Saturday, May 4, 2019
Travelling and Touring Kenyan Tourism Destinations : In Kenya there a number of tourists' attraction si...
Travelling and Touring Kenyan Tourism Destinations : In Kenya there a number of tourists' attraction si...: In Kenya there a number of tourists' attraction sites. Each attraction site has its unique features which makes it differ from the ot...
Tuesday, July 3, 2018
the smallest bird in the world
The bee hummingbird or Helena hummingbird (Mellisuga helenae) is a species of hummingbird which is the world's smallest bird. It is endemic to Cuba.They are among the smallest of birds, most species measuring 7.3–12 cm in length. The smallest extant bird species is a hummingbird, the 4cm bee hummingbird weighing less than 1.80 g.While all hummingbirds depend on flower nectar to fuel their high metabolisms and hovering flight, coordinated changes in flower- and bill shape stimulated the formation of new species of hummingbirds and plants. Due to this exceptional evolutionary pattern, as many as 140 hummingbird species can coexist in a specific region, such as the Andes range.
The hummingbird evolutionary tree shows ancestral hummingbirds splitting from insectivorous swifts (family Apodidae) and treeswifts (family Hemiprocnidae) about 42 million years ago, probably in Eurasia.One key evolutionary factor appears to be an altered taste receptor that enabled hummingbirds to seek nectar. By 22 million years ago the ancestral species of current hummingbirds became established in South America, where environmental conditions stimulated further diversification.Sexual size and bill differences likely evolved due to constraints imposed by courtship because mating displays of male hummingbirds require complex aerial maneuvers. Males tend to be smaller than females, allowing conservation of energy to forage competitively and participate more frequently in courtship. Thus, sexual selection will favor smaller male hummingbirds.
Female hummingbirds tend to be larger, requiring more energy, with longer beaks that allow for more effective reach into crevices of tall flowers for nectar. Thus females are better at foraging, acquiring flower nectar, and supporting the energy demands of their larger body size. Directional selection will thus favor the larger hummingbirds in terms of acquiring food.
Another evolutionary cause of this sexual bill dimorphism is that the selective forces from competition for nectar between the sexes of each species are what drive the sexual dimorphism.Depending on which sex holds territory in the species, it is advantageous for the other sex to have a longer bill and be able to feed on a wide variety of flowers, decreasing intraspecific competition.For example, in species of hummingbirds where males have longer bills, males do not hold a specific territory and have a lek mating system. In species where males have shorter bills than females, males defend their resources and therefore females must have a longer bill in order to feed from a broader range of flower.( wikipedia).
The hummingbird evolutionary tree shows ancestral hummingbirds splitting from insectivorous swifts (family Apodidae) and treeswifts (family Hemiprocnidae) about 42 million years ago, probably in Eurasia.One key evolutionary factor appears to be an altered taste receptor that enabled hummingbirds to seek nectar. By 22 million years ago the ancestral species of current hummingbirds became established in South America, where environmental conditions stimulated further diversification.Sexual size and bill differences likely evolved due to constraints imposed by courtship because mating displays of male hummingbirds require complex aerial maneuvers. Males tend to be smaller than females, allowing conservation of energy to forage competitively and participate more frequently in courtship. Thus, sexual selection will favor smaller male hummingbirds.
Female hummingbirds tend to be larger, requiring more energy, with longer beaks that allow for more effective reach into crevices of tall flowers for nectar. Thus females are better at foraging, acquiring flower nectar, and supporting the energy demands of their larger body size. Directional selection will thus favor the larger hummingbirds in terms of acquiring food.
Another evolutionary cause of this sexual bill dimorphism is that the selective forces from competition for nectar between the sexes of each species are what drive the sexual dimorphism.Depending on which sex holds territory in the species, it is advantageous for the other sex to have a longer bill and be able to feed on a wide variety of flowers, decreasing intraspecific competition.For example, in species of hummingbirds where males have longer bills, males do not hold a specific territory and have a lek mating system. In species where males have shorter bills than females, males defend their resources and therefore females must have a longer bill in order to feed from a broader range of flower.( wikipedia).
In Kenya there a number of tourists' attraction sites. Each attraction site has its unique features which makes it differ from the other. Examples of attractions are those attractions with traditional artifacts, attractions with wildlife, attractions with historical records of various kenyan prominent leaders and politicians, attractions with cultures of kenyan people among others. All these attractions have different benefits to different groups of visitors/tourists. The choice of a destination depends with ones' motive towards that destination of choice. For example, a visitor who is interested in visiting places/ destinations with these artifacts cannot be told what to do when he, she arrives at the destination apart from the guiding rules of the attraction.When travelling to Kenya , different tour companies with the best tour guides will do their best to make sure that you, as their clients you are satisfied with what they have told you. The tour guide make sure that you achieve your goal of travelling to The destination.
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