Sex-specific foraging behaviour in northern gannets Morus bassanus: incidence and implications

Stauss, C.; Bearhop, Stuart; Bodey, Thomas W.; Garthe, Stefan; Gunn, Carolyn; Grecian, W. James; Inger, Richard; Knight, Mairi E.; Newton, Jason; Patrick, Samantha C.; Phillips, Richard A.; Waggitt, James J.; Votier, Stephen C.

doi:10.3354/meps09734

Cited by 79 publications

(90 citation statements)

References 63 publications

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“…Sex is also known to influence Gannet foraging behaviour (Lewis et al 2001;Ismar et al 2010;Mullers and Navarro 2010;Stauss et al 2012). Again, subject to the caveat of small sample sizes, we detected no statistical sex differences in foraging trip parameters and in the use of particular foraging areas.…”

Section: Discussionmentioning

confidence: 40%

Foraging behaviour and habitat use of chick-rearing Australasian Gannets in New Zealand

et al. 2014

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Patchily distributed marine pelagic prey present considerable challenges to predatory seabirds, including Gannets (Morus spp.) departing from large breeding colonies. Here, for the first time, we used GPS data loggers to provide detailed spatial, temporal, and habitat metrics of chick-rearing Australasian Gannets (Morus serrator) foraging behaviours from two distant colonies in New Zealand. Our goal was to examine the extent to which Gannet foraging tactics vary across disparate habitats, and determine whether the observed differences are consistent with predictions derived from foraging studies of other gannet species. Foraging trip performance was highly consistent between colonies, and sexes, and no significant differences in any of the variables analyzed were observed. However, Gannets from Farewell Spit (FS) dove in shallower waters (0 50 m) than birds from Cape Kidnappers (CK, [50 m), which is consistent with previous dietary studies suggesting that FS Gannets feed mainly on coastal prey, whereas CK birds feed on species with a more oceanic distribution. Diving frequencies were similar in the two colonies suggesting that Gannets were foraging in habitats with similar levels of food availability. Further studies are needed to understand the relationship between prey availability, oceanography and geographic features, to better interpret foraging tactics of Australasian Gannets.Keywords Foraging range Á Diving behaviour Á Morus serrator Á Food sources Á GPS data loggers Á Seabirds Communicated by C. Barbraud. G. E. Machovsky Capuska (&)Á

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Section: Discussionmentioning

confidence: 40%

Foraging behaviour and habitat use of chick-rearing Australasian Gannets in New Zealand

et al. 2014

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“…Therefore, we report only results for KD h=9.1, as this is similar to values commonly used in the analysis of gannet spatial data (Stauss et al 2012, Waggitt et al 2014) and directly comparable with the time-in-area approach. Results for KD ad hoc are included in Table S2 The mean bootstrapped proportion of all for aging events occurring in the core foraging area at 25, 50 and 75% probability of use was larger when designated using KD analysis than with the time-in-area approach (Table 2).…”

Section: Proportion Of Foraging Events In Core Foraging Areamentioning

confidence: 94%

“…, whereby σ 2 = 0.5(var x + var y), where x and y are 2-dimensional coordinates, and (2) KD h = 9.1 , where h = 9.1 km, based on the mean scale of area restricted search (ARS) behaviour in gannets of 9.1 km (Hamer et al 2009); a similar value to that used in previous studies where h = 10, also based on the mean scale of ARS behaviour identified by Hamer et al 2009(Stauss et al 2012. The Least Squared Cross Validation (LSCV) method was test ed, but deemed inappropriate for this data as the algorithms failed to converge and thus failed to identify the optimal smoothing parameter.…”

Section: Behaviour Analysismentioning

confidence: 99%

Time-in-area represents foraging activity in a wide-ranging pelagic forager

Warwick-Evans¹,

Atkinson²,

Gauvain³

et al. 2015

Mar. Ecol. Prog. Ser.

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Successful Marine Spatial Planning depends upon the identification of areas with high importance for particular species, ecosystems or processes. For seabirds, advancements in biologging devices have enabled us to identify these areas through the detailed study of at-sea behaviour. However, in many cases, only positional data are available and the presence of local biological productivity and hence seabird foraging behaviour is inferred from these data alone, under the untested assumption that foraging activity is more likely to occur in areas where seabirds spend more time. We fitted GPS devices and accelerometers to northern gannets Morus bassanus and categorised the behaviour of individuals outside the breeding colony as plunge diving, surface foraging, floating and flying. We then used the locations of foraging events to test the efficiency of 2 approaches: time-in-area and kernel density (KD) analyses, which are widely employed to detect highly-used areas and interpret foraging behaviour from positional data. For KD analyses, the smoothing parameter (h) was calculated using the ad hoc method (KD ad hoc ), and KD h=9.1 , where h = 9.1 km, to designate core foraging areas from location data. A high proportion of foraging events occurred in core foraging areas designated using KD ad hoc , KD h=9.1 , and time-inarea. Our findings demonstrate that foraging activity occurs in areas where seabirds spend more time, and that both KD analysis and the time-in-area approach are equally efficient methods for this type of analysis. However, the time-in-area approach is advantageous in its simplicity, and in its ability to provide the shapes commonly used in planning. Therefore, the time-in-area approach can be used as a simple way of using seabirds to identify ecologically important locations from both tracking and survey data.

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“…Indeed, there are multiple biological reasons to distinguish between phenotypic variation that is sex-or age-related and individual-level specialisation (Bolnick et al 2002). In marine predators, sex differences may arise from the influence of size dimorphism on sex-specific parental roles, intersexual competition, foraging and locomotory efficiency (including diving capability), or habitat specialisation (González-Solís et al 2000, Shaffer et al 2001, Phil lips et al 2004a, Breed et al 2006, Staniland & Robinson 2008, Quillfeldt et al 2011, Stauss et al 2012; these mechanisms are potentially, but not necessarily, different from those generating individual specialisation. Similarly, differences in behaviour are often associated with variation in foraging abilities (i.e.…”

Section: Introductionmentioning

confidence: 99%

Methods for detecting and quantifying individual specialisation in movement and foraging strategies of marine predators

Carneiro¹,

Bonnet‐Lebrun²,

Manica³

et al. 2017

Mar. Ecol. Prog. Ser.

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There is increasing realisation that individuals in many animal populations differ substantially in resource, space or habitat use. Differences that cannot be attributed to any a priori way of classifying individuals (i.e. age, sex and other group effects) are often termed 'individual specialisation'. The aim of this paper is to assess the most common approaches for detecting and quantifying individual specialisation and consistencies in foraging behaviour, movement patterns and diet of marine predators using 3 types of data: conventional diet data, stable isotope ratios and tracking data. Methods using conventional diet data rely on a comparison between the proportions of each dietary source in the total diet and in the diet of individuals, or analyses of the statistical distribution of a prey metric (e.g. size); the latter often involves comparing ratios of individual and population variance. Approaches frequently used to analyse stable isotope or tracking data reduced to 1 dimension (trip characteristics, e.g. maximum trip distance or latitude/longitude at certain landmarks) include correlation tests and repeatability analysis. Finally, various spatial analyses are applied to other types of tracking data (e.g. distances between centroids of distributions or migratory routes, or overlap between distributions), and methods exist to compare habitat use. We discuss the advantages and disadvantages of these approaches, issues arising from other effects unrelated to individual specialisation per se (in particular those related to temporal scale) and potential solutions.

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Sex-specific foraging behaviour in northern gannets Morus bassanus: incidence and implications

Cited by 79 publications

References 63 publications

Foraging behaviour and habitat use of chick-rearing Australasian Gannets in New Zealand

Foraging behaviour and habitat use of chick-rearing Australasian Gannets in New Zealand

Time-in-area represents foraging activity in a wide-ranging pelagic forager

Methods for detecting and quantifying individual specialisation in movement and foraging strategies of marine predators

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