Long-term individual foraging site fidelitywhy some gannets don't change their spots. Ecology, 96(11), There may be differences between this version and the published version. You are advised to consult the publisher's version if you wish to cite from it.http://eprints.gla.ac.uk/113930/ shown that individual foraging site fidelity (IFSF -when individuals consistently forage in only a 19 small part of their population's home range) occurs in some colonial breeders. Short-term IFSF 20 could result from animals using a win-stay, lose-shift (WSLS) foraging strategy. Alternatively, it 21 may be a consequence of other forms of individual specialisation. Pelagic seabirds are colonial 22 central-place foragers, classically assumed to use flexible foraging strategies to target widely 23 2 dispersed, spatiotemporally patchy prey. However, tracking has shown that IFSF occurs in many 24 seabirds, although it is not known whether this persists across years. To test for long-term IFSF 25 and to examine alternative hypotheses concerning its cause, we repeatedly tracked 55 northern 26 gannets from a large colony in the North Sea within and across three successive breeding 27 seasons. Gannets foraged in neritic waters, predictably structured by tidal mixing and thermal 28 stratification but subject to stochastic wind-induced overturning. Both within and across years, 29 coarse to mesoscale (10s km) IFSF was significant but not absolute and foraging birds departed 30 the colony in individually consistent directions. Carbon stable isotope ratios in gannet blood 31 tissues were repeatable within years and nitrogen ratios were also repeatable across years, 32 suggesting long-term individual dietary specialisation. Individuals were also consistent across 33 years in habitat use with respect to relative sea surface temperature and in some dive metrics yet 34 none of these factors accounted for IFSF. Moreover, at the scale of weeks, IFSF did not decay 35 over time and the magnitude of IFSF across years was similar to that within years, suggesting 36 that IFSF is not primarily the result of WSLS foraging. Rather, we hypothesise that site 37 familiarity, accrued early in life, causes IFSF by canalising subsequent foraging decisions. 38Evidence from this and other studies suggests that IFSF may be common in colonial central-39 place foragers, with far-reaching consequences for our attempts to understand and conserve these 40 animals in a rapidly changing environment. 41 42

The use of biologging devices continues to increase with technological advances yielding remarkable ecological insights and generating new research questions. However, as devices develop and are deployed more widely, there is a need to update our knowledge of the potential ethical impacts to allow scientists to balance these against the knowledge gained. We employed a suite of phylogenetically controlled meta‐analyses on a dataset comprising more than 450 published effect sizes across 214 different studies to examine the effects of biologger tagging on five key traits in birds. Overall, we found small but significant negative effects of tagging on survival, reproduction, parental care. In addition, tagging was positively associated with foraging trip duration, but had no effect on body mass. Meta‐regressions revealed that flying style, migration distance and proportional tag mass were significant influences producing these deleterious effects, with attachment type and position additionally important covariates influencing survival‐ and reproduction‐based effect sizes. There was a positive correlation between the effects of tagging on survival and reproduction, highlighting that effects may be cumulative, with the full effects of tagging not necessarily apparent in studies focused on single traits. We discuss the tradeoff between these negative effects and the advances gained through the use of biologgers. Finally, given the number of studies from our initial literature search that lacked sufficient data for inclusion in analyses, we provide recommendations on the essential information that all biologging studies should report in order to facilitate future assessments of impacts on animals.

Summary1. Many aspects of animal behaviour differ consistently between individuals, giving rise to the growing field of animal personality research. While between-individual variation has long been of interest to biologists, the role of within-individual variation has received less attention. Indeed, many models assume that the extent of withinindividual variation is the same across individuals despite the fact that individuals may often differ in their variability. 2. Recently, the importance of within-individual variability or predictability has been recognized within the field of animal behaviour. However, there is a lack of a consensus on how best to quantify it. This situation, in turn, has led to the development of a variety of different methods aimed at assessing how variable or predictable different individuals are. 3. Here, we review the indices that have been proposed as proxies of individual predictability. We then introduce existing techniques called hierarchical generalized linear models (HGLMs) and double-hierarchical generalized linear models (DHGLMs) as general tools for quantifying predictability. HGLMs and DHGLMs are extensions of random intercept mixed models that exploit the fact that variation in variances as well as variation in means can be modelled within a single overarching framework. 4. Explicit modelling of the within-individual residual variation by (D)HGLMs makes more efficient use of the data, performs better on unbalanced data sets and captures more of the uncertainty involved in modelling within-individual variation than other proposed indices. In addition, (D)HGLMs yield an estimator of population-wide variation in predictability, which can serve as a standardized effect size for comparisons across traits and studies. We call this estimator CV P , the coefficient of variation in predictability. 5. The different methods described here and the standardized effect size CV P should open new avenues for studying individuality in animal behaviour. Since sound understanding of individual variation is central to many studies in ecology and evolution, these methods have wide application both in the field of animal personality research and beyond.