Category Animal Records

What has caused the decline in grey whale numbers?

Often, conservation stories underline the importance of the role of all creatures-big and small-for balance in ecosystem. For instance, krill crustaceans barely two inches long are a huge link in the global food chain. If such a small organism can have a telling impact on the food chain, one can only imagine the kind of effect larger animals have in an ecosystem. So, when the population of a large animal plunges, it is always a cause for concern.

Grey whales are among the largest animals on Earth- nearly 50 feet long and weighing over 40 tonnes. These giants are known for their long annual migration of more than 15,000 km “between feeding grounds in the Arctic and breeding grounds in Baja Mexico” Recent research has revealed that the number of these fascinating creatures is witnessing a worrying slump- by nearly 40% in just six years. From 27,000 whales in 2016, the number stands at a concerning 16,650 today. Several factors are attributed to this decrease. One of them is the increase in strandings in 2019, when about 600 of these creatures washed up dead along the west coast of North America Though boat collisions and killer whale attacks caused a few of these deaths most of the dead whales were malnourished which takes us to n crucial of interconnectedness in an ecosystem. It is believed that the malnourishment could be the result of “the whales’ food sources of tiny crustaceans and other invertebrates they prey on in the Arctic shifting due to environmental changes. Further, the overall population among West Coast grey whales “coincides with diminished reproduction” While there were 383 baby whales during the calf production season last year, there have been a mere 217 newborns this year – “the lowest number since such counts began in 1994”

Grey whales were close to extinction several decades ago due to commercial whaling before their population improved due to timely conservation efforts. Even then, the 80s and 90s saw a plunge of about 40%, and eventually they rebounded. It is important for this whale population to recover too because they keep the population of certain other creatures in the food chain in check. Even in death-as carcasses- these large marine mammals help feed several other organisms.

Often, grey whales are washed up dead along the U.S. west coasts. Though boat collisions and killer whale attacks cause some deaths, researchers say malnourishment is a major reason. With tiny crustaceans and other invertebrates shifting due to environmental changes, the grey whales are left without food.

Picture Credit : Google 

WHAT KIND OF CREATURES ARE BATS?

Bats, of which there are more than 1300 species, are the second largest group of mammals. Megabats, also known as fruit bats because of what they eat, can have a wingspan of just under two metres. The flying fox is the largest bat. The smaller microbats are mostly carnivorous and eat insects; even small amphibians. Vampire bats are the only microbats that feed on animal blood.

More than 40 species of bats live in the United States. Bats are the only mammals that can fly. Instead of arms or hands, they have wings. The wings have a bone structure similar to the human hand. Between the bones are flaps of skin. Bats are very light weight to make it easier for them to fly. The western pipistrelle bat weighs less than a penny, while the greater mastiff bat weighs about two ounces (57 grams).

Bats have fur on their bodies, sometimes including their head. Their wings, however, do not have fur. Bats can be a range of colors, including red, tan, brown, and gray. A bat’s ears are very important because bats use them to hunt for food. The ears tend to be large and noticeable, many times sticking up on the side of the head. The Allen’s big-eared bat has ears so long that they make up two thirds of its body length.

The smallest bat in the United States is the western pipistrelle bat, which grows to about 2.5 to 3.5 inches (six to nine centimeters) long with an eight-inch (20-centimeter) wingspan. The largest bat in the U.S. is the greater mastiff bat. It can grow as long as seven inches or more with a wingspan of 21 to 23 inches (53 to 58 centimeters).

The majority of bats in the United States are insectivores. They hunt at night and eat flying insects such as mosquitoes, beetles, and moths, many of which are considered pests. Bats provide an important ecological service by eating tons of insects. In a single midsummer night, the 20 million Mexican free-tailed bats from Bracken Cave in central Texas eat more than 200 tons of insects.

Not all bats eat insects. Some live on a diet of nectar and fruit. Bats that feed on nectar also serve as pollinators to nighttime blooming plants. To attract these flying mammals, flowering plants have evolved a musty or rotten perfume. The smell is created by sulphur-containing compounds, which are uncommon in most floral aromas, but have been found in the flowers of many plant species that specialize in bat pollination.

Vampire bats do exist, but there are none in the United States. The closest vampire bats are found in Mexico.

Insect-eating bats hunt using a type of natural sonar called echolocation. They emit a high-frequency sound (undetectable to people) that bounces off surrounding objects. When a sound hits an object, or better yet, an insect, it bounces back to the bat’s pronounced ears and gives the bat an audible map for the shape, distance, and location of nearby objects. Everything happens so quickly that a bat can make almost instant turns to catch a flying insect. A bat’s echolocation system is so advanced and precise that scientists study bats to make sonar equipment for ships.

A bat’s nose can be very useful characteristic for identifying a bat species. Some are small and simple, others are shaped like a pig’s nose, and some even have noses shaped like leaves.

Credit : The National Wildlife Federation

Picture Credit : Google 

Which is the largest rodent?

The term rodent conjures up images of tiny rats and mice that scuttle through dark holes and leaky pipes in urban sprawls. But did you know that the largest rodent in the world lives in the grassy wetlands of South America is nearly 1.2 metres tall and can weigh nearly 66 kg?

They are called capybaras. These creatures are semi-aquatic and spend much time in rivers. They have partially webbed feet, which helps them swim and dive. They are fast swimmers and can hold their breath for up to 5 minutes under water! This helps them to evade predators such as jaguars and anacondas by diving into water. If all else fails they can bark like dogs to scare off a predator!

They are usually found in large groups and communicate with each other with the help of grunts and whistles. These cuddly creatures are herbivores and eat mostly grass, but will consume fruits, grain and vegetables whenever possible.

They are raised on farms for meat in some countries and their skin is harvested to make high quality leather. They are related to guinea pigs and look quite cute and furry. They are kept as pets in countries like Japan and the U.S.A.

Picture Credit : Google