About Notiosorex crawfordi (Coues, 1877)
Crawford's gray shrew, with the scientific name Notiosorex crawfordi, is one of the smallest desert mammals and one of the world's smallest homeotherms. When fully grown, it measures only 1.5 to 2 inches (3.8 to 5.1 cm) long, with half of that total length made up by the tail, and weighs just 3 to 5 grams (0.11 to 0.18 oz). It has gray-brown fur on its upper body and light gray fur on its underparts. Its long tail is gray, with a lighter shade of gray on the underside. It has small but relatively prominent ears. Crawford's gray shrews are born in the summer in litters of three to six individuals. At birth, they are naked and pink, and are roughly the same size as a honeybee. They grow rapidly and reach adult size in about four to five weeks. Young Crawford's gray shrews feed solely on milk produced by their mother, with no additional water intake. After two to three weeks, their diet shifts to food that the mother brings back to the nest and regurgitates for the juveniles. By fall, young Crawford's gray shrews leave the nest to live independently. As adults, their diet shifts from regurgitated food to intact prey that they kill themselves. Adult Crawford's gray shrews eat lizards, small mice, and scorpions, but their main food source is a wide variety of arthropods. This shrew has a very high metabolic rate, so it eats up to 75% of its body weight every day, and occasionally eats its full body weight in a single day. This high metabolic rate can be dangerous because it can cause the shrew to overheat. Heat generated from metabolism, combined with heat absorbed from the surrounding environment, leaves the shrew at high risk of overheating. This species expends energy at a very fast rate. When resting, the average Crawford's gray shrew has a heart rate of about 1000 beats per minute, and a respiratory rate of 800 breaths per minute. The breeding season of Crawford's gray shrew is reported to range from spring to fall, or to occur year-round. About three weeks after mating, the female gives birth to three to five offspring. Crawford's gray shrew has poor vision, so it uses its highly sensitive ears and long nose to hunt prey. It also uses echolocation, similar to bats, emitting high-pitched squeaks to locate prey. The shrews store food during the night so they do not need to forage outside during the day. When threatened, the gray shrew can emit a musky odor to make itself less appealing to mammalian predators.
