In April, the members of the team went to Filfla (a solitary limestone islet 4.5km South of mainland Malta) to monitor the Yellow Legged Gull’ s colony. Trail cameras were set up close to some nests in order to assess predation events of this species on the European Storm Petrel (Hydrobates pelagicus), the smallest focus species of the project.

Two researchers of the project searching for gulls’ nests.

A nest of Yellow-Legged Gull being monitored with a camera, to record predation on Storm Petrel.

Two researchers handling, taking measures and ringing a Yellow-Legged Gull on Filfla

Yellow Legged Gulls (Larus michahellis) are both voracious predators and scavengers so their diet is quite wide, including squid, fish and other marine food, refuse, terrestrial small mammals and other birds.

An adult Yellow-Legged Gull being measured on Filfla

Gulls nesting on the lower slopes of Filfla, are known to predate on Storm Petrels. Some of the scree nests may be set up strategically in front of Storm Petrel burrow entrances and the predation might have caused a decline in the Hydrobates pelagicus‘ population in the last decades. Through the analysis of Gulls’ regurgitates we want to assess the degree of predation and the potential geographical variation.

Regurgitates of Yellow-Legged Gulls, collected on Filfla for further analysis. Many of these pellets contain the remains of Storm Petrels

This predator-prey interaction is supposed to be rather young and Storm Petrels on Filfla might still lacking successful strategies to avoid it. The predation by Yellow Legged Gulls on the small tube-noses also occurs in other colonies of the Mediterranean Sea, well studied for instance on Benidorm Island (Western Mediterranean, Spain).

The team hopes the regurgitate analyses and the trail cameras will shed light on quantity, quatlity and behavioural aspects of this inter-specific conflicts between Larus michahellis and the Storm Petrels on Filfla.

Nest of Yellow-Legged Gull being mapped with GPS.

Nest of Yellow legged Gull with two eggs, the left one in the process of hatching. Visible throuhg the hole in the egg is the beak with the egg tooth on top.