Snake birds, also known as anhingas, are a group of water birds that are known for their long, snakelike necks and propensity to swim with just their necks above water. Though they may resemble snakes in the water, snake birds are actually medium-sized birds that can fly very well. Let’s take a closer look at the size of these fascinating waterfowl.
What are snake birds?
Snake birds, or anhingas, are diving birds that belong to the Anhingidae family. There are 4 living species of snake birds:
- Anhinga – found in sub-Saharan Africa
- Oriental darter or Asian darter – found in South and Southeast Asia
- Australasian darter – found in Australia and New Guinea
- American darter or anhinga – found in North America and South America
Some key facts about snake birds:
- They live near lakes, rivers, and swamps.
- They spend a lot of time swimming with just their long neck poking out of the water, which gives them their snake-like appearance.
- They hunt for fish by spearing them with their long, sharp beak.
- They do not have waterproof plumage like other water birds. Their feathers get soaked as they swim and dive, which helps them dive more easily.
- After swimming, snake birds perch on branches and spread their wings out to dry.
How big do snake birds get?
Snake birds are medium-sized water birds. Here are the approximate sizes of the different snake bird species:
Species | Length | Wingspan | Weight |
---|---|---|---|
Anhinga | 28-35 inches | 43-46 inches | 2.2-3.3 pounds |
Oriental darter | 30-36 inches | 48 inches | 2.2-3.7 pounds |
Australasian darter | 35-39 inches | 51-55 inches | 2.9-5.5 pounds |
American darter | 32-34 inches | 48 inches | 2.3-3.3 pounds |
As the table shows, snake birds are generally 2-3 feet long from bill to tail, with wingspans around 4 feet across. Their weights range from about 2 to 5 pounds. The Australasian darter is the largest species.
How do snake bird sizes compare to other birds?
At 2-3 feet long and a few pounds, snake birds are considered medium-sized birds. Here’s how their sizes compare to some other common water birds:
- Smaller than cormorants – Cormorants are chunky, all-black water birds that are around 32-40 inches long.
- Smaller than herons – Great blue herons can reach 46 inches long with a wingspan of nearly 6 feet.
- Larger than grebes – Grebes are small diving birds that are typically 12-22 inches long.
- Similar in size to loons – Loons are swimming birds in the same general size range as snake birds.
Snake birds are medium-sized compared to other common waterfowl. They are larger than small diving birds like grebes but smaller than large wading birds like herons and cranes. Their size puts them in the same general class as loons, coots, and some ducks.
How heavy are snake bird bodies and wings?
One interesting aspect of snake birds is that they have unusually dense, heavy bodies and wings compared to other birds their size. This helps them dive and stay submerged as they swim and hunt underwater.
- Bodies – A snake bird’s body has neutral buoyancy, meaning it weighs enough to stay submerged but not enough to sink rapidly. Their bodies are estimated to be 20-25% denser than other birds their size.
- Wings – Their wings are also quite heavy and not very conducive to sustained flight. Snake bird wings are estimated to be 50% heavier than the wings of similar-sized flying birds.
This combination of heavy wings and dense bodies allows snake birds to effectively dive and swim to catch fish. But it means they have to work harder to take flight and tend to fly slowly and laboriously with their necks retracted.
Do male and female snake birds differ in size?
There is little sexual dimorphism between male and female snake birds. This means that males and females are very close to the same size.
Any differences in size tend to be very minor, with males perhaps averaging slightly larger than females in some cases. But in general, male and female snake birds are remarkably similar in length, wingspan, and weight.
This lack of size difference between the sexes suggests that factors like male-male competition and gender-based mating strategies do not play a major role in driving snake bird evolution and development.
How do baby snake bird sizes compare?
Baby snake birds, called chicks, are quite small compared to the adults. Here are some facts about snake bird chick sizes:
- Newly hatched chicks weigh 25-35 grams, about 1-1.5 oz.
- They are only about 2.5 inches long when first hatched.
- After a month, they grow to around 150 grams or 5 oz.
- They reach adult size after about 2 months.
So snake bird chicks start out quite tiny but have a very rapid growth phase as juveniles, putting on weight and size quickly in their first few months of life. This helps explain why adults must hunt frequently – they need to feed their fast-growing young!
How do snake bird sizes change during evolution?
The fossil record shows that primitive snake birds from 30+ million years ago were generally smaller than modern species. Some key size changes include:
- Leggy ancestor species had shorter necks and bodies, with total lengths around 18 inches.
- Early snake bird fossils had more abbreviated neck vertebrae.
- Over time, neck vertebrae increased in number and length.
- Wingspans also increased in early snake bird evolution.
These evolutionary trends show a general increase in snake bird sizes over the past 30 million years. Necks got longer, wingspans broader, and body mass increased compared to ancient predecessors. This allowed them to become more effective at foot-propelled diving and underwater hunting.
Conclusion
To summarize key points on snake bird sizes:
- Snake birds are medium-sized water birds, around 2-3 feet long with 4 foot wingspans.
- Their dense bodies and heavy wings help them dive and swim.
- Males and females are very close in size, with little sexual dimorphism.
- Chicks start out tiny but grow rapidly.
- Primitive fossil species were smaller than modern snake birds.
So while they may look snakelike slithering through the water, snake birds are medium-sized, adept swimming birds. Their elongated necks and wings evolved to make them powerful underwater hunters.