Diet Choice in the Herring Gull: Constraints Imposed by Reproductive and Ecological Factors

Pierotti, Raymond; Annett, Cynthia A.

doi:10.2307/1938925

Cited by 204 publications

(133 citation statements)

References 29 publications

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“…2). Similar switching in foraging behavior between anthropogenic and natural resources due to changes in natural food availability were reported for other taxa and bears in other systems; for example, herring gulls (Larus agrentatus) switched from foraging on mussels to foraging on garbage during severe weather years when natural prey was scarce (Pierotti and Annett 1991), and black bears in Minnesota supplemented their diets during poor natural food production years by feeding in garbage dumps (Rogers 1987). However, patterns differed for urban black bears in the Lake Tahoe region where bears continued to forage on anthropogenic resources regardless of natural food availability (Beckmann and Berger 2003b).…”

Section: Discussionmentioning

confidence: 64%

Foraging ecology of black bears in urban environments: guidance for human‐bear conflict mitigation

et al. 2015

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Abstract. Urban environments offer wildlife novel anthropogenic resources that vary spatiotemporally at fine scales. Property damage, economic losses, human injury, or other human-wildlife conflicts can occur when wildlife use these resources; however, few studies have examined urban wildlife resource selection at fine scales to guide conflict mitigation. We studied black bears (Ursus americanus) in the urban area of Aspen, Colorado, USA from 2007 to 2010 to quantify bear foraging on natural and anthropogenic resources and to model factors associated with anthropogenic feeding events. We collected fine-scale spatiotemporal data by tracking GPS-collared bears at 30-min intervals and backtracked to bear locations within 24 hours of use. We used discrete choice models to assess bears' resource selection, modeling anthropogenic feeding (use) and five associated random (availability) locations as a function of attributes related to temporally changing natural (e.g., ripe mast) and human (e.g., garbage) food resources, urban characteristics (e.g., housing density), and land cover characteristics (e.g., distance to riparian area). We backtracked to 2,675 locations used by 24 bears and classified 20% as foraging locations. We found that bears foraged on both natural and anthropogenic food sources in the urban environment, with 77% of feeding events being anthropogenic. We documented inter-and intra-annual foraging patterns in which bears foraged extensively in urban areas when natural food production was poor, then switched to natural food sources when available. These patterns suggest that bears balance energy budgets and individual safety when making foraging decisions. Overwhelmingly, garbage was the main anthropogenic food source that bears used. Selection of foraging sites was not only influenced by presence of garbage but also by proximity to riparian habitat and presence of ripe anthropogenic fruit trees. We found that while 76% of the garbage containers at random locations were bear-resistant, 57% of these bear-resistant containers were not properly secured. We recommend conflict mitigation focus on reducing available garbage and anthropogenic fruit trees, particularly near riparian areas, to make urban environments less energetically beneficial for foraging. Additionally, deploying bear-resistant containers is inadequate without education and proactive enforcement to change human behavior to properly secure garbage and ultimately reduce human-bear conflict.

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Section: Discussionmentioning

confidence: 64%

Foraging ecology of black bears in urban environments: guidance for human‐bear conflict mitigation

et al. 2015

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“…Logger data for herring gulls breeding on, for example, Oland showed a high proportion of mixed foraging trips, suggesting that individuals from this colony might be forced to forage on the mainland after the razor clam beds become inundated by the tide. Herring gulls are flexible and opportunistic predators that can adapt their diet to the habitat (Pierotti & Annett, 1991; Schwemmer & Garthe, 2008; Sibly & McCleery, 1983) and might act as an indicator for changes in prey availability (Courtens, Verstraete, Vanermen, Van de Walle, & Stienen, 2017) close to their breeding colony during incubation.…”

Section: Discussionmentioning

confidence: 99%

“…Former studies of foraging behavior and food composition in herring gulls were mainly based on visual observations and pellet analysis (e.g., Kim & Monaghan, 2006; Kubetzki & Garthe, 2003; Pierotti & Annett, 1991; Steenweg, Ronconi, & Leonard, 2011), but GPS data loggers and stable isotope analysis now allow the collection of information on individual movement patterns and foraging behaviors (e.g., Shamoun‐Baranes, Bouten, Camphuysen, & Baaij, 2011; Votier et al., 2010; Wilson et al., 2002). Within‐colony variation in individual movement patterns was recently demonstrated for roof‐nesting herring gulls, based on GPS data (Rock et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Intercolony variations in movement patterns and foraging behaviors among herring gulls (Larus argentatus) breeding in the eastern Wadden Sea

Enners¹,

Schwemmer²,

Corman³

et al. 2018

Ecology and Evolution

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Herring gulls (Larus argentatus) are opportunistic predators that prefer to forage in the intertidal zone, but an increasing degree of terrestrial foraging has recently been observed. We therefore aimed to analyze the factors influencing foraging behavior and diet composition in the German Wadden Sea. Gulls from three breeding colonies on islands at different distances from the mainland were equipped with GPS data loggers during the incubation seasons in 2012–2015. Logger data were analyzed for 37 individuals, including 1,115 foraging trips. Herring gulls breeding on the island furthest from the mainland had shorter trips (mean total distance = 12.3 km; mean maximum distance = 4.2 km) and preferred to feed on the tidal flats close to the colony, mainly feeding on common cockles (Cerastoderma edule) and shore crabs (Carcinus maenas). In contrast, herring gulls breeding close to the mainland carried out trips with a mean total distance of 26.7 km (mean maximum distance = 9.2 km). These gulls fed on the neobiotic razor clams (Ensis leei) in the intertidal zone, and a larger proportion of time was spent in distant terrestrial habitats on the mainland, feeding on earthworms. δ 13C and δ 15N values were higher at the colony furthest from the mainland and confirmed a geographical gradient in foraging strategy. Analyses of logger data, pellets, and stable isotopes revealed that herring gulls preferred to forage in intertidal habitats close to the breeding colony, but shifted to terrestrial habitats on the mainland as the tide rose and during the daytime. Reduced prey availability in the vicinity of the breeding colony might force herring gulls to switch to feed on razor clams in the intertidal zone or to use distant terrestrial habitats. Herring gulls may thus act as an indicator for the state of the intertidal system close to their breeding colony.

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“…Calcium plays a major role in gull nutrition; it is an important component of eggshells and is necessary for bone development of chicks (e.g. Pierotti & Annett 1990, 1991. Liocarcinus spp.…”

Section: Discussionmentioning

confidence: 99%

At-sea distribution and behaviour of a surface-feeding seabird, the lesser black-backed gull Larus fuscus, and its association with different prey

Schwemmer¹,

Garthe²

2005

Mar. Ecol. Prog. Ser.

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The lesser black-backed gull Larus fuscus is a typical surface-feeding seabird with a widespread, patchy distribution in the SE North Sea. During the 1990s, breeding numbers along the German North Sea coast increased exponentially. Analyses of a multiple-year data set revealed changes in the at-sea distribution that seemed to reflect an increase in the numbers of breeding birds. Detailed recordings of feeding and resting behaviour at sea revealed area utilisation by the lesser black-backed gull. Observations at sea and dietary analysis revealed that swimming crabs Liocarcinus spp. are a major dietary item of this gull species. This natural food source was primarily captured close to the shore; at longer distances from the coast the gulls mainly fed on other natural prey items or discarded fishes from trawlers and avoided competition with other breeding gull species. During July and August 1990 to 1995 L. fuscus abundance was significantly correlated with fishing effort, while in May and June there was no such correlation. Time of day was the main environmental variable influencing the gulls' flight activity and indicated an association between activity and availability of their major natural prey, swimming crabs. Distinct patterns and changes in the at-sea distribution and foraging behaviour of L. fuscus in the SE North Sea reflect anthropogenic and natural influences in their habitats.

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Diet Choice in the Herring Gull: Constraints Imposed by Reproductive and Ecological Factors

Cited by 204 publications

References 29 publications

Foraging ecology of black bears in urban environments: guidance for human‐bear conflict mitigation

Foraging ecology of black bears in urban environments: guidance for human‐bear conflict mitigation

Intercolony variations in movement patterns and foraging behaviors among herring gulls (Larus argentatus) breeding in the eastern Wadden Sea

At-sea distribution and behaviour of a surface-feeding seabird, the lesser black-backed gull Larus fuscus, and its association with different prey

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