Importance of predictable anthropogenic food subsidies for an opportunistic gull inhabiting urban ecosystems

Carmona, Marı́a José; Aymí, Raül; Navarro, Joan

doi:10.1007/s10344-020-01446-2

Cited by 16 publications

(18 citation statements)

References 50 publications

(56 reference statements)

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“…At the same time, modified inland areas present a high level of urbanization with high percentages of paved surfaces such as roads and buildings. And even when human intervention has been demonstrated to facilitate the presence of birds (Cereghetti et al, 2019;Carmona et al, 2021), urban areas also can generate ecological traps for bird nesting (Reynolds et al, 2019), increase bird mortality by collisions with moving vehicles (Erritzoe et al, 2003), and increased competition for good quality food and native trees for nesting (Seress and Liker, 2015).…”

Section: Discussionmentioning

confidence: 99%

“…If human intervention have been shown to increase ecosystem variability and the availability of resources for birds (Cereghetti et al, 2019;Carmona et al, 2021), this could potentially be also true for modified beach areas that correspond to an intermediate level of human intervention (Doxa et al, 2012). However, rocky shores could present higher intervention than beaches, and that reflects on non-differences with modified inland areas richness (Figure 2).…”

Section: Discussionmentioning

confidence: 99%

“…In spring, paved surface cover is a variable that determines species composition. Possibly for the human presence and food subsidies for birds (Cereghetti et al, 2019;Carmona et al, 2021).…”

Section: Discussionmentioning

confidence: 99%

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Bird Communities in Coastal Areas. Effects of Anthropogenic Influences and Distance From the Coast

et al. 2022

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Urbanization effects have been studied all over the world, documenting impact in species richness, abundances and changes in species communities. Birds have been broadly used as study models. In general, urbanization affects birds, reducing species richness, especially in the urban core, and increasing species richness in areas with intermediate levels of disturbance, such as suburbs. Urbanization also changes species assemblages depending on urban characteristics and resources available, creating habitats for different species. Even when more than half of the cities in the world are on the coast, the effects of urbanization on habitat use of terrestrial and marine birds in coastal urban environments has received little attention. We hypothesized that coastal cities would present different bird diversity in modified marine areas and modified inland areas as terrestrial and marine ecosystems coexist. We predict that modified marine areas will have higher species richness than modified inland areas and natural marine areas. For bird assemblages, we expect to find similar species compositions between sites with similar habitat characteristics more than closeness. We compare habitat use of marine and terrestrial avifauna in the human-modified coastal city of Valparaiso, Chile, characterized by a range of urban developments within city boundaries. We specifically compare corrected bird abundance in six different possible habitats for birds, according to distance to the coast, and human influence. Bird counts (50 m fixed radius) were conducted in winter and spring of 2019. Bird species richness and abundances, corrected by the probability of detection, were estimated. Additionally, species composition and occupancy of bird species in those habitats were calculated. Results show that coastal urban cities can provide different habitats for bird species. Modified inland habitats differ from semi-natural inland habitats and from the modified beaches in species richness and species composition. Environmental heterogeneity in coastal cities seems to allow the coexistence of marine and terrestrial bird species, showing differences in species richness and bird assemblages for marine-inland environments and natural- modified habitats. Results highlight the need to consider these factors for urban planning in order to conserve bird diversity in coastal urban areas.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Bird Communities in Coastal Areas. Effects of Anthropogenic Influences and Distance From the Coast

et al. 2022

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“…Hence, agricultural resources could simply be too energy‐ or time‐demanding for raising chicks. In contrast, anthropogenic food subsidies found in urban environments tend to be highly predictable (Carmona et al 2021, Spelt et al 2021). Moreover, they are generally ubiquitous, typically causing lower food competition.…”

Section: Discussionmentioning

confidence: 99%

Context‐dependent specialisation drives temporal dynamics in intra‐ and inter‐individual variation in foraging behaviour within a generalist bird population

Baert

Stienen

Verbruggen

et al. 2021

Oikos

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Individual niche variation is common within animal populations, and has significant implications for a wide range of ecological and evolutionary processes. However, individual niche differences may also temporally vary as a result of behavioural plasticity. While it is well understood how niche variation is affected by changes in resource availability, comparatively little is known about the extent to which individual niche differences may vary within the annual cycle due to internal drivers. Here, we assess how time‐ and energy‐constraints imposed by incubating and brood rearing affect inter‐ and intra‐individual variation in the foraging behaviour of lesser black‐backed gulls, a generalist seabird with strong individual niche variation. To this end, we compared daily foraging trips of 22 breeding and 23 non‐breeding GPS‐tracked adult gulls from two colonies in the Southern Bight of the North Sea over the course of the breeding season. We find that breeding birds, unlike non‐breeding ones, did indeed alter their foraging behaviour during the breeding season. Both sexes reduced their searching effort by increasingly revisiting earlier foraging locations, allowing for shorter and more frequent foraging trips. Breeding females also showed pronounced shifts in their habitat use and strongly specialised on urbanised foraging habitats throughout the breeding season. Hence, while individual variation in habitat use remained largely consistent within non‐breeders and in breeding males, individual variation among breeding females almost completely disappeared. Female lesser black‐backed gulls are on average smaller, and therefore often outcompeted by males for the most profitable food sources. The temporal specialisation on spatially reliable anthropogenic food sources during breeding hence suggests a complex interplay between intrinsic competitive constraints, resource reliability and shifting time‐ and energy budges in shaping temporal dynamics in individual niche variation within our study population.

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“…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.…”

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confidence: 99%

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

Langley

Bearhop

Burton

et al. 2022

Ibis

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Despite urbanization's general erosion of biodiversity, towns and cities provide novel opportunities for some species. During the 20th century, gulls (Laridae) colonized urban areas around the world where they flourished. At the same time, some coastal populations declined. The reasons for this difference are not fully understood, partly because little is known about any ecological differences between urban and non‐urban gulls, such as their foraging ecology. Here we compare the movement ecology and habitat selection of Lesser Black‐backed Gulls Larus fuscus graellsii breeding at two neighbouring colonies – one urban and one coastal – in north‐west England. We used bird‐borne GPS loggers to first compare colony‐level movement behaviour and habitat selection and then investigated individual‐level habitat use. We observed clear colony‐level habitat segregation: urban breeders preferentially foraged in urban areas whereas coastal breeders foraged primarily in coastal habitats and avoided urban areas. Coastal breeders also had larger core and home‐ranges than urban breeders, possibly due to differences in colony size. However, we also found inter‐individual differences in habitat use, which may have important management implications. These findings suggest a link between nesting and foraging ecology, and thus management or environmental change altering food availability will impact gulls at the coastal and urban sites differently.

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Importance of predictable anthropogenic food subsidies for an opportunistic gull inhabiting urban ecosystems

Cited by 16 publications

References 50 publications

Bird Communities in Coastal Areas. Effects of Anthropogenic Influences and Distance From the Coast

Bird Communities in Coastal Areas. Effects of Anthropogenic Influences and Distance From the Coast

Context‐dependent specialisation drives temporal dynamics in intra‐ and inter‐individual variation in foraging behaviour within a generalist bird population

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

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