Can an introduced predator trigger an evolutionary trap in a colonial seabird?

Igual, José Manuel; Forero, Manuela G.; Gómez, Tomás; Oro, Daniel

doi:10.1016/j.biocon.2007.02.003

Cited by 49 publications

(38 citation statements)

References 56 publications

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“…The large uncertainty in our abundance estimates is a consequence of error propagation across two different model predictions -the predicted nest density based on recorded calling rate, and the predicted overall abundance extrapolated from the predicted nest density per habitat type. Additional uncertainty may arise because nest density may vary due to social attraction and the presence of invasive predators in addition to suitable habitat (Igual et al 2007;Major and Jones 2011). While more intensive calibration work with more recorder locations across an exhaustive habitat gradient and more precise habitat mapping might lead to tighter relationships between recorded calling rate and nest density, and between predicted nest density and habitat features, such intensive work is likely not realistic for the majority of remote islands for which population assessments of nocturnal burrow-nesting seabirds are required.…”

Section: Discussionmentioning

confidence: 99%

Estimating population size of a nocturnal burrow-nesting seabird using acoustic monitoring and habitat mapping

Oppel¹,

Hervías²,

Oliveira³

et al. 2014

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Estimating population size of a nocturnal burrow-nesting seabird using acoustic monitoring and habitat mapping. Nature Conservation 7: 1-13. doi: 10.3897/natureconservation.7.6890 Abstract Population size assessments for nocturnal burrow-nesting seabirds are logistically challenging because these species are active in colonies only during darkness and often nest on remote islands where manual inspections of breeding burrows are not feasible. Many seabird species are highly vocal, and recent technological innovations now make it possible to record and quantify vocal activity in seabird colonies. Here we test the hypothesis that remotely recorded vocal activity in Cory's shearwater (Calonectris borealis) breeding colonies in the North Atlantic increases with nest density, and combined this relationship with cliff habitat mapping to estimate the population size of Cory's shearwaters on the island of Corvo (Azores). We deployed acoustic recording devices in 9 Cory's shearwater colonies of known size to establish a relationship between vocal activity and local nest density (slope = 1.07, R 2 = 0.86, p < 0.001). We used this relationship to predict the nest density in various cliff habitat types and produced a habitat map of breeding cliffs to extrapolate nest density around the island of Corvo. The mean predicted nest density on Corvo ranged from 6.6 (2.1-16.2) to 27.8 (19.5-36.4) nests/ha. Extrapolation of habitat-specific nest densities across the cliff area of Corvo resulted in an estimate of 6326 Cory's shearwater nests (95% confidence interval: 524). This population size estimate is similar to previous assessments, but is too imprecise to detect moderate changes in population size over time. While estimating absolute population size from acoustic recordings may not be sufficiently precise, the strong positive relationship that we found between local nest density and recorded calling rate indicates that passive acoustic monitoring may be useful to document relative changes in seabird populations over time. RESEARCH ARTICLE Launched to accelerate biodiversity conservation A peer-reviewed open-access journalSteffen Oppel et al. / Nature Conservation 7: 1-13 (2014) 2

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Section: Discussionmentioning

confidence: 99%

Estimating population size of a nocturnal burrow-nesting seabird using acoustic monitoring and habitat mapping

Oppel¹,

Hervías²,

Oliveira³

et al. 2014

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“…In reverse, there may well be situations where prey have well developed riskreduction behaviours to indigenous predators, that actually result in increased lethal effects for an introduced predator, because they are inappropriate for that predator that may have a particularly novel hunting behaviour, or habitat specialisation (e.g. Igual et al 2007). …”

Section: Evolutionary or Cultural Lag And Constraints On Non-lethal Cmentioning

confidence: 99%

Predation in bird populations

Cresswell

2010

J Ornithol

253

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One of the classic ecological questions is how predators affect population size. This is often assessed by measuring how many individuals are killed by a predator, yet such direct effects may only be a relatively minor part of population dynamics. Predators frequently affect prey populations indirectly, with the fear of predation resulting in costly behavioural compensation leading to potentially large population and community effects. Large observable lethal effects may then just represent the most easily observed "special" cases of the effects of predation on populations, with the costs of non-lethal effects being ubiquitous and usually dominant. This review explores these two ideas: that cases where there are no population effects due to predation, and cases where lethal effects dominate, are unusual and involve special circumstances. First, systems where predation effects appear not to arise include complete avoidance of predators by prey; when other environmental factors limit populations so that predation is not additive to mortality; when there are other more vulnerable prey for a predator; when predators interact; because the relationship of perceived predation risk with predator abundance is usually a non-linear function, and simply because non-lethal effects have not been considered. Second, lethal effects tend to dominate over non-lethal effects when there is a high cost of compensating for predation risk associated with either resource constraint or a particularly vulnerable niche or life history stage (e.g. the nest stage generally for birds); when prey are the most popular prey of a predator or linear trophic chains operate; when there is evolutionary lag such as introduced predators and naïve prey populations; and when there are several predator species hunting the same prey in diverse ways. The presence of predators may or may not affect the size of a bird population at any particular life history stage, although in most cases it will through non-lethal effects and occasionally through lethal effects.But the presence of predators will always affect intra-and interspecific competition and so will always affect population dynamics. Studies that wish to fully demonstrate that predation has no effect on bird populations must show that lethal effects and the costs of non-lethal compensation by the prey do not significantly change its density and so the level of competition.3

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“…Therefore, plasticity may be not enough to adapt to climate change given these additional factors for which many seabird species were not previously exposed and selected for. For instance, Igual et al (2007) showed that Cory's shearwaters, due to their limited behavioral plasticity and heavy evolutionary loads, did not perceive the presence of invasive predators signaling differences in predation risk and in turn of breeding success.…”

Section: Predicting the Future Impacts Of Climate On Seabirdsmentioning

confidence: 99%

Seabirds and climate: knowledge, pitfalls, and opportunities

Oró

2014

Front. Ecol. Evol.

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As a physical driver of ecosystem functioning, it is not surprising that climate influences seabird demography and population dynamics, generally by affecting food availability. However, if we zoom in ecologically, seabirds are in fact very heterogeneous, ranging in size from very small to very large species (with a difference of more than two orders of magnitude in body weight), from planktivorous forms to predators of large fish and squid, from benthic to pelagic, from species with small foraging ranges to species feeding throughout the whole circumpolar region, and from resident species (at a spatial mesoscale) to trans-equatorial migrating seabirds that travel large distances across several oceanographic systems. Due to this high variability and the difficulty in obtaining direct reliable estimates of long-term food availability, global climatic indices have been extensively used in studying seabird demography and population dynamics. However, the use made by researchers of these indices has certain conceptual and methodological pitfalls, which I shall address in this review. Other factors, such as anthropogenic impacts (including oil-spills and interaction with fisheries), may further alter or confound the association between climate and seabird demography. These pitfalls and environmental noise, together with the inability to incorporate resilience, may bias our predictions regarding the future impact of global warming on seabirds, many of which have vulnerable populations.Keywords: predictive models, resilience, methodological bias, evolution, global change, climate, seabirds HISTORICAL BACKGROUNDA search performed in June 2014 using the words "climate & seabird" in the ISI Web of Science resulted in 946 items. Even though some of those items dealt with other marine organisms or were focused on some related issues (such as oceanographic processes), that result represents a large number of scientific contributions on the topic of how climate may influence seabird ecology. The influence of climate on marine organisms has been extensively studied in seabirds because, compared to most other species (except some marine mammals such as seals and sealions), their demography and population dynamics can be easily monitored in breeding colonies.Up to the 90s, the changes in demographic parameters and population size in seabirds were explored mostly in relation to intrinsic features of the colonies such as their size or the presence of predators (Hunt et al., 1986). The effects of climate (mostly in the form of oceanographic indices) on seabird ecology were seldom analyzed in those years (Myres, 1979), and research efforts were addressed mostly to determining the distribution of seabirds at sea (Abrams, 1985). The influence of oceanographic features was outlined especially when extreme and anomalous events occurred (such as cyclones or El Niño-Southern Oscillation (ENSO) years (e.g., Blomqvist and Peterz, 1984;Graybill and Hodder, 1985), whereas some pioneering studies dealt with the relationship between climatic ev...

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Can an introduced predator trigger an evolutionary trap in a colonial seabird?

Cited by 49 publications

References 56 publications

Estimating population size of a nocturnal burrow-nesting seabird using acoustic monitoring and habitat mapping

Estimating population size of a nocturnal burrow-nesting seabird using acoustic monitoring and habitat mapping

Predation in bird populations

Seabirds and climate: knowledge, pitfalls, and opportunities

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