Animals Wildlife 8 of the Biggest Babies in the Animal Kingdom By Angela Nelson Writer Boston University Angela Nelson is a Pulitzer Prize-winning digital editor and storyteller who covered a variety of general interest stories on MNN (now part of Treehugger) from 2014-2019. our editorial process Twitter Twitter Angela Nelson Updated May 31, 2017 Share Twitter Pinterest Email Animals Wildlife Pets Animal Rights Endangered Species We're gonna need a bigger scale Photo: Rudi Hulshof/Shutterstock You might think the biggest bundles of joy that arrive in the animal world belong to the largest animals. And while that's certainly true in some cases, it's not a universal rule. For example, the average kangaroo stands 5 to 7 feet tall and weighs about 200 pounds, but kangaroo babies, or joeys, are only 2 centimeters long and weigh less than a gram. Many different types of bears have tiny babies, too. Newborn pandas weigh just 3 to 5 ounces and are 1/900th the size of the mother. And as the Washington Post reports, of the placental mammals, even giant pandas have the tiniest babies in comparison to the size of the mother. So who are the proud parents of the heftiest newborn animals? Click through for eight of them. Cute as they are, these baby warthogs (pictured) don't make the cut. Blue whales Photo: National Geographic/YouTube Blue whales are the largest known animals to have ever lived on Earth: Adults can measure 100 feet long and weigh 200 tons. So it's not surprising that when a baby blue whale is born, the calf itself is as big as some of the other largest animals on the planet. According to National Geographic, baby blue whales spend about a year growing inside a mother, and when they're born, they're about 25 feet long and weigh up to 3 tons. And boy do they grow fast. Blue whale calves eat nothing but mother's milk and gain about 200 pounds every day for its first year. Giraffes Photo: Ralph Daily/flickr Giraffes make the list not because of their weight — babies weigh only about 150 pounds — but for their height. Adult giraffes can be 15 to 20 feet tall, and females give birth standing up. That means babies have a long way to fall (about 5 feet) when they come out! But don't worry — the calves are born 6 feet tall and can stand and walk within an hour of being born. Newborns are already about one-tenth the size of mom, according to National Geographic. And after about 10 hours, these quick learners are ready to run along with their families. Now, most new parents don't get much sleep, but luckily, giraffes are well-suited for sleep deprivation. These lumbering giants can go weeks without getting some shut-eye and usually sleep for only five minutes at a time. Elephants Photo: Derek Keats/Wikimedia Commons Elephants are the largest land animal in the world and have the longest gestational period of any mammal — around 22 months. When calves finally greet the world, they're about 1/40th the size of an adult at 3 feet tall and upwards of 200 pounds, according to National Geographic. But don't let their size fool you. Elephant calves are completely dependent on the mother. They're born blind, though they can stand up shortly after birth, and they nurse for up to three years. Luckily, elephants live in a matriarchal society and mamas have lots of help from other female relatives, who all pitch in with child-rearing. Hippos Photo: Frank Wouters/Wikimedia Commons The hippopotamus is the second-largest land animal, with adults standing at five feet tall, up to 17 feet long and weighing up to 8,000 pounds. Their name comes from the Greek term for “river horse,” which makes sense because these excellent swimmers spend 16 hours a day in the water and can hold their breath for five minutes. A female hippo will have only one calf every two years and has a gestational period of about eight months. They even give birth under water, meaning their 100-pound, four-feet-long calves have to swim to the surface to take their first breath. Calves can nurse on land or under water, and soon after the birth, the mom and calf will join a school for protection. Rhinos Photo: International Rhino Foundation/Wikimedia Commons The average adult rhinoceros is only slightly smaller than an average adult hippo, with some species growing to 13 feet long, 6 feet tall and weighing 5,000 pounds. Every 2.5 to 5 years, a female rhino will reproduce and carry her calf for 15 to 16 months. When she gives birth, the baby rhinoceros will stand two feet tall and weigh up to 140 pounds, the San Diego Zoo says. A calf can stand up soon after birth and will eat solid food (hippos are herbivores) after just 10 days, though it will continue to nurse for at least a year. These doting mothers will care for her calf for up to four years before nudging them toward independence. Kiwi birds Photo: Hannes Grobe/Wikimedia Commons You may be wondering what a seven-pound bird that stands just 17 inches tall is doing on a list of biggest animal babies. The kiwi bird is notable not for the size of its offspring but for the size of its egg-to-body weight ratio. According to the Audubon Society, this flightless bird lays an egg that's one quarter of its body weight. This is the largest of any bird in the world, ratio-wise. In other words, that would be like a 100-pound woman giving birth to a 25-pound baby! Ouch. But why is it so over-sized? One theory says the kiwi bird used to be much larger (about the size of an emu or ostrich), therefore its egg was much larger. And as the bird evolved and adapted, it got smaller but the egg didn't. Recent research points to precocity — with big eggs, chicks hatch ready to run with enough yolk in their bellies to last more than two weeks. Horses Photo: Callipso/Shutterstock Like giraffes, horses make this list for their height, not their weight. After a gestational period of about 11 months, a foal is born with legs that are almost as long as an adult's. In fact, their legs are so long, they may find it hard to reach the grass below to eat. Those long limbs combined with their smaller bodies weigh up to 180 pounds. Most foals are born at night as the darkness provides protection from predators. After just a few hours, a foal can stand and run alongside its mother. And feasting on her milk, it'll gain 3 to 4 pounds a day and will start eating solid foods after 10 days. Cows Photo: Joseph Sohm/Shutterstock While cow babies aren't huge, they're notable for two things they have in common with human babies. First, calves weigh about 7 percent of their mother's weight, which is roughly the same proportion as a baby to a woman. So a 1,000-pound heifer would give birth to a 70-pound calf, like a 140-pound woman would have a 9-pound baby. Cows and humans also have similar gestational periods of about 280 days. A baby cow will nurse from its mother for nine weeks or so. Cows are emotionally complex animals, and mothers and their babies have very close bonds. If a calf is missing, a mother will walk for miles to try to find it. And when they sleep, they often snuggle together with sleeping arrangements determining social hierarchy.