Cuban Rock Iguana Dark-eyed Junco House Finch Killer Whale Siberian Hamster Wolf Spider

ANIMAL SPOTLIGHT

WOLF SPIDERS are large hairy spiders that are brown in color. Unlike many other spiders, they do not build webs. Instead, they live on the ground in leaf litter or in burrows. Wolf spiders are common and can be found all around the world. They are often seen in lawns and gardens. In fall, when the weather turns cold, wolf spiders move into houses to find warm spots for the winter. Wolf spiders are ambush hunters. Instead of using a web to catch their prey, they sit and wait for their prey to walk by. They eat just about anything they can catch, including flies, mosquitoes, crickets, beetle larvae, and even other spiders. They bite their prey with sharp fangs and inject venom that liquefies the prey’s internal organs. The spider then sucks out the “soup.” Wolf spiders live for about two years. When mature, males attract females by waving their front legs. After mating, the female wraps 50-200 eggs in a sac made of spider silk. She attaches the sac to the rear of her abdomen and carries it around for about a week. At the end of that time, she opens the sac and the spiderlings crawl onto her abdomen. They ride around with their mother for another week, until they are large enough to hunt for themselves. Even though there are over 36,000 known species of spiders in the world, not much is known about them. Scientists are using wolf spiders to study many aspects of spider behavior. They have found that wolf spider males have brushes or tufts on their first pair of legs that they raise and lower in distinct patterns to attract females. Females favor males with large and more symmetrical tufts. Even thought they are hunters, wolf spiders are also prey to other species. They have many behaviors to keep from being eaten, including freezing, slowing their movement, and avoiding other hunters. They even check for silk and excreta find out if there are other hunters in the area.

Photo Courtesy Dr Matt Persons Click here for more info

WHALES are divided into two major groups, baleen whales and toothed whales. Baleen whales have fibrous plates in their mouths made out of a horny material similar to fingernails. They use the fibers to strain small organisms out of the ocean water. Toothed whales have teeth and eat larger prey such as fish, seals and squid. Members of the toothed whales include: sperm, white and beaked whales, dolphins and porpoises. One of the most popular toothed whales is the Orca or Killer Whale. Orcas are large black and white whales that can grow to 9.4 meters (28 feet) long. They live in tropical, temperate and polar waters, but appear to prefer cooler coastal areas where prey is abundant. They breed any time of the year and calves are born after 13-16 months gestation. Calves get milk from their mothers for about a year. Adult orcas eat seabirds, turtles, fish (including sharks), whales, dolphins, porpoises, seals and sea lions. They hunt in groups of two to 20 animals and are very efficient killers. Since it is difficult to observe whales' feeding behavior underwater, scientists are using radio tags to find out what orcas are doing. Using the radio transmitter, they can record the depth and velocity of individual whales. They can also track resident whales (ones living in a certain location) and transient whales (ones just visiting an area), to see if their feeding behavior is different. So far, they have found that resident orcas feed in upper waters where fish are concentrated. Transient orcas feed in deeper locations. They have also found that orcas rest more at night than they do in the day.

Photo Courtesy Dr Robin W. Baird Click here for more info

HOUSE FINCHES are small brown birds with dark streaks below. Males have additional yellow, orange or red coloring on forehead, breast and rump. House finches are native to the American west, but they were imported to New York by pet dealers in the 1940s. Since then they have spread from the east coast all the way to the Mississippi River. House finch diets are composed mainly of weed seeds, but they also eat buds, insects, food scraps, fruit and suit. They have also been known to drink sugar-water from hummingbird feeders. Nests are built of grasses, leaves, twigs, string, wool and other odds and ends in cavities in trees, cacti, and bird houses. They nest March through August and females lay 4-5 blue-white eggs speckled with brown. Eggs are incubated 12 to 16 days and nestlings fledge in 11 to 10 days. House finches are of special interest to scientists because males are colorful and females are plain. Since males can only become colorful if they eat foods rich in carotenoid pigments and are in good health, scientists have been conducting tests to see if color acts a signal about their condition and health. Recent studies have found that females are attracted to redder males. Nutritional condition, the presence of carotenoids in the diet and parasites can affect male feather color.

Photo Courtesy Dr Geoffrey Hill. Click here for more info

CUBAN ROCK IGUANAS are one of eight species of iguanas found in the Caribbean. They are large lizards and can grow to a length of 4-5 feet. They live in coastal scrub forests with plenty of rocks, caves and crevices. Like all lizards, iguanas are ectothermic, which means their body temperature depends on the external environment. They use different behaviors to keep thie bodies at the right temperature. If it is too cold, they can bask in the sun on rocks. If too hot, they can hide in the shade. Even though they are very dangerous looking, they are herbivores (eat only plants). They eat leaves, flowers and fruits of as many as 58 native plants in Cuba. It takes anywhere from two to nine years for iguanas to mature into adults. When they are young, they are in danger of being eaten by predators that have been brought to the Caribbean islands by humans, including dogs, cats and mongoose. Adult iguanas mate in early summer and the females lay eggs 40 days later. Females make nest burrows and lay 2-6 eggs. The eggs take 65-90 days to incubate. After the hatchlings make their way out of their eggs, they must also dig themselves out of the nest. All rock iguanas are threatened or endangered species. Humans have replaced their natural island food, introduced predators and taken over their habitat with human building. Scientists are now studing how human behavior affects the Cuban rock iguana. In areas where people have moved into the iguana's habitat, the iguanas behave differently. The are forced to live closer together. Because of this over-crowding, they are more aggressive, especially the males. Males spend more time communicating with each other and less time with the females. Like other lizards, they use body motions like head-bobbing and tongue touching to communicate. All this aggressive behavior makes the situation stressful and may make it difficult to court, mate and lay eggs.

Photo Courtesy Dr Emilia Martins. Click here for more info

DARK-EYED JUNCOs are small gray and white birds commonly seen at bird feeders in winter in the United States. Juncos are migratory, which means they move from one location to another during the year. Juncos breed in Canada and the northern U.S. in summer. In winter, they migrate to the southern and central portions of the U.S. There are four races of juncos. They all have pink bills and white outer tail feathers, but males differ in body color. The slate-colored junco has a dark gray head, back and sides. The Oregon junco has a black head and brown back and sides. The gray-headed junco of the southern rockies is mostly gray with brown backs. The white-winged junco of South Dakota and Wyoming is pale gray above and has two white wingbars. Juncos feed off the ground, collecting insects in summer and seeds in winter. If you watch them at a birdfeeder, you will notice that the prefer to feed on the ground below the feeder. In summer, the female builds a nest of grasses, roots and bark on the ground or under brush. Juncos have 2 broods (batches of nestlings) from April through August. The female lays 4 or 5 brown-speckled eggs and incubates them (keeps them warm) for 11 to 12 days. Nestlings fledge in 12 to 13 days. Scientists have been using juncos to answer questions about migration and the affects of the hormone testosterone on behavior.

Photo Courtesy Dr Ellen Ketterson. Click here for more info

SIBERIAN HAMSTERS can be kept as pets, but they come from the cold northern regions of Russia, called Siberia. The hamsters live on flat steppes covered with short grass. Today much of the land has been turned to grazing land or is plowed for agriculture, but they can still make their home near fields were the land is ungrazed or untilled. They live in burrows with several openings to allow for ventilation and escape. Males and females share burrows and males help take care of the young when they are born. Hamsters eat many things including: grasses, seeds, moths, beetles, grasshoppers and other insects. They have to search large areas to find food and have pouches in their cheeks to carry food back to their burrows. Some actually find food (undigested seeds) in drying cow pattys. Yuck! Hamsters cannot see very well, so they mark trails with body scents. They have at least six chemical odors that come from: the corners of their eyes, glands behind their ears, pouch entrances, abdomen, feces and urine. They roll and scratch to leave their scent. The scent lasts at least eight days. Scientists are working with Siberian hamsters to answer questions about physiology and behavior. Hamsters respond to day-length by changing color (brown in summer to white in winter), changing the amount of fat in their bodies and changing their ability to fight disease. Scientists hope that if we figure out the relationship between hormones (communication chemicals) made by fat cells and ability to fight disease in hamsters, we will be able to help people fight disease in new ways in the future.

Photo Courtesy Dr Gregory Demas. Click here for more info

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