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Physiology and functional anatomy of nectarivorous birds
Sejfová, Zuzana ; Janeček, Štěpán (advisor) ; Sam, Kateřina (referee)
Hummingbirds, sunbirds and a large part of honeyeaters belong to the most specialized nectarivores. During the evolution they have developed a number of adaptations in reaction to the specificity of their diet. The amount of studies focused on the adaptations connected with the digestion of nectar is not big, but is still growing. One of the characteristics of these birds is very fast and effective transport of consumed sugars across the intestinal epithelium. Furthermore they are tolerant to a very low nitrogen intake and extremely high daily intake of water. Sunbirds and honeyeaters are able to modulate the rate of water absorption in the intestine, but hummingbirds are not and they absorb almost all the consumed water. During the evolution excessive water intake together with a low concentration of salt presented in the diet led to changes in renal morphology that allows the production of an exceptionally dilute urine. The hovering flight of hummingbirds is well known and very well studied. The unique anatomy of hummingbird's wings allows the power production also during upstroke. Thanks to this hummingbirds are able to hover for a very long time and even in condition that are unsuitable for flight. Also sunbirds and honeyeaters sometimes hover during feeding. Nevertheless the mechanics of their hovering...
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Morphological adaptations for nectarivory in birds
Sailerová, Barbora ; Hořák, David (advisor) ; Janeček, Štěpán (referee)
Scientists have been interested in adaptation of nectar-feeding birds for a long time. I tried to summarize information about these adaptation. About hummingbirds's, sunbird's and honeyeater's bill and tongue, about body size and how flower influences nectar intake. Nectar-feeding birds has extended and curved bill, which is an adaptation to flowers visiting by these birds. The tongue is a tool for nectar intake, its inner structure allows nectar intake. Tongue is tubular and hummingbird's and sunbird's tongue is proximal bifurcate, honeyeater's tongue has brush tip. Nectar-feeding birds are generally of small body size and larger species have to intake more insects because of higher energetic requirements. Some flowers don't allow to perch and nectar-feeding birds have to intake nectar in flight. Therefore especially hummingbirds and some sunbirds evolved a hovering. If its possible, these birds perch when they collect nectar.
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Physiology and functional anatomy of nectarivorous birds
Sejfová, Zuzana ; Janeček, Štěpán (advisor) ; Sam, Kateřina (referee)
Hummingbirds, sunbirds and a large part of honeyeaters belong to the most specialized nectarivores. During the evolution they have developed a number of adaptations in reaction to the specificity of their diet. The amount of studies focused on the adaptations connected with the digestion of nectar is not big, but is still growing. One of the characteristics of these birds is very fast and effective transport of consumed sugars across the intestinal epithelium. Furthermore they are tolerant to a very low nitrogen intake and extremely high daily intake of water. Sunbirds and honeyeaters are able to modulate the rate of water absorption in the intestine, but hummingbirds are not and they absorb almost all the consumed water. During the evolution excessive water intake together with a low concentration of salt presented in the diet led to changes in renal morphology that allows the production of an exceptionally dilute urine. The hovering flight of hummingbirds is well known and very well studied. The unique anatomy of hummingbird's wings allows the power production also during upstroke. Thanks to this hummingbirds are able to hover for a very long time and even in condition that are unsuitable for flight. Also sunbirds and honeyeaters sometimes hover during feeding. Nevertheless the mechanics of their hovering...
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|
|
Morphological adaptations for nectarivory in birds
Sailerová, Barbora ; Hořák, David (advisor) ; Janeček, Štěpán (referee)
Scientists have been interested in adaptation of nectar-feeding birds for a long time. I tried to summarize information about these adaptation. About hummingbirds's, sunbird's and honeyeater's bill and tongue, about body size and how flower influences nectar intake. Nectar-feeding birds has extended and curved bill, which is an adaptation to flowers visiting by these birds. The tongue is a tool for nectar intake, its inner structure allows nectar intake. Tongue is tubular and hummingbird's and sunbird's tongue is proximal bifurcate, honeyeater's tongue has brush tip. Nectar-feeding birds are generally of small body size and larger species have to intake more insects because of higher energetic requirements. Some flowers don't allow to perch and nectar-feeding birds have to intake nectar in flight. Therefore especially hummingbirds and some sunbirds evolved a hovering. If its possible, these birds perch when they collect nectar.
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