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City gulls and their rural neighbours: Changes in escape and agonistic behaviour along a rural-to-urban gradient

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

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Abstract

Since industrial revolution, human population size has increased sevenfold and became increasingly urban with currently 54% of the world’s population living in cities. Although urbanisation has generally a negative impact on wildlife, some species such as sea gulls (Larus spp.), have successfully adapted to human-dominated habitats. Gull populations breeding in coastal cities have increased since WWII, while at the same time declining in their natural breeding habitats. This is mainly attributed to gulls being generalist scavengers that benefit from increased food availability in urbanised areas (e.g., landfills, human discard), but also to increased ambient temperatures and the absence of predators. The rising presence of gulls in coastal cities leads to increasing numbers of human-gull conflict, mainly due to their bold or even aggressive behaviour towards humans. In our study, we explored behavioural changes in escape and agonistic behaviour of Herring (L. argentatus) and Lesser black-backed gulls (L. fuscus) along a rural-to-urban gradient in Liverpool City and the Sefton Coast. A total of 48 approach experiments were conducted to measure flight initiation distance (FID), flight distance and escape speed, which were used as dependent variables in three Generalized Linear Models (GLMs), including ‘species’ as the fixed factor and ‘degree of urbanisation’ as a covariate. A total of 230 video-recordings obtained during feeding sessions were used to establish the rate of agonistic interactions at 22 sampling locations with differing degrees of urbanisation. In total, 585 agonistic interactions of Herring gulls and 103 of Lesser black-backed gulls were recorded. Number of agonistic interactions (incl. long calls, mew calls, oblique posture, jabbing, pecking) was used as the dependent variable in a Generalized Poisson Log Linear Regression Model, using ‘species’ as the fixed factor, ‘degree of urbanisation’ and ‘group size’ as covariates. In both species, shorter FID, shorter flight distance, a reduced escape speed and increased numbers of agonistic interactions were significantly related to increased urbanisation, suggesting greater boldness and aggression in city gulls. Moreover, Herring gulls performed significantly higher rates of agonistic interactions than Lesser black-backed gulls. Moreover, boldness was significantly correlated to aggression when both species were lumped.

Item Type: Book Section
Subjects: Q Science > QL Zoology
Divisions: Biological & Environmental Sciences (new Sep 19)
Publisher: Nova Science Publishers, Inc.
Date Deposited: 05 Aug 2020 10:34
Last Modified: 05 Aug 2020 10:34
Editors: Daniels, JA
URI: https://researchonline.ljmu.ac.uk/id/eprint/13052

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