‘Planet Earth: Incredible Families’
Which animal family do you think is the weakest, more independent and spread out?
Thomas: There are numerous examples, but one would be the Maleo. The Maleo is an endangered, chicken-sized bird that’s native to Indonesia. After mating, the female will dig a deep hole in either volcanic soil or in sand and lay a single, oversized egg (relative to her body size). She’ll then cover the egg with the soil or sand and leave. The egg is either incubated with energy from the sun, if the egg is laid in the sand, or by geothermal means if it’s in volcanic soil. When the chick hatches, it has to not only escape from the egg, but then scratch itself to the surface and fly off into the forest. There’s absolutely no maternal or paternal care at all.
Sea turtles would be another example. Instead of laying one egg, they deposit lots of eggs because so many of their offspring don’t make it to adulthood, but once the eggs hatch, the young must fend for themselves.
In your opinion, which animal family is the strongest in the world, or the most tightly knit?
Thomas: Elephants certainly have very strong bonds. In the Callitrichidae, the marmosets and tamarins, you have not only the adult male and adult female taking care of offspring, but actually older siblings will take turns caring for younger siblings. That’s how they learn to become good parents — by not only observing how their parents care for young, but by assisting them in caring for young.
One species that people may not think about very often is the common Vampire bat, which is a very altruistic species. They are thought to be the only bats that will actually adopt an orphaned bat. They also exhibit a really interesting behavior — they are a colonial species that lives in small groups. Vampire bats need to feed every couple of days. If a bat is not successful in feeding and won’t make it through another daylight period to be able to hunt the next night, it actually will solicit food from a family member, who will regurgitate just enough blood to allow that bat to survive for one more evening’s attempt at feeding. In doing so, the bat that regurgitates the blood actually minimizes its own survival chances because now it has less food, but the colony helps support each other. Typically colony members are family members, so they help each other survive as a group.