Nothing makes a morning as excellent as rays of sunlight pouring through your curtains, along with the sound of birds singing outside in the trees.
Nature is full of beauty, and the peak of this beauty is birds, with their colors, sizes, and singing.
Most birds are shrouded in mystery, and humans rarely observe them. If you like birds, you might want to get into bird watching or any related field, but first, you need to understand birds. So let us get right into it;
Are Birds Animals?
Yes, a bird is an animal. Birds are classified under the Kingdom Animalia that has all multicellular eukaryotic organisms.
Birds ingest food; they reproduce and can move independently; all these are the characteristics of animals; thus, a bird qualifies to be an animal. The mistake people make is thinking of animals instead of mammals.
The Origin And Evolution Of Birds
The greatest hit in terms of dinosaurs is Jurassic park; the death and destruction caused by those prehistoric giants were colossal.
As much as the creatures were an impressive feat, all the scientists needed to do to see a dinosaur was look out the window.
I am saying this because birds are descended from dinosaurs. Dinosaurs are a fascination to humans, and millions of dollars have been invested in archaeological research to understand these creatures.
From this research, we know that 150 million years ago, birds were giant mammals roaming the planet.
About 65 million years ago, the earth was hit by an asteroid, and it caused mass extinction across the globe.
The asteroid killed most mammals, but some could survive by burrowing into the ground or hiding underwater to get away from the initial heat.
In the following years, there were no plants, and the earth was freezing, so the survivors had to feed on smaller prey.
The enormous herbivorous dinosaurs did not survive since they couldn’t seek shelter from the heat and could not get enough food. The surviving dinosaurs had to adapt; they grew smaller and smaller after the hit.
This reduction happened in 12 mutations, and it changed them from an average of 163 kilos to the Archaeopteryx, which was 0.8 kilos.
Their predatory nature was an advantage in this reduction of size since it requires a smaller body.
On the other hand, plant-eaters require a large body to digest all the cellulose they ingest. A large body meant that they needed more food, and it was not available.
Small carnivorous bodies could be sustained by the little food available, which meant their survival.
A dinosaur named Kulindadromeus Zabaikalicus provided proof that dinosaurs had feathers. Some were fine and clearly defined as modern birds, while others were primitive, like bristles and hairs.
Taking all these factors together, the connection between birds and dinosaurs becomes clearer. Evolving into smaller dinosaurs with feathers provided early birds with several advantages. They would be able to glide, climb trees, and maybe even fly.
These advantages would allow them to hunt a more comprehensive range of prey, increasing the meal options, thus securing their survival.
And there you have it; over 15,000 species of dinosaurs are running and flying around the planet today.
Basic Characteristics Of A Bird
To get a keener understanding of the difference between a bird and an animal, we need to look at the characteristics of birds.
Most are general and apply to all birds, while others are species-specific for thousands of evolutionary years. Here are some features;
- Birds have feathers that help them keep warm. In some predatory birds, the feathers act as camouflage to add to their hunting arsenal.
- Birds have wings for flight. All birds have wings, but they can’t fly; only those with hollow wings can fly, like robins. Flightless birds such as ostriches and kiwis have wings, but they move by running.
- Birds reproduce by laying eggs. The eggs then get incubated for a specific time depending on the bird species, and a chick hatches.
- Birds have internal auditory meatus; this means that they have ear holes instead of ears. So they can perceive sound but have no external ear features.
- Birds have two legs since the primary movement method for birds is flying. Due to evolution, some birds have adapted and use legs for many different purposes, including hunting.
- Birds are warm-blooded. This means that their bodies keep up a given temperature regardless of the changes in the surrounding. This is why there are feathers to keep the birds warm when it’s cold.
- Birds have hollow bones. They have no bone marrow making them light enough to fly. The bones have a matrix for additional support for flight, takeoff, and landing.
- Birds have wings. All birds have wings, some have grown vestigial, and they are not used for flight, but they are present.
Characteristics Of Mammals
Most people confuse mammals and animals. Animals refer to all organisms in a kingdom, while mammals are under the Animalia class. To shed more light on the matter, let us look at some characteristics of mammals;
- All mammals have a spinal cord and backbone. The vertebrae protect the spinal cord that transmits signals from the mammal’s brain to the body’s muscles.
- All mammals have hair or fur. The fur protects mammals from the hot sun, low temperatures, and it helps keep moisture.
- Mammals have mammary glands; that secrete milk that mammals use to sustain their offspring.
- Mammals have sweat glands that help cool the body when the surrounding environment is hot.
- They have a heart with four chambers; the upper chambers are atriums, and the lower are ventricles. These allow the mammal to pump large volumes of blood throughout its body.
- They have different types of teeth that serve other purposes.
- They are warm-blooded; this means their bodies can generate internal heat to moderate their temperature.
- Their lower jaw (mandible) articulates with the skull; thus, only the lower jaw moves during chewing.
- Most mammals have external ears for the perception of sound. Some marine mammals like the dolphin don’t have external ears.
Similarities Between Mammals And Birds
Birds and mammals are both in Kingdom Animalia; thus, they must have some significant similarities.
You have to be aware of these similarities to understand the evolution of birds and mammals; here are some of the most important similarities;
- Both mammals and birds are endothermic. They are warm-blooded; hence they can keep their body temperature constant even if the surroundings change.
- Both mammals and birds are vertebrates. Being vertebrates means that they have skeletal systems and a backbone. A skeletal system helps maintain the animal’s structure and movement.
- Both mammals and birds have a heart. Both require a lot of energy to move; thus, they consume a lot of oxygen. The heart helps pump the blood throughout the body and separate clean blood from deoxygenated blood.
- Mammals and birds have similar blood components. They both have erythrocytes and leukocytes. Red blood cells have hemoglobin that is useful in carrying oxygen around the body. White blood cells help with immune systems.
- Caring for their offspring. Both species care for their young after they hatch or are born. The specific time of care varies, but they all care for the young at the beginning stages.
Differences Between Mammals And Birds
Knowing the characteristics of birds and mammals, we can know the differences between them. Some differences are minor while others are widely different; let us get down to details and understand nature;
- Birds have feathers, while mammals have fur covering their bodies. Some feathers are delicate and might confuse fur, but all birds have feathers, and animals have hair.
- Birds have two legs while mammals have four legs since legs are the primary movement mode in mammals.
- Mammals have a nose and mouth for feeding, perceiving taste, and smell, while birds have beaks for the same reasons.
- Birds lay eggs while mammals give birth. Mammals have internal fertilization; the male and female reproductive cells fertilize inside the female; in birds, eggs are fertilized, and they hatch outside the bird.
- Birds have internal ears, while mammals have external ears.
- Birds have hollow bones with a crisscrossed structural matrix for additional support, while mammals have bone marrow in their bones.
Many people ask whether birds are animals or not, and most people think they are not. The fact is, birds are animals, just like mammals and reptiles.
They are all in the same kingdom but are from different classes. Birds and mammals have several differences and similarities.
Understanding these is important for anyone who has an interest in zoology. Birds are both beautiful and an essential part of any ecosystem in which they exist.
It seems hard to believe, but birds are descended from dinosaurs. Millions of years of evolution changed the primitive giants into smaller and better-adapted bird species found all over the planet today.