Amargosa vole facts for kids
Quick facts for kids Amargosa vole |
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| Conservation status | |
Scientific classification  |
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| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Rodentia |
| Family: | Cricetidae |
| Subfamily: | Arvicolinae |
| Genus: | Microtus |
| Species: | |
| Subspecies: |
M. c. scirpensis
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| Trinomial name | |
| Microtus californicus scirpensis Bailey, 1900
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The Amargosa vole (Microtus californicus scirpensis) is a small rodent. It is one of 17 types, or subspecies, of the California vole. Its closest relative is another subspecies called M. californicus vallicola.
Contents
What Does It Look Like?
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The Amargosa vole has a long, low body shape. Its feet and whiskers are gray. Its back is covered in dark, almost black fur. The tail has two colors: black on top and gray underneath.
Male Amargosa voles are usually longer and heavier than females. This difference between males and females is called sexual dimorphism.
These voles have a special tooth setup. They have one incisor (front tooth) on each side, top and bottom. They do not have canines or premolars. They have three molars on each side, top and bottom. This is written as 1.0.0.31.0.0.3. They also have a small opening in the bone behind their front teeth.
Where Do They Live?
Amargosa voles live in a very small area. They are found only in certain parts of California. Specifically, they live in the Mojave Desert in Inyo County. Their home is mostly along a 10-mile (16 km) stretch of the Amargosa River. They also live in the small streams and marshy areas connected to the river.
Scientists believe they have always lived in a small area. This is because they need very specific places to survive.
Their Special Home
Amargosa voles need a very particular type of habitat. They only live along the Amargosa River. They need marshy areas with standing water. The land must also be fairly flat, with less than a 20 percent slope.
The marshes where they live are usually small, about one to five acres in size. Their home is unique because it's made of small, wet areas. These wet spots are surrounded by dry desert. This means their homes are naturally separated from each other.
They need medium to thick plants to live. Their favorite plant is bulrush (Scirpus olneyi). Other plants often found in their habitat include seepweed (Suaeda torreyana), arrowweed (Pluchea sericea), quailbush (Atriplex lentiformis), southern reed (Phragmites australis), and saltgrass (Distichlis spicata).
It's estimated that only about 247 acres (1.00 km2) of land meets their needs. This shows how limited their habitat is.
What Do They Eat?
Amargosa voles mostly eat soft, green plants. This includes grasses and forbs (small flowering plants). At certain times of the year, they might also eat roots and seeds.
When they want to eat seeds from plants, they stand on their back feet. Then they chew off the plant stem. This makes the seeds fall down so they can reach them.
They are usually most active around sunrise and sunset. But if the weather is very hot and dry, they change their habits. They will mostly look for food at night instead.
Vole Families and Social Life
Amargosa voles are active all year long. They do not hibernate. They often interact with other voles. They live in family groups in burrows. A group might include one male, several females, and their young.
Female voles usually use an area of about 0.02 acres (81 m2). Males use a slightly larger area, about 0.03 acres (120 m2). However, females often travel further than males when it's not breeding season.
During the peak breeding season, usually in March and April, males can be territorial. This means they try to keep other males out of their home areas. But the home areas of males and females can overlap.
These voles don't travel far each day. They usually stay within 16–17 feet (4.9–5.2 m) of their burrow entrance. This is enough to find food and meet their needs. How far they travel can change based on their environment and how many other voles are around. Voles do move to new areas during their lives. But it's hard for them to move far because their habitat is broken up by desert.
How Do They Have Babies?
Amargosa voles usually live for about one year. Even with such a short life, they can have many litters of babies. This helps them keep their population going.
They can have babies all year round. But most pregnancies happen in March and April. They need green plants to reproduce. So, the time they have the most babies matches when plants grow in the spring. This is also partly controlled by when the first rains happen.
A pregnancy lasts 21 days. The babies, usually 4-5 young, are ready to leave their mother after 14 more days. Females can get pregnant again right after giving birth. This lets them have many litters one after another.
Young females can have babies very early, sometimes as young as 3 weeks old. Males become ready to reproduce at just 6 weeks old. Scientists can tell how old a vole is by looking at its third molars, which grow after 22 days. They also look at how their fur changes.
Why Are They in Danger?
One big problem for the Amargosa vole is that their home is being destroyed. In the past, marsh areas were purposely removed. This happened to make space for buildings or land for farm animals.
Other things, like building roads and railroads, have also hurt their habitat. These projects changed how water flows between the river and the marshes. This also made their habitat even more broken up. It makes it hard for voles to move between good living areas.
Many groups of Amargosa voles already depend on floods to connect them. More broken-up land makes this problem worse. Because groups of voles are separated, there can be genetic problems. This includes inbreeding, which means voles that are too closely related have babies. This can make the voles less healthy.
Other Threats
New plants and animals brought into the area also threaten the Amargosa vole. One very aggressive plant is tamarisk (Tamarix spp.). This plant changes the types of plants in the marsh. It also changes how water flows. Tamarisk can use so much water that it dries up the standing water the voles need.
Two other animals brought into the area are house cats and house mice. House cats are known to hunt and eat voles. The relationship between Amargosa voles and house mice is not fully understood.
Other possible threats include pumping water from underground. Also, building structures to change water flow can hurt the voles. These actions reduce the surface water that feeds the marshes where the voles live.
How Are They Being Protected?
The Amargosa vole is listed as endangered in California. It is also listed as endangered by the United States government. The International Union for the Conservation of Nature also lists it as vulnerable.
The Amargosa vole was once thought to be extinct in 1976. But three years later, 21 voles were found! Today, scientists believe there are only about 67 voles left. This is based on the most recent counts.
Special protected areas were set aside for the voles in 1984. This happened when they were first listed as federally endangered. Even though their habitat is naturally broken up, human actions make it worse. If the good habitat spots become too separated, voles can't move between them. This stops gene flow, which is the sharing of genes between groups. This makes the subspecies even more at risk. One main goal for conservation is to keep paths open between marsh areas. This helps voles move around and keeps their genetic diversity strong.
There's good news for protecting this subspecies. Most of the Amargosa vole's home is on land owned by the Bureau of Land Management, The Nature Conservancy, and the California State Lands Commission. This land has been named an Area of Critical Environmental Concern. This special status helps stop actions that threaten the voles. These actions include burning and grazing by livestock.
- NatureServe. 2017. Microtus californicus scirpensis. NatureServe Explorer. Version 7.1. Accessed 23 June 2017.
