Dances with wolves: the invasion of a gobbling skink and the counterpunch of the native opponent

Shi-Ping Huang, Jhan-Wei Lin, Chun-Chia Chou, Chen-Pan Liao, Jung-Ya Hsu, Jing-Fu Tsai, Shao-Lun Liu, Wen-San Huang

This is a plain language summary of a Functional Ecology research article which can be found here.

It is well-known that competition from invasive species can harm the persistence of native species. But sometimes the native species fights back, dealing with the new pressure accordingly. Here we present an invasive-native skink system, common sun skink (Eutropis multifasciata) and long-tailed sun skink (Eutropis longicaudata), before and after the invasion. We show how the invader’s behavior leads to its dominance, as well as how the native species has changed its behavior to cope with the new threat.

Common sun skink was first recorded in southern Taiwan in 1992 and first appeared at our long-term monitoring site of the long-tailed sun skink in 2012. The population and the number of egg clutches of the native skink then drastically decreased. Through field data collection and laboratory experiments, it turns out that the invasive skink is similar to the native skink in morphology and diet, but it is superior behaviorally—the invader eats food more efficiently and willingly consumes eggs and juveniles of the native species. On the contrary, the viviparous invader has no eggs and the native species never eats the juveniles of the invasive species.

A female skink (Eutropis longicaudata) protected her eggs from being attacked by an invasive species (E. multifasciata) that wants to eat them (credit: W.-S. Huang)

However, the native skink is fighting back. Female long-tailed sun skink started to display parental care behavior two years after the invasion and the frequency of this behavior rose to 100% within five years. Through manipulation, we found that the mothers which stay with the egg clutch would chase common sun skink away to protect their eggs. Such parental care behavior has been previously reported in an insular population of the same species, as a strategy to cope with the egg predation pressure from abundant egg-eating snake on the island. Here we found this behavior again, moreover the behavior has increased in response to the rise the of invasive common sun skink. We believe this behavior shift could help the native skink to overcome the asymmetry of egg predation between these two species, and there is perhaps a glimmer of hope of coexistence. Nevertheless, the common sun skink still dominates the game, and the future of the long-tailed sun skink is currently dark.

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