturdy, irregular shape with some type of specifically-designed landing platform.
An example of this is snapdragons, where only a bee of just the right size and weight is able to trigger the flower to open, while all others (which are too small or too heavy) are excluded. Typically, pollen sticks to the “fur” of a bee or else the bees collect the pollen in specially-modified areas on their legs. | | | | Butterflies are diurnal and have good vision but a weak sense of smell. They can see red. Butterfly-pollinated flowers are brightly-coloured (even red) but odourless. These flowers are often in clusters and/or are designed to provide a landing platform.
Butterflies typically walk around on a flower cluster, probing the blossoms with their tongues. Examples of butterfly-pollinated flowers would be many members of the plant family Compositae, where many small flowers are arranged into a flat-topped head, and other plants, such as the milkweeds, where the flowers occur in large clusters. The individual flowers are typically tubular with a tube of suitable length for butterflies. | | Most moths are nocturnal and have a good sense of smell. Moth-pollinated flowers typically are white or pale colours so they will be at least somewhat visible on a moonlit night.
Often, moth-pollinated flowers may only be open at night. They typically use a strong, sweet perfume to advertise their presence in the darkness, and typically this odour is only exuded at night (evolutionarily, it doesn’t make sense to waste energy producing attractant in the daytime when it is useless). Moths are hover-feeders, so these flowers have deep tubes to precisely match the length of a specific moth’s tongue. One famous story relates that Charles Darwin found an extra ordinarily long, tubular flower in South America and predicted that someday, someone would find a moth with a tongue of matching length.
After much searching, around a hundred years later, indeed, this moth was found. More recently, a flower with an even-longer tube was found on Madagascar, and Dr. Gene Kritsky out at Mt. St. Joe has been interested in trying to find the “missing” moth that goes with it. In moth-pollinated flowers, the petals are flat or bent back so the moth can get in, and hover close to the flower. | Birds, especially hummingbirds, have good eyes and seem to be especially attracted to red. However, birds have a poor sense of smell (yes, it is OK to carefully put fallen babies back into the nest — the parents cannot smell your scent).
Bird-pollinated flowers are brightly-coloured, especially red but lack odour. Their petals are recurved to be out of the way. Hummingbirds are hover-feeders, so the flowers are designed to dust the birds head/back with pollen as the bird probes the flower for nectar. Flowers such as Columbine, red Salvia, and Fuchsia are favourite nectar sources for hummingbirds. | | Bats are nocturnal with a good sense of smell. While many bats depend on echolocation rather than sight to navigate, those species which serve as pollinators do have good vision.
Also, bats which pollinate flowers have long, bristly tongues to lap up nectar and pollen. Since these flowers are open at night, they are white or light-coloured so they’ll be visible in moonlight. Bat-pollinated flowers have a musty smell like the smell of bats. These flowers are large and sturdy to withstand insertion of the bat’s head as it licks nectar and pollen. Flies are attracted to rotting meat. Thus, fly-pollinated flowers may be nondescript or brownish red in colour, and typically have a strong, “bad,” rotten sort of smell. | Attained from: http://biology. clc. uc. edu/courses/bio106/pollinat. htm on 20th Nov, 2012