The case for lethal control of gulls on seabird colonies

Scopel, Lauren C.; Diamond, Antony W.

doi:10.1002/jwmg.21233

Cited by 21 publications

(18 citation statements)

References 48 publications

(98 reference statements)

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“…Although removing specialist gulls is strongly advocated as a cost-effective management strategy [ 16 , 17 ], opportunistic predation by large gulls cannot be effectively managed using the same techniques. This is because removed individuals would be quickly replaced by conspecifics that require no specialized behavior.…”

Section: Discussionmentioning

confidence: 99%

“…Incorrect classification of specialists has important empirical repercussions because lethal control of large gulls is strongly advocated to control specialist individuals that predate conservation-important bird species [ 16 , 17 ]. Behavioral metrics that could be used concurrently to improve identification of predatory bird-specialists include: predation outside of a bird’s own breeding territory [ 18 , 19 ], use of specialized hunting behaviors [ 12 , 20 , 21 ], and elongation of breeding territories into feeding territories [ 12 , 22 ] or defense of separate feeding territories [ 10 , 14 , 15 ].…”

Section: Introductionmentioning

confidence: 99%

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Opportunistic predation of birds by breeding Herring Gulls (Larus argentatus)

et al. 2020

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Dietary specialization, exploiting a small fraction of available food resources, is commonly reported for gulls and skuas. Predation of birds by these species is usually considered a specialist strategy employed by the minority of the population but non-specialists also predate birds and may actually have a greater impact on the prey species. To date, most studies have focused on predatory bird-specialists, down-playing the possible importance of opportunistic predation by non-specialists. We addressed this by studying diet (regurgitated pellets and prey remains) and behavior of breeding Herring Gulls ( Larus argentatus ) over three summers at Gull Island, a mixed-species breeding colony in Lake Ontario. One-third of all pellets analyzed contained bird remains, primarily the most numerous breeding bird: Ring-billed Gull ( L . delawarensis ) chicks (51%) and adults (36%). Although all but one pair of Herring Gulls ate birds, all pairs maintained broad and mostly similar diets, with birds accounting for at most one-third of prey. Behavior also indicated that Herring Gulls at Gull Island were not predatory bird-specialists because predation was too infrequent to meet energetic requirements, was largely unsuccessful and was only ever observed when Ring-billed Gulls strayed into Herring Gull breeding territories. Instead, bird predation appeared mainly opportunistic, increasing with seasonal availability, access to shoreline, proximity to nesting Ring-billed Gulls and breeding territory size. Compared with predatory specialist Herring Gulls in the same region, individuals that predated birds at Gull Island did not display specialist behaviors and killed six times fewer birds (0.1–0.4 per day, on average) but were over 20 times more numerous (98% of the population versus 4%). Thus, our results indicate that opportunistic predation by non-specialists may have important consequences for prey species. Since opportunistic predation cannot be effectively managed using techniques widely advocated for specialist predators, it is essential to investigate cause of predation by large gulls prior to lethal management.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Opportunistic predation of birds by breeding Herring Gulls (Larus argentatus)

et al. 2020

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“…A full summary of the time series for all species at all colonies is included in Table S1 (Scopel and Diamond 2017), and diet estimates for common terns were derived from video observations in 2016.…”

Section: Seabird Study Area and Diet Data Collectionmentioning

confidence: 99%

“…Georges Bank juveniles are generally expected to remain on Georges Bank or travel "inshore" (Boyar et al 1973;Anthony and Waring 1980;Reid et al 1999;Overholtz et al 2004), rather than spending time in the Bay of Fundy around MSI, and such behaviour has been suggested by others (Iles 1971;Waring 1980 in Tupper et al 1998). The absence of acoustic data after 2012 and the collapse of the MSI tern colony in 2006 make future links between these data sets currently impossible, but the tern colony has now been restored (Scopel and Diamond 2017), and this link could be explored further if acoustic sampling were resumed.…”

Section: Connectivity Between Spawning Components and Juvenile Habitatmentioning

confidence: 99%

Seabird diets as bioindicators of Atlantic herring recruitment and stock size: a new tool for ecosystem-based fisheries management

Scopel

Diamond

Kress

et al. 2018

Can. J. Fish. Aquat. Sci.

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Ecosystem-based fishery management requires understanding of relationships between exploited fish and their predators, such as seabirds. We used exploratory regression analyses to model relationships between Atlantic herring (Clupea harengus) in the diet of seabird chicks at nine nesting colonies in the Gulf of Maine and four types of fishery-and survey-derived herring data. We found several strong relationships, which suggests spatial structuring in herring stocks and likely patterns of herring movements before they recruit into the fishery. Some types of herring data seldom used in stock assessments -notably acoustic surveys, fixed-gear landings, and mass-at-age (i.e., weight-at-age) -correlated as strongly with seabird data as more commonly used series, such as mobile-gear landings and modeled spawning stock biomass. Seabird chick diets collected at specific locations thus offer a promising means to assess the size, distribution, and abundance of juvenile herring across a broad area prior to recruitment, which is a major source of uncertainty in fisheries. Common terns (Sterna hirundo) showed the most potential as a bioindicator, correlating well and showing consistent spatial patterns with 11 of 13 fishery data series.Résumé : La gestion écosystémique des pêches nécessite une compréhension des liens entre les poissons exploités et leurs prédateurs, tels que les oiseaux marins. Nous avons utilisé des analyses de régression exploratoires pour modéliser les relations entre le hareng de l'Atlantique (Clupea harengus) dans l'alimentation de jeunes oiseaux de mer dans neuf colonies de nidification dans le golfe du Maine, et quatre types de données sur les harengs issues de la pêche et de campagnes d'évaluation. Nous avons relevé plusieurs relations marquées qui indiqueraient la présence d'une structure spatiale dans les stocks de harengs et de probables motifs de déplacement des harengs avant leur recrutement dans la pêche. Certains types de données sur les harengs rarement utilisés dans les évaluations des stocks, dont des données de relevés acoustiques, de débarquements de navires à engins fixes et de poids selon l'âge, présentent une corrélation tout aussi forte avec les données sur les oiseaux de mer que des séries plus couramment utilisées, comme les débarquements de navires à engins mobiles et la biomasse modélisée du stock reproducteur. Les régimes alimentaires des jeunes oiseaux de mer prélevés en des sites précis constituent donc une approche prometteuse pour évaluer la taille, la répartition et l'abondance des harengs juvéniles avant leur recrutement à l'échelle d'une grande région, des facteurs qui constituent une importante source d'incertitude dans les pêches. Les sternes pierregarins (Sterna hirundo) montrent le meilleur potentiel comme bioindicateur, puisqu'elles présentent une bonne corrélation et des motifs spatiaux concordants avec 11 des 13 séries de données issues de la pêche. [Traduit par la Rédaction]

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“…() found some success with monofilament lines, which prevent gulls from landing and nesting, but others have found this method to be largely ineffective (Morris et al ,. Scopel & Diamond ).…”

mentioning

confidence: 99%

An evaluation of canes as a management technique to reduce predation by gulls of ground‐nesting seabirds

Boothby

Redfern

Schroeder

2019

Ibis

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The best documented method to decrease predation of breeding seabirds by gulls are culling regimes; however, studies on the effectiveness of this method show ambiguous results. Here we tested an alternative method, using bamboo canes erected in four breeding sites of Arctic Tern Sterna paradisaea as a gull‐deterrent. Although we found fewer predation attempts in the caned areas than in the control areas, canes did not reduce the probability of predation success per attempt. This pilot study documents that the use of canes as a conservation strategy to reduce gull predation is promising, economic and simple, and is thus probably a versatile tool for conservation managers.

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The case for lethal control of gulls on seabird colonies

Cited by 21 publications

References 48 publications

Opportunistic predation of birds by breeding Herring Gulls (Larus argentatus)

Opportunistic predation of birds by breeding Herring Gulls (Larus argentatus)

Seabird diets as bioindicators of Atlantic herring recruitment and stock size: a new tool for ecosystem-based fisheries management

An evaluation of canes as a management technique to reduce predation by gulls of ground‐nesting seabirds

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