How Gull-ible can we be around urban Larus?

The weather on the northern hemisphere is getting warmer which means beach days are approaching. Every beach dweller can confirm that seagulls (Larus sp.) can be very cunning and cheeky in order to steal food. Is this their ancestral behaviour or has this evolved with the rising of urban areas? Pavlova and Wronski (2020) studied seagull boldness and aggressiveness on a rural-urban gradient by measuring flight initiation distance, fight distance and escape speed. They predicted agonistic behaviour to be more prevalent in urban seagulls and in bigger groups compared to their rural counterparts and small groups. Sampling occurred in Liverpool, Crosby and Southport during the gulls’ breeding season.

Flight initiation distance was quantified by measuring the observer’s distance towards the bird and slowly walking towards it, stopping when the bird flew or walked away. The duration until landing or ceasing walking was timed and the distance flown or walked was measured to quantify escape time and flight distance. Escape speed was calculated by dividing flight distance by flight time

Agonistic behaviours were counted using video recordings and degree of urbanisation was calculated as percentage proportion of urban and suburban land cover divided by two. This resulted in a gradient of 19% to 100% urbanised area. Data were analyzed statistically with generalized linear models (GLM).

Their results showed significantly shorter flight initiation distance, shorter flight distance and slower escape speed in urban seagulls, indicating increased boldness of urban gulls. The number of agonistic behaviours also increased with increasing degree of urbanisation, confirming the hypothesis that urban gulls are more aggressive than rural ones. Bigger groups also showed more agonistic interactions, confirming this hypothesis as well.

Finally, they found a strong positive correlation between flight initiation distance and escape and agonistic behaviour, indicating shy individuals to be less aggressive than bold ones (Pavlova, O. & Wronski, T., 2020).

This study confirms the feeling most people have of aggressive seagulls in urban areas. Other studies found urban seagulls to be less hesitant to forage in unknown feeding stations (Castano, M.V. et al., 2023) and gulls to be mainly motivated to visit urban areas by food abundance rather than breeding opportunities (Huig, N. et al., 2015).

Thus, if you want to enjoy a calm day without having to scare away every seagull that comes near you, you may want to find a nice rural spot with more wary gulls!

 

Sources

Castano, M.V., Zumpano, F., Biondi, L.M. et al. Does urbanization affect behavioral responses to novel objects in marine birds? The Olrog’s Gull as a case of study. Urban Ecosyst 27, 427–437 (2024). https://doi.org/10.1007/s11252-023-01465-2

Pavlova, O and Wronski, T (2020) City gulls and their rural neighbours: Changes in escape and agonistic behaviour along a rural-to-urban gradient. In: Daniels, JA, (ed.) Advances in Environmental Research. Nova Science Publishers, Inc., New York, pp. 33-62. ISBN 978-1-53618-000-8