파충류샵
Reptiles are highly attuned to ambient temperatures and employ elegant adaptations to exploit a range of microhabitats. These traits often result in seasonal movements between foraging, breeding and overwintering habitats.
파충류샵Terrestrial ectotherms rarely migrate; however, aquatic reptiles regularly undertake long distance migrations. In some cases these movements put them in conflict with human resource utilization, such as when breeding migrations cross busy roads or migratory pathways are utilized for fishery activities.
Sea Turtles
Sea turtles are known to migrate long distances for food and other environmental factors. These migrations help them avoid predators and reach areas with high food availability and a higher fat stores, which increases their overall fitness and survival rates.
Researchers have identified migration pathways through satellite tracking of 81 adult female loggerhead sea turtles (Caretta caretta) that were tagged after nesting at beaches throughout the Gulf of Mexico. The migration tracks were analyzed to determine the displacement distance from each beach to oceanic foraging sites using great-circle distances, assuming travel around land masses.
The resulting displacement distances for these turtles are similar to the predicted ranges of equivalent-sized marine mammals and fish. However, the navigational cues that these turtles use during their migrations remain largely a mystery. It is thought that they use a combination of astronomical and geomagnetic cues to navigate.
For example, the sun and moon may act as light sources during these journeys. Additionally, they may utilize a “sun compass,” which uses solar radiation to orient themselves in a way that corresponds to the position of the sun. It is also believed that green sea turtles, at least, can use the Earth’s magnetic fields to acquire positioning information during their migrations. These turtles can orient themselves along the ocean floor by using a method of navigation called “bicoordinate mapping.” These techniques allow them to systematically identify the location of their intended foraging habitat.
Land Turtles
Reptiles that live on land are also often migratory. For example, Green Turtles (Chelonia mydas) that nest on the beach at Tortuguero, Costa Rica must travel to coastal feeding areas that are hundreds 파충류샵 or even thousands of kilometers away. Hatchlings of these turtles are believed to drift around gyres, or circular current systems, which serve as moving open ocean nursery grounds, before they eventually reach their feeding areas. The return journey home to breeding beaches may take up to 12 years.
Most of Kentucky’s snake species are terrestrial, and some have long distance breeding migrations. Like other reptiles, they make these migrations to find suitable habitat or food supplies. For example, Garter Snakes (Thamnophis lemasteri) migrate to their winter den sites in the fall for hibernation and back to their summer feeding locations in the spring. They usually have 3 toes on their hind limbs and are characterized by a ridge along the center of their top shell (carapace), with radiating yellow or orange lines on the large scutes of the upper shell, and dark smudges on their lower shell (plastron).
The terrestrial Grass Snake (Panax quinquefasciatus) has been shown to undertake breeding migrations between ponds that are overflowing in the fall and dry up in the summer. This is thought to be related to seasonal changes in food availability.
Snakes
Snakes are a type of reptile that is cold-blooded, which means their body temperature matches the temperature of their environment. This makes them sensitive to changes in their surroundings. For example, if the air gets hot, they might move to a shaded rock where it is cooler. When the weather turns cold, they will move to an area with more sun where it is warmer.
Snake migration is important because it allows snakes to reach dens where they can overwinter. They are dependent on outside sources of heat and can’t survive without a warm place to hibernate until spring.
They also need to reach areas where they can mate and lay eggs. Some species of snakes, such as garter snakes, show fidelity to both their den sites and summer feeding areas, returning to these locations year after year. Other snakes, such as rattlesnakes, undertake long distance breeding migrations.
There are about 2,900 known living snake species, and they can be found on every continent except Antarctica. Snakes are legless carnivorous reptiles of the suborder Serpentes (order Squamata). They have no limbs or external ears, and they focus 70% of their mostly solitary existence on tracking, capturing, and digesting their living prey. They have flexible lower jaws that allow them to eat animals 75% larger than their heads.
Amphibians
Many amphibians undertake seasonal movements between their breeding habitats, oviposition sites and overwintering sites. Terrestrial snakes and lizards tend to migrate over short distances, while fully aquatic marine turtles can move hundreds of kilometers between foraging and breeding areas.
A wide range of environmental factors can influence reptile migration. Temperature is known to be the most important factor, but daylength and precipitation also have a strong impact.
In many industrialized countries, roads cut through and fragment habitats, causing millions of amphibian roadkills each year. Amphibian conservationists have developed mitigation measures such as protection fences to allow amphibians to avoid these deadly encounters.
Amphibians such as the pond-breeding Ambystoma salamander (above) migrate to their breeding ponds en masse with the first warm rains of spring. The heavily trafficked Waterloo Road, which separates the Pine HIlls of the Ozark Uplift and LaRue Swamp of the Coastal Plain, is a major route for these frogs and toads during this time. A single vehicle can crush dozens of these slow-moving animals.
We studied relationships between the migration dates of common frogs and common toads and plant phenology. We found that phenological phases of goat willow, horse-chestnut and European larch correlated closely with migration dates of these amphibians. However, these correlations are weaker than the relationship with temperature. The reason for this may be that other environmental factors, such as daylength and temperature sum, are integrated into plant phenology.