The introduction of colubrid species into island ecosystems often has disruptive effects, impacting native fauna and altering predator-prey dynamics. However, little is known about the interactions that occur when multiple non-native species are introduced to the same island.

On the island of Mallorca (Spain), several introductions have occurred over the centuries. The alien colubrid Macroprotodon mauritanicus is now considered naturalized, having been introduced by the Romans about 2,200 years ago. In contrast, Hemorrhois hippocrepis was introduced recently, with its presence documented only since 2006. Despite this short timeframe, the species has already spread widely and severely impacted local fauna, while eradication attempts have failed so far.

A recent note published in Acta Herpetologica provided the first evidence of interspecies predation in Mallorca, documenting an adult M. mauritanicus preying on a juvenile H. hippocrepis. This observation represents the first record of interspecific ophiophagy for M. mauritanicus. It also demonstrates the inclusion of a newly introduced species into the diet of a naturalized one, signaling a clear trophic response to a novel resource within the island's confined ecosystem.

Interestingly, these two species also coexist in North Africa, where predation between them has never been documented. The event witnessed in Mallorca may stem from the unique characteristics of the insular context, which features simplified food webs, limited space, and higher encounter rates. Ultimately, this observation suggests that M. mauritanicus may exert some degree of predation pressure on H. hippocrepis, a fully invasive species on the island. If confirmed by further observations, this novel interaction could influence the future dynamics of the biological invasion.

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