Local use of landfills by a yellow‐legged gull population suggests distance‐dependent resource exploitation

Egunez, Alexandra; Zorrozua, Nere; Aldalur, Asier; Herrero, Alfredo; Arizaga, Juan

doi:10.1111/jav.01455

Cited by 21 publications

(17 citation statements)

References 25 publications

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“…), yellow‐legged gulls ( Larus michahellis , Egunez et al. ), and white storks ( Ciconia ciconia , Gilbert et al. ), is increasing in different parts of the world.…”

Section: Discussionmentioning

confidence: 99%

“…After visual exploration of the trajectories, we divided the tracking data into yearly individual trajectories starting on 15 January, to minimize the probability of the starting point falling within a migration (following recommendations in Spitz et al 2017). We used the R packages adehabi-tatLT (Calenge 2006) and rpostgisLT (Dukai et al 2016) for data processing and exploration, respectively. We screened the resulting yearly individual trajectories to assess whether they included sufficient data for model fitting.…”

Section: Data Preparationmentioning

confidence: 99%

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Partial migration in a subtropical wading bird in the southeastern United States

et al. 2020

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The function of migration is to allow exploitation of resources whose availability is heterogeneous in space and time. Much effort has been historically directed to studying migration as a response to seasonal, predictable fluctuations in resource availability in temperate species. A deeper understanding of how different migration patterns emerge in response to different patterns of resource variation requires describing migration patterns of species inhabiting less predictable environments, especially in tropical and subtropical areas. We provide the first individual‐based, quantitative description of migratory patterns in a subtropical wading bird in the southeastern United States, the wood stork (Mycteria americana). Using GPS tracking data for 64 individuals tracked between 2004 and 2017, we classified migratory behavior at the individual‐year level using information theory‐based model selection on nonlinear models of net squared displacement. We found that the wood stork population is partially migratory, with 59% of individuals seasonally commuting between winter ranges in Florida and summer ranges elsewhere in the population range (migrants), and 28% remaining in a single area in Florida year‐round (residents). Additionally, 13% of storks act as facultative migrants, migrating in some years but not in others. Comparing the distribution of residents and migrants suggests that different migratory strategies might be associated with the use of different or differently distributed resources, possibly including food supplementation from human activities. The existence of facultative migrants shows the potential for plastic change in migratory patterns. Partial migration in wood storks may be an adaptation to high heterogeneity and unpredictability of food resources. We suggest that future research should focus on wading birds as model species for the study of partial migration as an adaptation to heterogeneous and unpredictable environments.

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“…), yellow‐legged gulls ( Larus michahellis , Egunez et al. ), and white storks ( Ciconia ciconia , Gilbert et al. ), is increasing in different parts of the world.…”

Section: Discussionmentioning

confidence: 99%

Section: Data Preparationmentioning

confidence: 99%

Partial migration in a subtropical wading bird in the southeastern United States

et al. 2020

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“…Studies based on ring‐recovery data, and more recently from satellite‐tracking devices, have demonstrated that distance to a particular food resource determines the extent to which it will be used by individuals from nearby gull colonies, even at relatively small scales (e.g. tens of kilometres; Egunez et al , ). In other words, even though gulls are efficient flyers and are able to cover long distances to find food (Isaksson et al , ; Kazama et al , ), there is evidence that the use of certain feeding sources can be very local.…”

Section: Introductionmentioning

confidence: 99%

Evaluating the effect of distance to different food subsidies on the trophic ecology of an opportunistic seabird species

et al. 2020

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The availability of food subsidies of anthropogenic origin has strong consequences on the trophic ecology and population dynamics of several opportunistic species. However, evidence suggests that the use of certain feeding sources is very local, and hence, potentially important food subsidies may have a relatively small area of influence, resulting in only limited impact from the large geographic-scale perspective. In the south-eastern part of the Bay of Biscay, the Yellow-legged Gull Larus michahellis population is distributed across several colonies, which are located close to each other but have variable dependence on the landfills and fishing harbours in the area. This population is therefore a good model to test the influence of anthropogenic food subsidies on the trophic ecology of an opportunistic species at the local scale. Distance to the nearest fishing harbour showed a stronger effect on the diet of Yellow-legged Gull chicks than distance to the nearest landfill site. Gulls notably reduced their consumption of marine prey (mostly comprised of fishing discards) in relation to decreasing distance of their colony to the nearest fishing harbour. This result has direct implications from a management standpoint, since fish discards were also found to have only a limited effect on diet at regional scales, but a very high impact at the local scale. Moreover, those colonies that consumed a higher proportion of marine prey showed better population trends. In line with European Union policies, a reduction in the availability of fish discards, together with the closure of landfill sites, will occur in the coming years, probably leading to a change in the trophic ecology and dynamics of Yellow-legged Gull populations.

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“…Many species of gulls take great profit from exploiting feeding sources of human origin all around the world, such as fish discards or refuse tips [1][2][3]. When such resources are abundant and predictable over time, they can have a very deep impact into population parameters like survival [4], breeding performance [5,6], or dispersal [7,8].…”

Section: Introductionmentioning

confidence: 99%

“…The Basque region in northern Iberia is closing all its open-air landfills [8], which hence provides a good chance to account for the effects of this process on the diet and territory use of the local yellow-legged gulls Larus michahellis. The population of this species within the region reached a size of up to ca.…”

Section: Introductionmentioning

confidence: 99%

Between the Land and Sea: How Yellow-Legged Gulls Have Changed Their Dependence on Marine Food in Relation to Landfill Management

Arizaga¹,

Zorrozua²,

Egunez³

2018

Seabirds

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The Basque region (Spain) is closing all its open-air landfills, which hence provides an excellent chance to account for the effects on the trophic and spatial ecology of the local yellow-legged gulls Larus michahellis, which highly depend on refuse tips to forage. The closure of several landfills across the region was mainly compensated by a higher intake of terrestrial food (mainly earthworms), though only in summer. The exploitation of terrestrial prey was marginal in winter, and seasonal trophic differences emerged, unlike findings when landfills were still open. With only one landfill now open in theory, movement and territory use analyses showed that two landfills were frequently visited. Positions at two of the target foraging habitats (landfills, pastures) summed ca. 10% of all stationary positions suggesting that, at least in these habitats, gulls seemed to invest a relatively small amount of time, which might support the idea that they were able to obtain food in a fast way and, probably, from resources that they know well and have a predictable temporal distribution.

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Local use of landfills by a yellow‐legged gull population suggests distance‐dependent resource exploitation

Cited by 21 publications

References 25 publications

Partial migration in a subtropical wading bird in the southeastern United States

Partial migration in a subtropical wading bird in the southeastern United States

Evaluating the effect of distance to different food subsidies on the trophic ecology of an opportunistic seabird species

Between the Land and Sea: How Yellow-Legged Gulls Have Changed Their Dependence on Marine Food in Relation to Landfill Management

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