The tropics are the regions of Earth surrounding the Equator , where the sun may shine directly overhead . This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's axial tilt ; the width of the tropics (in latitude) is twice the tilt. The tropics are also referred to as the tropical zone and the torrid zone (see geographical zone ).
29-417: See text The hermits are tropical and subtropical hummingbirds in the subfamily Phaethornithinae , comprising 37 species in six genera . They occur from southern Mexico , through Central America , to South America as far south as northern Argentina . Their plumage typically involves greens, browns, rufous or grey. Most species show some green or bronze iridescence to the upperparts, but this
58-603: A 2007 DNA hybridization study suggested that the hermits were basal to the rest of the family. A molecular phylogenetic study of the hummingbirds published in 2007 found that the family consisted of nine clades . When Edward Dickinson and James Van Remsen Jr. updated the Howard and Moore Complete Checklist of the Birds of the World for the 4th edition in 2013, they divided the hummingbird family into six subfamilies based on
87-511: A break in rainfall during mid-season when the Intertropical Convergence Zone or monsoon trough moves poleward of their location during the middle of the warm season; Typical vegetation in these areas ranges from moist seasonal tropical forests to savannahs . When the wet season occurs during the warm season, or summer , precipitation falls mainly during the late afternoon and early evening hours. The wet season
116-408: A lesser degree, they will capture small arthropods . The long, decurved bills typical of this group of hummingbirds are an adaptation to certain flowers. This is taken to an extreme in the two sicklebills ( Eutoxeres spp. ) with their very decurved bills. Many species, including the rufous-breasted hermit , also use the heliconias for nesting, attaching their conical nest to the underside of one of
145-474: A long decurved bill (except for three species, P. koepkeae , P. philippii and P. bourcieri , with virtually straight bills) with a red or yellow base to the lower mandible, and their two central tail feathers are elongated and tipped with white, buff or ochre. The crown of the head is flat, and two pale facial stripes enclose a dusky mask. Most hermits are restricted to the edge and undergrowth of forest, woodland and second growth, but some species (e.g.
174-500: Is a time when air quality improves, freshwater quality improves and vegetation grows significantly due to the wet season supplementing flora, leading to crop yields late in the season. Floods and rains cause rivers to overflow their banks, and some animals to retreat to higher ground. Soil nutrients are washed away and erosion increases. The incidence of malaria increases in areas where the rainy season coincides with high temperatures. Animals have adaptation and survival strategies for
203-420: Is far less conspicuous than that of many other hummingbirds. The male and female plumages of hermits are very similar, with differences limited to details of bill-shape, tail-shape and/or strength of colours/patterns. Most species of hermit do not show the strong sexual dimorphism usually associated with hummingbirds; green hermit is an exception to this rule. Hermits in the type genus , Phaethornis , have
232-431: Is one of the six subfamilies that make up the hummingbird family Trochilidae . The subfamily is divided into three tribes : Lampornithini (mountain gems) containing 18 species, Mellisugini (bees) containing 37 species and Trochilini (emeralds) containing 115 species. The hummingbirds were formerly divided into two subfamilies, the hermits ( Phaethornithinae ) and the nonhermits (Trochilinae). The results from
261-585: Is that the tropics represent a ' Garden of Eden ', a heaven on Earth, a land of rich biodiversity or a tropical paradise. The alternative is that the tropics consist of wild, unconquerable nature. The latter view was often discussed in old Western literature more so than the first. Evidence suggests over time that the view of the tropics as such in popular literature has been supplanted by more well-rounded and sophisticated interpretations. Western scholars tried to theorise why tropical areas were relatively more inhospitable to human civilisations than colder regions of
290-605: The Andes as far south as the northernmost parts of Chile and Perú . The climate is changing in the tropics, as it is in the rest of the world. The effects of steadily rising concentrations of greenhouse gases on the climate may be less obvious to tropical residents, however, because they are overlain by considerable natural variability. Much of this variability is driven by the El Niño-Southern Oscillation (ENSO) . The Tropics has warmed by 0.7–0.8 °C over
319-732: The Pantropic . The system of biogeographic realms differs somewhat; the Neotropical realm includes both the Neotropics and temperate South America, and the Paleotropics correspond to the Afrotropical , Indomalayan , Oceanian , and tropical Australasian realms . Flora are plants found in a specific region at a specific time. Some well-known plants that are exclusively found in, originate from, or are often associated with
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#1732782533986348-451: The T. leucurus , but as it was described first, its scientific name was adopted for the entire species; pale-tailed barbthroat ( T. niger ). This, however, has not been accepted by all authorities, notably SACC , which consider both T. niger and T. leucurus as valid species. Additionally, Mallet-Rodrigues (2006) suggested the taxon loehkeni should be considered a valid species, the bronze-tailed barbthroat . Three additional species,
377-579: The Waterberg Biosphere of South Africa , and eastern Madagascar rainforests. Often the soils of tropical forests are low in nutrient content, making them quite vulnerable to slash-and-burn deforestation techniques, which are sometimes an element of shifting cultivation agricultural systems. In biogeography , the tropics are divided into Paleotropics (Africa, Asia and Australia) and Neotropics (Caribbean, Central America, and South America). Together, they are sometimes referred to as
406-719: The axial tilt of the Earth . The Tropic of Cancer is the Northernmost latitude from which the Sun can ever be seen directly overhead , and the Tropic of Capricorn is the Southernmost. This means that the tropical zone includes everywhere on Earth which is a subsolar point at least once during the solar year . Thus the maximum latitudes of the tropics have equal distances from the equator on either side. Likewise, they approximate
435-463: The planalto hermit ) also occur in more open habitats. Many species of hermits form leks and congregate on traditional display grounds, where females visit to choose a mate. Male hermits are generally less aggressive than other male hummingbirds, although both sexes will defend a feeding territory . Most hermits are associated with heliconias , but will utilize other nectar sources (flowers of Centropogon , Passiflora , Costus , etc.). To
464-476: The tooth-billed hummingbird ( Androdon aequatorialis ), the green-fronted lancebill ( Doryfera ludovicae ) and the blue-fronted lancebill ( D. johannae ), have been included in this subfamily in the past, but are now placed in Trochilinae . Tropical Due to the overhead sun, the tropics receive the most solar energy over the course of the year, and consequently have the highest temperatures on
493-544: The Northern Hemisphere. A popular explanation focused on the differences in climate. Tropical jungles and rainforests have much more humid and hotter weather than colder and drier temperaments of the Northern Hemisphere, giving to a more diverse biosphere. This theme led some scholars to suggest that humid hot climates correlate to human populations lacking control over nature e.g. 'the wild Amazonian rainforests'. Trochilinae 3, see text Trochilinae
522-399: The angle of the Earth's axial tilt. This angle is not perfectly fixed, mainly due to the influence of the moon, but the limits of the tropics are a geographic convention, and their variance from the true latitudes is very small. Many tropical areas have both a dry and a wet season. The wet season , rainy season or green season is the time of year, ranging from one or more months when most of
551-459: The average annual rainfall in a region falls. Areas with wet seasons are disseminated across portions of the tropics and subtropics , some even in temperate regions. Under the Köppen climate classification , for tropical climates , a wet-season month is defined as one or more months where average precipitation is 60 mm (2.4 in) or more. Some areas with pronounced rainy seasons see
580-460: The geographic region; these usages ought not be confused. The Earth's axial tilt is currently around 23.4° , and therefore so are the latitudes of the tropical circles , marking the boundary of the tropics: specifically, ±23°26′09.8″ (or 23.43605°). The northern one is called the Tropic of Cancer , and the southern is the Tropic of Capricorn . As the Earth's axial tilt changes, so too do
609-961: The last century—only slightly less than the global average—but a strong El Niño made 1998 the warmest year in most areas, with no significant warming since. Climate models predict a further 1–2 °C warming by 2050 and 1–4 °C by 2100. Tropical plants and animals are those species native to the tropics. Tropical ecosystems may consist of tropical rainforests , seasonal tropical forests , dry (often deciduous) forests , spiny forests, deserts , savannahs, grasslands and other habitat types. There are often wide areas of biodiversity , and species endemism present, particularly in rainforests and seasonal forests. Some examples of important biodiversity and high-endemism ecosystems are El Yunque National Forest in Puerto Rico , Costa Rican and Nicaraguan rainforests, Amazon Rainforest territories of several South American countries, Madagascar dry deciduous forests ,
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#1732782533986638-414: The molecular results and redefined the subfamily Trochilinae to contain three clades, each of which they placed in a separate tribe : Lampornithini (mountain gems), Mellisugini (bees) and Trochilini (emeralds). A comprehensive phylogenetic study that sampled 284 hummingbird species was published in 2014. It confirmed the nine clades found in the earlier study but found that the hermits were sister to
667-578: The planet. Even when not directly overhead, the sun is still close to overhead throughout the year, therefore the tropics also have the lowest seasonal variation on the planet; "winter" and "summer" lose their contrast. Instead, seasons are more commonly divided by precipitation variations than by temperature variations. The tropics maintain wide diversity of local climates, such as rain forests , monsoons , savannahs , deserts , and high altitude snow-capped mountains . The word "tropical" can specifically refer to certain kinds of weather , rather than to
696-463: The plant's broad leaves. Eutoxeres Ramphodon Phaethornis Glaucis Threnetes The taxonomy of some groups has changed significantly in recent years. Apart from those issues discussed at Phaethornis , a taxonomic problem occurs with the Threnetes leucurus / T. niger complex. Schuchmann & Hinkelmann (1999) considered the sooty barbthroat a melanistic variant of
725-561: The topazes clade (subfamily Florisuginae ) containing the genera Topaza and Florisuga . Many of the traditional genera in the emerald clade (Trochilini) were shown to be polyphyletic . As a result, many of the genera in this part of the tree have been revised. Florisuginae – topazes Phaethornithinae – hermits Polytminae – mangoes Heliantheini – brilliants Lesbiini – coquettes Patagoninae – giant hummingbird Lampornithini – mountain gems Mellisugini – bees Trochilini – emeralds The above cladogram of
754-516: The tropical and polar circles . The tropics constitute 39.8% of Earth's surface area and contain 36% of Earth's landmass . As of 2014 , the region was home also to 40% of the world's population , and this figure was then projected to reach 50% by 2050. Because of global warming , the weather conditions of the tropics are expanding with areas in the subtropics , having more extreme weather events such as heatwaves and more intense storms. These changes in weather conditions may make certain parts of
783-469: The tropics include: Tropicality refers to the image of the tropics that people from outside the tropics have of the region, ranging from critical to verging on fetishism. Tropicality gained renewed interest in geographical discourse when French geographer Pierre Gourou published Les pays tropicaux ( The Tropical World in English), in the late 1940s. Tropicality encompassed two major images. One,
812-568: The tropics uninhabitable. The word "tropic" comes via Latin from Ancient Greek τροπή ( tropē ), meaning "to turn" or "change direction". The tropics are defined as the region between the Tropic of Cancer in the Northern Hemisphere at 23°26′09.8″ (or 23.43605°) N and the Tropic of Capricorn in the Southern Hemisphere at 23°26′09.8″ (or 23.43605°) S; these latitudes correspond to
841-726: The wetter regime. The previous dry season leads to food shortages into the wet season, as the crops have yet to mature. However, regions within the tropics may well not have a tropical climate. Under the Köppen climate classification, much of the area within the geographical tropics is classed not as "tropical" but as "dry" ( arid or semi-arid ), including the Sahara Desert , the Atacama Desert and Australian Outback . Also, there are alpine tundra and snow-capped peaks, including Mauna Kea , Mount Kilimanjaro , Puncak Jaya and
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