GPS tracking reveals landfill closures induce higher foraging effort and habitat switching in gulls

Abstract

Background Landfills are a major subsidy for some animals, with implications for their life history and demography. Gulls feed extensively on food from landfills and closures are expected to have ecological consequences, but how this influences movement ecology is virtually unknown. Methods We used GPS-tracking to quantify foraging behaviour and habitat choice of lesser black-backed gulls (Larus fuscus) breeding at two colonies before and after closure of two nearby landfills. Results Following closure, gulls from both colonies travelled further and for longer to forage. Gulls also changed habitat selection, although this differed by colony - birds from one colony shifted to agricultural habitats, while at the other, increased their use of urban areas. These behavioural responses had no effect on adult body condition but hint at potential direct effects of higher foraging costs and indirect impacts by shifting to new habitats. Conclusions Our results demonstrate how landfill availability influences gull foraging movements and habitat selection. We also emphasize the value of biologging to detect rapid behavioural responses in contrast to more conventional demographic approaches, which is especially important for animals that spend the majority of their lives away from direct observation.

Urban and coastal breeding lesser black‐backed gulls (Larus fuscus) segregate by foraging habitat

“…We modelled RSFs for the four most visited foraging habitats (agriculture, coastal, marine and urban), fitting separate models for each year. Landfills were previously an important habitat for coastal breeders; however, the closure of a major landfill prior to the study period in April 2017 (Langley et al 2021) meant that this resource was rarely used and was not included in our analysis.…”

“…However, we note that observed inter-individual differences may partly be driven by variation in the number of fixes and foraging trips. The closure of a large nearby landfill prior to the study period may have influenced the observed patterns of individual habitat use, with birds at the coastal site switching to visiting agricultural habitats more frequently in 2017 postclosure (Langley et al 2021). These findings highlight that while much focus may be on population-level responses, the interindividual differences revealed may be important for management, as problem individuals may have disproportionately large impacts (Sanz-Aguilar et al 2009, Swan et al 2017.…”

“…During the 20th century, several gull species (Laridae) began breeding in towns and cities around the world (Smith & Carlile 1993, Dwyer et al 1996, Soldatini et al 2008, Yorio et al 2016. These generalist foragers exploited abundant anthropogenic subsidies in urban environments (Carmona et al 2021, Langley et al 2021 and also benefitted from predator-free breeding habitat and heat island effects (Rock 2005, Zelenskaya 2019). Urban gull populations increased rapidly, but this intensified conflict with people via disease transmission (Girdwood et al 1985, Hatch 1996, bird-strikes (Neubauer 1990) and nuisance behaviours (e.g.…”

“…2021, Langley et al . 2021) and also benefitted from predator‐free breeding habitat and heat island effects (Rock 2005, Zelenskaya 2019). Urban gull populations increased rapidly, but this intensified conflict with people via disease transmission (Girdwood et al .…”

Resource selection by New York City deer reveals the effective interface between wildlife, zoonotic hazards, and humans

“…Landscape-independent fragmentation (LIF) results from anthropogenic disturbances which change animals' perception and use of their environment (Berger-Tal & Saltz 2019). For example, resource subsidies lead to LIF whereby fertilized vegetation, gardens, or waste byproducts (Becker et al 2015;Langley et al 2021) provide stable, often predictable, resources which influence wildlife host movement (Ossi et al 2020;Ranc et al 2020) and contact patterns at the human interface, where zoonotic hazard becomes risk. Tick-borne disease emergence is intertwined with land use change and habitat fragmentation (Diuk-Wasser et al 2021) and tick-borne diseases are the most common vector-borne zoonoses in temperate North America, Europe, and Asia.…”