Analysing spatial and temporal variation in colony size: an approach using autoregressive mixed models and information theory

The spatial and temporal variation in population sizes of animal colonies are rarely studied simultaneously. I examined factors determining colony size (number of nests) for 23 colonies from the only breeding population of rook Corvus frugilegus in Spain over 7 years. Population sizes within colonies were highly predictable over time, with autocorrelations up to a distance (lag) of 6 years. Autoregressive mixed models were used to explain colony size as a function of environmental factors, while controlling for temporal autocorrelation. These factors included refuse tips, widely used as food resource, and a derived variable that incorporated the two factors most often related to avian colony size (inter-colony competition and foraging habitat around colonies). Autoregressive models provided a better fit to the data than models which did not consider temporal autocorrelation. The information-theoretic (AIC_c-based) approach revealed uncertainty in the selection of the best model explaining colony-size, but relatively strong support for certain variables. The highest weights of evidence were for year (ω _i  = 0.90) and the number of competitors per unit of foraging habitat (i.e., derived variable; ω _i  = 0.63), showing that the size of rook colonies in Spain was negatively affected by inter-colony competition relative to the foraging habitat surrounding the colonies. This variable measured within a 6-km radius from the colonies had ~30 times higher weight of evidence (more plausible) than the same variable measured within 3 km, indicating that food limitation may occur outside the breeding period. Sizes of colonies tended to decrease when distance between the colony and the nearest refuse tip increased. There was some evidence supporting the idea that the effect of the number of competitors per unit of foraging habitat on colony size varied from year to year, but statistical power was weak. These findings suggest that variation in number of rook nests within colonies reflects spatial and temporal heterogeneity of net food via both inter-colony competition and foraging habitat around the colony. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Habitat assessment by parasitoids: mechanisms for patch use behavior

Animals foraging for patchily distributed resources may optimizetheir foraging decisions concerning the patches they encounter,provided that they base these decisions on reliable informationabout the profitability of the habitat as a whole. Females ofthe parasitoid Lysiphlebus testaceipes exploit aphid hosts,which typically aggregate in discrete colonies. We show herehow between-colony travel time and the number of aphids in previouslyvisited colonies affect parasitoid foraging behavior. We firstassumed that parasitoids use travel time and previous colonysize to estimate a mean rate of fitness gain in the habitatand derived quantitative predictions concerning the effect ofthese two variables on patch residence time and patch-leavingrate of attack. We then tested these theoretical predictionsin laboratory experiments in which female parasitoids were allowedto visit two successive colonies. As predicted, the observedresidence time in the second colony increased with increasingtravel time and decreasing size of the first colony. Patch-leavingrate of attack decreased with increasing travel time but wasnot affected by previous colony size. These results suggestthat parasitoids use these two variables to assess habitat quality.However, discrepancies between the data obtained and quantitativepredictions show that the effect of travel time on patch usemay be more complex than assumed in our model.     

A review of the occurrence of inter‐colony segregation of seabird foraging areas and the implications for marine environmental impact assessment

Understanding the determinants of species’ distributions is a fundamental aim in ecology and a prerequisite for conservation but is particularly challenging in the marine environment. Advances in bio‐logging technology have resulted in a rapid increase in studies of seabird movement and distribution in recent years. Multi‐colony studies examining the effects of intra‐ and inter‐colony competition on distribution have found that several species exhibit inter‐colony segregation of foraging areas, rather than overlapping distributions. These findings are timely given the increasing rate of human exploitation of marine resources and the need to make robust assessments of likely impacts of proposed marine developments on biodiversity. Here we review the occurrence of foraging area segregation reported by published tracking studies in relation to the density‐dependent hinterland (DDH) model, which predicts that segregation occurs in response to inter‐colony competition, itself a function of colony size, distance from the colony and prey distribution. We found that inter‐colony foraging area segregation occurred in 79% of 39 studies. The frequency of occurrence was similar across the four seabird orders for which data were available, and included species with both smaller (10–100 km) and larger (100–1000 km) foraging ranges. Many predictions of the DDH model were confirmed, with examples of segregation in response to high levels of inter‐colony competition related to colony size and proximity, and enclosed landform restricting the extent of available habitat. Moreover, as predicted by the DDH model, inter‐colony overlap tended to occur where birds aggregated in highly productive areas, often remote from all colonies. The apparent prevalence of inter‐colony foraging segregation has important implications for assessment of impacts of marine development on protected seabird colonies. If a development area is accessible from multiple colonies, it may impact those colonies much more asymmetrically than previously supposed. Current impact assessment approaches that do not consider spatial inter‐colony segregation will therefore be subject to error. We recommend the collection of tracking data from multiple colonies and modelling of inter‐colony interactions to predict colony‐specific distributions.     

Foraging decisions of individual workers vary with colony size in the greenhead ant Rhytidoponera metallica (Formicidae, Ectatomminae)

Summary. The ability of worker ants to adapt their behaviour depending on the social environment of the colony is imperative for colony growth and survival. In this study we use the greenhead ant Rhytidoponera metallica to test for a relationship between colony size and foraging behaviour. We controlled for possible confounding ontogenetic and age effects by splitting large colonies into small and large colony fragments. Large and small colonies differed in worker number but not worker relatedness or worker/brood ratios. Differences in foraging activity were tested in the context of single foraging cycles with and without the opportunity to retrieve food. We found that workers from large colonies foraged for longer distances and spent more time outside the nest than foragers from small colonies. However, foragers from large and small colonies retrieved the first prey item they contacted, irrespective of prey size. Our results show that in R. metallica, foraging decisions made outside the nest by individual workers are related to the size of their colony.Received 23 March 2004; revised 3 June 2004; accepted 4 June 2004.     

Influence of density‐dependent competition on foraging and migratory behavior of a subtropical colonial seabird

Density‐dependent competition for food resources influences both foraging ecology and reproduction in a variety of animals. The relationship between colony size, local prey depletion, and reproductive output in colonial central‐place foragers has been extensively studied in seabirds; however, most studies have focused on effects of intraspecific competition during the breeding season, while little is known about whether density‐dependent resource depletion influences individual migratory behavior outside the breeding season. Using breeding colony size as a surrogate for intraspecific resource competition, we tested for effects of colony size on breeding home range, nestling health, and migratory patterns of a nearshore colonial seabird, the brown pelican (Pelecanus occidentalis), originating from seven breeding colonies of varying sizes in the subtropical northern Gulf of Mexico. We found evidence for density‐dependent effects on foraging behavior during the breeding season, as individual foraging areas increased linearly with the number of breeding pairs per colony. Contrary to our predictions, however, nestlings from more numerous colonies with larger foraging ranges did not experience either decreased condition or increased stress. During nonbreeding, individuals from larger colonies were more likely to migrate, and traveled longer distances, than individuals from smaller colonies, indicating that the influence of density‐dependent effects on distribution persists into the nonbreeding period. We also found significant effects of individual physical condition, particularly body size, on migratory behavior, which in combination with colony size suggesting that dominant individuals remain closer to breeding sites during winter. We conclude that density‐dependent competition may be an important driver of both the extent of foraging ranges and the degree of migration exhibited by brown pelicans. However, the effects of density‐dependent competition on breeding success and population regulation remain uncertain in this system.     

Spatial patterns, temporal variability, and the role of multi-nest colonies in a monogynous Spanish desert ant

Abstract 1. The colonies of the Spanish desert ant Cataglyphis iberica are polydomous. This study describes the temporal and spatial patterns of the polydomy in this species at two different sites, and presents analyses of its role in reducing the attacks of the queen over sexual brood, and in allowing better habitat exploitation.
2. The spatial distribution of nests was clumped while colonies were distributed randomly. Mean nearest neighbour distance ranged from 3.4 to 7.0 m for nests and from 12.3 to 14.1 m for colonies. Distance of foragers searching for food varied among nests: mean values were between 6.1 and 12.6 m.
3. At both sites, the maximum number of nests per colony occurred in summer, during the maximum activity period of the species. Colonies regrouped at the end of this period but overwintered in several nests.
4. Nest renewal in C. iberica colonies was high and showed great temporal variability: nests changed (open, close, re-open) continuously through the activity season and/or among years. The lifetime of up to 55% of nests was only 1–3 months.
5. Polydomy in C. iberica might decrease the interactions between the queen and the sexual brood. In all colonies excavated just before the mating period, the nest containing the queen did not contain any virgin female. Females were in the queenless nests of the colony.
6. The results also suggest that polydomous C. iberica colonies may enhance habitat exploitation because foraging activity per colony increases with nest number. The relationship between total prey input and foraging efficiency and number of nests per colony attains a plateau or even decreases after a certain colony size (four to six nests). This value agrees with the observed mean number of nests per colony in C. iberica .     

Foraging arena size and structural complexity affect the dynamics of food distribution in ant colonies

Food acquisition by ant colonies is a complex process that starts with acquiring food at the source (i.e., foraging) and culminates with food exchange in or around the nest (i.e., feeding). While ant foraging behavior is relatively well understood, the process of food distribution has received little attention, largely because of the lack of methodology that allows for accurate monitoring of food flow. In this study, we used the odorous house ant, Tapinoma sessile (Say) to investigate the effect of foraging arena size and structural complexity on the rate and the extent of spread of liquid carbohydrate food (sucrose solution) throughout a colony. To track the movement of food, we used protein marking and double-antibody sandwich enzyme-linked immunosorbent assay, DAS-ELISA. Variation in arena size, in conjunction with different colony sizes, allowed us to test the effect of different worker densities on food distribution. Results demonstrate that both arena size and colony size have a significant effect on the spread of the food and the number of workers receiving food decreased as arena size and colony size increased. When colony size was kept constant and arena size increased, the percentage of workers testing positive for the marker decreased, most likely because of fewer trophallactic interactions resulting from lower worker density. When arena size was kept constant and colony size increased, the percentage of workers testing positive decreased. Nonrandom (clustered) worker dispersion and a limited supply of food may have contributed to this result. Overall, results suggest that food distribution is more complete is smaller colonies regardless of the size of the foraging arena and that colony size, rather than worker density, is the primary factor affecting food distribution. The structural complexity of foraging arenas ranged from simple, two-dimensional space (empty arenas) to complex, three-dimensional space (arenas filled with mulch). The structural complexity of foraging arenas had a significant effect on food distribution and the presence of substrate significantly inhibited the spread of food. Structural complexity of foraging arenas and the resulting worker activity patterns might exert considerable influence on socioecological processes in ants and should be considered in laboratory assays.     

Habitat use by Mountain Plovers in prairie dog colonies in northeastern New Mexico

ABSTRACT Mountain Plovers (Charadrius montanus) are grassland birds that often breed in close association with colonies of black‐tailed prairie dogs (Cynomys ludovicianus). However, not all colonies provide plover nesting habitat or habitat of equal quality, and the characteristics of colonies important for plovers remain poorly understood. Over two years, I used plover distribution surveys, territory mapping, and habitat sampling to study habitat use by plovers in prairie dog colonies in shortgrass prairie in northeastern New Mexico. My objective was to document important components of plover breeding habitat in colonies by comparing characteristics of used and unused habitats at three spatial scales: colony, territory, and nest‐site. I found evidence of plover breeding in 14 of 44 colonies in 2009 and 13 of 43 colonies in 2010. Based on logistic regression, the probability of a colony being occupied by plovers was positively associated with colony size, but negatively associated with mean vegetation height. Preference for larger colonies could relate to minimum habitat requirements, or a potential tendency of this species to nest in social clusters. Shorter vegetation height was strongly correlated with greater bare ground and lower forb/subshrub cover, all characteristics that may be related to plover predator avoidance and foraging microhabitat. At both the territory and nest‐site scale, areas used by plovers had shorter vegetation, more bare ground, and less forb/subshrub cover than unused areas. Nest sites were also more sloped, perhaps to reduce risk of flooding, and located further away from the nearest prairie dog burrow, perhaps to reduce risk of disturbance. Overall, my results show that plover use of prairie dog colonies was influenced by landscape and habitat features of colonies, and suggest that large colonies are particularly valuable because they are most likely to contain adequate areas with preferred habitat characteristics.     

Does foraging efficiency vary with colony size in the fairy martin Petrochelidon ariel?

Colonial breeding occurs in a wide range of taxa, however the advantages promoting its evolution and maintenance remain poorly understood. In many avian species, breeding colonies vary by several orders of magnitude and one approach to investigating the evolution of coloniality has been to examine how potential costs and benefits vary with colony size. Several hypotheses predict that foraging efficiency may improve with colony size, through benefits associated with social foraging and information exchange. However, it is argued that competition for limited food resources will also increase with colony size, potentially reducing foraging success. Here we use a number of measures (brood feeding rates, chick condition and survival, and adult condition) to estimate foraging efficiency in the fairy martin Petrochelidon ariel, across a range of colony sizes in a single season (17 colonies, size range 28–139 pairs). Brood provisioning rates were collected from multiple colonies simultaneously using an electronic monitoring system, controlling for temporal variation in environmental conditions. Provisioning rate was correlated with nestling condition, though we found no clear relationship between provisioning rate and colony size for either male or female parents. However, chicks were generally in worse condition and broods more likely to fail or experience partial loss in larger colonies. Moreover, the average condition of adults declined with colony size. Overall, these findings suggest that foraging efficiency declines with colony size in fairy martins, supporting the increased competition hypothesis. However, other factors, such as an increased ectoparasitise load in large colonies or change in the composition of phenotypes with colony size may have also contributed to these patterns.     

Varying foraging patterns in response to competition? A multicolony approach in a generalist seabird

Reducing resource competition is a crucial requirement for colonial seabirds to ensure adequate self‐ and chick‐provisioning during breeding season. Spatial segregation is a common avoidance strategy among and within species from neighboring breeding colonies. We determined whether the foraging behaviors of incubating lesser black‐backed gulls (Larus fuscus) differed between six colonies varying in size and distance to mainland, and whether any differences could be related to the foraging habitats visited. Seventy‐nine incubating individuals from six study colonies along the German North Sea coast were equipped with GPS data loggers in multiple years. Dietary information was gained by sampling food pellets, and blood samples were taken for stable isotope analyses. Foraging patterns clearly differed among and within colonies. Foraging range increased with increasing colony size and decreased with increasing colony distance from the mainland, although the latter might be due to the inclusion of the only offshore colony. Gulls from larger colonies with consequently greater density‐dependent competition were more likely to forage at land instead of at sea. The diets of the gulls from the colonies furthest from each other differed, while the diets from the other colonies overlapped with each other. The spatial segregation and dietary similarities suggest that lesser black‐backed gulls foraged at different sites and utilized two main habitat types, although these were similar across foraging areas for all colonies except the single offshore island. The avoidance of intraspecific competition results in colony‐specific foraging patterns, potentially causing more intensive utilization of terrestrial foraging sites, which may offer more predictable and easily available foraging compared with the marine environment.     

Foraging-area size and food density: Some predictive models

It has been observed that when food increases in density along an environmental gradient, the size of foraging areas used by desert ant colonies decreases. Factors that could cause this inverse relationship are explored. Four models of ant foraging are developed and presented in the form of equations for calculating net foraging energy as a function of size of the foraging area. These are used to predict the optimal sizes of foraging areas under conditions of different food densities. Only one of the models predicts an inverse relationship between density of food and size of foraging area when food is the limiting factor in colony reproduction. In this model, the foraging areas of adjacent colonies are assumed to be overlapping and the number of foragers assigned to each square meter of the foraging area is constant, regardless of food density or distance from the nest entrance. Tests for distinguishing among the four models, as well as for determining whether colonies are or are not food limited, are discussed.     

An energetic correlate between colony size and foraging effort in seabirds, an example of the Adélie penguin Pygoscelis adeliae

Central-place foraging seabirds alter the availability of their prey around colonies, forming a "halo" of reduced prey access that ultimately constrains population size. This has been indicated indirectly by an inverse correlation between colony size and reproductive success, numbers of conspecifics at other colonies within foraging range, foraging effort (i.e. trip duration), diet quality and colony growth rate. Although ultimately mediated by density dependence relative to food through intraspecific exploitative or interference competition, the proximate mechanism involved has yet to be elucidated. Herein, we show that Adélie penguin Pygoscelis adeliae colony size positively correlates to foraging trip duration and metabolic rate, that the metabolic rate while foraging may be approaching an energetic ceiling for birds at the largest colonies, and that total energy expended increases with trip duration although uncompensated by increased mass gain. We propose that a competition-induced reduction in prey availability results in higher energy expenditure for birds foraging in the halo around large colonies, and that to escape the halo a bird must increase its foraging distance. Ultimately, the total energetic cost of a trip determines the maximum successful trip distance, as on longer trips food acquired is used more for self maintenance than for chick provisioning. When the net cost of foraging trips becomes too high, with chicks receiving insufficient food, chick survival suffers and subsequent colony growth is limited. Though the existence of energetic studies of the same species at multiple colonies is rare, because foraging metabolic rate increases with colony size in at least two other seabird species, we suggest that an energetic constraint to colony size may generally apply to other seabirds.     

The effects of colony characteristics on life span and foraging behavior of individual wasps (Polybia occidentalis,Hymenoptera: Vespidae)

Summary We studied the effects of intrinsic colony characteristics and an imposed contingency on the life span and behavior of foragers in the swarm-founding social waspPolybia occidentalis. Data were collected on marked, known-age workers introduced into four observation colonies.To test the hypothesis that colony demographic features affect worker life span, we examined the relationships of colony age and size with worker life span using survivorship analysis. Colony age and size had positive relationships with life span; marked workers from two larger, older colonies had longer life spans (¯X = 24.7 days) than those from two smaller, younger colonies (¯X = 20.1 days).We quantified the effects of experimentally imposed nest damage on forager behavior, to determine which of three predicted behavioral responses by foragers to this contingency (increased probability of foraging for building material, increased rate of foraging, or decrease in age of onset of foraging) would be employed. Increasing the colony level of need for materials used in nest construction (wood pulp and water) by damaging the nests of two colonies did not cause an increase in either the proportion of marked workers that gathered nest materials or in foraging rates of marked individuals, when compared with introduced workers in two simultaneously observed control colonies. Instead, nest damage caused a decrease in the age at which marked workers first foraged for pulp and water. The response to an increase in the need for building materials was an acceleration of behavioral development in some workers.     

Costs and benefits of colony size vary during the breeding cycle in Black-headed Gulls Chroicocephalus ridibundus

We studied the effects of colony size on individual reproductive success in a multi-site population of Black-headed Gulls Chroicocephalus ridibundus where colony size ranged from 10 to 5,000 pairs. By focusing on family size, the number of chicks attended by individually marked parents, and accounting for between-individual variation, we detected a negative colony-size effect during the very first days of life of the chicks that was compensated by a subsequent increase in the proportion of surviving chicks with colony size. We suggest that this result originates in the interplay between overcrowding costs acting on hatching success, and benefits of colonial breeding, most probably more efficient food-searching (foraging enhancement), acting on chick survival. However, the frequency of complete colony failure increased with decreasing colony size. Taking this hazard risk into account yielded a corrected estimate of the effect of colony size on breeding success, and indicated that the largest colonies were the most productive. This pattern is congruent with the previous finding that larger colonies are more attractive to dispersing breeders.     

Forager abundance and its relationship with colony activity level in three species of South American Pogonomyrmex harvester ants

The proportion of foragers in ant colonies is a fairly constant species-specific characteristic that could be determined by intrinsic or extrinsic factors. If intrinsic factors are relevant, species with similar life history characteristics (e.g., colony size and foraging strategies) would be expected to have a similar proportion of foragers in their colonies. Within the genus Pogonomyrmex, North American species can vary largely in their colony size, whereas only species with small colonies are known in South America. We studied the characteristics of the foraging subcaste in three sympatric South American species of Pogonomyrmex harvester ants, and compared it with the available information on other species of the same genus. We used two mark-recapture methods and colony excavations to estimate the number and proportion of foragers in the colonies of P. mendozanus, P. inermis, and P. rastratus, and to test the relationship between forager external activity levels and abundance per colony. Forager abundance in the three studied species was lower than in most North American species. The percentage of foragers in their colonies ranged 7–15 %, more similar to North American species with large colonies than to those with small colony size. Foraging activity was positively correlated with forager abundance in all three species, implying that colony allocation to number of foragers allows for higher food acquisition. Further comparative studies involving a wider range of traits in South and North American species would allow to unveil the role of environmental factors in shaping each species’ particular traits.     

Quantifying the effect of colony size and food distribution on harvester ant foraging

Desert seed-harvester ants, genus Pogonomyrmex, are central place foragers that search for resources collectively. We quantify how seed harvesters exploit the spatial distribution of seeds to improve their rate of seed collection. We find that foraging rates are significantly influenced by the clumpiness of experimental seed baits. Colonies collected seeds from larger piles faster than randomly distributed seeds. We developed a method to compare foraging rates on clumped versus random seeds across three Pogonomyrmex species that differ substantially in forager population size. The increase in foraging rate when food was clumped in larger piles was indistinguishable across the three species, suggesting that species with larger colonies are no better than species with smaller colonies at collecting clumped seeds. These findings contradict the theoretical expectation that larger groups are more efficient at exploiting clumped resources, thus contributing to our understanding of the importance of the spatial distribution of food sources and colony size for communication and organization in social insects.     

Invasive alien plants affect grassland ant communities, colony size and foraging behaviour

Ants are dominant members of many terrestrial ecosystems and are regarded as indicators of environmental changes. However, little is known about the effects of invasive alien plants on ant populations, particularly as regards the density, spatial distribution and size of ant colonies, as well as their foraging behaviour. We addressed these questions in a study of grassland ant communities on five grasslands invaded by alien goldenrods (Solidago sp.) and on five non-invaded grasslands without this plant. In each grassland, seven 100 m² plots were selected and the ant colonies counted. Ant species richness and colony density was lower in the plots on the invaded grasslands. Moreover, both of these traits were higher in the plots near the grassland edge and with a higher number of plant species in the grasslands invaded by goldenrods but not in the non-invaded ones. On average, ant colony size was lower on the invaded grasslands than the non-invaded ones. Also, ant workers travelled for longer distances to collect food items in the invaded areas than they did in the non-invaded ones, even after the experimental removal of some ant colonies in order to exclude the effect of higher colony density in the latter. Our results indicate that invasive alien goldenrods have a profound negative effect on grassland ant communities which may lead to a cascade effect on the whole grassland ecosystem through modification of the interactions among species. The invasion diminishes a major index of the fitness of ants, which is a colony’s size, and probably leads to increased foraging effort of workers. This, in turn, may have important consequences for the division of labour and reproductive strategies within ant colonies.     

Fine‐scale foraging habitat selection by two diving central place foragers in the Northeast Atlantic

Habitat selection and spatial usage are important components of animal behavior influencing fitness and population dynamic. Understanding the animal–habitat relationship is crucial in ecology, particularly in developing strategies for wildlife management and conservation. As this relationship is governed by environmental features and intra‐ and interspecific interactions, habitat selection of a population may vary locally between its core and edges. This is particularly true for central place foragers such as gray and harbor seals, where, in the Northeast Atlantic, the availability of habitat and prey around colonies vary at local scale. Here, we study how foraging habitat selection may vary locally under the influence of physical habitat features. Using GPS/GSM tags deployed at different gray and harbor seals’ colonies, we investigated spatial patterns and foraging habitat selection by comparing trip characteristics and home‐range similarities and fitting GAMMs to seal foraging locations and environmental data. To highlight the importance of modeling habitat selection at local scale, we fitted individual models to colonies as well as a global model. The global model suffered from issues of homogenization, while colony models showed that foraging habitat selection differed markedly between regions for both species. Despite being capable of undertaking far‐ranging trips, both gray and harbor seals selected their foraging habitat depending on local availability, mainly based on distance from the last haul‐out and bathymetry. Distance from shore and tidal current also influenced habitat preferences. Results suggest that local conditions have a strong influence on population spatial ecology, highlighting the relevance of processes occurring at fine geographical scale consistent with management within regional units.     

Colony size does not predict foraging distance in the ant Temnothorax rugatulus: a puzzle for standard scaling models

Body size is often positively correlated with ecologically relevant traits such as fecundity, survival, resource requirements, and home range size. Ant colonies, in some respects, behave like organisms, and their colony size is thought to be a significant predictor of many behavioral and ecological traits similar to body size in unitary organisms. In this study, we test the relationship between colony size and field foraging distance in the ant species Temnothorax rugatulus. These ants forage in the leaf litter presumably for small arthropod prey. We found colonies did not differ significantly in their foraging distances, and colony size is not a significant predictor of foraging distance. This suggests that large colonies may not exhaust local resources or that foraging trips are not optimized for minimal distance, and thus that food may not be the limiting resource in this species. This study shows T. rugatulus are behaving in ways that differ from existing models of scaling.     

Taking a trip to the shelf: Behavioral decisions are mediated by the proximity to foraging habitats in the black‐legged kittiwake

For marine top predators like seabirds, the oceans represent a multitude of habitats regarding oceanographic conditions and food availability. Worldwide, these marine habitats are being altered by changes in climate and increased anthropogenic impact. This is causing a growing concern on how seabird populations might adapt to these changes. Understanding how seabird populations respond to fluctuating environmental conditions and to what extent behavioral flexibility can buffer variations in food availability can help predict how seabirds may cope with changes in the marine environment. Such knowledge is important to implement proper long‐term conservation measures intended to protect marine predators. We explored behavioral flexibility in choice of foraging habitat of chick‐rearing black‐legged kittiwakes Rissa tridactyla during multiple years. By comparing foraging behavior of individuals from two colonies with large differences in oceanographic conditions and distances to predictable feeding areas at the Norwegian shelf break, we investigated how foraging decisions are related to intrinsic and extrinsic factors. We found that proximity to the shelf break determined which factors drove the decision to forage there. At the colony near the shelf break, time of departure from the colony and wind speed were most important in driving the choice of habitat. At the colony farther from the shelf break, the decision to forage there was driven by adult body condition. Birds furthermore adjusted foraging behavior metrics according to time of the day, weather conditions, body condition, and the age of the chicks. The study shows that kittiwakes have high degree of flexibility in their behavioral response to a variable marine environment, which might help them buffer changes in prey distribution around the colonies. The flexibility is, however, dependent on the availability of foraging habitats near the colony.