Australian herpetologists have found that Cunningham's spiny-tailed Skinks actively protect their young from predators. Within three years, scientists have twice recorded attacks by these lizards on venomous snakes, and twelve times - on crows-whistlers. As noted in an article for the Australian Journal of Zoology, this behaviour is extremely rare among reptiles. Reptiles are difficult to call responsible parents: for most of them, the top care for their offspring is the protection and warming of the clutch. However, there are exceptions: for example, some Australian lizards from the skink family (Scincidae) have complex social behaviour, including caring for their young.
A team of herpetologists led by Gregory S. Watson from the University of the sunshine coast decided to learn more about the family relationships of Cunningham's spiny-tailed Skinks (Egernia cunninghami), which live in South-Eastern Australia. These large viviparous lizards prefer areas with granite outcrops: cracks in individual boulders and cracks between them serve as their shelters.
Scientists observed several family groups of prickly-tailed Skinks in the state of New South Wales during three breeding seasons: in January-February 2016, 2018 and 2019. In total, the team spent 32 days near the lizards.
During this time, the authors managed to catch the birth of young Skinks four times. The other members of the group, both adults and teenagers, treated the newborns peaceably. Cubs quickly began to show independence and move away from their relatives by more than a meter, which made them vulnerable to attacks from predators. However, the parents were alert and ready to protect their offspring.
In the course of observations, Watson and his colleagues twice recorded how adult Skinks drove away venomous Eastern brown snakes (Pseudonaja textilis) that tried to prey on recently born cubs. In one case, the mother bit the predator on the torso and forced it to crawl away. In another case the snake was attacked jointly by a male and female: grabbing the reptile by its head and torso, they dragged it 16 meters away from the burrow.
In another 12 cases, Skinks were attacked by whistling crows (Gymnorhina tibicen) that landed on rocks near the burrow. These medium-sized omnivorous birds can pose a danger to their young, so it is not surprising that lizards behave aggressively towards them. In five cases, scientists identified the assailant as a recently born mother. Fortunately for the birds, they always managed to fly away before the Skinks could bite them.
Previously, this behaviour was not observed for representatives of the genus Egernia. It was believed that these lizards protect their young from predators only indirectly, giving them an alarm signal in case of danger. Moreover, among other reptile species, active protection of offspring was reliably recorded only in crocodiles, which drive predators away from the clutch, as well as in Asian mabuy (Eutropis longicaudata) — ovipositing Skinks. According to the authors, the behaviour of E. cunninghami not only saves the life of cubs but also helps them understand which animals pose a threat.
But yellow-bellied three-toed Skinks (Saiphos equalis) can reproduce both by live birth and by laying eggs. However, recently scientists have recorded an extremely unusual pregnancy in one female of this species. First, the lizard laid eggs, and then, after a few weeks, gave birth to a live baby.