By Sonja Chandler
As humans celebrate Mother’s Day, the Big Idea takes a look at recent research into other animal mothers. Findings highlight the intricate relationship between parents and offspring and draw attention to how we need to appreciate mothers – wherever they are!
Australian Fairy Wren mothers teach chicks the secret password
Flinders University researchers have found that mother superb Fairy Wrens sing a distinctive ‘incubation call’ to their eggs late in incubation – a call that becomes a meal ticket. After they hatch, the nestlings make begging calls that contain ‘signature elements’ of this call which parents recognise and respond to.
Each female sings a unique song and her eggs learn it. Cuckoo hatchlings in a Fairy Wren nest don’t learn the signature elements and so when they beg for food the fairy wren parents ignore them, thus thwarting the intentions of cuckoo parents to get others to raise their offspring.
Amazonian turtles hang with hatchlings
Using microphones near captive and wild adults and hatchlings, biologists from Brazil’s National Institute for Amazonian Research found that adult turtles made sounds. Baby turtles also started making noises around a day before they hatched. When hatchlings were released into the wild close to females, the females seemed to respond to the calls and came close to the hatchlings.
By attaching radio transmitters to female turtles, they found that females left the nesting area only after eggs had hatched and the hatchlings were in the water – and the hatchlings swam away with them! This suggests that river turtle hatchlings might not have to navigate their environment all alone.
Conservationists should also take note: although well-intentioned, removing eggs from a nesting spot to incubate and hatch in ‘safe’ places might not be the best thing to do. And, releasing hatchlings into water where there are no waiting females might be putting the little turtles at risk.
Turtle mothers wait for the best day to lay eggs
Also on turtles, it seems that egg-carrying females are able to stop their eggs from developing so they can wait until conditions are right to go onto land and lay them.
At the Healesville Sanctuary, Monash University researchers studying four different species of turtles found that females produce a mucus-like substance inside their reproductive tracts where the eggs are stored. The mucus causes oxygen levels to decrease and stops eggs from developing further.
Once eggs are laid, they are exposed to normal oxygen levels again, restarting egg development. Researchers say this capability allows the turtle mothers to select when and where to lay their eggs, taking into account food supplies and a secure environment.
Mother goats don’t forget their kids
Researchers at Queen Mary, University of London, have found that mother goats can remember their kids’ calls for up to 11–17 months. To find this, they recorded the bleating of five-week-old pygmy goats and then played back the sounds to the kids’ mothers at later times.
Not only were the goat mothers able to recognise their own kid’s bleating, they remembered them at least one year after weaning. The researchers say this behaviour suggests that animals remember socially important partners.
It could help mother goats and their daughters maintain social relationships and prevent mothers from mating with their sons, when those sons become sexually mature.
Sacrificing skin to feed her young
A new species of worm-like amphibian was discovered in French Guiana earlier this year by Harvard University researchers. The legless amphibian is a caecilian (pronounced ‘siss-ee-lee-an’) and is named Microcaecilia dermatophaga meaning ‘little skin-eating caecilian’ – literally, the hatchlings eat their mother’s skin!
Caecilians live only in the moist tropics and most species live underground; nearly blind, their eyes are covered by bone and they only see in black and white. They have large mouths and sharp teeth for eating invertebrates like termites and worms.
The new species is one of only four known species with young that eat their mother’s skin. The females grow an extra layer of fat-rich skin, and the young scrape it off with a set of specialised ‘baby’ teeth and eat it. As the young grow, adult teeth replace their earlier set and they move onto other food sources.