Interference competition in a threatened seabird community: A paradox for a successful conservation

Oro, Daniel; Pérez‐Rodríguez, Antón; Martı́nez-Vilalta, Albert; Bertolero, Albert; Vidal, Francesc; Genovart, Meritxell

doi:10.1016/j.biocon.2009.03.023

Cited by 51 publications

(57 citation statements)

References 56 publications

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“…We expect this decrease derives from two processes: predation and competition for nesting islets. We assume there will be a strong negative impact of this gull on native species as predation success and competitive abilities are directly linked to body size (Lindstrom 1988;Jonart et al 2007;Oro et al 2009;Schröder et al 2009) and the Caspian gull is much larger than most of the native waterbirds which are potential prey and competitors; (3) Assuming that the large body size of Caspian gull does correspond with its competitive ability, this species will also displace native waterbirds from safe islets located in the center of the reservoir to suboptimal islets located near the shore (i.e., exposed to the predatory activity of native corvids); (4) The increasing population of Caspian gull will lead to increased nest predation on islets visited by this gulls and consequently lower nesting success of native waterbirds at the invaded reservoir as compared with the control one; (5) Over time, the invasion of the Caspian gull will lead to a decline in the population size of small-bodied native predators, namely corvids, as an effect of scramble competition.…”

Section: Introductionmentioning

confidence: 99%

An invasive gull displaces native waterbirds to breeding habitats more exposed to native predators

et al. 2014

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The effect of invasive opportunistic predators may include population changes in both native prey and native predators as well as alteration of predator-prey interactions. We analyzed the activity of native magpie Pica pica and changes in population, nest sites and nesting success probability of native waterbirds (namely: grebes, ducks, rails and native gulls) in response to the population growth of the invasive Caspian gull Larus cachinnans. The study was carried out at a reservoir in southern Poland and at a similar control reservoir where the Caspian gull was absent. Both the invasive gulls and the native magpie are opportunistic predators of nests of native waterbirds. The population increase of the invasive gull led to a decline in the population of native black-headed gulls Larus ridibundus only. However, the invasive gull displaced all the native species from the breeding islets located in the central part of the reservoir to islets located close to the shoreline. The latter were frequently visited by magpies, which depredated on nests along the shores, leading to an up to threefold decrease in nesting success as compared with nests located in the central area of the invaded reservoir. Predation by Caspian gulls was rarely observed. Thus, the invasion of Caspian gull caused complex direct and indirect effects on the waterbird community that included competition for breeding sites, changes in the spatial distribution of nests and alteration of predation rate by native predators. Moreover, the effects of invasion may not be reflected by changes in population size of native species.

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Section: Introductionmentioning

confidence: 99%

An invasive gull displaces native waterbirds to breeding habitats more exposed to native predators

et al. 2014

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“…by white-tailed eagles Haliaeetus albicilla, Hipfner et al 2012), competition with larger gulls (e.g. Oro et al 2009) or interactions with commercial fisheries (e.g. Frederiksen et al 2004).…”

Section: Retrospective Models Of Population Dynamicsmentioning

confidence: 99%

The decline of Norwegian kittiwake populations: modelling the role of ocean warming

Sandvik¹,

Reiertsen²,

Erikstad³

et al. 2014

Clim. Res.

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The black-legged kittiwake Rissa tridactyla is a pelagic seabird whose population has recently declined in most parts of the North Atlantic and which is red-listed in most bordering countries. To investigate a possible cause for this decline, we analysed the population dynamics of 5 kittiwake colonies along the Norwegian coast, ranging from 62° to 71°N, over the last 20 to 35 yr. By quantifying the importance of sea surface temperatures (SST) in relevant areas of the North Atlantic, we tested the importance of climatic conditions throughout the populations' annual cycles. We found no synchrony among colonies; however, SST affected population dynamics, explaining between 6% and 37% (average 18%) of the variation in annual population growth rate. While dynamics of the southerly colonies were mainly affected by winter conditions in the Grand Banks area, dynamics of the northernmost colonies were dominated by autumn conditions off Svalbard. Negative slopes indicated stronger population decline under warmer ocean conditions. Population dynamics were affected both via adult survival and offspring recruitment, as evidenced by the presence of unlagged effects as well as effects lagged by the age at recruitment. Finally, we performed population viability analyses taking into account the projected warming trends for the future. The median time to extinction of the Norwegian colonies was 52 to 181 yr without considering covariates; 45 to 94 yr when considering the effects of SST but ignoring future warming; and 10 to 48 yr when ocean warming, based on a 'business as usual' scenario, was taken into account.

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“…In theory, landscape scale AES would benefit also preys of threatened predators of agro-ecosystems (Delibes-Mateos et al, 2009;Fernandez et al, 2006). Nevertheless, it is known that the same agricultural policy may be favourable for some species of conservation concern but detrimental to others , and complex interactions between species, such as interference competition, may often generate conflicts between conservation actions (Oro et al, 2009). Multi-species problems cannot be solved by local studies and single-species experts.…”

Section: Discussionmentioning

confidence: 99%

Spatial analysis of lanner falcon habitat preferences: Implications for agro-ecosystems management at landscape scale and raptor conservation

Sarà

2014

Biological Conservation

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a b s t r a c tSicily hosts the largest European population of the endangered lanner falcon, a poorly known species which needs conservation planning based on habitat preferences. A distribution model on 10 Â 10 km cells of Sicily was described using Generalized Linear Models and variation partitioning methods. This modelling approach extracted explanatory factors, pure and joint effects of greatest influence from subsets of variables controlled for multi-collinearity and spatial autocorrelation. Analytical cartography used the environmental favourability function to assess habitat preferences, and the insecurity index estimated the degree to which lanner falcon occupancy is represented in the Natura2000 networks of Sicily. The lanner population is not randomly distributed across the geographical space as the significant latitudinal effect revealed. The most parsimonious explanatory model suggested traditional agro-ecosystems (i.e. arable lowlands and grasslands, with rugged terrains and cliffs) as the best predictors of lanner occupancy, and gave strong support to the negative effects of land abandonment and intensification (i.e. increase of heterogeneous areas and shrubby vegetation). The variation partitioning method suggested how an alteration of traditional agro-ecosystems might enhance interference competition with the peregrine falcon and limit lanner falcon occupancy. Most of the lanner falcon favourable habitats fall outside the Natura2000 networks, thus the main challenge for its conservation is represented by agri-environmental measures to be taken within the Common Agricultural Policy of the European Union. Conservation of traditional agro-ecosystems devoted to top-predators, like the lanner falcon, requires single environmental management agreements for multiple farm units, deployed at landscape scale on a network of favourable areas.

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Interference competition in a threatened seabird community: A paradox for a successful conservation

Cited by 51 publications

References 56 publications

An invasive gull displaces native waterbirds to breeding habitats more exposed to native predators

An invasive gull displaces native waterbirds to breeding habitats more exposed to native predators

The decline of Norwegian kittiwake populations: modelling the role of ocean warming

Spatial analysis of lanner falcon habitat preferences: Implications for agro-ecosystems management at landscape scale and raptor conservation

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