Effects of alarm call playback on the behaviour of wild European herring gulls

Abstract

Playback of audio recordings is a well-established method of eliciting behavioural responses in the wild. The effects of audio playback on the behaviour of wild European herring gulls (Larus argentatus) has not been well researched however. The present study was conducted in order to address this using playback of recordings of European herring gull alarm calls, European herring gull food begging calls, a woodland dawn chorus or silence to wild free-living birds that had been attracted to the study site by the scattering of a highly palatable food mixture. Each call type was played 8–9 times in randomised order across the 40 day study period with only one call being played per day. Playback was initiated 30 s after two or more gulls had landed within the within the baited area and continued for 2 min thereafter. The number of birds on the ground within this area was recorded at 10 s intervals during the 30 s before the playing of the calls was initiated through to the 30 s afterwards. Results were clear and showed that whilst groups of herring gulls typically arrived in close temporal proximity to each other and quickly began consuming the food, they took flight within seconds of hearing their own species’ alarm calls even though there was still food left to be eaten. The woodland dawn chorus produced a similar effect for reasons that are not fully understood. The begging calls were largely without effect and as with the ‘silent’ condition numbers of gulls on the ground appeared to decrease in relation to a reducing amount of food left to be eaten. These data together demonstrate that whilst wild European herring gulls respond with flight upon hearing their own species’ alarm calls, other sounds can produce this effect also.